Contam 3.1
Contam 3.1
Contam 3.1
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William Stuart Dols
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SEE PROFILE
NISTIR 7251
CONTAM User Guide and Program
Documentation
George N. Walton
W. Stuart Dols
NISTIR 7251
CONTAM User Guide and Program
Documentation
George N. Walton
W. Stuart Dols
iii
ABSTRACT
This manual describes the computer program CONTAM version 2.4 developed by NIST.
CONTAM is a multizone indoor air quality and ventilation analysis program designed to help
you determine: airflows and pressures infiltration, exfiltration, and room-to-room airflows and
pressure differences in building systems driven by mechanical means, wind pressures acting on
the exterior of the building, and buoyancy effects induced by temperature differences between
the building and the outside; contaminant concentrations the dispersal of airborne
contaminants transported by these airflows and transformed by a variety of processes including
chemical and radio-chemical transformation, adsorption and desorption to building materials,
filtration, and deposition to building surfaces; and/or personal exposure the prediction of
exposure of building occupants to airborne contaminants for eventual risk assessment.
CONTAM can be useful in a variety of applications. Its ability to calculate building airflows and
relative pressures between zones of the building is useful for assessing the adequacy of
ventilation rates in a building, for determining the variation in ventilation rates over time, for
determining the distribution of ventilation air within a building, and for estimating the impact of
envelope air-tightening efforts on infiltration rates. The program has also been used extensively
for the design and analysis of smoke management systems. The prediction of contaminant
concentrations can be used to determine the indoor air quality performance of buildings before
they are constructed and occupied, to investigate the impacts of various design decisions related
to ventilation system design and building material selection, to evaluate indoor air quality control
technologies, and to assess the indoor air quality performance of existing buildings. Predicted
contaminant concentrations can also be used to estimate personal exposure based on occupancy
patterns.
Version 2.0 contained several new features including: non-trace contaminants, unlimited number
of contaminants, contaminant-related libraries, separate weather and ambient contaminant files,
building controls, scheduled zone temperatures, improved solver to reduce simulation times and
several user interface related features to improve usability. Version 2.1 introduced more new
features including the ability to account for spatially varying external contaminants and wind
pressures at the building envelope, more new control elements, particle-specific contaminant
properties, total mass released calculations and detailed program documentation. Version 2.4
introduced two new deposition sink models, a one-dimensional convection/diffusion contaminant
model for ducts and user-selectable zones, new contaminant filter models, control super nodes,
super filters and super airflow elements, a duct balancing tool, building pressurization and model
validity tests and several other usability enhancements.
Key Words: airflow analysis; building controls; building technology; computer program;
contaminant dispersal; controls; indoor air quality; multizone analysis; smoke control; smoke
management; ventilation
iii
DISCLAIMER
This software was developed at the National Institute of Standards and Technology by
employees of the Federal Government in the course of their official duties. Pursuant to title 17
Section 105 of the United States Code this software is not subject to copyright protection and is
in the public domain. CONTAM is an experimental system. NIST assumes no responsibility
whatsoever for its use by other parties, and makes no guarantees, expressed or implied, about its
quality, reliability, or any other characteristic. We would appreciate acknowledgement if the
software is used. This software can be redistributed and/or modified freely provided that any
derivative works bear some notice that they are derived from it, and any modified versions bear
some notice that they have been modified.
Users are warned that CONTAM is intended for use only by persons competent in the field of
airflow and contaminant dispersal in buildings and is intended only to supplement the judgement
of the qualified user. The computer program described in this report is a prototype methodology
for computing the airflows and contaminant migration in a building. The calculations are based
upon a simplified model of the complexity of real buildings. These simplifications must be
understood and considered by the user.
Certain trade names and company products are mentioned in the text or identified in an
illustration in order to adequately specify the equipment used. In no case does such an
identification imply recommendation or endorsement by the National Institute of Standards and
Technology, nor does it imply that the products are necessarily the best available for the purpose.
iv
ACKNOWLEDGEMENTS
Much of the work that went into developing this version of CONTAM was sponsored by the
Naval Surface Warfare Center Dahlgren Division under Military Interdepartmental Purchase
Request # N00178-05-MP-00139. The authors appreciate the interest and input of Kathrina
Urann, Matthew Wolski and the entire IBTK team throughout this project.
The authors would like to acknowledge the programming skills of Brian Polidoro for his work on
the CONTAM user interface, SimReadW and ContamRV, as well as his efforts in developing
and maintaining the NIST IAQAnalysis Website. We would further like to acknowledge the
testing of the beta versions of the software by the following people: NIST student interns Ryan
Berke, Jacob Weber, Ivette Morazzani, and David Heinzerling; Steven Strege and Terry Fay of
Hughes Associates Inc.; James Odasso and Kevin Good of Battelle Columbus; and Dr. Fred
Loquasto III of Toyon Research Corporation. We also appreciate the continued collaboration
with John Goforth and Mike Mercer of Lawrence Livermore National Laboratory in developing
the socket communication capabilities of CONTAM.
vi
TABLE OF CONTENTS
Abstract ............................................................................................................................. iii
Disclaimer ......................................................................................................................... iv
Acknowledgements ............................................................................................................v
Document Revision History ............................................................................................ vi
Introduction ........................................................................................................................1
Getting Started .................................................................................................................10
Using CONTAM...............................................................................................................19
Working with the SketchPad ..........................................................................................19
Working with Project Files .............................................................................................31
Configuring ContamW ...................................................................................................33
Working with Walls .......................................................................................................36
Working with Levels ......................................................................................................38
Working with Zones .......................................................................................................40
Working with Airflow Paths ..........................................................................................45
Working with Simple Air-handling Systems .................................................................64
Working with Ducts .......................................................................................................70
Working with Controls ...................................................................................................86
Working with Species and Contaminants.....................................................................105
Working with Sources and Sinks..................................................................................111
Working with Kinetic Reactions ..................................................................................125
Working with Occupant Exposure ...............................................................................129
Working with Data and Libraries .................................................................................132
Working with Weather and Wind.................................................................................137
Working with WPC Files .............................................................................................145
Working with Schedules...............................................................................................153
Working with Simulations ............................................................................................157
Working with Results ...................................................................................................173
Working with Project Annotations ...............................................................................203
Special Applications of CONTAM ...............................................................................204
Working with TRNSYS .................................................................................................207
Getting Help ...................................................................................................................220
Theoretical Background ................................................................................................221
Model Assumptions ......................................................................................................221
Contaminant Analysis ..................................................................................................223
Airflow Analysis ..........................................................................................................232
References .......................................................................................................................248
Appendix A - PRJ File Format .....................................................................................251
Appendix B - ContamX TCP/IP Socket Communication ..........................................286
Program Execution .......................................................................................................287
ContamX TCP/IP Message Formats ............................................................................288
vii
INTRODUCTION
CONTAM is a multizone indoor air quality and ventilation analysis computer program designed
to help you determine:
PROGRAM MODIFICATIONS
Program Enhancements
CONTAM 3.1 is the latest version in the line of CONTAM programs. The history of major
enhancements is provided below. The latest version of CONTAM is backwards compatible with
previous versions, meaning you can open existing project files created with previous versions.
Once updated to the latest version of the program, project files can not be saved as or opened
with previous versions. Therefore, you should maintain older copies of your existing project
files.
Throughout this manual you will find new features (latest revision) of the program highlighted as
illustrated by this paragraph.
Version 3.1
TRNSYS-CONTAM Multizone Airflow, Heat Transfer and Contaminant Analysis - This
capability includes modifications to ContamW and ContamX and the creation of a new TRNSYS
Type and the software utilities to provide a new coupling process that enables ContamX to be
more directly coupled with TRNSYS Type56.
ContamW Pseudo-geometry - Provide ability to define scaling factor for drawing on the
ContamW SketchPad and view wall dimensions on the SketchPad. This feature is an aid to
utilities provided for the TRNSYS-CONTAM coupling that create three-dimensional
representations for TRNSYS Type56 multizone heat transfer calculation.
ContamW Temperature Plots - Provide ability plot temperatures in ContamW.
ContamX - Added socket communication messages that provide for the transfer of
temperatures and airflow to/from ContamX.
Type98 - Acts as a bridge between ContamX and Type56 for TRNSYS simulations.
Utilities - Created software utilities CONTAM3DExport.exe to extrude scaled CONTAM prj
representations to form Trnsys3d idf files and Type56-98Coupler.exe to form the linkage
between Type56 and Type98.
CVODE - Implemented a variable time step solver for transient contaminant transport
calculations. CVODE, is a general-purpose code for solving ordinary differential equations, that
provides for variable time steps, high-order integration methods, and automatic error control.
Usability Enhancements
Particle Plots - Provide ability plot particle distributions when simulating multiple size
ranges with ContamW.
Result Mode Toolbar - Provide toolbar buttons to manipulate result time step display.
Simulation Time Step Analysis - Provide ability for user to check schedules and input files
(wth, ctm, dvf, cvf) for maximum time step required to capture all scheduled events.
Program/Project Configuration - Modified ContamW configuration to separate out Programrelated options from Project-related options.
Result File Output - Provide user with control over output of simulation result files .csm,
.log, and .srf.
Resolved Program Issues
Restart File - Restart (rst) file did not properly account for Deposition/Resuspension
source/sinks. Also, modified restart file behavior to only write restart data at the end of each
day (24:00:00) and/or at the end of the last day if shorter than 24 hours. User is no longer
require to select the time to use when utilizing the restart file, only the date.
PLD File and Duct Terminals - Duct terminals were not being output to the Path Location
Data (pld) file.
Results Display Window and Duct Leakage - The results display window was not providing
duct leakage airflow results for zones having junctions in them with associated duct leakage.
Version 3.0a
Self-Regulating Vent - A new airflow element has been added to CONTAM. The self-regulating
vent limits the airflow rate in both directions through a flow path with user-defined limiting air
pressure differences. CONTAM implements the self-regulating vent as described by Axley 2001
Residential Passive Ventilation Systems: Evaluation and Design.
Surface Node Results File - Added new results file (.srf) for Boundary Layer and
Deposition/Resuspension source/sink elements.
New Zone Color Option - Now when revealing the level below there is an option to see the zone
colors of the zones on the level below.
Resolved Program Issues
ContamW
Fix - crash could occur when deleting a level.
Fix - enable transient simulation times that span the Dec/Jan transition, i.e., allow simulations
to start before December and end after January.
Fix - when replacing a wind pressure profile with the Find & Replace dialog the wall azimuth
and wind speed modifier should be set to the defaults.
Fix - allow plotting of results for a simulation that span the Dec/Jan transition.
Fix - crash occurred when deleting zones having occupancy schedules that referenced them.
Fix - incorrect painting of the toolbar for some Windows themes.
Fix - cubic spline airflow element curves were not plotted correctly if their curves were
invalid.
Modification - consolidated variable density airflow calculation parameters.
ContamX
Fix - Matrix reordering issue when very large project files encountered fatal errors when
matrix reordering was attempted due to size of index parameter.
Fix - Prevent intermittent program crash when running under Windows 7 64 bit OS.
Fix - Contaminant summary file (.csm) issues: values when working with non-trace boundary
layer diffusion and deposition/resuspension source sinks were likely too high due to
summation of the source contributions over multiple iterations of the variable density
iterations within each time step; combinations of non-trace and trace contaminants could
result in trace contaminant-related summations not being accounted for. However, these issue
did not affect sim file results.
Fix - Issue related to non-trace contaminant calculations involving Boundary Layer Diffusion
and Deposition/Resuspension sources whereby the contribution of mass added to the zone in
which these source/sinks were located was incorrectly calculated.
Fix - Issues related to Deposition with Resuspension source/sink element when performing
variable density calculations.
Fix - Power Law source/sink model was not utilizing the correct source/sink element
function.
Fix - Enable DVF files to handle Dec/Jan transition.
Fix - Issues related to Decaying (exponential decay) source elements: generation rate was not
reset when scheduling the source on/off, and the generation rate was being compounded
when multiple Decaying sources were being used.
Modification - Improved variable density calculations.
Version 3.0
Coupled Multizone/CFD - Implemented the ability to simulate an internal zone using
computational fluid dynamics (CFD). Details of this capability are provided via the NIST
Multizone Modeling website.
Deposition/Resuspension Source/Sink Element - Added a new source/sink element that accounts
for both deposition and resuspension of particle contaminants to/from a surface.
Windows 7 64-bit - ContamX crashed intermittently due to data copy error.
Usability Enhancements
Editing Context Menu - Right mouse button to provide cut, copy and paste functions.
Version 2.4c
New control types - Added new mathematical functions: exp, ln, log10, etc.
TCP/IP socket simulation control - Enabled multi-day simulation control.
Operating System Compatibility
CONTAM Fonts - ContamW SketchPad now utilizes internal bitmap patterns instead of font
files.
HTML Help - The ContamW help system has been converted to HTML help for
compatibility with the Windows Vista operating system.
CONTAM Log Files - The contamx2.log and contamw2.log files are now stored in the users
application directory (home directory for Linux version of ContamX).
Usability Enhancements
ContamX Non-Convergence Information - If the ContamX airflow calculation fails to
converge, a list of airflow nodes that failed to converge will be provided in the contamx2.log
file.
Error List - ContamW generates a list of problem icons that is displayed in the newly
implemented Building Check Problems dialog box when a PRJ file does not pass the building
check performed prior to a simulation. This includes airflow paths that do not have valid
location data when working with WPC files.
Create WPC File Dialog - The WPC dialog box has been modified to enable "manual"
generation of PLD files to aid in the creation of WPC files, and the Weather page of the
Simulation Parameters property sheet has been modified accordingly.
Recent file list - Added list of recently opened project files to the File menu.
Open Project Input/Output Files - Provided the ability to open CONTAM-related input and
output files from the File menu. Files are opened based on file extension associations of
Windows.
Result Plotting - Right click on SketchPad icons when viewing results to activate result
plotting.
SketchPad Navigator - Display a small icon SketchPad window to simplify navigation of the
main SketchPad with larger icons: from main menu select View - SketchPad Navigator.
Duct Results Display - duct velocity calculated based on upstream air density.
CSM File Format - modified CSM file format to provide more detail related to source/sinks.
Resolved Program Issues
Cubic Spline Elements - Enabled the use of cubic spline elements in duct segments.
CSM File - WPC file contaminants filtered by envelope flow paths were not being accounted
for in the Contaminant Summary File.
DVF and WTH File - WTH file records were being skipped when using both a DVF and a
WTH file.
Duct Balancing - After duct balance is performed the flow rates of "mass flow type" fans
could be incorrectly set as though they were volume flow types.
Flow Limits - Flow limits of airflow paths were set back to none upon file read.
CVF/DVF Node Selection - Node drop down list was improperly sorted causing potential for
setting of incorrect nodes.
Version 2.4b
Building Controls
Occupancy Sensor - Added zone occupancy sensor type.
Gage Pressure Sensor - Added gage pressure sensors for zones, duct junctions and terminals.
Source/Sink Elements
NRCC Sources - Added powerlaw and peak contaminant source types based on NRCC
material emission database.
Super Source/Sinks - Implemented ability to combine multiple source/sink elements into a
single super source/sink element.
Usability Enhancements
Enhanced deletion capabilities - Provided ability to delete multiple items from the SketchPad
with a single deletion operation.
Results display - Improved control over selection of simulation time for results display.
Wind pressure display - Provided ability to review transient wind pressures resulting from
wind data provided by WPC files.
SketchPad dragging - Hold down the mouse wheel to drag the SketchPad when scroll bars
are visible.
Library Manager - Use the Ctrl and Shift keys to select multiple items from the element lists
and perform copy and delete opperations on them.
Version 2.4a
Number of building components - The limit on the total number of each type of building
component (i.e., zones, paths, ducts, sources/sinks, etc.) that can be created within a single
project has been increased from 32 767 to 2 147 483 647.
Short time-step method - A new simulation mode that solves contaminant dispersal equations
using an explicit solution method.
1D Zones - The ability to simulate selected zones as one-dimensional convection/diffusion
zones has been implemented. This provides the ability to more realistically simulate the
transport of contaminants through "long" or "tall" zones, e.g., hallways and shafts, better
accounting for transport times through these 1D zones.
1D duct model - Implementation of one-dimensional convection/diffusion elements in
ductwork, thus providing more realistic contaminant transport results through the duct
system. This requires the use of the short time-step method.
Duct temperature calculations - When simulating 1D ducts in the short time-step mode,
CONTAM can now calculate duct temperatures based on the "mixing" of air streams at the
duct junctions and the source (zone) air temperatures from which air is introduced into the
duct system.
Simulation results data - Modified the zone and junction pressures as reported to the simulation
results file to more closely resemble gage pressures. Zone pressures are now referenced to the
ambient pressure at the level on which the zone is located. Junction static pressure is now
referenced to the zone in which the junction is located at the height of the junction within the
zone.
Automated duct balancing - Added simulation option to automatically balance duct systems.
This will greatly simplify the task of defining detailed duct systems in CONTAM.
Building model verification tests
Building pressurization test - Simulation option to automatically determine building envelope
airtightness based on a simulated fan pressurization test.
Building airflow test - Simulation option that generates a set of data, mostly related to
building ventilation, that can be used to gauge the reasonableness of model inputs before
beginning analysis of a building.
Cubic spline airflow elements
Contaminant Filters
New filter models - CONTAM has added particle and gaseous filter models that greatly
increases the user-s flexibility to create models based on measured filter performance data,
e.g., MERV and breakthrough curves.
Filter super elements - enables multiple filter models to be combined into a single filter
element, e.g., a particle pre-filter combined with a gaseous filter.
Contaminant summary file - This file is generated when simulating contaminants to provide
information related to source/sink contaminant generation and removal, filter loading and
breakthrough, and contaminant transport between building zones and ambient.
Deposition sink models - Added Deposition Velocity and Deposition Rate sink models to
simplify the definition of sinks based on more familiar deposition terminology.
Control super elements - The task of creating building control systems has been improved by
reducing the amount of user input required, increasing the amount of flexibility in defining
control systems and enabling the sharing of control elements, e.g., sensors, within and between
projects.
TCP/IP socket simulation control - ContamX can be controlled via the TCP/IP Socket
communication protocol based on a pre-defined set of messages that include control commands
and data exchange. ContamX can also be compiled and run under Linux based operating
systems, and a Linux-compatible executable is now available on the NIST web site.
Usability enhancements
Find - search for items on SketchPad by Name and Number
Find-and-replace - search for and replace properties of building components within a project
SketchPad movement
Ctrl + arrow key => skip 10 cells in direction of arrow
Shift + arrow key => move to next icon in the direction of arrow
Mouse wheel for scrolling:
Wheel => up/down Shift+Wheel => page up/down
Alt+Wheel => left/right Shift+Alt+Wheel => page left/right
Keyboard icon placement - use keyboard to place icons on the SketchPad
Floating status bar
User-defined zone colors
User-defined duct colors and automated duct tracing/coloring tool
Generate bitmap file (.bmp) of SketchPad
Enhancements from version 2.0 to 2.1
Wind pressure and contaminant fields - The ability to incorporate data from exterior airflow and
pollutant transport models, e.g., plume and puff dispersion models, to utilize detailed ambient
wind pressure and contaminant data fields to provide boundary conditions on the airflow paths of
the envelope of built structures
Control elements - New control elements to simulate time delays associated with spin-up/down
of fans and the opening/closing of dampers and to perform integration, peak determination of
sensor output over time, maximum, minimum and exponential operations
Particle analysis - Modified contaminant properties to simplify the analysis of airborne particles
Mass release calculation - The calculation of total mass released by contaminant sources during
a simulation
Program Documentation - Programming documentation of the software was produced which can
be obtained from the NIST website. This documentation includes details of CONTAM input and
output file formats [Walton and Dols 2003].
Enhancements from version 1.0 to 2.0
Building controls - Controls include sensors, actuators, modifiers and links. Control actuators
can be used to modify various characteristics of building components based on control signals
obtained from sensors and even modified by signal modifiers. For example, a sensor can be used
to obtain a contaminant concentration within a zone, and a proportional control actuator can be
used to adjust supply airflow into the zone based on the sensed concentration.
Scheduled zone temperatures - Zone temperatures can now be varied through the use of userdefined schedules. This allows for the change in zone pressures due simply to the change in
temperature within the zone according to the ideal gas relationship.
Contaminants
Non-trace contaminants - You can now account for the impact of contaminant concentrations
on the density of the air, e.g., water vapor.
Unlimited number of contaminants - CONTAM no longer restricts the number of
contaminants you can simulate. The previous limitation was 10.
Contaminant-related libraries - Contaminant related elements can now be shared through
CONTAM library files. These elements include contaminant species, filters, source/sinks and
kinetic reactions.
Numerics
Variable air density - CONTAM now provides the ability to simulate non-flow related
processes that can lead to the accumulation/reduction of mass within building zones, e.g., due
to non-trace contaminant sources and to variations in the zone pressure due to the change in
zone temperature.
Sparse matrix techniques implemented to greatly reduce transient simulation times for large
problems.
Separated solver from graphical user interface to provide for batch execution of simulations
and directly utilize .PRJ files.
Transient weather
Separate transient weather and contaminant files - Weather files (.WTH) no longer contain
contaminant concentrations (except for outdoor humidity ratio). This means you don-t have
to create different weather files depending on the types of contaminants you are simulating.
CONTAM now provides you with the option of simulating transient ambient contaminant
concentrations using a contaminant file (.CTM).
Weather file creation/conversion software - NIST has developed a software tool that allows
you to convert existing weather files to CONTAM 2.0 compatible weather files. You can
convert your existing 1.0-compatible files, TMY2 and EnergyPlus weather files.
User interface
Longer zone names - Zone names can now be up to 15 characters long.
SketchPad zooming feature - You can now reduce the icon size of the SketchPad to allow the
display of larger projects on the screen.
Results Display
Net inter-zone airflows displayed for highlighted zones in Results Display Window
Airflow direction indicators are now displayed in the Status Bar when viewing
airflow path results
Distinct simple air-handling system zones - The implicit zones of multiple simple
air-handling system are now distinguished from each other to allow for the plotting
of individual system zones
SYSTEM REQUIREMENTS
CONTAM runs under Windows XP, Vista, 7 and 8.
GETTING STARTED
INSTALLING CONTAM
Obtaining CONTAM
CONTAM installs from a set of installation files that you can obtain from NIST. These files can
be downloaded from the NIST website (www.bfrl.nist.gov/IAQanalysis).
Installing CONTAM
After downloading CONTAM from the NIST website, double-click the Microsoft installer file
(.MSI) to begin the installation process. Choose a folder into which you want to install the
program, or simply select the default location which is "C:\Program Files\NIST\CONTAM XX"
(where XX refers to the version number).Follow the directions to complete the installation. This
installation will not remove or overwrite previous versions of CONTAM.
Files Installed
The following table lists the files installed by the setup program. For each file, the directory to
which it is installed, the name and a brief description are given. The <program> directory is
selected when you install the program.
Directory
File Name
contamw3.exe
contamx3.exe
<program>
contam.cfg
cwhelp30.chm
olch2d32.dll
*.prj, *.wth and *.ctm
<program>\samples
*.lb?
Description
ContamW - User interface
ContamX - Solver
Configuration file
Help file
Charting dynamic link library
Sample project files
CONTAM library files
Uninstalling CONTAM
The CONTAM setup program also provides you with an uninstall feature. You uninstall
CONTAM much as you would a typical Windows program. Access the Control Panel from the
Settings selection of the Start menu. Select Add/Remove Programs from the Control Panel.
Select CONTAM XX from the list of installed programs and click the "Add/Remove" button to
uninstall CONTAM.
10
RUNNING CONTAM
As indicated in the Installing CONTAM section, CONTAM actually consists of two executable
programs: ContamW and ContamX. ContamW is the graphical user interface and ContamX is
the simulation engine. Typically you will activate ContamX via a menu command from within
ContamW. However, ContamX can be utilized as a command-line tool and even utilized within
script or batch files.
Runnning ContamW
Run ContamW by selecting CONTAM XX (where XX is the version number, e.g., 3.0) from the
NIST program group of the Start menu.
Runnning ContamX as a Command-line Program
The easiest way to run ContamX as a command-line program is by locating the contamx2.exe
file and related projects and supporting files within a common directory. The command-line
format for running ContamX is as follows:
CONTAMX3 <project filename>
If you leave off the project file name, you will be prompted to enter one, therefore when running
in batch mode be sure to provide a filename.
Running ContamX with TCP/IP Socket Communication
ContamX can be run in a TCP/IP socket communication mode that enables more precise control
over the simulation including execution control and data transfer via TCP/IP sockets. This mode
of execution can be implemented under either Windows or Linux and was originally developed
to enable interoperability between ACATS (Analytical Conflict and Tactical Simulation)
software developed by Lawrence Livermore National Laboratory and ContamX. See Appendix B
for details and a complete description of the TCP/IP messaging structure.
11
USER TASKS
The use of CONTAM to analyze airflow or contaminant migration in a building involves five
distinct tasks:
1. Building Idealization: Form an idealization or specific model of the building being
considered,
2. Schematic Representation: Develop a schematic representation of the idealized building
using the ContamW SketchPad to draw the building components,
3. Define Building Components: Collect and input data associated with each of the building
components represented on the SketchPad,
4. Simulation: Select the type of analysis you wish to conduct, set simulation parameters, and
execute the simulation,
5. Review & Record Results: Review the results of your simulation and record selected
portions of the results.
Task 1 - Building Idealization
Building idealization refers to the simplification of a building into a set of zones that are relevant
to the user's goal in performing an analysis. A building can be idealized in a number of ways
depending on the building layout, the ventilation system configuration and the problem of
interest. This idealization phase of analysis requires some engineering knowledge on the part of
the user and is an acquired skill that you can develop through experience in airflow and indoor
air quality analysis and by becoming familiar with the theoretical principles and details upon
which indoor air quality analysis is based.
It is important to note that CONTAM provides a macroscopic model of a building. In this
macroscopic view, each zone is considered to be well-mixed. Well-mixed means that a zone is
characterized by a discrete set of state variables, i.e., temperature, pressure and contaminant
concentrations. Temperature and contaminant concentration do not vary spatially within a zone,
and contaminants mix instantly throughout well-mixed zones. However, pressure does vary
hydrostatically within all zones.
Beginning with CONTAM version 2.4, one-dimensional convection/diffusion zones can be
implemented within CONTAM. This feature can be useful in simulating contaminant transport
through long or tall zones that are characterized by a single, dominant flow direction. One
dimensional convection/diffusion duct models can also be implemented to more realistically
capture contaminant transport within entire duct systems.
CONTAM is well suited for analyzing the interaction between the zones of a building on a
macroscopic level but is not well suited for the analysis of the microscopic airflow and
contaminant characteristics within a given zone of a building. Computational Fluid Dynamics
(CFD) analysis is better suited for analyzing the airflow and contaminant transport characteristics
of a given zone of a building. However, the computational resources required to perform a CFD
analysis for an entire building is currently prohibitive. The one-dimensional convection/diffusion
model provides an intermediate level of detail between the well-mixed and CFD models.
Task 2 - SketchPad Representation
Developing the SketchPad representation will be the focus of your interaction with ContamW.
With ContamW's SketchPad you will be able to draw a diagram a SketchPad diagram of
your building idealization using drawing tools and libraries of icons to represent components of
12
the building system. CONTAM translates your diagram into a system of equations that will than
be used to model the behavior of the building when you perform a simulation.
See Working with the SketchPad in the Using CONTAMW section.
Task 3 Data Entry
Data entry can be one of the more time-consuming parts of the process of using ContamW. It
involves the determination and input of the numerical values of the parameters associated with
each of the SketchPad icons. These icons represent the elements of the building model and
include air leakage paths (windows, doors, cracks), ventilation system elements (fans, ducts,
vents), contaminant sources, filters, and sinks and control network components. Each of these
elements is associated with a number of parameters, and you must obtain the values of these
parameters for entry into the model. Depending on the element and the application, these values
can be obtained from building-specific data, engineering handbooks, and product literature. In
many cases, a degree of engineering judgement will be involved. ContamW allows you to create
libraries of these elements that you can use in current and future modeling efforts.
Detailed information is provided for the various components throughout the Using CONTAMW
section.
Task 4 Simulation
Simulation is the use of CONTAM to solve the system of equations assembled from your
SketchPad representation of a building to predict the airflow and contaminant concentrations of
interest. This step involves determining the type of analysis that is needed; steady state, transient
or cyclical, and a number of other simulation parameters. These parameters depend on the type
of analysis you wish to perform (steady state or transient), and include convergence criteria and
in the case of a transient analysis, time steps and the duration of the analysis.
See Working with Simulations in the Using CONTAMW section.
Task 5 Review & Record Results
ContamW allows you to view the simulation results on the screen and to output them to a file for
input to a spreadsheet program or other data analysis programs including those developed by
NIST and available on the CONTAM website (e.g., SimRead2 and ContamRV). Airflows and
pressure differences at each flow element can be viewed directly on the SketchPad. Contaminant
concentrations for a zone can also be plotted as a function of time directly from the SketchPad.
You can then decide which data you wish to examine more closely and export these to a tabdelimited text file that can then be imported into a spreadsheet for further analysis. There is also
a controls-related feature that provide the ability to report the values of user-selected control
nodes to a control "log" file for each time step of a transient simulation.
See Working with Results in the Using CONTAMW section.
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Title Bar
The title bar is the typical rectangular region at the top of the main ContamW window. The
CONTAM project filename will be displayed within this region.
Menu
The menu is typical of a Windows program with differences that provide functionality specific to
the CONTAM application. It is through this menu that most ContamW operations can be
performed including: saving and retrieving project files, selecting various modes of display,
setting up and performing simulations, as well as accessing the on-line help system. Note that
some of the menu items have shortcuts or hot-keys that enable quick access; for example, to save
the current project file use the Ctrl+S key combination.
Toolbar
The toolbar, shown in the following figure, appears below the menu and provides convenient
shortcuts to some of the menu items. Several of the toolbar buttons are similar to those found in
other Windows applications. Other buttons provide a shortcut to functionality specific to
ContamW.
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Status Bar
The status bar, shown in the following figures, is the region displayed below the SketchPad at the
bottom of the main window. This region is broken up into three separate panes that display
various information depending on the current mode of the SketchPad.
ContamW 2.4 now provides you with a floating status bar which will display in the region of the
caret whenever you select certain icons on the screen providing a more convenient means to
review icon information. This is similar to Tool Tips that appear when you hover over a toolbar
button with the Windows cursor. You can turn this feature on and off via the View Floating
Status Bar or Ctrl+T for Tool tips.
Left Pane
This pane always displays the type and number of building component icon, e.g., zone, path, air
handling system, etc.
In the normal mode of operation, the leftmost pane displays summary information of the
currently highlighted cell or icon.
In the simulation results mode, the leftmost pane displays the results for the currently highlighted
icon. For a zone this includes the temperature and pressure relative to the ambient pressure at the
elevation of the level on which the zone is located. For duct junctions and terminals it displays
the temperature and static pressure relative to the zone in which the junction or terminal is
located. For paths and duct segments it will display the airflow and pressure drop across the path
or segment along with symbols to indicate the direction of flow (>, <, ^, v). For a simple air
handling system icon the outdoor airflow, recirculation airflow and exhaust airflows for the
implicit flow paths will be displayed.
Many units of display can be controlled by selecting the SI or IP system of units in the Project
Configuration Properties accessible via the View Options... menu command.
Center Pane
In the normal mode of operation, the center pane indicates the location of the currently
highlighted icon or cell in SketchPad coordinates (numbered from the top-left corner). In the
simulation results mode the center pane displays the current simulation time step for which the
results are being displayed.
Right Pane
The rightmost pane displays the name and number of the current level and the total number of
levels in the project.
Figure - Status Bar during Normal Mode and Results Viewing Mode respectively
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Building Components
Building components are the items that characterize the physical makeup of a building that you
define using ContamW. This section briefly describes these components.
Levels
CONTAM represents buildings in terms of multiple levels, accounting for the communication of
air and contaminants between these levels. Levels typically correspond to floors of a building,
but a suspended ceiling acting as a return air plenum or a raised floor acting as a supply plenum
may also be treated as a level.
Walls
Walls are used to designate zones which are regions surrounded by walls, floor and ceiling.
These walls include the building envelope and internal partitions with a significant resistance to
airflow.
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17
Occupants
Occupants can be used to determine the amount of contaminant exposure a person would be
subjected to within a building. Occupants can also generate contaminants. You can set a schedule
to establish each occupants movement within a building. Occupant schedules can also be used
to define periods of times when occupants are not in the building. (See Working with Occupant
Exposure)
Weather
CONTAM enables you to account for either steady-state or varying weather conditions. Weather
conditions consist of ambient temperature, barometric pressure, humidity ratio, wind speed and
direction, as well as ambient contaminant concentrations.
Simulation
In CONTAM, simulation is the process of forming a set of simultaneous equations based upon
the information stored in the project file, performing the numerical analysis to solve the set of
nodal equations according to user-defined specifications, and creating simulation results files that
can be viewed using the ContamW interface. There are three basic types of simulations that you
can perform for airflow and contaminant analysis using CONTAM: steady state, transient and
cyclical. (see Working with Simulations)
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USING CONTAM
This section provides detailed information on how to use the features of the CONTAM program
as well as a detailed explanations of the terminology of the user interface.
Keyboard Shortcuts:
Ctrl + PageUp to increase cell size
Ctrl + PageDown to decrease cell size
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22
Icon
Category
Component Icons
Walls
Zones
Duct
Segments
Duct
Junctions
Duct
Terminals
Simple AHS
Airflow
Paths
Source/Sinks
Occupants
Controls
Table - CONTAM SketchPad Icons (shown in default colors)
Delete by region
Menu command: Tool Delete by Region
Tool bar button:
Delete by box:
Menu command: Tool Delete by Box
Tool bar button:
Delete by coordinates
Menu command: Tool Delete by Coordinates
Then press Delete to display the Multiple Icon Deletion Options dialog box shown below. Use
the check boxes to select the types of icons you want to delete, select the level(s) from which you
want to delete the icons using the Ctrl and Shift keys to select multiple levels from the list, then
click the OK button to perform the deletion.
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Searchable items:
Airflow Paths - including Supplies and Returns of Simple Air Handling Systems
Control Nodes - sub-nodes of super nodes will defer to the super node
Duct Junctions
Duct Segments
Occupants
Source/Sinks
Zones - including implicit supply and return zones of simple air handling systems
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items from the list by selecting the item and clicking the Remove button. This allows you to
refine the set of items for replacement.
Building Component
Air Handling System
Airflow Path
Control Node *
Duct Junction
Duct Segment
List Parameters
Kinetic reaction in return
Kinetic reaction in supply
Outdoor air filter
Return air filter
Outdoor air schedule
Air handling system
Filter
Schedule
Airflow element
Filter
Schedule
Wind pressure option and Profile
Control type
Color
Schedule
Color
Duct flow element
Filter
Schedule
Value Parameters
Minimum outdoor airflow
Return system volume
Supply system volume
Airflow rate
Azimuth angle
Constant wind pressure value
Multiplier
Relative elevation
Wind speed modifier
N/A
Relative elevation
Temperature
Length
Loss coefficient
Duct Terminal
Balanced
Color
Filter
Schedule
Wind pressure option and Profile
Occupant
Inhalation schedule
Source/sink element
Schedule
Species
1D zone
Color
Zone
Kinetic reaction
Name
Schedule
* Control nodes are not replacable using this feature
Source/Sink
Azimuth angle
Constant wind pressure value
Balance loss coefficient
Design flow rate
Free face area
Relative elevation
Temperature
Terminal loss coefficient
Wind speed modifier
Body weight
Multiplier
Peak inhalation rate
Multiplier
Floor area
Temperature
Volume
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CONFIGURING CONTAMW
The Program and Project options of ContamW are available from the View menu. Program
options can be saved to the CONTAM.CFG file located in the CONTAM Program Directory.
Upon startup, ContamW looks for this file and loads the saved settings if the file exists. This way
you can set ContamW to start with the same default settings each time you run the program.
Project options are saved with the current project file.
NOTE: The path name of the EWC-to-WPC file converter does not appear in the configuration
dialog boxes; however, if a converter is selected when you click the Save button it will be saved
to the CONTAM.CFG file. The value saved will be that which you have set in the WPC File
selection of the Weather menu. To reset the converter name back to "null," you must edit the
configuration file manually.
Project Options
All of these settings are saved with the CONTAM project.
Units
The following parameters define the units and temperature that will be used by default
throughout the project when you are providing input to the program. You do not have to use
these units throughout the project; however, you should select the primary set of units for
convenience when entering data throughout a project. You can change these defaults at any time
while working with a project, and you can select different units for individual parameters as you
enter them.
System of Units: You can select the appropriate radio button to set the system of units that
you would like the program to use. You can either select the International System of Units
(SI) or the Inch-Pound (IP) system of units.
Units of Flow: You can select the appropriate radio button for the most commonly used units
of flow in the current project. These are the units in which airflow simulation results will be
displayed within the status bar. ContamW converts all airflow rates to and performs all
calculations in mass flow units of kg/s. Note that all volumetric airflow rate units are at
standard temperature and pressure.
Initial Zone and Junction Temperature: This value will be the default temperature used
whenever you create a new zone, duct junction or terminal within the current project. If you
change this value, you will be prompted as to whether or not you would like to update the
temperatures of all existing zones, junctions and terminals.
SketchPad Dimensions
Size: This is the width and height of the SketchPad. These dimensions are presented in both
cell units and units of length as defined by the Scaling Factor below. The SketchPad is made
up of square cells that represent each space wherein an icon may be placed. The default (and
minimum) values are 66 cells wide and 58 cells high.
Scaling Factor: Set the dimension of a cell in order to calculate SketchPad locations and
wall dimensions in the units provided when displaying Pseudo-Geometry on the SketchPad.
Show Pseudo-Geometry: Use the Scaling Factor to present location and wall dimensions on
the SketchPad in the Status Bar. This feature can be useful when working with the TRNSYSCONTAM coupling capability that requires geometrical data for the TRNSYS building
representation used by TRNSYS Type56. It can also be useful to set airflow path multipliers,
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because wall areas can be displayed. The extents of items (dx and dy) will be displayed in the
Status Bar as you draw them.
Origin: Set the location (column and row) of the origin to be used when calculating the
position of items on the SketchPad. A special icon will appear on the SketchPad at the
specified location. By default the origin represents the bottom-left of the SketchPad grid
(column 1, row 56) and y-values are positive above the origin. You can invert the y-axis so
that y-values are negative above the origin.
NOTE: You can also set the origin by right-clicking on the SketchPad and selecting "Set
Origin" from the context menu.
Program Options
Units
The Program units define the units and temperature that will used to populate the Project units
(presented above) when you create a new project file.
SketchPad Display
Show Floating Status: Check this box to display the Floating Status box on the SketchPad.
You can also turn the floating status box on and off via the View Floating Status
(Ctrl+T) menu command.
Show Zone Colors: Check this box to display zone fill colors on the SketchPad. If this box
is not checked, then all zones will be filled using the "Background" palette color. You can
also turn the color zones option on and off via the View Color Zones (Ctrl+Z) menu
command.
Show Duct Colors: Check this box to display duct colors on the SketchPad. If this box is not
checked, then all ducts will be displayed using the "Ducts" palette color. You can also turn
the color ducts option on and off via the View ColorZones (Ctrl+Z) menu command.
Maximize ContamW at startup: Check this box to maximize the ContamW window when
the you start the program.
Cell/Icon Size
Current Cell/Icon Size: There are seven options for displaying icons on the SketchPad (1x1,
2x2, 3x3, 4x4, 5x5, 8x8, and 16x16). The default option is 8x8. This is a "zooming" feature
that provides a visual aid to enable you to view sketches in more detail or to fit larger
sketches within the program window. The cell size has no effect on the project simulation.
There are two "zooming" buttons provided on the toolbar to quickly increase and decrease
the cell size according to the available cell sizes below.
Available Cell Sizes: Use these check boxes to select which sizes you want available. The
1x1 size causes problems with some versions of the Window 98 operating system. If this is
the case for you, then deselect the 1x1 check box and click the "Save Configuration" button.
Cell Jump: Use this to set the number of SketchPad cells the cursor will jump when you use
the Shift + Arrow Keys to maneuver around the SketchPad.
Colors
Palettes: ContamW provides the ability to modify the color of items displayed on the
SketchPad. You can select one of four available palettes. You can not modify the colors of
the "Default" palette, but you can modify the other three "User Palettes." Select a palette to
display the colors of the palette in the Palette Colors section below.
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Palette Colors: These are the colors use to display items on the SketchPad. Click the color
box to change the color used to display each type of item. Only the colors of the User
Palettes can be changed. The following is a brief description of each category.
Foreground - Defined icons including walls
Background - Background of SketchPad cells, default zone fill and fill of all zones
when Color Zones option is not active.
Flow Results - Lines displaying scaled flow results for airflow paths and duct
terminals
Pres Results - Lines displaying scaled pressure difference results across airflow
paths in the Results and Wind Pressure view modes
Drawing Line - Cell highlight when drawing on the SketchPad
Undefined - Undefined icons
Controls - Defined control icons
Ducts - Default color of defined ducts and color of all defined ducts when Color
Ducts view option is not active
Errors - Background color of cells when an error condition is being highlighted on
the SketchPad. Errors are indicated when a building check fails. Building checks are
performed when you choose Run Simulation or Create ContamX Input File from
the Simulation menu.
Cursor - SketchPad drawing and icon selection cursor
Highlight - Icon highlighting color for find operation
Sub Level - All icons on sub-level when sub-level display option is activated via the
Level Reveal Level Below (Ctrl+Shift+B) menu command.
Results Display
Results Lines: You can select whether or not to display the airflow rates and pressure
differences across airflow paths on the SketchPad when in the Results Display Mode.
Both Pressure and Flow: Display both the airflow rates (green lines) and pressure
differences (red lines).
Pressure Only: Display only the pressure difference lines.
Flow Only: Display only the airflow lines.
Time Step Navigation: Set the number of simulation time steps to skip when using the
Results Navigation jump commands.
See Viewing Results in the Working with Results section.
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Drawing Walls
You can draw walls using either of the two wall drawing tools previously described in the
"Working with the SketchPad" section. Use the box drawing tool to quickly draw a rectangular
region and the wall drawing tool to draw a free form wall. Use the wall drawing tool to draw
almost any shape wall. Walls must always form complete enclosures. Therefore, a wall cannot
have an open or dangling end. It also may not be drawn across building component icons. You
will receive a warning message if you attempt to draw an invalid wall.
Deleting Walls
You can delete a wall by moving the caret to any portion of the wall and selecting Delete from
the Edit menu or using the keyboard shortcut Del key. ContamW will highlight the section of
wall to be deleted and request confirmation to delete the indicated section. If the caret is on the
intersection of three or more walls, you will be given multiple options of wall segments to delete.
If you select "No" when asked to confirm deletion, the next option for deletion will become
highlighted until you either delete a section or all of the options are exhausted.
Modifying Walls
You modify the positions or shapes of walls by adding and deleting wall sections. For example
in the following figures, if you want to modify the zone in figure (a) to obtain the zone in figure
(d), you would first add the dark line in figure (b) then delete the dark line in figure (c).
When modifying walls you may need to move or delete other icons. For example in the
following figures, to create drawing (c) from drawing (a), you would delete the lighter line and
the lighter zone icon from figure (b). You must delete one of the two zone icons, or you will end
up with two zone icons within the same enclosed wall area. This is not permitted, and you will
receive a message indicating a zone definition error.
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37
Creating Levels
When you first start ContamW, a default level is created so that you can begin working on a
drawing right away without having to create a new level. There are three commands in the Level
menu that you use when creating new levels. These are the Copy Level, Paste Level, and Insert
Blank Level commands. Whenever you create a new level, whether it is blank or a copy of
another level, ContamW will give it a default name that will consist of a number enclosed within
the "<" and ">" characters. You can modify this name later by editing the data associated with a
level.
You must be careful when copying levels within ContamW. For example, you might have an air
handler defined within a duct system on a level and then copy it to another level. This would
create another air handler on the new level. If the ductwork is connected between the two levels,
the two air handlers may act against each other. You must be careful to make connections
between building levels in a manner that makes sense for your purposes.
Creating Blank Levels
Menu Command: Level Insert Blank Level (Above/Below Current Level)
Keyboard Shortcut: None
Toolbar Button: None
Use these commands to create a blank level. When you create a blank level, you must select
whether you want it created above or below the current level.
Copying and Pasting levels
Menu Command: Level Copy Level along with
Level Paste Level (Above/Below Current Level)
Keyboard Shortcut: None
Toolbar Button: None
With ContamW you can copy an entire level and insert it as an entire level anywhere within the
current project. Use the Copy Level command to copy the level currently displayed on the
SketchPad; move to either the level above or below where you wish to insert the copied level and
use one of the Paste Level commands to insert the copied level.
Viewing Levels
If a project has more than one level, you can specify the level that you want to view or modify on
the SketchPad by using the level commands. All level-related commands are located under the
Level menu. There are also some shortcut keys and toolbar buttons provided for your
convenience.
Moving Up/Down a Level
Menu Command: Level Go to (Level Above/Below)
Keyboard Shortcut: Page Up, Page Down
Toolbar Button:
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Use this command to change which level you want the SketchPad to display.
Changing the Currently Active Level
Menu Command: Level Go to (Level Above/Below)
Keyboard Shortcut: Page Up, Page Down
Toolbar Button:
Use this command to change which level you want the SketchPad to display.
Displaying Multiple Levels
Menu Command: Level Reveal Level Below
Keyboard Shortcut: Ctrl+Shift+B
Toolbar Button: None
Use this command to see both the current level and the level below the current level at the same
time. ContamW will display the walls and building component icons of the level below in gray.
This feature is useful for aligning building features between adjacent levels.
Deleting Levels
Menu Command: Level Delete Level
Keyboard Shortcut: None
Toolbar Button: None
Use this command to delete an entire level. Once you have deleted a level, you cannot undo the
deletion. You may want to save a copy of the file prior to deleting a level; this is the only way to
prevent losing your work.
Modifying Levels
To modify level data, you access the Level Data dialog box using the Edit Level Data
command of the Level menu. You can also use the keyboard shortcut F8 to display the dialog
box. The following section shows the information contained on the "Level Data" dialog box.
Level Data
This is the information associated with each level that you create. ContamW will provide default
values for this data, but you can modify it as required for your particular building.
Name: Name to identify the level. All level names must be unique.
Elevation of this level: The elevation of the base of the level above ground.
Distance to level above: This is the height of the level from floor to ceiling. ContamW will use
this value to calculate zone volumes based on the floor area of each zone.If you change this
value, a dialog box will appear asking if you would like ContamW to adjust the volumes of the
zones on the level based on the new level height. If you select Yes, then the zone volumes will
be adjusted by Vnew = Vold * Hnew / Hold. If there are phantom zones on the level, you will be
advised that their volumes were not adjusted, so you should handle those zones individually.
Checking Levels
Menu Command: Level Check Current Level
Keyboard Shortcut: None
Toolbar Button: None
Use this feature to check the data for the currently displayed level and make sure the building
components are defined. Errors will be highlighted in red on the SketchPad.
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Creating Zones
You create zones by drawing walls upon the SketchPad. The wall drawing operations are
described in the Drawing Walls section of this manual. The shape and size of zones as drawn
upon the SketchPad do not provide the underlying model with any scaling information.
However, the manner in which the enclosed regions border each other is significant. Any zones
between which you wish to provide a direct connection (via an airflow path) must share a
common wall. Therefore, when drawing a building floor plan, you should try to maintain the
general topology of the actual floor plan. While scale is not significant, ContamW does provide
you with the SketchPad coordinates that may help you when laying out your project.
The dimensions of your zones are determined when you define them. If you change the shape or
size of a region on the SketchPad that contains a zone icon, the dimensions do not change
according to the model unless you actually modify the properties of the associated zone icon.
Deleting Zones
You delete a zone by first deleting the zone icon. After you delete the zone icon, delete the wall
or walls necessary to eliminate the enclosed region that is left behind. You must avoid the
existence of an enclosed region without a zone icon; CONTAM will not perform a simulation
with an undefined zone icon in a project.
Modifying Zones
You modify the SketchPad representation of a zone by adding and removing walls. This
procedure is described in the Modifying Walls section of this manual. To modify the parameters
of a zone, you use the icon definition procedure (See Defining Building Component Icons) to
display its properties and make the desired changes.
Once you define a zone, you can move the zone icon anywhere within the zone using the Cut
and Paste functions of the Edit menu. These commands will only allow you to paste the icon
into the zone in which it is currently located.
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Defining Zones
After you draw the enclosed region of a zone, you must define the zone. To define a zone you
must first draw a zone icon within the enclosed region (See Drawing Building Component Icons)
and then use the icon definition procedure (See Defining Building Component Icons) to display
and edit the properties of the zone.
The properties of each zone include a name, temperature (constant or scheduled), pressure
(variable or constant), volume, information describing contaminant behavior within the zone, and
1D zone information. You must provide each zone with a name that is unique to each level of a
project. For this reason, you cannot copy zone data within a level. However, you can copy entire
levels of data, including zone data, from one level to another (See Creating Levels). Detailed
descriptions of zone properties are given under Zone Properties below.
Only normal zones require definition. Ambient and phantom zone icons appear as defined icons
as soon as you place them onto the SketchPad. However, you must include the volume of
phantom zones in the volume of the associated normal zone below it.
Zone Properties
This section provides detailed descriptions of the specific zone properties. The following
sections are the context-sensitive help topics that you can access by pressing F1 when working
with property pages of the "Zone Properties" property sheet.
Zone Zone Data Properties
These are the basic properties that describe a zone.
Zone Name: This is the symbolic name of the zone. Enter a name up to 15 characters in length.
Zone names must be unique within each level of a building.
Dimensions
Volume: Zone volume is used in the dynamic contaminant calculations. For phantom zones,
the zone volume is set at the standard zone icon on the lowest level for the entire height of
the zone and includes the volume of the phantom zones on the levels above.
Floor Area: Instead of the volume, you may enter a floor area. Floor area is then multiplied
by the height of the current building level to compute a volume. This area is not used for any
other purpose by CONTAM.
Color: Select a zone fill color to help you distinguish zones on the SketchPad. You must
activate the Color Zones option from the View menu in order to display zone colors on the
SketchPad.
Include in Building Volume: This refers to the calculation of whole building air change
rates that you can now have CONTAM perform during simulation. The associated check box
is checked by default, so if you do not want the zone to be included in the whole building
volume you should uncheck this box. The air change rate and building pressurization
calculations will calculate the total rate of airflow from ambient into all of the zones having
this box checked. Typically, you would include all conditioned space in the building volume;
for example, you might not want to include an attic or crawl space.
Temperature
Constant or Scheduled: Select to either maintain zone temperatures at a constant value or
to change according to a user-defined schedule. If you select Scheduled, then you must
associate a temperature schedule with the zone. Selecting Scheduled will also set the
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simulation run control to vary the density within building zones during simulation (See
Airflow Numerics Properties in the Working with Simulations section).
Temperature: Set the value you want ContamW to use as the constant temperature of the
zone when you select the "Constant" radio button. Whenever you create a new zone,
ContamW will use the default value which you can override by entering another value. You
can set the default zone temperature via the Options command of the View menu.
Temperature Schedule: Select the temperature schedule you want to associate with this
zone when you select the "Scheduled" radio button. (See Working with Schedules).
Pressure: The zone air pressure relative to ambient can be specified as either variable or
constant. Typically you would set the zone pressure to be variable and allow it to be calculated
during the simulation. However, you might set the pressure to be constant if you want to simulate
a fan pressurization (blower door) test of a building (see Building Pressurization Test in the
Applications section of the manual) or to perform analytic test cases of CONTAM.
Zone Contaminant Properties
These are the contaminant-related properties of a zone. Contaminants must be defined prior to
defining contaminant data for a zone. To define contaminants, select Data then Contaminants
from the main program menu.
Zone Name: This is the symbolic name of the zone as entered on the Zone Data property page.
Contaminant Concentrations: Select variable or constant. Typically you would set this to
variable and allow ContamX to calculate the contaminant concentration within the zone during
simulation. However, you may wish to set this to constant as a simple means of creating a simple
contaminant source within a zone. If you set this to constant, the contaminant concentrations in
this zone will begin and remain at the values you set for the initial concentrations.
Initial Concentration: Select a contaminant from the list and enter the initial contaminant
concentrations for dynamic (transient) simulations. Note that only those species youve selected
to be contaminants (to use during simulation) appear in the list. If a species for which you wish
to set an initial concentration does not appear in the list you must set "Use in simulation"
property of the corresponding species to be true (See Creating Species and Contaminants). You
can reset these initial values through the Run Control Properties of the Simulation Parameters.
IMPORTANT: Changing the number of contaminants, i.e. those species used in the simulation,
will reset the initial concentrations of all zones to the default contaminant concentrations. You
can reset all of these concentrations via the Run Control Properties as indicated above or
individually here.
Sum of Non-trace Initial Concentrations: This value is provided as a check for you to insure
that you input a reasonable set of initial values when using non-trace contaminants. This value
should be very close to 1.0.
Kinetic Reactions: If there are previously defined kinetic reactions within the current project,
you may select one from the list of names. Click the "New Reaction" button to define a new
kinetic reaction. To view or modify existing kinetic reaction data click the "Edit Reaction"
button. Setting this field to <none> indicates no reactions in the zone. You can also import
kinetic reactions from a contaminant-related library file (See Working with Data and Libraries).
Zone Detailed Zone Properties
These are the properties used to define 1D convection/diffusion zones in which contaminant
concentrations can vary along a user-specified axis. This option is provided for cases in which
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you need to account for the delay in contaminant transport within long or tall zones. If this
feature is enabled, ContamX will subdivide this zone along the specified axis into multiple cells
or sub-nodes for the purposes of contaminant transport calculations.
Zone Name: This is the symbolic name of the zone as entered on the Zone Data property page.
Zone Type
CFD Zone: Only one CFD zone is allowed per CONTAM project. Use the CFD0
Editor to define the CFD properties of the zone, e.g., zone mesh and boundaries.
1D Zone Data
Axial Dispersion Coef: Enter the axial dispersion coefficient and units for the zone. Note
that the zone dispersion coefficient is not necessarily the molecular diffusion properties of
the defined contaminants. This coefficient is empirically based and should account for
turbulent mixing as well.
Axis End Point CoordinatesDefine the end points, Point 1 and Point 2, of the axis of the
1D zone. These coordinates will define the direction along which contaminant transport will
be calculated when treating this zone as a 1D convection diffusion zone. These values are
required to establish the relationship of other building components with respect to this zone,
i.e., flow paths, duct junctions and terminals, simple air-handling unit supply and return
points, contaminant source/sinks, sensors and occupants.
While the coordinate system is user-defined, ContamW will verify the relationship of 1D
zones to associated building components prior to running a simulation to insure that the
coordinates "match up." This verification is performed automatically when you select either
the Run Simulation or Create a ContamX Input File command from the Simulation
menu. If there are discrepancies, messages will be displayed notifying you of the nature of
the discrepancies.
X and Y: The X and Y values are in absolute coordinates. These values can be based
on scale drawings and/or a user-defined coordinate system. Unlike walls on the
SketchPad, axes are not required to be rectilinear, i.e., you may specify axes that are
not horizontal or vertical in the x-y plane.
Rel Elevation: Enter the Z-coordinate as the height relative to the base of the zone.
Cell Size: This is the cell size into which ContamX will sub-divide the zone during
simulation if the zone is to be treated as a 1D convection/diffusion zone. If the axis
length is not evenly divisible by the cell size, then the cell size will be adjusted as
needed. While there is no strict guidance on the selection of cell size, it should
generally be on the order of the flow velocity along the axis times the simulation
time step.
Units: Set the units of the above items.
Axis Orientation on the SketchPadThe orientation of the axis on the SketchPad is useful
when using a results viewing tool such as ContamRV. ContamRV can display the variation
of concentration within 1D zones if the simulation output options are set to write to the 1D
results files (See Simulation - Output Properties in the Simulation Parameters section). Mass
43
fractions of 1D zone cells are written to the 1D results file in the order from Point 1 to Point
2 of the Axis End Points. The "Axis Orientation" enables ContamRV to color the rectilinear
region of the zone on the SketchPad even if the axis endpoints specify an axis that is not
actually horizontal or vertical in the plan view, e.g., a slanted hallway.
CFD Zone Data
CFD Zone ID: This identifier will be used to name the CFD files associated with this
project. These files will be generated by the CFD0 Editor and ContamX. For example, using
the CFD0 Editor you import a PRJ file that contains a CFD Zone. Once you have used the
CFD0 Editor to define the CFD domain, you will use the CFD0 Editor to generate a .CFD
file having the same name as the PRJ file but with the CFD Zone ID appended to it, e.g.,
MyProject_CfdZone.cfd. Running a coupled simulation will generate more similarly named
files having various extensions.
44
Airflow Elements
Each airflow path must refer to an airflow element. Airflow elements describe the mathematical
relationship between the flow through an airflow path and the pressure drop across the path.
ContamW provides you with several mathematical models or types to choose from. Each of
these airflow element types is described in detail in the Airflow Path Properties section. While
every airflow path must refer to a single airflow element, multiple paths can refer to the same
airflow element. Airflow elements can also be stored within a CONTAM library file and shared
between different CONTAM project files (See Working with Data and Libraries).
Description
Small and large one-way flow paths
Small and large one-way flow paths
Directional fan flow paths
46
display the results of a simulation, those paths with pressures or flows outside the limits will be
highlighted.
Location: These are the absolute X and Y coordinates and units for the selected airflow path.
The Z coordinate will be taken as the Relative Elevation of the airflow path with respect to the
building level on which the path is located.
These values are required for flow paths through the building envelope when using a Wind
Pressure and Contaminant (WPC) file (see Wind Pressure and Ambient Contaminant Files) or
for any path that connects to a 1D convection/diffusion zone (see 1D Zone Data). These
coordinates will be verified by ContamW against a WPC file or the axis of the 1D zones to
which the path connects. This verification is performed automatically when you select either the
Run Simulation or Create a ContamX Input File command from the Simulation menu.
Airflow Path Wind Properties
Wind Pressure Option: There are three wind pressure options for openings in the building
envelope:
1. No wind pressure
2. Constant pressure
3. Pressure dependent on wind speed and direction
When you select one of the above options, the following data entry options that correspond to the
wind pressure option that you selected will be made available for your input.
Constant Pressure Data: Enter a constant wind pressure (wind speed and direction
independent).
Variable Pressure Data: Variable wind pressures are computed from the product of the
following three parameters:
1. The dynamic pressure of the wind at some reference height. ContamX will determine this
pressure based on either the steady state wind data (see Wind Properties) or the transient
wind data from a weather file (see Defining Transient Weather and Wind).
2. A coefficient accounting for local terrain effects (Wind Pressure Modifier).
3. A pressure coefficient accounting for relative wind direction (Wind Pressure Profile).
Wind Pressure Modifier: CONTAM uses this value to account for differences between
wind velocity profiles at the building site and that at a measurement location, e.g. an airport
weather station (See Working with Weather and Wind). CONTAM only requires this value if
you are implementing Variable Wind Pressure for an airflow path. CONTAMW will provide
a default value for this based on the data entered via the Weather and Wind Parameters
Property Page or you can override the default value for a particular airflow path.
Wall Azimuth Angle: Enter the direction the wall faces (clockwise from north).
Profile: The wind pressure profile accounts for the wind direction effects. You may select a
previously defined wind pressure profile from those contained in the Name list. Click the
"New Profile" button to define a new wind pressure profile. To view or modify wind pressure
profile data, click the "Edit Profile" button. After you press the "New Profile" or "Edit
Profile" button, the Wind Pressure Profile page will be displayed with a graphical
representation of the profile.
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Mass Flow Rate: CONTAM provides a mass flow rate boundary condition to CFD.
Pressure: CONTAM provides a pressure boundary condition to CFD.
Pressure Boundary Condition Type
Linear: When a pressure boundary condition is provided by CONTAM to CFD, the linear
coefficient (C = 1.0) and exponent (Exp = 1.0) will be used for each interface cell in the CFD
zone. This simple model should be used for large openings with potential two-way flow
(recirculation) across the openings, where the Stagnation and Static Pressure Model
normally cause numerical issues. This is the default model.
Stagnation and Static Pressure: When a pressure boundary condition is provided by
CONTAM to CFD, a stagnation pressure is imposed for inflows of the CFD zone, and a
static pressure is imposed for outflows of the CFD zone. Numerically, a static pressure is set
for CFD outflows as follows: a linear coefficient with the order of 103 is used so that the
CFD local pressure can be maintained as a difference of 10-3 from the external boundary
pressure. This may cause numerical issues for large openings with two-way flows, where a
slight change of dynamic pressure head could cause a huge airflow at the boundary. In such
cases, a linear model should be used. When comparing a coupled simulation to CFD-only
simulation (all zones simulated by CFD), the flow coefficients and exponents in a coupled
simulation are very important, which are normally unknown. Above all, a linear model brings
more numerical stability while a stagnation and static pressure model is a means of setting
CFD pressure boundary conditions.
Airflow Element Types
This is a list of available airflow elements or mathematical models that provide the relationship
between airflow and pressure difference for airflow paths. See Airflow Analysis in the
Theoretical Background section of the manual for mathematical details.
One-way Flow using Powerlaw Models
These one way flow models permit flow in the direction of the pressure drop. CONTAM
provides you with the following powerlaw flow models.
1. Q = C(P)^n: This is the general form of the powerlaw model in volumetric flow form that
allows you to directly input the coefficient, C, and exponent, n.
2. F = C(P)^n: This is the general form of the powerlaw model in mass flow form that
allows you to directly input the coefficient, C, and exponent, n.
3. Leakage Area Data: This model refers to effective leakage areas as described in Chapter
26 of the 2001 ASHRAE Handbook of Fundamentals.
4. Connection (ASCOS) Data: Refers to the airflow description used in the ASCOS program
[Klote 1982].
5. Orifice Area Data: Relates the opening description to the orifice area data.
6. Crack Description: A narrow opening described by its length and width.
7. Test Data (1-point): Uses a single flow rate and pressure drop along with an estimate for
the pressure exponent, n.
8. Test Data (2-points): Uses two flow rates with their corresponding pressure drops to define
the flow using the powerlaw model.
9. Stairwell: Data corresponding to a stairwell is fit to the powerlaw model.
50
51
Flow Exponent (n): Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Powerlaw Model: F = C(P)^n
This model allows you to directly enter the coefficient C and exponent n for the mass flow
version of the powerlaw model.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
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Flow Coefficient (C): The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from IP units to SI units.
Flow Exponent (n): Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Powerlaw Model: Leakage Area
Leakage area refers to a description of airflow features given in Chapter 26 of the 2001
ASHRAE Handbook of Fundamentals [ASHRAE 2001]. Table 1 of this reference provides
typical leakage areas for residential buildings.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Leakage Area: There are three possible ways to enter the leakage area: per item, per unit length,
and per area. Select the radio button for the type of leakage area to be described, then enter the
appropriate value for the type of leakage selected.
Per Item: Enter a total leakage value for an item, this is usually used for a doorway or window something that can be classified as an item.
Per Unit Length: Commonly used to describe an interface such as a wall/ceiling junction.
Per Unit Area: Used to describe an area such as a wall or floor.
Reference Conditions: Be sure to check the reference condition for the reported leakage areas.
Two sets of reference conditions are common [ASHRAE 2005 p 27.13]:
Discharge coefficient of 1.00 at a reference pressure difference of 4.0 Pa and
Discharge coefficient of 0.611 at a reference pressure difference of 10 Pa.
Discharge Coefficient: Enter the discharge coefficient for the leakage area at the reference
pressure difference.
Flow Exponent: Enter the flow coefficient for the leakage area at the reference pressure
difference. The flow exponent is not reported and therefore must be estimated. For openings
associated with infiltration, measurements usually indicate an exponent between 0.6 and 0.7.
Pressure Difference: Enter the reference pressure difference for the associated leakage rating.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Powerlaw Model: Connection (ASCOS)
The ASCOS connection element is provided for compatibility with the ASCOS program [Klote
1982]. It is an implementation of the more general orifice flow element based upon the orifice
equation.
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Q = K Ao (2 P / )
The inputs for the ASCOS connection are the opening area, Ao, and the dimensionless flow
coefficient, K. Data describing a connection are reduced to the powerlaw model with an
exponent of 0.5. The orifice flow element (see Powerlaw Model: Orifice Area) provides a more
general implementation.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Flow Coefficient: The flow coefficient K is related to the dynamic effects and is typically close
to 0.6 for an orifice and slightly higher for other openings in buildings.
Flow Area: Ao, refers to the observable area of the opening.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Powerlaw Model: Orifice Area
This airflow element allows you to input the description of an orifice.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Cross-sectional Area: This refers to the observable area of the opening.
Flow Exponent (n): Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Discharge Coefficient: The discharge coefficient, C, is related to the dynamic effects and is
typically close to 0.6 for a sharp-edged orifice and slightly higher for other openings in
buildings.
Hydraulic Diameter: The hydraulic diameter is equal to (4 Area / Perimeter). For square
openings this equals the square root of the area, and for long thin openings it is two times the
width.
Reynolds Number: The transition from laminar flow to turbulent flow occurs over a very broad
range of Reynolds numbers with the flow being fully laminar approximately below 100.
Note: The hydraulic diameter and Reynolds number have little impact on the calculations.
Generally you should use the default values except for special circumstances where you need
them to be modified. The parameters above describe the flow characteristics of an orifice in
typical operation. At extremely low pressure drops the use of the powerlaw model leads to a
division by zero during the network solution process. ContamX avoids this problem by changing
to a linear model in this region. The model is based conceptually on the flow changing from
turbulent to laminar at very low pressures. The Hydraulic diameter and Reynolds number are
used to determine a point where the model changes from the powerlaw to linear.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
54
Tamura 1998]. This model should only be used between zones on different levels of a building
(paths through floors), not between zones on the same level (paths through walls).
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Distance Between Levels: The vertical distance between doorways of the stairwell. This is
typically equal to the "Distance to level above" of the level below the path with which this
element is to be associated.
Cross-sectional area: This is the horizontal, cross-sectional, area of the shaft.
Density of People: A large number of people in the stairwell influences the flow resistance of
the stairwell. The experiment used densities of 1, 2, and 3 people per square meter. These are the
only units available in ContamW. The following conversion is provided for your convenience.
1 m2 = 10.76 ft2
Stair Treads: There are two options for this field: open tread and closed tread. This refers to the
front of the tread whether or not the tread is open effects flow.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Powerlaw Model: Shaft
This airflow element allows you to enter a description of a shaft, and ContamW converts the
information to a powerlaw relationship assuming a pressure exponent of 0.5. A shaft will
normally be modeled as a vertical series of zones connected by low resistance openings (this
shaft airflow element) through the floors. The resistance is based on a conduit friction model
using the Darcy-Weisbach relation and Colebrooks equation for the friction factor [ASHRAE
2005, p2.7].
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Distance Between Levels: This is the distance between openings for the stairwell.
Cross-sectional area: This is the horizontal, cross-sectional, area of the shaft, not the opening.
Perimeter: The perimeter of the horizontal cross-section of the shaft. This number is used in
conjunction with the area to create the hydraulic diameter.
Roughness: This refers to the average size of the protrusions from the shaft wall into the airflow.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
One-way Flow Using Quadratic Flow Models
ContamX performs airflow calculations using the mass flow quadratic relationship
(P = aF + bF) between mass flow rate and pressure difference across a flow path for the
following types of airflow elements. Where F is the mass flow rate, P is the pressure difference
across a flow path, and a and b are flow coefficients.
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Quadratic Model: P = aQ + bQ
This model allows you to directly enter the coefficients, a and b, into the volume flow version of
the quadratic flow model. Where P is the pressure drop and Q is the volumetric flow rate.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Coefficients: The coefficients must be expressed in SI units because of the way ContamW
handles unit conversions. The units of the coefficients at standard conditions are as follows:
a [Pa s/sm3]
b [Pa (s/sm3)2]
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Quadratic Model: P = aF + bF
This model allows you to directly enter the coefficients, a and b, into the mass flow version of
the quadratic flow model. Where P is the pressure drop and F is the mass flow rate.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Coefficients: The coefficients must be expressed in SI units because of the way ContamW
handles unit conversions. The units of the coefficients are as follows:
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Quadratic Model: Crack Description
This model employs a quadratic relationship of the form P = aQ + bQ where Q is the volume
flow rate [Baker, Sharples, and Ward 1987]. CONTAM uses the mass flow version of that
formula: P = aF + bF where P is the pressure drop and F is the mass flow rate.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Crack Dimensions:
Length: The overall length of the crack
Width: Width of the crack
Depth: The distance along the direction of airflow
Number of Bends: The number of bends in the flow path.
Description: Field for entering a more detailed description of the specific airflow element.
Quadratic Model: Test Data (2 points)
Measured data (2 points) is reduced to the mass flow version of the quadratic model.
57
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Data: Data consists of two sets of pressure drops and corresponding flow rates.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Two-way Flow Models
These models enable you to simulate openings through which two-way airflow might occur (e.g.
doorways and open windows). When viewing results of these models, the bidirectional flow will
be indicated on the SketchPad if it occurs. You can also use ContamWs airflow plotting feature
to plot both airflows or to simply plot the net airflow. There must be a density difference across
the associated airflow path in order for bidirectional flow to occur across these types of airflow
elements. See Doorways (Large Openings) in the Theory section for a more detailed explanation.
The Relative Elevation of flow paths that implement these models should be set to the bottom of
the flow path as opposed to the mid-height used for other element types.
Two-way Flow Model: Single Opening
This is a model for flow through large openings such as doorways through which air can flow in
two directions simultaneously throughout the opening.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Height: The overall height of the opening, not to be confused with the Relative Elevation of flow
paths with which the element is associated.
Width: The width of the opening. Again, before entering the dimension make sure to select the
proper units from the drop down menu.
Flow Coefficient: An experimentally determined value. Experiments by Weber and Kearney
[Weber and Kearney 1989] have shown the default value of 0.78 to work well for most
applications.
Minimum Temperature Difference for Two-Way Flow: A two-way flow is driven by the
temperature (actually air density) difference between the two zones. When this temperature
difference approaches zero the algorithm used for solving the flow tends towards a division by
zero problem. To avoid this undefined situation the two-way model reverts to a one-way power
law model at this "minimum temperature difference" using the opening size to define the orifice
at T set in this field. ContamW uses a default value of 0.01 C.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Two-way Flow Model: Two-opening
This model accounts for two-way flow due to the stack effect acting over the height of a tall
opening. It uses two power law flow models at different heights to approximate a single tall
opening.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
58
Height: The overall height of the opening, not to be confused with the Relative Elevation of flow
paths with which the element is associated.
Width: The width of the opening.
Flow Coefficient: This is an experimentally determined value. Experiments by Weber and
Kearney have shown the default value of 0.78 to work well for most applications.
Description: Field for entering a more detailed description of the specific airflow element.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Backdraft Damper Models
The Backdraft Damper models make it possible to model a feature that has different flow
resistances depending on the direction of the pressure drop, with greatly reduced (or zero) flow
in one direction. Note that there are similar models available for duct flow elements.
Backdraft Damper Model: Q = C(P)^n
This is the volumetric flow form of the backdraft damper airflow model.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Pressure Difference: Enter a flow coefficient and exponent for both the positive and negative
flow directions of the flow path. P>0 refers to the pressure difference across the flow element
that would lead to an airflow in the positive flow direction (See Airflow Path Properties) and
P<0 would lead to a flow in the opposite direction.
Flow Coefficients: The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from IP units to SI units.
Flow Exponents: Flow exponents vary from 0.5 for large openings where the flow is dominated
by dynamic effects, and 1.0 for narrow openings dominated by viscous effects. Measurements
usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Description: Field for entering a more detailed description of the specific airflow element.
Backdraft Damper Model: F = C(P)^n
This is the mass flow form of the backdraft damper airflow model.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Pressure Difference P>0 or P<0: This indicates the direction of predominant flow for the
model.
Flow Coefficients: The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from the IP units to SI units.
59
Flow Exponents: Flow exponents vary from 0.5 for large openings where the flow is dominated
by dynamic effects, and 1.0 for narrow openings dominated by viscous effects. Measurements
usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Description: Field for entering a more detailed description of the specific airflow element.
Self-regulating Vent Model
This element limits the airflow rate in both directions through a flow path with user-defined
limiting air pressure differences. CONTAM implements the self-regulating vent as described in
[Axley 2001]289794217.
Flow is calculated based on the following equations for positive and negative pressure
differences across the element. The positive flow direction is set for each airflow path.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Maximum Flow Rate (Q0) - an empirical value that sets the maximum airflow rate that will be
allowed to pass through the airflow path.
Regulating Pressure (P0) - an empirical value that represents the approximate pressure
difference above which the airflow will be limited to the maximum flow rate Q0.
Reverse Flow Fraction (f) - the fraction of the Maximum Flow Rate to which the airflow
through this element will be limited when the pressure difference is negative across the airflow
path.
Description - You can provide a more detailed note to describe this airflow element.
Fan and Forced Flow Models
These airflow element models enable you to easily create forced airflow elements as airflow
paths between two zones, as opposed to implementing a duct model or simple air handling
system. There are three types of fan models to choose from: constant mass flow rate, constant
volumentric flow rate, and fan performance curve.
Fan Model: Constant Mass Flow Fan
This model describes an airflow element having a constant mass flow rate. This airflow element
will provide the specified constant mass flow rate regardless of the density of the air being
delivered by the fan.
Name: Enter the name you want to use to identify the airflow element. The airflow element will
be saved within the current project and can be associated with multiple airflow paths.
Design (maximum) Flow: Enter the maximum mass flow rate. This value can be modified by
the path schedule.
Description: Field for entering a more detailed description of the specific airflow element.
60
flow rate and the pressure rise into the appropriate edit boxes, the next step is to press the "<<
Insert <<" button. Once you have entered four data points a cubic fit will automatically be
generated and displayed as a line on the graph.
Revising Fan Curve Data Points
To edit existing data points, highlight the line of data to revise in the list of Fan Curve Data to
the left of the Insert, Replace and Delete buttons. The values from that data set will then appear
in the edit boxes to the right of the buttons.
If you need to modify the flow rate, enter the new flow rate in the "Flow rate" edit box and then
press the "<< Replace <<" button. The new data will now replace the old data.
If the Pressure Rise needs to be modified there are two available options:
1. Replace the data point completely. To overwrite an existing pressure rise and refit the fan
curve, select the data set to be modified by highlighting it in the data list and then type the
new pressure rise in the "Pressure rise" edit box then press the "<< Replace <<" button.
2. Change the point used to fit the cubic polynomial but leave the marker for the original data
point intact. With this option you may "tweak" the curve in the event there is some issue
with the originally entered fan curve, such as a point of contraflecture.
Cubic Spline Models
Cubic spline models enable you to create airflow elements based on a curve fit to a user-defined
set of data points. The cubic spline fit used to generate the curve guarantees a first-order
differentiable relationship between flow and pressure as required by the CONTAM solver.
During simulation, the sign of the pressure difference will be based on the Positive Flow
Direction defined for the flow paths with which the spline elements are associated. For example,
a drop in pressure in the direction of positive flow (i.e. Pressure in from zone Pressure in to
zone > 0) will utilize a positive pressure from the spline data.
There are some basic requirements for each of these elements. They require a minimum of four
data points, so a curve will not be displayed until the minimum number of points is entered. All
models require that the slope be greater than zero for all segments of the curve fit. If there is an
error in the curve fit when you click the OK button, an error message will be displayed indicating
the offending segments of the curve and a reason for the error. Segments are numbered from zero
to the number of data points minus one. For example "seg 0: y <= 0" will be displayed if
the segment between the first two data points has a slope less than or equal to zero.
Name: Enter the name you want to use to identify the airflow element.
Description: Field for entering a more detailed description of the specific airflow element.
Curve Data: Create and edit the list of data points to define the curve for the airflow element.
The type of cubic spline element you are editing determines the independent and dependent
variables for the curve. The labels of the list, data entry fields and associated units will change
accordingly, as will the axes of the plot. Use the data entry fields along with the "Add" button to
create new and edit existing data points. Use the "Delete" button to remove the currently selected
data point from the list.
Icon: Choose either the small or large opening icon as appropriate for the specific airflow
element. The icon has no effect on the simulations.
Cubic Spline: F vs P
Mass flow as a function of Pressure drop across the element.
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Cubic Spline: Q vs P
Volume flow as a function of Pressure drop across the element.
Cubic Spline: P vs F
Pressure drop as a function of Mass flow through the element.
Cubic Spline: P vs Q
Pressure drop as a function of Volume flow through the element.
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The rate at which air is recirculated via the implicit recirculation flow path, Wrec, is determined
by
Wrec = min(Wret, Ws - W'o ).
The rate at which outdoor air is brought in by the system via the implicit outdoor airflow path,
Wo, is determined by
Wo = Ws - Wrec.
And the rate at which exhaust airflows to the ambient via the implicit exhaust flow path, Wex, is
determined by
Wex = Wret - Wrec.
Based on this algorithm the amount of outdoor air the system will provide, Wo, will be between
Wo_min and foWs as long as the demand for supply air, Ws, is sufficient to provide this value.
Otherwise the system will provide Ws. When the sum of the supply flows, Ws, exceeds the
sum of the return flows, Wret, the balance is made up of outdoor air. Any excess return air is
exhausted via the implicit exhaust flow path.
the excess return air is exhausted. Similarly if the return flow plus the minimum outdoor airflow
do not sum to the supply flow then outdoor air is brought in to make up the difference.
Outdoor Air Schedule: This is a schedule of the fraction of outdoor air, fo, to be introduced to
the simple air handling system. If the schedule is set to "<none>", then the fraction of outdoor air
defaults to 100 % (100 %outdoor air, 100 % exhaust and no recirculation). You define a new
Outdoor Air schedule by pressing the "New Schedule" button and following the procedure for
editing a Week Schedule.
Name: This drop down box contains the names of all previously defined schedules within the
current project. You can select an existing schedule from the list and use the "Edit Schedule"
button to view and modify its properties, create a "New Schedule" and even select a schedule
from a CONTAM Library via the "Library..." button. You can also choose to not apply a
schedule by selecting "<none>" from the list.
Description: Displays the detailed description of the selected outdoor air schedule.
Outdoor Air Intake Location: These are the absolute X, Y and Z coordinates and units that
define the location of the outdoor air intake of the selected air handling system. These values are
required when using a Wind Pressure and Contaminant (WPC) file (see Working with WPC
Files).
NOTE: You must first check either the Wind Pressures or Contaminant Concentrations check
boxes on the Wind Pressure and Contaminants (WPC) File Parameters dialog box to be able to
access these coordinate input fields (see Create WPC File Dialog).
Air-handling System - Supply System Properties
System Volume: Enter a value for the supply sub-system (implicit supply zone) of the simple air
handler (e.g., supply-side duct work etc.). This volume is very similar to a zone volume and will
be used in the simulation of contaminant transport.
Contaminant Data: All of the defined contaminants in the project will be displayed in this list
box.
Initial Concentration: Select a contaminant from the list and enter the initial contaminant
concentrations for the supply air sub-system of this simple air handling system. Note that only
those species you have selected to be contaminants (to use during simulation) appear in the list.
If a species for which you wish to set an initial concentration does not appear in the list you must
set the "Use in simulation" property of the corresponding species to be true (See Creating
Species and Contaminants). You can reset these initial values through the Run Control Properties
of the Simulation Parameters.
NOTE: Changing the number of contaminants, i.e. those species used in the simulation, will
reset the initial concentrations of all zones to the default contaminant concentrations. You can
reset all of these concentrations via the Run Control Properties as indicated above or individually
here.
Sum of Non-trace Initial Concentrations: This value is provided as a check for you to insure
that you input a reasonable set of initial values when using non-trace contaminants. This value
should be very close to 1.0.
Kinetic Reaction: You define a new kinetic reaction by pressing the "New Reaction" button and
then completing the kinetic reaction matrix. You can edit an existing matrix by selecting the
proper matrix from the drop down box and pressing the "Edit Reaction" button. You must have
previously defined contaminants in order to implement a kinetic reaction.
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Description: Field that shows a more detailed description of the specific reaction if entered
by the user. This description can be modified by pressing the "Edit Reaction" button next to
the description field and then changing the description field for the reaction.
Name: This contains a list of names of all previously created reactions. The reaction selected
from this box will define the behavior of the specific supply system being modified.
Air-handling System - Return System Properties
System Volume: Enter a value for the return sub-system (implicit return zone) of the simple air
handler (e.g., return-side duct work etc.). This volume is very similar to a zone volume and will
be used in the simulation of contaminant transport.
Contaminant Data: All of the defined contaminants in the project will be displayed in this list
box.
Initial Concentration: Select a contaminant from the list and enter the initial contaminant
concentrations for the return air sub-system of this simple air handling system. Note that only
those species you have selected to be contaminants (to use during simulation) appear in the list.
If a species for which you wish to set an initial concentration does not appear in the list you must
set the "Use in simulation" property of the corresponding species to be true (see Creating Species
and Contaminants). You can reset these initial values through the Run Control Properties of the
Simulation Parameters.
NOTE: Changing the number of contaminants, i.e. those species used in the simulation, will
reset the initial concentrations of all zones to the default contaminant concentrations. You can
reset all of these concentrations via the Run Control Properties as indicated above or individually
here.
Sum of Non-trace Initial Concentrations: This value is provided as a check for you to insure
that you input a reasonable set of initial values when using non-trace contaminants. This value
should be very close to 1.0.
Kinetic Reaction: You define a new kinetic reaction by pressing the "New Reaction" button and
then completing the kinetic reaction matrix. You can edit an existing matrix by selecting the
proper matrix from the drop down box and pressing the "Edit Reaction" button. You must have
previously defined contaminants in order to implement a kinetic reaction.
Description: Field that shows a more detailed description of the specific reaction if entered
by the user. This description can be modified by pressing the "Edit Reaction" button next to
the description field and then changing the description field for the reaction.
Name: This contains a list of names of all previously created reactions. The reaction selected
from this box will define the behavior of the specific return system being modified.
Air-handling System - Filter Properties
As the names suggest, outdoor air filters affect the air brought in by the simple air-handling
system from outside the building, while recirculation air filters affect the return air being
circulated back through the air handler. You may either create, edit or delete the filters associated
with the implicit outdoor air and recirculation flow paths of the simple air-handler. Creating a
new filter or modifying an existing one will display the Filter dialog box. For an explanation of
contaminant filters see Working with Filters in the Using CONTAM section of the manual.
Supply and Return Point - System Properties
Design Flow Rate: Enter the design maximum airflow rate for the supply or return.
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AHS: You must associate each supply and return point with an existing simple air-handling
system.
Name: This drop down box contains the names of all previously created Air-handling
Systems. The AHS selected from this box will define the behavior of the specific
supply/return system being modified. Once an existing AHS is selected it may be edited by
pressing the "Edit AHS" button.
Description: Displays the description of the currently selected Simple AHS.
Location: These are the X, Y and RelHeight (Z) coordinates and units for the selected
supply/return point. X and Y are absolute coordinates and RelHeight is relative to the level on
which the supply/return point is located.
These values are required for any supply/return point that is located within a 1D
convection/diffusion zone (see 1D Zone Data). These coordinates will be verified by ContamW
against the axis of the 1D zone in which it is located. This verification will be performed
automatically when you select either the Run Simulation or Create a ContamX Input File
command from the Simulation menu.
Supply and Return Point - Filter and Schedule Properties
Filter: You may either create, edit or delete the filter associated with a supply/return point. This
filter will act upon the associated contaminant(s) as air flows to/from the zone in which the
supply/return point is located. Creating a new filter or modifying an existing one will display the
Filter dialog box. For an explanation of contaminant filters see Working with Filters in the Using
CONTAMW section of the manual.
Schedule: You can associate a schedule with the supply/return point to control the fraction of the
design airflow rate that flows to/from the zone in which the supply/return point is located
according to the time of day and day of the week.
Description: Field that shows a more detailed description of the specific schedule if entered
by the user. You can modify this description by pressing the "Edit Schedule" button next to
the description field and then changing the description field for the schedule.
Name: This drop down box contains the names of all previously created schedules. The
schedule selected from this box will define the behavior of the specific supply/return system
being modified.
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Drawing Ducts
You draw ducts using the duct drawing tool previously described in the Working with the
SketchPad section. After you complete the "finalize drawing object" stage of duct drawing, the
completed duct will appear as an undefined set of red duct icons. The color red indicates that the
duct is not yet defined. Once you have defined the duct components, they will be displayed in
blue. A directional duct segment icon will be displayed within each duct segment, and each
junction and terminal point will be replaced with an icon indicating the type of junction or
terminal point you have defined.
Drawing Duct Segments
ContamW provides certain constraints when drawing ducts to insure that a valid duct system will
be drawn that conforms to the underlying model of nodal equations upon which CONTAM is
based. When drawing a duct, you cannot cross over a line that you are currently drawing. Ducts
can cross over walls, but you cannot draw ducts over any other building component icons. After
each duct segment is drawn, the ends of the segment will be automatically replaced by either an
undefined terminal point or junction icon. You can only begin or end a duct segment drawing in
an unoccupied SketchPad cell or on an undefined duct icon. For this reason, you are advised to
draw the entire duct system, on a given level, before you define the individual duct segments. If
you cross over a previously drawn duct segment, either defined or undefined, while drawing a
new duct segment, no junction will be placed where the two segments cross.
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Vertical duct segments do not appear directly on the SketchPad, because the SketchPad displays
only plan-view drawings. Vertical duct segments are associated with vertically connected
junctions or terminal points. These vertical junction and terminal icons provide access to the
properties of the vertical segments that are located below the level upon which the vertical
junction or terminal appears.
Drawing Duct Junctions
Undefined horizontal duct junction icons are drawn automatically at the intersections of the ducts
after you finalize drawing a duct. Each time you begin or end drawing a duct segment upon an
undefined duct segment, junction or terminal point, ContamW will automatically provide an
undefined junction icon if there is not yet one at the junction location.
All vertical junctions are connected to vertical duct segments that are located below the level
upon which the vertical junction appears. You can create a vertical junction that is isolated from
other ducts on a level that is connected either up, down or both up and down to ductwork on
adjacent levels. To do this, finalize the drawing object immediately after setting the initial
location of the duct object. To do this, you simple press LMB (double click) or twice at the
desired location on the SketchPad when you have the duct drawing tool selected. This will place
a single undefined terminal point icon within the SketchPad cell. You can later define this
undefined terminal point icon as the specific type of junction that you need and associate it with
a vertical duct segment.
Drawing Duct Terminal Points
Undefined horizontal terminal point icons are automatically drawn by ContamW at the end of
each duct segment that does not end on another previously drawn duct icon.
You can also create terminal points that are isolated from other ducts on a level but connected
either up or down to ductwork on an adjacent level by finalizing the drawing object immediately
after setting the initial location of the duct object. To do this, you simply press LMB (double
click) or twice at the desired location on the SketchPad when you have the duct drawing tool
selected. This will place a single undefined terminal point icon within the SketchPad cell. You
can later define this terminal point as the specific type that you need and associate it with a
vertical duct segment.
Coloring Duct Systems
You can use the Duct System Coloring Tool to automatically color sections of the duct system
that are associated with fans (forced flow elements) within the duct. You access the Duct System
Coloring Tool via the ViewDuct Coloring... menu command. This will display the Duct
System Coloring dialog box that contains a list of all duct segments that contain fans (forced
flow elements). Select the fan whose ducts you wish to color. Set the inlet side, outlet side and
fan segment colors, then click the Set Colors button to have ContamW trace the duct system on
the inlet and outlet sides of the fan segment and set the colors.
Use the ViewColor Ducts menu command to toggle the colors in which ducts are displayed
on the SketchPad between the custom duct colors and the default color.
Deleting Ducts
Deleting currently defined ducts is a two-step process. That is, if you want to delete a duct
segment, junction or terminal, you must first undefine the item. To undefine a duct segment you
must highlight the special duct segment icon (that indicates the positive flow direction) and press
the Delete key or select Delete from the Edit menu. This will highlight the entire duct segment
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from its two end-points and prompt you to confirm the undefine operation by displaying a
message box. Once you undefine a duct segment, it will again be displayed in red and the special
duct segment icon will be converted back to a straight segment icon. To delete the duct segment
you highlight any portion of the undefined segment or associated undefined terminal and
perform the deletion. The entire segment to be deleted will be highlighted, and you will be asked
to confirm the deletion.
There are several items you should consider when deleting ducts. You cannot delete an
undefined junction that is still connected to a defined duct segment. If you delete a junction that
is between two undefined segments, the junction will be removed to form a single segment. You
cannot delete a terminal without deleting its associated segment.
Deleting the ducts defined on the SketchPad does not delete any duct flow elements that you may
have defined. These flow elements can only be deleted using the CONTAM Library Manager,
accessible through the Data menu for each type of data element.
Modifying Ducts
In order to modify the layout of a duct system, you must undefine any portions to which you
want to connect a new duct (i.e. form a junction). To modify the parameters of a duct segment,
junction or terminal, you use the icon definition method to display its properties and make the
desired changes. You do not have to undefine the item to change its properties, only to change
the physical layout.
To remove a junction from between two segments, you should first undefine the two duct
segments, remove the junction and then redefine the newly formed longer segment. To split a
segment into two segments, double-click the LMB with the duct drawing tool on the undefined
segment where you wish to place the junction.
Defining Ducts
After you draw a duct, you must define each duct segment, junction, and terminal point. Each of
these duct components is defined using the icon definition procedure (See Defining Building
Component Icons) to display and edit the properties of the component.
Defining Duct Segments
You define each duct segment by using the icon definition procedure on any portion of an
undefined duct segment. This will display the "Duct Segment Properties" property sheet.
Detailed descriptions of all duct segment properties are given in the Duct Segment Properties
section of this manual. Once you have defined the properties of a duct segment, a special icon
will be displayed indicating the positive flow direction of the duct segment (see Directional Duct
Segment Icons). From now on, you use this icon to access the properties of the duct segment.
When defining a duct segment, you must associate the segment with a duct flow element.
CONTAM combines duct flow element data with segment specific data such as length and
dynamic losses to determine the frictional resistance, volume, and leakiness of a particular duct
segment.
You can also define contaminant filtering properties of duct segments. You can define a filter for
each contaminant contained in your CONTAM project. A duct filter could be used, for example,
to simulate the deposition of particles on the inside surface of a duct.
As previously mentioned, duct flow elements contain duct leakage information. The CONTAM
model implements all leakage at the junctions and terminals of a duct segment. This means that
half of the leakage associated with a duct segment occurs at each end of the segment. The
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leakage between a junction and the zone in which the junction is located (as determined on the
SketchPad) is a function of the duct element leakage characteristics and the pressure difference
between the junction and the zone. You should consider this leakage model when accounting for
leakage of a duct that passes through multiple zones. You should put a least one junction (or
terminal) in each zone within which you want to account for duct leakage.
Directional Duct Segment Icons
These are the icons that indicate a defined duct segment. The direction that the small arrow
points indicates the positive flow direction of the duct segment.
Duct Flow Element Name: You may select a previously defined airflow element from those
contained in the Name list. Click the "New Element" button to define a new airflow element. To
view or modify airflow element data click the "Edit Element" button. Every duct segment must
have an airflow element associated with it. This field may not be left blank.
Model Summary: This summarizes the information associated with the duct flow element
currently displayed in the Name field.
Duct Segment - Segment Properties
Segment Data:
Duct segment length: Enter the length of the duct segment. This will be used along with the
cross-sectional area to determine the volume of the duct segment.
Sum of loss coefficients: This is the sum of all dynamic loss coefficients due to junction
losses and all fittings in the segment. This term only applies to the Darcy-Colebrook duct
flow element model (see Ducts in the Airflow Analysis section).
Positive Flow Direction: In the case of fans and backdraft dampers it is necessary to know
which direction is defined as positive. The arrows represent the positive direction for
pressure drop and airflow.
Color: You can set the color of each segment individually here, or you can use the automated
Duct System Coloring Tool to color sections of ducts related to forced flow elements within the
duct system. You access the Duct System Coloring Toolvia the ViewDuct Coloring... menu
command (See Drawing Ducts).
Segment Summary Information: This field displays information about the selected ductflow
element.
Duct Segment - Filter & Schedule Properties
Filter: You may select a previously defined filter from those contained in the associated Name
list. Click the "New Filter" button to define a new filter. Click the "Edit Filter" button to view or
modify existing filter data. Setting this field to <none> indicates no filter for this airflow path.
(See Contaminant Filters under Working with Contaminants)
Schedule: If there are previously defined schedules within the current project, you may select
one from the Name list. Click the "New Schedule" button to define a new schedule. To view or
modify an existing schedule click the "Edit Schedule" button. Setting this field to <none>
indicates no schedule. (See Working with Schedules)
Duct Flow Element - Shape, Size and Leakage
Duct Shape: You can implement several different shapes of ducts including: round, rectangular,
oval or other. Select the shape you want and the appropriate dimensions will be made available
for you to enter under the Duct Dimension parameters.
Duct Dimensions: The data entered here is dependent on the duct shape. For circular ducts, the
diameter is the only parameter needed. Rectangular ducts require you to enter the width and
height, and oval ducts require you to input the major and minor dimensions. The other option
allows you to enter a perimeter and a flow area to define the dimensions for a duct of any other
shape.
Leakage: Leakage of air between the duct and the surrounding zone may be described in terms
of a leakage rate (per unit surface area of duct segment) at a given pressure or by use of the
leakage classification. If you enter a leakage rate and a pressure difference, the value for the
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leakage class is automatically calculated by ContamW and placed in the "Leakage Class" field.
Similarly, if you input a leakage class, a default value of 250 Pa is used for the pressure
difference, and a leakage rate will be calculated based on the pressure difference and the leakage
class you entered. See [ASHRAE 2005 Chapter 35]
Duct Flow Element Types
This is a list of available duct flow elements or mathematical models that provide the
relationship between airflow and pressure difference for duct segments. See Airflow Analysis in
the Theoretical Background section of the manual for mathematical details.
Darcy-Colebrook Model
The most common model to use for CONTAM duct systems is the Darcy-Weisbach relation and
Colebrook's natural roughness function.
Darcy-Colebrook Model
Powerlaw Models
Three versions of the powerlaw model are included:
1. Orifice resistance model
2. Resistance: F = C(P)^n (mass flow)
3. Resistance: Q = C(P)^n (volume flow)
Forced Flow Models
Three types of forced flow models are included:
1. Fan - performance curve
2. Constant mass flow
3. Constant volume flow
Backdraft Damper Models
The Backdraft Damper models make it possible to model a feature (e.g. a smoke control damper)
that has different flow resistances depending on the direction of the pressure drop, with greatly
reduced (or zero) flow in one direction.
1. Backdraft Damper: F = C(P)^n (mass flow)
2. Backdraft Damper: Q = C(P)^n (volume flow)
Cubic Spline Flow Models
These models provide the ability to create user-defined duct flow elements based on a set of data
points to which a cubic spline curve is fit. There are four versions that relate either mass flow or
volume flow to pressure difference across the flow element (or vice versa). The cubic spline
curve fit insures that the relationship between flow and pressure is differentiable as required by
the CONTAM airflow solver.
1. F vs P: Mass flow rate as a function of Pressure difference
2. Q vs P: Volume flow rate as a function of Pressure difference
3. P vs F: Pressure difference as a function of Mass flow rate
4. P vs Q: Pressure difference as a function of Volume flow rate
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Darcy-Colebrook Model
This model uses the Darcy-Weisbach relation and Colebrooks natural roughness function
[ASHRAE 2005 p 35.7].
Name: Enter a unique name you want to use to identify the duct flow element. The element will
be saved within the current project and can be associated with multiple duct segments.
Description: Field for entering a more detailed description of the specific duct flow element.
Roughness: The flow resistance due to friction is calculated from Colebrooks function and the
roughness factor [ASHRAE 2005 p 35.7]. Some typical values are given here.
Smooth
Medium Smooth
Average
Medium Rough
Rough
0.03 mm
0.09 mm
0.15 mm
0.90 mm
3.00 mm
0.0001 ft
0.0003 ft
0.0005 ft
0.0030 ft
0.0100 ft
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
Powerlaw Model: Orifice Area
This airflow element allows you to describe the airflow through an orifice, and ContamW
converts it to a powerlaw relationship.
Name: Enter a unique name you want to use to identify the duct flow element. The element will
be saved within the current project and can be associated with multiple duct segments.
Description: Field for entering a more detailed description of the specific duct flow element.
Flow Exponent (n): Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Discharge Coefficient (C): The discharge coefficient is related to the dynamic effects and is
typically close to 0.6 for an orifice and slightly higher for other openings in buildings.
Hydraulic Diameter: The hydraulic diameter is equal to (4 Area / Perimeter). For square
openings this equals the square root of the area, and for long thin openings it is two times the
width.
Reynolds Number: The transition from laminar flow to turbulent flow occurs over a very broad
range of Reynolds numbers with the flow being fully laminar approximately below 100.
Note: The hydraulic diameter and Reynolds number have little impact on the calculations.
Generally you should use the default values except for special circumstances where they need to
be modified. The values above describe the flow characteristics of an orifice in typical operation.
At extremely low pressure drops the use of the powerlaw model leads to a division by zero
during the network solution process. ContamX avoids this problem by changing to a linear
model in this region. The model is based conceptually on the flow changing from turbulent to
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laminar at very low pressures. The Hydraulic diameter and Reynolds number are used to
determine a point where the model changes from the powerlaw to linear.
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
Powerlaw Model: F=C(P)^n
This airflow element allows you to directly enter the coefficients C and n for the mass flow
version of the powerlaw model.
Name: Enter a unique name you want to use to identify the duct flow element. The element will
be saved within the current project and can be associated with multiple duct segments.
Description: Field for entering a more detailed description of the specific duct flow element.
Flow Coefficient (C): The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from IP units to SI units.
Flow Exponent (n): Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
Powerlaw Model: Q=C(P)^n
This airflow element allows you to directly enter the coefficients C and n for the volumetric flow
version of the powerlaw model.
Name: This is the name you give to this airflow element. This name must be unique within a
project.
Description: Field for entering a more detailed description of the specific duct flow element.
Flow Coefficient (C): The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from IP units to SI units.
Flow Exponent (n): Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
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Name: Enter a unique name you want to use to identify the duct flow element. The element will
be saved within the current project and can be associated with multiple duct segments.
Description: Field for entering a more detailed description of the specific duct flow element.
Design (max) Flow: Enter the maximum volume flow rate. You can use the duct segment
schedule to modify this value.
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
Backdraft Damper: Q=C(P)^n
This is the volumetric flow version of the Backdraft Damper duct flow element. The Backdraft
Damper models make it possible to model a feature (e.g. a smoke control damper) that has
different flow resistances depending on the direction of the pressure drop, with greatly reduced
(or zero) flow in one direction.
Name: Enter a unique name you want to use to identify the duct flow element. The element will
be saved within the current project and can be associated with multiple duct segments.
Description: Field for entering a more detailed description of the specific duct flow element.
Pressure Difference: Enter a flow coefficient and exponent for both the positive and negative
flow directions of the duct segment. P>0 refers to the pressure difference across the flow
element that would lead to an airflow in the positive flow direction (See Duct Segment
Properties ) and P<0 would lead to a flow in the opposite direction.
Flow Coefficients: The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from IP units to SI units.
Flow Exponents: Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
Backdraft Damper: F=C(P)^n
This is the mass flow version of the Backdraft Damper duct flow element. The Backdraft
Damper models make it possible to model a feature (e.g. a smoke control damper) that has
different flow resistances depending on the direction of the pressure drop, with greatly reduced
(or zero) flow in one direction.
Name: Enter a unique name you want to use to identify the duct flow element. The element will
be saved within the current project and can be associated with multiple duct segments.
Description: Field for entering a more detailed description of the specific duct flow element.
Pressure Difference: Enter a flow coefficient and exponent for both the positive and negative
flow directions of the duct segment. P>0 refers to the pressure difference across the flow
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element that would lead to an airflow in the positive flow direction (See Duct Segment
Properties ) and P<0 would lead to a flow in the opposite direction.
Flow Coefficients: The coefficients may only be expressed in SI units due to the conversion
method used. Use the following conversion to convert from the IP units to SI units.
Flow Exponents: Flow exponents vary from 0.5 for large openings where the flow is
dominated by dynamic effects, and 1.0 for narrow openings dominated by viscous effects.
Measurements usually indicate a flow exponent of 0.6 to 0.7 for typical infiltration openings.
Shape Size and Leakage: You must enter data to physically describe each duct airflow element.
You input these values on the Shape Size and Leakage property page associated with each duct
airflow element.
Duct Junction and Terminal Properties
This section provides detailed descriptions of the specific duct junction and terminal properties.
The following sections are the context-sensitive help topics that you can access by pressing F1
when working with property pages of the "Duct Junction Properties" property sheet.
Duct Junction and Terminal - Junction Properties
Junction Number: This number is automatically generated by ContamW for identification
purposes and is unique to each junction. ContamW will renumber junctions and terminals when
saving a project if you have added or removed any junctions or terminals. These icons are
numbered starting at the top level in the upper left hand corner of the SketchPad moving left to
right and down the SketchPad then proceeding down through each level in the same manner.
Relative Elevation & Temperature: The elevation and temperature of the junction are used to
determine how the duct flow responds to and influences the building stack effect. Enter the
height of the midpoint of the junction or terminal point relative to the current building level.
Enter the temperature you wish the junction or terminal to use during simulation.
Note that you can have ContamX calculate duct temperatures when performing simulations using
the 1D Duct Model with the Short Time Step Method. See Contaminant Numerics Properties in
the Working with Simulations section.
Junction: If you are creating a junction that connects two duct segments, then select the type of
connection to create here. Items will be enabled/disabled depending on the valid connection
types.
Define Downward Duct: You define vertical duct segments as downward running ducts
accessed via the duct junction at the top of the downward segment. Press the "Define
Downward Duct" button to define vertical segments. The SketchPad duct icons that are
connected to the defined vertical duct will change to indicate the type of vertical connections
associated with the junction, i.e., connected downward, upward or both (see Junction and
Terminal Icons).
Terminal: If you are creating a terminal at the end of a duct segment, then select the type of
connection to create here. Items will be enabled/disabled depending on the valid connection
types.
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Location: Enter the absolute X and Y coordinates and units for the selected junction. The Z
coordinate will be taken as the Relative Height of the junction with respect to the building level
on which the junction is located.
These values are required for terminals located in the Ambient zone when using a Wind Pressure
and Contaminant (WPC) file (see Working with WPC Files) or for junctions and terminals
located within a 1D convection/diffusion zone (see 1D Zone Data). These coordinates will be
verified by ContamW against a WPC file or the axis of the 1D zone in which the junction or
terminal is located. This verification will be performed automatically when you select either the
Run Simulation or Create a ContamX Input File command from the Simulation menu.
Duct Junction and Terminal - Wind Pressure Properties
This set of properties is available only for those terminals that are located in the ambient zone
and thus potentially subject to wind effects.
Wind Pressure Option: There are three wind pressure options for duct terminals located in an
ambient zone:
1. No wind pressure
2. Constant pressure
3. Pressure dependent on wind speed and direction
When you select one of the above options, the following data entry options that correspond to the
wind pressure option that you selected will be made available for your input.
Constant Pressure Data: Enter a constant wind pressure (wind speed and direction
independent).
Variable Pressure Data: Variable wind pressures are computed from the product of the
following three parameters:
1. The dynamic pressure of the wind at some reference height.
ContamX will determine this pressure based on either the steady state wind data (See
Wind Properties) or the transient wind data from a weather file (See Defining Transient
Weather and Wind).
2. A coefficient accounting for local terrain effects (Wind Pressure Modifier).
3. A pressure coefficient accounting for relative wind direction (Wind Pressure Profile).
Wind Pressure Modifier: CONTAM uses this value to account for differences between
wind velocity profiles at the building site and that at a measurement location, e.g. an airport
weather station (See Working with Weather and Wind). CONTAM only requires this value if
you are implementing Variable Wind Pressure for an airflow path. ContamW will provide a
default value for this based on the data entered via the Weather and Wind Parameters
Property Page or you can override the default value for a particular airflow path.
Wall Azimuth Angle: Enter the direction the wall faces (clockwise from north).
Profile: The wind pressure profile accounts for the wind direction effects. You may select a
previously defined wind pressure profile from those contained in the Name list. Click the
"New Profile" button to define a new wind pressure profile. To view or modify wind pressure
profile data, click the "Edit Profile" button. After you press the "New Profile" or "Edit
Profile" button, the Wind Pressure Profile page will be displayed with a graphical
representation of the profile.
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Balance Terminal: Check this box if you would like ContamX to include this terminal in the
duct balancing procedure.
Design Flow Rate: Provide the design airflow rate for which you want ContamX to
determine a Balance Loss Coefficient. Specify positive values for supply flow terminals, i.e.
airflow from the duct system to the zone in which the terminal is located, and negative values
for return air terminals.
Max Balance Coefficient: Provide a maximum value for the Balance Loss Coefficient
below. This will be used to provide warning information if the Balance Loss Coefficient
determined by the automated balancing procedure of ContamX exceeds this value.
Balance Loss Coefficient: This is the loss coefficient determined via the automated
balancing procedure of ContamX. You can also modify it "manually." As noted above, this
value will be used to determine the effective loss coefficient (Ce) for the terminal.
Filter and Schedule
Junctions and terminals differ with respect to Filters and Schedules. Junctions can not have
filters associated with them and only the temperature of the junction can be scheduled or
controlled. Beginning with CONTAM version 2.4, terminals can be both filtered and scheduled.
The terminal temperature and loss coefficient can be scheduled (or controlled), although only
one type of schedule can be applied at a time.
Filter: You may either create, edit or delete the filter associated with this terminal. Creating a
new filter or modifying an existing one will display the Filter Properties dialog box. Use this
dialog box to create and edit filter elements as needed. For an explanation of contaminant filters
see Contaminant Filters in the Using CONTAM section of the manual.
Schedule: As of CONTAM version 2.4, terminals consist of both a duct segment and a terminal
junction during simulation. Each of these are schedulable items. You can select to schedule
either the Loss coefficient of the segment or the Temperature of the junction. The list of
schedules will contain those types (unitless or temperature) of schedules that exist in the project.
If there are previously defined schedules within the current project, you may select one from the
Name list. Click the "New Schedule" button to define a new schedule. To view or modify an
existing schedule click the "Edit Schedule" button. Setting this field to <none> indicates no
schedule. (See Working with Schedules)
Balancing Duct Systems
In CONTAM you can balance duct systems yourself by providing balance points, e.g., orifice
flow elements, at desired locations, or you can have CONTAM balance the system for you.
Versions of CONTAM prior to version 2.4 required you to balance the system manually by
adjusting the resistance of duct flow elements or local loss coefficients at desired balancing
points. Beginning with version 2.4, CONTAM provides the ability to automatically balance duct
systems using CONTAM duct terminals. See Duct Junction and Terminal - Terminal Properties
and Working with Simulations.
Automated Duct Balancing Procedure
Automated duct balancing is another mode of simulation in ContamX. When you initiate a
balance, ContamW will perform a pre-simulation check on the PRJ file and, if the check is
successful, save the PRJ file and execute ContamX. ContamX will perform its own set of prebalance checks to determine if a valid set of conditions has been defined. If this check is
successful, then the automated balancing mode of ContamX will be initiated. If the pre-check of
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ContamX is unsuccessful, an error message will be displayed indicating the nature of the precheck failure.
The automated procedure establishes relationships between fan elements and duct terminals by
first performing a steady state airflow simulation for the entire building system as defined, i.e.,
duct balance coefficients having not yet been modified. If there are no errors in the system
configuration, it then replaces fan elements with constant flow balancing fans, initializes fan
flow rates to the summation of design flows of associated terminals (the minimum flow required
for balancing), performs an airflow simulation, and checks for convergence of the duct balance
by comparing calculated airflows with design airflows for all balance terminals. If convergence
is not met, then the balance coefficients are adjusted (only increased) and the procedure is
repeated until either convergence or the maximum number of iterations are performed. Upon
completion of the balancing, ContamX will create a simulation results file (SIM file) that
contains the calculated airflow results of the balanced system (see items 0 and 1 below).
The automated balance procedure generates a duct balance result file which has the same name
as the project file but having the BAL extension. The contents of the balance report file will vary
depending on the results of the automated balance procedure (See Results Files in the Working
with Results section).
The basic steps to use the duct balancing feature are outlined below:
Draw duct system define segments, terminals and fans. Be sure to use separate fan flow
elements for each fan, as the balance procedure may need to adjust the flow rates individually
to achieve desired results. In order to obtain as realistic and reasonable results as possible,
you should provide known loss coefficients at each terminal and junction throughout the
system. Otherwise, the balancing procedure might not produce desired static pressures within
the system although design flows will be achieved.
Designate balancing terminals and set design airflow rates for each.
Observe feedback from balance procedure. There are six possible results. If the one of the
first two results (Success or Non-convergence) is obtained, a simulation results file will be
created that contains the airflow rates calculated based on the calculated balance coefficients.
If one of the four error results is obtained, then the simulation results are for the pre-balance
steady state calculation of the system as defined. The following list provides the six different
outcomes of the balance and their associated completion code as it will appear in the first line
of the duct balance results file.
0. Success: The balance procedure completed succesfully. You will be prompted to copy
balance coefficients to terminals and balance flow rates to constant flow fan elements when
using such elements to model the fan. Once you have responded to the prompts, you can
review the results of the balance on the SketchPad. Airflow rates from the terminals will be
displayed via the SketchPad results display method. Balance coefficients will not be saved
until you save the project, so you can maintain the original pre-balance file by saving the
post-balance file under a new name.
Performance curve fan elements are treated differently from constant flow fan elements,
because they can not be directly modified to provide the balance flow rates. If using fan
curve elements, consult the balance report file for setting the fan speed ratio to provide
design flow rates. Use the value reported to provide a speed ratio via a control signal or
schedule value to achieve the balance flow with the fan. If a value of 0.0 is reported, then the
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fan curve is not capable of providing the desired flow via a reasonable fan speed ratio and
pressure rise. In this case it is likely that a different fan should be used.
1. Non-convergence: The balance procedure was not able to obtain the desired balance flow
rates for all of the terminals within the preset number of iterations. You can choose to accept
the calculated balance coefficients and run the balance procedure again with the modified
coefficients as initial values. The balance report file will provide a relative flow coefficient
equal to the calculated flow rate divided by the design flow rate.
2. Error: No terminals to balance: There are no terminals having the Balance Terminal
option selected. Be sure to check the Balance Terminal check box to designate terminals to
be balanced.
3. Error: Invalid flow direction(s): This error occurs when the balance terminals associated
with a single fan have opposing design flow directions. Be sure the design flow direction of
all terminals matches that of the associated fan: positive design flow rates are out of the
terminal into the zone in which the terminal is located, and negative design flow rates are
into the terminal from the zone. The fan flow direction is user-selectable via the duct segment
icon of the associated fan.
4. Error: Failed to terminate link(s) at a fan: This error occurs when one or more balance
terminals can not be traced back through the duct system (links) to a forced flow element
(fan) within the duct system.
5. Error: Fan system includes supply and return terminal: This error occurs when a given fan
has balance terminals both upstream and downstream of the fan. Be sure to only attempt to
balance terminals on either the upstream or downstream side of a fan.
DUCT BALANCING NOTES:
Duct balancing is performed under consideration of the entire building system. When the
airflow calculation is performed during each iteration of the balancing procedure, the
resistances between zones are included. Interzonal resistances that are relatively high can
impact the balancing results.
During duct balancing, all junction temperatures are set to 20 C. Ambient conditions are
established by the steady state weather data with the exception that wind is set to 0 m/s.
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Control Elements
A control network can consist of many different control nodes, each of which is defined by a
control element. There are several different types of control elements provided, such as a report
element, that can be used to convert dimensionless sensor values to engineering units;
mathematical elements to perform simple mathematical and logical operations on input signals;
and classical control elements such as proportional/integral, band and limit controls. There is a
phantom control element that can be used to reference an existing control node, which is
convenient for linking nodes that may be on different levels of a building or simply too far apart
to conveniently draw a physical link. Each of these element types is described in detail in the
Control Element Types section. While every node in the control network must refer to a single
control element, multiple nodes can refer to the same control element using the phantom
node/control element.
Collections of control elements can be grouped into Control Super Elements, which can be
stored in CONTAM Library files and shared within and between projects. Super elements can
reduce the amount of drawing of repetitive control logic and enable the creation of custom
reusable sensors and control algorithms.
Drawing Controls
You draw controls using the links drawing tools previously described in the "Working with the
SketchPad" section. When you finalize the drawing of a set of control links, the appropriate icons
will be placed upon the SketchPad depending on where the link originates and where it
terminates. For example, if you begin drawing a control link directly on a zone icon, a sensor
icon will be placed adjacent to the zone icon, and if you terminate a control link on an airflow
path, an actuator icon will be placed adjacent to the airflow path icon (See Figure below).
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Deleting Controls
Deleting currently defined controls is a two-step process and can only be performed when
ContamW is in the normal mode, i.e., not viewing SketchPad results. That is, if you want to
delete a control link, sensor, actuator or node, you must first undefine the item. To undefine a
control you must highlight a control node or link and press the Delete key or select Delete from
the Edit menu. This will highlight either a single node (if no output signals) or a link segment
and prompt you to confirm the undefine operation by displaying a message box. Once you
undefine a control node or link segment, it will again be displayed in red. To delete the control
node or link you highlight any portion of the undefined node or link segment and perform the
deletion. The entire portion to be deleted will be highlighted, and you will be asked to confirm
the deletion. If you try to delete a node that is referenced by a phantom control element, you will
be warned. Deleting such elements prior to deleting those phantom nodes that reference them can
cause problems.
Hiding Controls
If there are controls in your project, you can hide them on the SketchPad. Use the View
Control Links menu command to toggle the display of the control network on and off.
Modifying Controls
To modify the parameters of a defined control node, you use the icon definition procedure (See
Defining Building Component Icons) to display its properties and make the desired changes. You
can not move and copy controls. To do this you must delete and redraw your control network,
therefore careful planning is advised in laying out your control networks.
Defining Controls
You must define all control nodes and sensor icons in order to perform a simulation. Control
links will be defined automatically upon definition of the node or sensor from which they
emanate. Generally, you should define control nodes in the direction of information flow
indicated by the link arrows. Define control nodes and sensors using the icon definition
procedure (See Defining Building Component Icons) to display and edit their properties.
Sensors
When you double-click an undefined sensor icon, the Control Sensor definition dialog box will
appear. The parameters will either be those for a zone sensor or flow path sensor depending on
the building component with which the sensor is associated.
As noted in the Drawing Controls section above, sensor icons can be placed automatically when
you begin drawing a control link on a sensible icon, e.g., zone or flow path. With CONTAM
version 2.4, you can now define zone sensors within any blank cell inside of a zone. This
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increases the previous limit of four zone sensors per zone and is done by selecting the "Sensor"
control element type when defining a control node as presented in the following sub-section.
Control Nodes
Double-clicking on an undefined control node icon will display the Control Element Types
dialog box from which you select the type of control element you wish to define. Control
elements can be categorized by the number of inputs that can be associated with them: unary,
binary and multiple. Therefore, when the Control Element Types dialog is displayed, various
types will be enabled/disabled for selection depending on the number of inputs that you have
drawn into the currently selected node.
Once you select the type of element you want to create, you assign values to the parameters of
the control elements. All control elements have an optional Name parameter with the exception
of the phantom for which the Name parameter will be used to reference the name of another
existing element. The name parameter is only required if you want to reference the element with
a phantom node.
Each element also has an optional Description field, which is filled in with a default value when
you create an element, but you may change the description. The description will be displayed in
the status bar when you highlight the control node on the SketchPad. Many of the elements do
not have any parameters other than the Name and Description, because they simply perform a
predetermined operation on the input(s) to the node, e.g., the "+ Add" element simply takes two
inputs, adds them and provides the results as an output signal. Other control elements have
additional parameters required to define their behavior, e.g., the "Constant" element has a value
parameter use to specify the constant value of the output signal from the control node.
Time Constant: sensor response time constant in units of seconds. ContamX will use this to
calculate a delay factor.
Delay = e-t/
The sensor output is calculated from the converted Sensor Challenge Value for the current
time step t (Out), the output from the previous time step t-t, and the Delay value as follows:
Output(t) = Out + [Output(t-t) Out] * Delay
Location: These parameters only apply to Mass fraction sensors associated with 1D zones.
Select whether you want the sensor to provide the Zone Average concentration of a 1D zone or
the value within a single 1D Cell of a 1D zone. The 1D cell option is only effective when
performing a simulation using the short time step method otherwise the sensor will provide a
value based on the zone average.
X, Y and Rel Elevation (Z) are the coordinates and units for the selected sensor. X and Y are
absolute coordinates and Rel Elevation is relative to the level on which the sensor is located.
These values are required for any sensor that is located within a cell of a 1D convection/diffusion
zone (see 1D Zone Data). If the sensor is to be located within a particular cell of a 1D zone, then
these coordinates will be verified by ContamW against the axis of the 1D zone in which it is
located. This verification will be performed automatically when you select either the Run
Simulation or Create a ContamX Input File command from the Simulation menu.
Description: Use this to describe the sensor in detail. This description will be displayed in the
status bar when you highlight the sensor icon. The description defaults to either "zone sensor" or
"path sensor."
Phantom control
Use this control element to reference a named control element that already exists elsewhere
within your project. Phantom nodes are useful when you need a control signal from a node that is
located remotely upon the SketchPad or when you are implementing one of the multiple-input
elements. This is useful in referencing a node on another level of a building, because ContamW
does not allow you to draw links between building levels. This can also be used to "cascade"
inputs into the multiple-input sum and average controls when you want to sum or average more
than three inputs or remotely located, named inputs.
Schedule
Use this control element to apply a schedule via the control network. A schedule can be applied
to airflow paths, simple air handling systems, inlets and outlets of simple air handling systems
and source/sinks. Control schedules will override schedules that are defined as a parameter of an
element. You can select an existing schedule or create a new one (See Creating Schedules).
Constant
Use this control element to define a simple constant. The constant is useful as input to other
control elements such as the mathematical, limit and switch controls.
Modifier
Use this control element to modify an input signal by providing a Gain and Offset parameter.
The input signal will be modified according to the following equation.
output = (input Offset) * Gain
The parameters for the Modifier control are:
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Sum and Average Sum or average multiple input signals and provide result as output
signal. Three signals can be directly input to using links drawn into the control node icon,
and more can be cascaded through the use of phantom nodes.
EXP(x) raise e to the power of x.
LN(x) calculate natural logarithm of x.
LOG10(x) calculate log base 10 of x.
POW(x,y) raise x to the power of y where x is input1 and y is input2.
SQRT(x) calculate the square root of x.
Polynomial(x) calculate polynomial of x based on user-defined polynomial coefficients.
SIN(x) calculate sine of x.
COS(x) calculate cosine of x.
TAN(x) calculate tangent of x.
MOD(x,y) calculate the floating point remainder of x divided by y where x is input1 and y
is input2.
CEIL(x) calculate the smallest integer that is greater than or equal to x.
FLOOR(x) calculate the largest integer that is less than or equal to x.
Limit switches
Limit switches provide the ability to set an output signal to either on or off (0 or 1) based upon
the difference between the two input signals.
Lower limit switch
output = 1 IF ( input1 < Limit )
[Limit = input2]
output = 0 otherwise.
Upper limit switch
output = 1 IF ( input1 > Limit )
[Limit = input2]
output = 0 otherwise
The band switches incorporate the control parameter, Band width, to provide a dead band
for the on/off control.
Lower band switch
output = 1 when input1 rises above input2 + Band width
output = 0 when input1 < input2
input2 is the lower limit of the band
Upper band switch
output = 1 when input1 falls below input2 Band width
output = 0 when input1 > input2
input2 is the upper limit of the band
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Limit controls
Limit controls provide the ability to set an output signal to a value ranging from 0.0 to 1.0 based
upon the difference between the two input signals. These would typically be used to provide an
error signal to a proportional controller.
Lower limit control
output = input2 - input1
Upper limit control
output = input1 - input2
The upper and lower limit controls can be used to prepare an error signal for the proportional
controls. If the input signal to an upper limit control is greater than the limit value, a positive
output results; e.g., if a contaminant concentration is too high, the positive signal could activate
an airflow device. If the input signal to a lower limit control is lower than the limit value, a
positive output results; e.g., if the air flow through an opening is too low, a positive signal could
activate a fan to provide the required flow.
Proportional and ProportionalIntegral
Proportional control This is a model of a simple proportional controller where the input
signal is an error signal that is typically a sensed value minus a set-point value which is obtained
by using other control functions, e.g. the constant control. The input signal is multiplied by the
proportionality constant parameter of the control, Kp. The output signal is limited to values
between 0 and 1, so you should set the proportionality constant accordingly. The output signal
could then be modified as required using other control elements.
output = input Kp
Proportional-Integral control This is a model of a simple P-I controller where the input
signal is an error signal. The output signal is limited to values between 0 and 1 and is modified
by the control parameters Kp and Ki according to the following equation.
output = output* + Kp (input - input*) + Ki (input + input*)
where output* and input* are the values of output and input at the previous time step. The Kp
and Ki factors must be tuned for the specific problem and time step. This is similar to an
"incremental" P-I algorithm described in equations (17-37) and (18-3) of [Stoecker and Stoecker
1989].
Scheduled Delay
This control element provides the ability to simulate time delays associated with the ramping
up/down of system components changing between states, e.g., the spin down of a fan or the
opening/closing of a damper. The scheduled delay element allows you to define a schedule
according to which the change of state occurs. The output will change according to this schedule
when the input changes.
Node Name: This is an optional name you can provide for this control node. This name can be
used to reference this node with a Phantom control node.
Schedule - Signal Increasing: Select/enter a day schedule that characterizes the delay in an
increasing signal. The schedule must be trapezoidal beginning with a value of 0.0 at time
00:00:00 and increase to a value of 1.0 before 24:00:00. Only one increasing time period per
schedule will be allowed.
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Schedule - Signal Decreasing: Select/enter a day schedule that characterizes the delay in a
decreasing signal. The schedule must be trapezoidal beginning with a value of 1.0 at time
00:00:00 and decrease to a value of 0.0 before 24:00:00. Only one decreasing time period per
schedule will be allowed.
Description: Enter an optional description for this control element.
Exponential Delay
This control element provides the ability to simulate time delays associated with the ramping
up/down of system components changing between states, e.g., the spin down of a fan or the
opening/closing of a damper. The exponential delay element allows you to define an exponential
delay based on a time constant.
Node Name: This is an optional name you can provide for this control node. This name can be
used to reference this node with a Phantom control node.
Time Constants:
Increase: Enter the amount of time it should take for the output signal to exponentially
increase by (1 1/e) % of the total change in the input signal when it rises from one state to
the next. The format is hh:mm:ss.
Decrease: Enter the amount of time it should take for the output signal to exponentially
decrease by (1 1/e) % of the total change in the input signal when it falls from one state to
the next. The format is hh:mm:ss.
NOTE: An amount of time of about 4.6 times the value entered above is required for the
output signal to increase/decrease by 99 % of the total change in the input signal.
Description: Enter an optional description for this control element.
Maximum and Minimum
The output will be the maximum or minimum of all input signals to the control node each time
step. Once a node is defined to be of this type, up to three input signals can be drawn directly
into it. More signals can be cascaded through the use of phantom control elements.
Node Name: This is an optional name you can provide for this control node. This name can be
used to reference this node with a Phantom control node.
Description: Enter an optional description for this control element.
Integrate over time
The output will be the integration over time of input signal 1 (horizontal) controlled by input
signal 2 (vertical). Integration occurs when input signal 2 > 0; there is no integration when input
signal 2 = 0; the integral is reinitialized to zero when input signal 2 < 0. A simple trapezoidal
integration method is used.
Running average
The output will be the average of the input signal integrated over the Time Span, tint:
out = in dt / tint
At the start of simulation, when the simulated time is less than the time span, the output will be
the average of the input up to that time.
Node Name: This is an optional name you can provide for this control node. This name can be
used to reference this node with a Phantom control node.
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Time Span: Enter the amount of time included in the running average, tint. The format is
hh:mm:ss.
Description: Enter an optional description for this control element.
Continuous Value File (CVF)
This control element allows you to implement general schedules by obtaining input values from
a file. This allows you to create schedules that are not restricted by the 12-day schedule limit of
CONTAMs week schedules. The file is referred to as a continuous value file. This file is an
ASCII file that you create according to the format specified in the Continuous Values File (CVF)
Format section in Part 2 of this document. You can only use one CVF file per simulation, and the
file may contain multiple lists of values. Value lists are referenced by Value name which are
column headings in the file.
Value Name: Select the name of a set of values from the list of headings as they appear in the
CVF file.
File Name: This field simply displays the CVF file that contains the data that will be used by the
control node during simulation. You must use the DataControlsContinuous Values File
menu item to select the file you want to use prior to creating CVF control nodes.
Node Name: This is an optional name you can provide for this control node. This name can be
used to reference this node with a Phantom control node.
Discrete Value File (DVF)
This control element allows you to implement scheduled discrete events by obtaining event times
and values from a file. This allows you to create schedules that do not repeat according to
CONTAMs week schedules. The file is referred to as a discrete value file. This file is an ASCII
file that you create according to the format specified in the Discrete Values File (DVF) Format
section. You can only use one DVF file per simulation, and the file may contain multiple lists of
events. Event lists are referenced by Value name which are column headings in the file.
Value Name: Select the name of a value from the list of headings as they appear in the .DVF
file.
File Name: This field simply displays the DVF file that contains the data you need. You must
use the DataControlsDiscrete Values File menu item to select the file you want to use
prior to creating a DVF control node.
Node Name: This is an optional name you can provide for this control node. This name can be
used to reference this node with a Phantom control node.
EndDate
The remainder of the file consists of data for all nodes for each date and time from StartDate to
EndDate:
date
time
value[1]
...
value[_nbvf]
The node data must start at time 00:00:00 on the StartDate and end at 24:00:00 on the EndDate.
The times must be in consecutive order, but the difference between successive times need not be
constant.
The file description may not begin with a "!". The StartDate and EndDate are used to verify
that the file data covers the entire period to be simulated. The StartDate may not be later than
the EndDate. Data elements on a single line are separated by tabs. The data must be in timesequential order. The file values must be in the units needed for the signal created by the control
node.
Node names may not include imbedded blanks. Data for nodes that are not in the project file will
be ignored. If a CVF node name in the project file is not included in the CVF, a fatal error will
result. ContamW will assist the user by checking node names. ContamX will perform the name
check before simulation begins.
EndDate
value
time
index
value
The file description may not begin with a "!". The StartDate and EndDate are used to verify
that the file data covers the entire period to be simulated. The StartDate may not be later than
the EndDate. Data elements on a single line are separated by tabs. The data must be in timesequential order. More than one node may change at the same time. The file values must be in
the units needed for the signal created by the control node.
Node names may not include imbedded blanks. Data for nodes that are not in the project file will
be ignored. If a DVF node name in the project file is not included in the DVF, a fatal error will
result. ContamW will assist the user by checking node names. ContamX will perform the name
check before simulation begins.
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The Super Node SketchPad enables only the modification of existing control sub-node icons, so
the control drawing tool will be disabled as will the ability to delete control network icons. The
Super Node SketchPad is activated by instantiating an existing control super element or doubleclicking on a Super Node icon. When the Super Node SketchPad is active, the upper left corner
of the SketchPad will display "Super Node:" followed by the name of the super node currently
displayed on the SketchPad. When working with super nodes the "Super Node" dialog box will
also be displayed as shown below.
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Modifying sub-node properties You can modify the properties of sub-nodes as you
desire. This will not affect existing instances of the super element; however, this will change
the default properties of new instances of the super element.
Modifying Super Element properties You can modify the super element properties as
you so desire. This will not affect existing instances as super nodes simply reference the
super element properties, but do not create new instances of them.
Control Super Element Properties
This section provides information on utilizing the Control Super Element dialog box that
together with the Super Element SketchPad enables you to manage and define control super
elements and is activated via the DataControlsSuper Elements... menu item. There are
two section of information presented: Element Manager and Element Properties editor.
Element Manager
This is used to select super elements for editing and creating new elements and activating the
CONTAMW Library Manager to work with Super Element Library files.
Name: This combo box provides you with the name of the currently active super element for
which the sketch data is also displayed on the Super Element SketchPad. The name should also
appear on the upper left corner of the sketchpad. You can also select other existing super
elements from the drop down list. This will change the super element displayed upon the
sketchpad as well as the properties displayed on this dialog box.
Check Element: While working with a super element, you can perform a check on it to
determine if is a fully defined super element. If the check passes then the super element is
considered to be fully defined. If the check fails, then ContamW will provide feedback in the
form of messages and highlighting of errors on the sketch. Even though a super element is
undefined, it can still be saved in its incomplete form.
There are a few basic reasons why the check could fail. Super elements are very similar to
control networks on the main SketchPad, so undefined super elements can result from problems
similar to main SketchPad control network as well as problems specific to super elements.
Potential reasons for undefined Super Elements:
Undefined sub-nodes (i.e., undefined sketch icons)
Incorrect number of inputs to control nodes
Circular control logic
No Output Node set
Pre-defined input to Input Node
New Element: This will create new super element having a default name of "SE_##" where ##
will depend on the number of existing super elements. New super elements have no sketch data,
so the SketchPad will be cleared. Once you create a super element, you do not have to save it.
Any modification you make to the sketch and properties will be maintained automatically with
the exception of the name which you must set via the "Rename Element" feature.
Library: Use this feature to activate the CONTAMW Library Manager to create control library
files, copy super elements to and from super element library files (type LB5) and delete unused
super elements from the current project file. (See Working with Data and Libraries)
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Element defined? This feature indicates whether or not a super element is fully defined (as
determined by ContamW) meaning it can be instantiated to create super nodes. Element
definition is verified by "checking." Checking is performed using the "Check Element" feature
described above, when you switch the currently displayed super element from the list of names,
or when you close the Control Super Elements dialog box, i.e., exit the super element editing
mode.
Super Node Reference Count: This is the number of instantiated super nodes that reference, the
super element. The super element can not be deleted from the project file unless this count is
equal to zero.
Edit Element Properties
These are the user-defined properties of the super element other than the sketch and control
nodes. These properties include the Name, Description, Input Node name and Output Node
name.
Rename Element: Use this feature to enter a new name for the super element and change it with
the accompanying button. The new name will be compared to existing names before being reset.
Description: Provide a detailed description of the super element of up to 255 characters. This
description will be displayed in the CONTAMW Library Manager. The description and the super
element name are currently the only means by which to identify the super elements when
viewing them in the library manager.
Input Node: The input node of the super element is the sub-node which will receive an input
signal if one is drawn to an instantiated supernode on the main SketchPad. This is not required to
be set. If needed, select a sub-node to serve as the main input for the super element from the list
of named sub-nodes. Note that you must have provided a name for the sub-node which you wish
to make the input node, and the sub-node must be of a type that accepts at least one input.
Multiple inputs
If you require a super element with multiple inputs, you can define a sub-node to be of type
phantom. Once you instantiate a super node from the super element, you can select a named
control element that you want the phantom sub-node to reference.
Output Node: The output node of the super element is the sub-node from which the signal will
be provided to an output drawn from an instantiated super node on the main SketchPad. This is
required to be set for a super element to be defined. Note that when instantiated, the output node
will assume the name of the super node for the purposes of referencing with phantom nodes on
the main SketchPad.
Control Super Nodes
Super nodes are instances of super elements having the same control logic and set of sub-nodes
as the super element. When you instantiate a super node from a super element, it takes on the
default values of the super element's sub-nodes; however, you can modify the values of the subnode parameters as needed.
Creating Super Nodes
To create a super node, you select the Super element... from the Control Element Types dialog
box just as you would define any other control node on the main SketchPad (See Defining
Controls). This will activate the Super Node SketchPad mode and the accompanying Super Node
dialog box. You then work with both the dialog box and sketchpad to select a super element to
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instantiate and to modify the sub-nodes as you require for the particular instance (See Control
Super Node Properties).
Once you have created the super node and exited the super node editing mode, the super node
will appear as a single icon (super node icon) on the main SketchPad.
Deleting Super Nodes
You delete super nodes from the main SketchPad by simply highlighting the super node icon and
pressing the delete key on the keyboard or selecting EditDelete from the main menu. If any of
the sub-nodes of the deleted super node are referenced by phantom nodes, you will be informed
and prompted as to whether you want to undefine the phantom nodes (and sub-nodes) that
reference them.
Modifying Super Nodes
Once you have instantiated a super node, you can modify the sub-nodes of a super node.
Activate the super node editing mode by double-clicking the super node icon on the main
SketchPad. Simply double-click on the sub-nodes whose properties you wish to modify and edit
them as you would nodes on the main SketchPad. Note that you can not modify the sketch in any
way, i.e., you can not draw or delete sub-nodes.
Control Super Node Properties
This section provides information on utilizing the Super Node dialog box that together with the
Super Node SketchPad enables you to manage and define control super nodes. This dialog box is
activated when creating a new super node or when modifying an existing one. There are two
section of information presented: Node Data and Element Data.
Node Data
This displays super node specific data used to identify a specific super node.
Name: As with all control node types, you can provide a name for the super node. Named
super nodes can be referenced by phantom nodes. When you name a super node, its output
sub-node will also be given the same name, because the output sub-node will be the node
actually referenced by any phantom nodes that refer to the super node.
Description: Enter a detailed description of the super node to help you identify the super
node. This description will appear in the status bar when you highlight the super node icon
on the SketchPad.
Element Data
This section enables you to select and set the super element from which to instantiate a new
super node. Once instantiated this section simply provides information on the super element from
which the super node was instantiated.
Name: Prior to instantiation of a super node, this combo box provides you with the name of
the currently active super element for which the sketch data is also displayed on the Super
Element SketchPad. The name should also appear in the upper left corner of the SketchPad.
You can also select other existing super elements from the drop down list. This will change
the super element displayed upon the sketchpad as well as the properties displayed on this
dialog box.
Create Super Node: Click this button to instantiate a super node from the currently selected
super element. Once instantiated, this button will be disabled along with the Name drop
down combo box.
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Note that when creating a new super node, until you create the super node, any changes you
make to sub-nodes of the displayed super element will modify sub-nodes of the super
element and not a super node.
Defined?: This indicates whether or not the currently selected super element is fully defined
if "YES" then a super node can be instantiated from the super element, otherwise not.
Description: This displays the detailed description of the currently displayed super element.
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given as the ratio of the mass of water vapor to that of dry air. You can convert between the two
using the following relationship.
Humidity ratio = mass fraction of H2O / (1 mass fraction of H2O)
For example, to create air from its typical constituents you might define the following set of nontrace contaminants (See Creating Species and Contaminants):
Molar
Default
Trace
Use in
Name Mass
Concentration
Contaminant Simulation
[kg/kmol] [kg_cont/kg_air]
N2
28
0.7554
Non-trace
Use
O2
32
0.2314
Non-trace
Use
Ar
40
0.0127
Non-trace
Use
CO2
44
0.0005
Non-trace
Use
H2O
18
0.0000
Non-trace
Use
Note in the above example, the Default Concentration = 1.0 kg/kg (see Project Species for
details).
As a simpler example, you might create a dry air contaminant, Air, and a water vapor
contaminant, H20, as follows.
Molar
Default
Trace
Use in
Mass
Concentration
Contaminant Simulation
[kg/kmol] [kg_cont/kg_air]
DryAir 28.9645
1.000
Non-trace
Use
H2O 18.0150
0.000
Non-trace
Use
Name
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Project Species
Species must be defined before any related elements (e.g. source/sinks, filters and kinetic
reactions) can be defined. From the Project Species page any previously defined species may be
viewed, edited, or deleted and new species may be defined. The following describes the
information that appears on the Project Species dialog box.
Species: This is a list of the species that are currently defined within the current project.
Species Properties: These are the properties of the currently highlighted species.
Contaminants: This is a list of the project species for which the "Use in Simulation" property is
set to "Use," i.e., these are selected to be contaminants in the simulation.
Contaminant Summary: This is a summary of contaminant-related information including the
number of non-trace contaminants and the summation of the default concentrations of the nontrace contaminants which must be 1.0.
NOTE: If the project contains water vapor, H2O, then its default concentration is not included in
this summation at this point, however, it will be accounted for by ContamX during simulation if
initial concentrations are set to ambient (see Simulation - Airflow Numerics Properties).
New, Edit and Delete: Click the "New" button to create a new species, or use the "Library..."
button to import/export species from/to a species library file. To modify the properties of an
existing species, highlight the species in the species list and click the "Edit" button. Click the
"Delete" button to delete the selected species.
IMPORTANT: Changing the number of contaminants, i.e. those species used in the simulation,
will reset the initial concentrations of all zones to the default contaminant concentrations. You
can reset all of these concentrations via the Run Control Properties of the simulation parameters
or via the Contaminant Data properties of the individual zones.
Species Properties
This section provides detailed descriptions of the specific species properties.
Name: You will use this name to refer to the species throughout the program. You must give
each species a name that is unique to the current project.
Molar Mass: The molar mass in g/mol or kg/kmol. CONTAM uses this value to convert
volumetric concentrations to mass fractions and to calculate the gas constant of the air mixture
made up by non-trace contaminants. You must enter a value of at least 1.0.
Default Concentration: CONTAM will apply this value as the default initial concentration for
each zone that you create. You can revise the initial concentration for individual zones as per
your requirements. This is also the ambient contaminant concentration during simulations which
do not utilize contaminant data from one of the external contaminant data files (CTM or WPC).
Diffusion Coefficient: This value will be used during simulations using the 1D Duct Model of
the Short Time Step Method (See Run Control Properties in the Working with Simulations
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section). The dispersal coefficient will be calculated from this value depending on the Reynolds
Number in a given duct segment.
Mean Diameter: Enter the mean particle diameter if this species is to be a particulate type
species. CONTAM utilizes this value when converting between particle count units and particle
mass and volume units and to determine filter efficiency of Simple Particle Filter elements for
this size particle (See Simple Particle Filter in the Working with Filters section).
NOTE: This is not necessarily meant to be, for example, the aerodynamic diameter as the current
contaminant source models do not treat particles different from gaseous contaminants.
Effective Density: Enter a density that you want CONTAM to use as the effective density of a
species you want to consider to be a particulate type species. Currently, CONTAM only utilizes
this value when converting between particle count units and particle mass and volume units.
Specific Heat: The specific heat of a contaminant will used during simulation only when the
Variable Junction Temperatures method is selected.
Decay Rate: This is an exponential decay constant based upon the half-life of the radioactive
species calculated using the following equation:
Decay Rate = ln(2) / 1/2,
where 1/2 is the half-life of the radioactive species in seconds.
ContamW will use this value to perform unit conversions for radioactive contaminants.
Radioactive species are only distinguished from other species by the units associated with them,
not by modeling the radioactive decay process. To model a radioactive decay, use a kinetic
reaction (See Kinetic Reaction Data).
Non-Trace Contaminant: Non-trace contaminants are those that can affect the density of the
air, i.e., are considered components of the air. See Non-trace Contaminants and Water Vapor.
Use in Simulation: This determines whether or not a species will be a contaminant. Checking
"Use in Simulation" indicates that a species will be a contaminant and used in the simulation.
Description: Use this to provide a more detailed description of the species.
Guideline Value: Currently not implemented.
Guideline Description: Currently not implemented.
Contaminant Files
You can account for changes in the ambient contaminant concentrations when performing
transient contaminant simulations using ambient contaminant (.CTM) files. If you associate a
contaminant file with your project (see Run Control Properties) ContamX will compare those
contaminants defined within your project file with those contained in the contaminant file. If
they match, ContamX will use the ambient concentrations in the contaminant file within the
simulation, otherwise they will be ignored.
You create the contaminant files external to ContamW. You can use a utility program provided
by NIST, Weather 2.0, to convert existing CONTAM 1.0 weather (which previously contained
ambient contaminant concentrations) files to CONTAM 2.0 weather and contaminant files.
Note that with this method the ambient concentration does not vary spacially, only temporally. If
you require spacial variations of outdoor contaminant level, then refer to the section entitled
Working with WPC Files.
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109
where:
MW = molar mass of contaminant [kg/kmol]
Vs = 24.05 m3 which is the volume of one kmol of air at T = 20 C and P = 101 325 Pa (1
atm)
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Source/Sink Elements
CONTAM uses mathematical relationships referred to as source/sink elements or models to
implement sources and sinks when performing contaminant simulations. CONTAM can
implement several source/sink models to generate contaminants within or remove contaminants
from a zone. Depending on the source/sink model, it could be used to emulate either a source, a
sink or both. Each of these source/sink element types is described in detail in the Source/Sink
Element Types section. Every source/sink must refer to a single source/sink element; however,
multiple source/sinks can refer to the same source/sink element.
Source/sink elements can also be stored within a CONTAM library file and shared between
different CONTAM project files (See Working with Data and Libraries).
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from a library file. Use the "New Element" button to define a new element. Activate the
CONTAMW Library Manager to import elements from library files via the Library button
(See Working with Data and Libraries). Use the "Edit Element" button to modify the
properties of the element displayed in the Name field.
Model Summary: This summarizes the information associated with the source/sink element
whose name is currently displayed in the Name field.
Source/Sink - Multiplier, Schedule & Location Properties
Species: This is the species associated with the source/sink.
Multiplier: A constant value by which the source strength will be multiplied during simulation.
With this feature you could define a source/sink element having a source strength per unit area
then use the multiplier as the area of the zone for each source/sink that uses the per unit area
source/sink element.
Schedule: You can use a schedule to modify the source strength as a function of time. Two
source/sink element types, Burst Source and Decaying Source, require the use of a schedule. If
there are previously defined schedules within the current project, you may select one from the
Name list. Click the "New Schedule" button to define a new schedule. To view or modify an
existing schedule click the "Edit Schedule" button. Setting this field to <none> indicates no
schedule (See Working with Schedules).
Location: These are the X, Y and Relative Elevation (Z) coordinates and units for the selected
source/sink. X and Y are absolute coordinates and Rel Elevation is relative to the level on which
the source/sink is located. To create a point source, set the Minimum and Maximum values to be
the same. To create a source which distributes emissions along the 1D axis of the zone, enter
Minimum and Maximum values that span the desired region of the zone in which the source is
located.
These values are required for any source/sink that is located within a 1D convection/diffusion
zone (see 1D Zone Data). These coordinates will be verified by ContamW against the axis of the
1D zone in which it is located. This verification will be performed automatically when you select
either the Run Simulation or Create a ContamX Input File command from the Simulation
menu.
Source/Sink Element Types
These are the source/sink element types or models that you can implement with CONTAM.
Refer to the related information for each specific model to obtain detailed descriptions of them.
CONTAM Elements:
Constant Coefficient Model: The general source/sink model allows constant contaminant
generation and deposition rates.
Pressure Driven Model: This model is for contaminant sources that are governed by the
pressure differences between zones.
Cutoff Concentration Model: This model will reduce emissions as the concentration within
the zone in which it is implemented approaches a specified cutoff concentration. This model
may be appropriate for some sources of Volatile Organic Compound (VOC).
Decaying Source Model: This model provides a source that will exponentially decay with
time according to a user-defined time constant. This model may also be appropriate for some
VOC sources.
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where:
R(t) = Removal rate at time t [M/T]
vd = Deposition velocity [L/T]
As = Deposition surface area [L2]
air(t) = Density of air in the source zone at time t [Mair/L3]
C (t) = Concentration of contaminant at time t [M / Mair]
This model differs from the Deposition Rate Sink Model in that it is not dependent on the mass
of air in the zone in which it is located.
Name: Enter a unique name you want to use to identify the source/sink element. The element
will be saved within the current project and can be associated with multiple source/sinks.
Deposition Velocity: Enter deposition velocity and units. The air density will be obtained at the
time of simulation from the zone in which the source/sink is located.
Surface Area: Enter desired surface area and units. You can enter a value of 1 and use the
source/sink multiplier to specify the total deposition surface area.
Species: Select a previously defined species from the drop down box.
Description: Field for entering a more detailed description of the specific sink/source element.
Deposition Rate Sink Model
This sink model is provided as a convenient means to create a sink using deposition rates. This
model is dependent on the mass of air in the zone in which the source/sink is located and will
behave similar to that of a kinetic reaction having the same reaction rate.
R(t) = kdVzair(t)C(t)
where:
R(t) = Removal rate at time t [M/T]
Vz = Zone volume [L3]
kd = Deposition rate [1/T]
air(t) = Density of air in the source zone at time t [Mair/L3]
C (t) = Concentration of contaminant at time t [M / Mair]
Name: Enter a unique name you want to use to identify the source/sink element. The element
will be saved within the current project and can be associated with multiple source/sinks.
Deposition Rate: Enter deposition rate and units. The volume and density will be obtained at the
time of simulation from the zone in which the source/sink icon is located.
Species: Select a previously defined species from the drop down box.
Description: Field for entering a more detailed description of the specific sink/source element.
Deposition with Resuspension Model
This source/sink model enables surface deposition with resuspension.
R(t) = dAsair(t)C(t)
S(t) = r Ar L(t)
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where:
R(t) = Removal rate at time t [M/T]
vd = Deposition velocity [L/T]
As = Deposition surface area [L2]
air(t) = Density of air in the source zone at time t [Mair/L3]
C (t) = Concentration of contaminant in zone air volume at time t [M / Mair]
Ar = Resuspension surface area [L2]
L (t) = Concentration of contaminant on the deposition surface at time t [M / L2]
Name: Enter a unique name you want to use to identify the source/sink element. The element
will be saved within the current project and can be associated with multiple source/sinks.
Deposition Velocity: Enter deposition velocity and units. The air density will be obtained at the
time of simulation from the zone in which the source/sink is located.
Deposition Surface Area: Enter desired surface area and units. You can enter a value of 1 and
use the source/sink multiplier to specify the total deposition surface area for each specific
instance of this element.
Resuspension Rate: Enter the resuspension rate and units.
Resuspension Surface Area: The resuspension surface area may be different from that of the
deposition surface are, e.g., a shoe impacting the deposition surface. Once associated with a
source/sink, the resuspension rate can be controlled by the source/sink schedule or control value.
Species: Select a previously defined species from the drop down box.
Description: Field for entering a more detailed description of the specific sink/source element.
Super Source/Sink Element
Combine multiple sub-elements into a single element that can be represented by a single icon on
the SketchPad.
Name: Enter a unique name you want to use to identify the source/sink element. The element
will be saved within the current project and can be associated with multiple source/sinks.
Description: Field for entering a more detailed description of the specific sink/source element.
Available Elements: This is a list of basic source/sink elements from which you can build the
super element. Items below this list provide information on the currently highlighted element.
Use the Edit and New buttons to modify or create basic types of source/sink elements for the list
of available elements.
Sub-Elements: Use the Add and Remove buttons to modify this list of sub-elements that make
up the super element.
NRCC Power Law Model
This is an empirically based model provided for compatibility with NRCC Material Emission
Database.
For t tp the initial emission factor is
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where a, b and tp are all emperical coefficients typically determined from emission chamber
measurements.
NOTE: This type of source can only be triggered once per simulation. If using a schedule, the
first non-zero schedule value will trigger the source, otherwise it will begin emitting
immediately.
Name: Enter a unique name you want to use to identify the source/sink element. The element
will be saved within the current project and can be associated with multiple source/sinks.
Initial Emission Factor: Enter the initial emission factor S0 and its units.
Coefficient: This corresponds to a in the above equation. It will be calculated based on S0, tp and
b. The value of a will be provided by the NRCC Data Base and stored by CONTAM, but the
Initial Emission Factor is provided as a more intuitive means for defining the model.
Exponent: Enter a value for the exponent b in the above equation.
PL Model Time: Enter the time tp until which the initial emission rate applies.
Description: Field for entering a more detailed description of the specific sink/source element.
NRCC - Peak Model
This is an empirically based model provided for compatibility with NRCC Material Emission
Database.
where a, b and tp are all emperical coefficients typically determined from emission chamber
measurements. The emission factor will increase up until time tp at which point it will begin to
decay.
NOTE: This type of source can only be triggered once per simulation. If using a schedule, the
first non-zero schedule value will trigger the source, otherwise it will begin emitting
immediately.
Name: Enter a unique name you want to use to identify the source/sink element. The element
will be saved within the current project and can be associated with multiple source/sinks.
Peak Emission Factor: Enter the peak emission factor a. This is the value of S(t) when time t =
tp.
Fitting Parameter: Enter a value for the paremeter b in the above equation.
Time of Peak: Enter the time tp at which the peak emission factor is achieved.
Description: Field for entering a more detailed description of the specific source/sink element.
and the mathematical relationship that describes the behavior of the filter during a simulation.
This is similar in nature to the relationship between airflow paths and airflow elements and
between duct segments and duct flow elements. In another sense, the filter is a specific instance
of a filter element.
The following building components can incorporate filters and are described as filter-ready:
1. Airflow paths
2. Implicit outdoor air and recirculation air paths of simple air-handling systems
3. Supplies and returns of simple air-handling systems
4. Duct segments
5. Duct terminals
Filter Elements
CONTAM uses mathematical relationships referred to as filter elements or models to implement
filters when performing contaminant simulations. CONTAM can implement several different
filter models to remove contaminants as they are transported through building components that
have filtering capabilities. These element types are described in detail in the Filter Element
Types section. Every filter must refer to a single filter element; however, multiple filters can
refer to the same filter element.
Filter elements can also be stored within a CONTAM library file and shared between different
CONTAM project files (See Working with Data and Libraries).
Creating Filters
You create filters for each building component for which you require a filter. When you are
defining one of the filter-ready building components presented above, a filter property page will
be provided that will enable you to establish whether or not to associate a filter, or to modify or
delete a previously defined filter for that component.
Deleting Filters
You can delete filters by accessing the properties of the individual component whose filter you
want to delete or by deleting the building component itself. Note that deleting a filter does not
delete the associated filter element (you can not delete a filter element that is currently associated
with a filter).
Modifying Filters
You modify a filter by accessing the Filter property page of the individual building component
icon and selecting the "Edit Filter" button to display the "Filter" dialog box.
Filter Properties
Filter Number: This number is automatically assigned by ContamW and can change as you add
and remove filters to or from a project. Each time you save a project, the filter numbers are
reassigned.
Even though this is the actual filter number used by CONTAM, a different number will be used
when presenting filter accumulation results in the contaminant summary file (.csm file). This file
will present filters according to the building component with which they are associated. For
example, filters associated with airflow paths and air handling system supply and return points
will be referenced by the path number and the letter "p" to indicate it is a path filter. Filters
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associated with ducts will be referenced by the duct segment number and the letter "d" or the
terminal number and the letter "t" for terminal.
Filter Element
Name: <required> You may select a previously defined filter element from those contained
in the Name list. Click the "New Element" button to define a new filter element. To view or
modify filter element data click the "Edit Element" button. You can also access the
CONTAM Library Manager to import filter elements from library files by clicking the
"Library" button (See Working with Data and Libraries). Every filter must have a filter
element associated with it.
Description: Displays the description of the filter element currently displayed in the Name
field.
Type: Displays the type of filter element for the filter currently displayed in the Name field.
Initial Filter Loading
Total Relative Load: Set the initial loading of the filter relative to the mass of the filter. This
can be set to zero to represent a "clean" filter at the beginning of a simulation; otherwise set
the value to establish the total mass of contaminants (as a percent of the mass of the filter)
accumulated on the filter at the start of a simulation. Relative load is only used for the
Gaseous Filter element which is currently the only element for which efficiency is described
as a function of filter loading.
Description: Use this field to provide a more detailed description of the filter element.
Edit Element Data: Select to define the specific properties of the filter element.
Filtered Species: This is a list of the species and filter efficiencies for the filter element.
Edit Filter Data: Use the Species and Efficiency fields to set and modify the Filtered Species
list along with the Add, Replace and Delete command buttons.
Efficiency: Use this to enter the filter efficiency for the currently highlighted species. Filter
efficiencies must be between 0.0 and 1.0.
Species: This is a list of all the species in either the current project or library file depending
on wether you are editing project data or library data. Select the species for which you want
to set a filter efficiency.
Simple Gaseous Filter
The simple gaseous filter element is made up of a set of species and associated efficiency vs.
loading curves. Therefore, the efficiency is a function of the amount of contaminant "absorbed"
by the filter. Each filter element can be associated with anywhere between one and the number of
species that exist within the current project. Only those species that you have selected to be
contaminants will be accounted for when you perform simulations.
Name: A unique name you want to use to identify the filter element.
Area: The face area and units of the filter element.
Depth: The depth of the filter element along the axis of airflow.
Density: The density of the filter media.
Area, Depth and Density are currently used to calculate the mass of the filter media which is in
turn used to calculate filter loading.
Description: Use this field to provide a more detailed description of the filter element.
Edit Element Data: Select to define the specific properties of the filter element.
Filter Curve Data: This is a list of relative loading and filter efficiency data pairs used to
define the filter curve for the currently selected species (see figure below). Once you have
entered at least three data points, ContamW will attempt to calculate a cubic spline fit to the
points. If there are any errors in the spline fit procedure, you will be notified and the
offending portion of the curve will be highlighted.
122
Species: This is a list of all the species in either the current project or library file depending
on whether you are editing project data or library data. Select the species for which you want
to display/edit filter curve data.
Breakthrough Efficiency: Set the breakthrough efficiency for each species. This value will
be used during simulation to report if and when the filter efficiency drops below this value.
Breakthrough is reported to the Contaminant Summary simulation result file (see Results
Files in the Working with Results section).
Filter Curve Data: This is the list of data points you create from which a filter curve is
generated using the cubic spline fit method. A minimum of four data points is required before
a curve will be generated. The space below will provide a plot of Relative Loading vs. Filter
Efficiency. Relative loading is the ratio of Mass of contaminant accumulated by the filter to
the Mass of the filter.
Use the Relative Loading and Efficiency data entry fields to set and modify the Filter Curve
Data list along with the Add and Delete buttons.
123
124
where
R rate of production or destruction of contaminant
K, reaction rate coefficients between contaminants and , in units of 1/s
C concentration of a reactant
CONTAM uses the convention that positive reaction coefficients produce an increase in species
concentration and negative coefficients decrease species concentrations. The units of
concentration are kg_species / kg_air (See Concentration Conversions).
Kinetic reactions can occur within zones of a building. To use kinetic reactions, you must have at
least one species for the project. Kinetic reactions can be associated with one or more zones
within a project. You can access the kinetic reaction data dialog box via the property sheets of
the zones that provide a kinetic reaction definition section (i.e. zones and simple air-handling
systems).
You can also access the Kinetic Reaction Data dialog box using the CONTAMW Data and
Library Manager: Kinetic Reactions to create and edit local project data or to share kinetic
reactions between CONTAM projects using contaminant libraries.
When you are defining building zones, you will be able to select a currently defined kinetic
reaction to associate with it, define new, modify existing or import kinetic reactions from
species-related CONTAM library files (i.e. LB0 library files). All kinetic reactions are defined
and modified using the Kinetic Reaction Data dialog box as described in the following section.
Reactant Species: This is a list of all the species in either the current project or library file
depending on how this dialog box was accessed. Select a species to be the reactant in the RP
Pair.
Product Species: This is a list of all the species in either the current project or library file
depending on how this dialog box was accessed. Select a species to be the product in the RP
Pair.
Reaction Coefficient: Use this edit field to set the reaction coefficient for the currently
highlighted RP Pair. The units of the coefficient are s-1.
Examples
The following are examples of kinetic reactions as implemented within CONTAMW.
Kinetic Reaction Example 1
To simulate the first-order decay of a species, you would set the coefficient of the
ReactantProduct Pair to the negative of the reaction rate in units of 1/s.
This figure shows kinetic reaction coefficients for two species reactions that will yield
exponential decays of each species according to the following equation:
Where,
Cj(t) = concentration of product contaminant j at time t
Ci(0) = initial concentration of reactant contaminant i at time 0
Kji = reaction rate coefficient between product j and reactant i (time constant)
In the above example, the reaction rate coefficients are as follows:
K11 = -0.0001388/s
K22 = -0.00003472/s
If the reaction is the only means of species removal, i.e., there is no dilution due to airflow, then
species C1 would decay at a rate of
126
This figure above shows the parameters for the "kr1" kinetic reaction element. This element
provides for two reactions that will yield an exponential decay of contaminant C1 according to
the equation
,
and the build-up of contaminant C2 according to
127
You would model this reaction chain by inputing coefficients based on the half-life of the
radioactive reactants. Convert half-life 1/2 to a first-order reaction coefficient, K21, using the
following equation:
In CONTAM, you would require two species C1 and C2 (if interested in contaminant C2) and
three reactant/product pairs have the following reaction coefficients characteristics:
K11 would have negative non-zero values (decay of C1)
K21 would have a non-zero positive value (build-up of C2 from C1)
K22 would have negative non-zero values (decay of C2)
128
CONTAM presents results in terms of E/t. Where t is the user-defined output time step
established for a transient simulation (See Results Files in the Working with Results section).
From these results you can calculate a dosage as desired.
To implement an occupant, you must first define at least one species. You then place an exposure
icon (shown below) on the SketchPad. Once you place the exposure icon on the SketchPad, you
can define its characteristics, move, copy, and delete it. You must then define an occupant
schedule for the exposure icon. The details of drawing, defining and modifying occupants are
described in the following sections.
Occupant exposure icon
Creating Occupants
You create an occupant by placing an exposure icon on the SketchPad (See Drawing Building
Component Icons). You can place them in any blank cell of the SketchPad. The "Exposure"
menu selection will be disabled (grayed out) if you pop-up on a location where ContamW does
not allow the icon to be placed.
Deleting Occupants
You delete exposure icons using the icon deletion procedure (See Deleting Building Component
Icons). Deleting occupant exposure icons from the SketchPad deletes the occupant data
associated with the icon, but it does not delete any occupant-related schedules that you might
have created. These schedules can only be deleted using the CONTAMW Library Manager,
accessible through the Data menu for each type of data element.
Modifying Occupants
To modify the parameters of an occupant, you use the icon definition procedure (See Defining
Building Component Icons) to display its properties and make the desired changes. You can also
move and copy occupants.
Moving Occupant Exposure Icons
Once you define an occupant, you can move the icon using the Cut and Paste functions of the
Edit menu. You can move the occupant exposure icon anywhere within the level upon which it
is currently located.
Copying Occupant Exposure Icons
Once you define an occupant, you can copy the icon using the Copy and Paste functions of the
Edit menu. You can copy an occupant to any blank cell on any level of a project.
129
Defining Occupants
After you draw an exposure icon on the SketchPad you must define it using the icon definition
procedure (See Defining Building Component Icons) to display and edit the properties. This will
display the "Occupant Exposure Properties" property sheet. Detailed descriptions of all occupant
exposure properties are given in the Occupant Properties section of this manual. Once you have
defined the properties, the icon will be displayed in black. From now on, you use this icon to
access the properties of the occupant.
Among the optional properties associated with an occupant are multiplier, inhalation, and
contaminant generation information. You would use the multiplier to proportionally increase the
contaminant generation rate associated with an individual exposure icon to represent the
contaminant generation of multiple occupants. You would input contaminant generation
information if you want to account for the contaminants generated by an occupant while they are
in the building. Inhalation information is useful for determining the dose received by an occupant
based upon their exposure to a contaminant. CONTAM does not currenlty implement the
calculation of contaminant dose, however, you can use the exposure information to determine the
dose of an occupant.
Occupant Properties
This section provides detailed descriptions of the specific occupant properties. Each of the
following subsections are the context-sensitive help topics that you can access by pressing F1
when working with property pages of the "Occupant Exposure Properties" property sheet.
Occupant Occupant Data Properties
Occupant Number: This is the number that appears in the status bar when you highlight an
icon. ContamW automatically assigns this number to each exposure icon once it is defined. This
number could change as you add and remove occupants to or from a project. Each time you save
a project, the occupant numbers are reassigned. Numbers are assigned beginning on the top level,
starting from the upper-left corner of the SketchPad, moving left-to-right and top-to-bottom of
the SketchPad.
Body weight/Peak inhalation rate: CONTAM uses these parameters to compute a contaminant
dose. Inhalation is defined in terms of a peak rate and a schedule. Body weights for typical
persons and inhalation values for different activity levels are available in the [EPA 1989].
NOTE: This feature and the associated Inhalation Schedule are not implemented in CONTAM
version 2.0 and beyond, because contaminant dose calculation is no longer performed by
CONTAM. However, occupant exposure is still determined from which you can obtain your own
dose calculations.
Description: Field for entering a more detailed description of the specific exposure.
Inhalation Schedule: Use this when you want to modify the peak inhalation rate according to a
schedule. If there are previously defined schedules within the current project, you may select one
from the Name list. Click the "New Schedule" button to define a new schedule. To view or
modify an existing schedule click the "Edit Schedule" button. Setting this field to <none>
indicates no schedule. (See Working with Schedules)
Edit Occupancy Schedule: Press the "Edit Occupancy Schedule" button to display the
Occupancy Week Schedule dialog box and define the movement of this occupant within the
building.
130
131
Local Project Elements sections. The Library File section displays the name of the currently
displayed library file and allows you to save, rename and open new and existing library files. The
Library Elements section displays the data elements contained in the library file that is currently
listed in the Library File section. The Local Project Elements section displays the data elements
that are contained in the current project file.
Opening Libraries
If a library file is currently opened, the name of the file will be displayed in the "Name" field of
the "Library File" section of the Library Manager. You can open a CONTAM library file using
the "Browse" button of the Library Manager. This will activate the File Open dialog box
typical of Windows applications. This dialog box is set to display only those files having the
three-character file extension associated with the type of data elements that you are currently
working with. Follow the typical procedure for opening a file using the Windows operating
system.
CONTAM 2.0 library files are of a different format than the 1.0 version. ContamW will allow
you to open a 1.0 version file and you will then be required to give the file a name when saving
the converted file. It is suggested that you save the file under a different name from that of the
133
1.0 formatted library file. The Open dialog box will display both the file Version information and
the Library file description.
Creating Libraries
Using the CONTAMW Library Manager, you create new libraries one of two ways. You can
either save an existing library under a new name using the "Save As" button, or use the "New"
button of the Library File section of the CONTAMW Library Manager dialog box. The "Save
As" method makes a copy of the currently displayed library file under a new name, but
maintains the original file. The "New" method clears the data currently displayed and allows you
to start with an empty library file.
Deleting Libraries
You must use the file deletion commands of your operating system to delete CONTAM library
files.
Modifying Libraries
You modify CONTAM library files using the CONTAMW Library Manager. The CONTAMW
Library Manager allows you to create new data elements within the library, copy data elements
from the local project into the library, modify library data elements, and delete data elements
from the library.
Creating Library Data Elements
You use the "New" button contained within the "Library Elements" section of the CONTAMW
Library Manager to create a new data element. You can only create the type of data element that
is currently being displayed by the Library Manager (e.g. airflow elements, ductflow elements,
schedules, etc. ). The "New" button will activate the ContamW dialog box associated with
creating the type of data element that you are currently working with.
Species must be available in order to create new contaminant-related elements such as
Sources/Sinks, Filters and Kinetic reactions.
Copying Library Data Elements (between the Project and Library)
You can either copy data element from a library to the local project or from the local project to
the library. All copying is done between the local project and the library file that is currently
indicated in the "Name" box of the Library File section of the CONTAMW Library Manager. If
the name box is blank, then you are dealing with a new/unnamed library file. To copy data
elements, you use the "Copy " and " Copy" buttons. These copy buttons indicate the
direction of the copy operation. If an element exists in both the library file and the local project,
then the copy buttons will be disabled to prevent you from overwriting elements with the same
name. You may rename local data elements without affecting their associations with building
components that refer to them in the local project.
Some elements rely on other types of elements for proper implementation, e.g., source/sinks
require an associated species and week schedules require day schedules. If you copy one of these
elements that requires a sub element, ContamW will prompt you to replace existing elements of
the same name if they already exist within the destination file.
Modifying Library Data Elements
To modify a library data element, you must first highlight the Element Name within the list of
elements in the Library Elements section of the CONTAMW Library Manager. You then click
on the "Edit" button next to the list. This will activate the ContamW dialog box associated with
134
displaying the properties of the type of data element with which you are currently working. You
then make the desired changes and click the "OK" button to make the changes take affect.
Deleting Library Data Elements
To delete a library data element, you highlight the Element Name in the Library Elements
section of the CONTAMW Library Manager then click on the "Delete" button next to the list.
You will be prompted to confirm the deletion, and the data element will no longer be displayed
in the list of Library Elements. However, the deletion will not be affected until you save the
library file. You can retrieve the previously deleted data elements by reopening the library file as
long as you don't save the file after deleting the elements.
Deleting data elements that have associated sub-elements will not delete the sub-elements. You
must delete the sub-elements using a separate Library Manager operation.
not referenced within the project. You will be prompted to confirm the deletion, and the data
element will no longer be displayed in the list of Project Elements. However, the deletion will
not be affected until you save the project file. You can retrieve the previously deleted data
elements by reopening the project file as long as you don't save the file after deleting the
elements.
Deleting data elements that have associated sub-elements will not delete the sub-elements. You
must delete the sub-elements using a separate Library Manager operation.
136
where
VH Approach wind speed at the upwind wall height (usually the height of the building)
Cp Wind pressure coefficient
The wind pressure coefficient can be further generalized in terms of a local terrain effects
coefficient and the direction of the wind relative to the wall under consideration. The following
equation is that used by CONTAM when calculating wind pressures on the building.
where
wind speed modifier coefficient accounting for terrain and elevation effects
f coefficient that is a function of the relative wind direction. CONTAM refers to this
function as the wind pressure profile.
The relative wind direction is given by
where
138
(1)
where H is the wall height and Ao and a depend on the terrain around the building [ASHRAE
1993, p 14.3]:
The wind speed, VH, at the top of the wall, elevation H, is then given by
An updated method, from that presented in ASHRAE 1993, of accounting for local terrain
effects is presented Chapter 16 of ASHRAE 2005. Using this method, VH is calculated according
to the following equation:
where
Table 1 in Chapter 16 of ASHRAE 2005 contains values for the above parameters. ContamW
calculates Ch according to equation (1) above and provides for the input of the local terrain
constant, Ao, but not . Therefore, in order to implement the updated method, you must adjust the
value of Ao according to the following equation:
set of steady state simulations prior to performing transient simulations. This may enable you to
better identify any problems that may arise from working with transient weather. ContamW also
provides a means to verify that you have your wind related data input correctly (See Checking
Wind Pressure Data).
Defining Steady State Weather and Wind
To define the steady state weather and wind data you use the Edit Weather Data selection of
the Weather menu or the F7 keyboard shortcut. This will display the "Weather and Wind
Parameters" property sheet. The property sheet contains four different pages of parameters
including: Weather, Wind, Location and Wind Pressure Display. Detailed descriptions of all
wind and weather properties are given in the Weather and Wind Properties section of this
manual.
You use the Weather page to define steady state weather and wind data. The Location page
allows you to input the altitude of the building site which ContamW will use to determine a
default barometric pressure if you do not know what it should be for a given building site.
Default values of these two pages will provide conditions of no wind, 20 C and a barometric
pressure of 1 atmosphere (approximately 101 kPa).
The Wind page parameters allow you to enter the prevailing wind direction and other values
used by ContamW to determine a wind speed modifier. The wind speed modifier is determined
from the local terrain constant and the velocity profile exponent. Default values are provided for
suburban terrain.
Checking Wind Pressure Data
ContamW enables you to verify wind information visually on the SketchPad using the Wind
Pressure and Wind Pressure Type selections of the View menu. When reviewing this display,
you should check if the direction of flow makes sense based on the wind data provided on the
Wind Pressure Display property page (WP Display) or contained in the WTH and WPC file (see
Working with WPC Files). When reviewing WTH and WPC file pressures, you can use the
Results Navigation controls under the View menu to step through the data in the WPC file. The
date and time of the corresponding data from either file will be displayed in the status bar.
When you choose to display wind pressure results, colored lines (Pres Results color) will appear
on the SketchPad. Wind pressure will only be displayed for those airflow paths and duct
terminals connected to the ambient zone, having the Wind Pressure Option set to Variable or
Constant or, if using a WPC file, a pressure specified in the WPC file. The wind pressure display
will reveal the relative magnitude of the pressure drop and the direction of airflow across the
openings in the building envelope. You can move the caret to each of the airflow paths for which
a wind pressure is being displayed to show the wind pressure, azimuth angle and elevation of the
airflow path in the ContamW status bar. When the caret is placed in the ambient zone, the wind
speed and direction will be displayed in the status bar if the wind pressure type is set to either
WP Display or WTH.
Defining Transient Weather and Wind
In order to implement transient weather and wind, you must create a CONTAM-compatible
weather file. You must create the weather file external to CONTAM. NIST provides a utility
program, WEATHER 2.0, to create CONTAM-compatible weather files.
WEATHER 2.0 enables you to convert existing CONTAM 1.0 weather files to the 2.0 format
weather and ambient contaminant files. You can also convert TMY2 and EnergyPlus (.EPW)
weather files to the CONTAM 2.0 weather file format and create weather file templates into
140
which you can place your own data (e.g., experimental data). Both weather and ambient
contaminant files are ASCII text files that can be created and edited using spreadsheet software
according to the formats provided within this manual.
Weather File Format
The CONTAM weather file is a tab-delimited ASCII text file. These files are easily created,
imported and modified using typical spreadsheet applications. They can be saved as tabdelimited text files for use with CONTAM. It is described below because it may be necessary for
the you to create a weather file from sources not already provided. In the listing below I1
indicates a character string, I2 indicates a short integer and R4 indicates a four-byte real
number. Individual lines of data are separated by dashes (these dashes are only shown here for
format presentation purposes and should not be included in the actual files). Each day must begin
with time 00:00:00 and end with time 24:00:00. The time interval between 00:00:00 and
24:00:00 can be either regular or irregular ContamX will interpolate as necessary. Comments
are allowed and are indicated by an "!" (exclamation point). Anything that appears on a line
following a comment indicator is ignored by the weather file reader. Comments are provided by
the weather file creation software (Weather 2.0) that show header information for the data in the
file.
WeatherFile ContamW 2.0 ! file and version identification
----I1 descr[] ! weather file description
----I1 start _date ! day of year (1/1 12/31)
I1 end_date ! day of year (1/1 12/31)
----!Date DofW Dtype DST Tgrnd
----! for each day: start_date end_date
I1 date ! date (1/1 12/31)
I2 dayofwk ! day of week Sun Sat (1 - 7)
I2 daytype ! type of day for schedule reference (1 12)
I2 DST ! daylight savings time indicator (0 or 1)
R4 Tground ! ground temperature [K]
----!Date Time Ta Pb Ws Wd Hr Ith Idn Ts Rn Sn
----! for each day: start_date end_date
! for each time: 00:00:00 - 24:00:00 increment may be variable
I1 date ! date (1/1 12/31)
I1 time ! time of day (00:00:00 24:00:00)
R4 tmpambt ! ambient temperature [K]
R4 barpres ! barom. pressure(Pa) NOT corrected to sea level
R4 windspd ! wind speed [m/s]
R4 winddir ! wind direction [deg]: 0=N, 90=E, 180=S, ...
R4 humratio ! humidity ratio [g H20/kg dry-air]
R4 solhtot ! total solar flux on horizontal surface [W/m^2]
R4 solhdif ! diffuse solar flux on horizontal surface [W/m^2]
R4 tskyeff ! effective sky temperature [K]
I2 rain ! rain indicator 0 or 1
I2 snow ! snow indicator 0 or 1
141
-----
The Tground, solar, sky, rain and snow values are not used in CONTAM. They are reserved for
thermal analysis, if it is added to the program.
Editing Weather Files
You can import weather files into a spreadsheet program for editing. However you must make
sure that the date format is compatible with CONTAM when you save the file. One well-known
spreadsheet program will convert the CONTAM date format of mm/dd into the mmm-dd form.
For example the CONTAM date format for January 1 is "1/1", but the spreadsheet program will
convert it to "Jan-01" unless you "force" it to import the first column of data the one that
contains date information as text. Another option is to accept the default importing option then
change the cell format for each date to the CONTAM format mm/dd prior to saving the file as
tab-delimitted.
Temperature: ContamX uses the ambient temperature when calculating outside air density and
building stack effects.
Absolute Pressure: Absolute barometric pressure (not corrected to sea level). If you don't know
this value, you can enter the altitude of the building site on the Location Properties page to have
ContamW calculate the barometric pressure for you.
Relative Humidity: Relative humidity as a fraction, i.e., between 0.0 and 1.0. This value will be
used along with Ambient Temperature and Pressure to calculate the Humidity Ratio and Mass
Fraction of H2O.
Humidity Ratio: The mass of water vapor per mass of air (excluding water vapor) calculated
based on the Temperature, Pressure and Relative Humidity.
Humidity Ratio = Mass Fraction / (1 Mass Fraction)
Mass Fraction (H2O): The mass of water vapor per mass of air (including water vapor). These
are the default units of contaminants in CONTAM. This value is provided so you can use it as
the default contaminant concentration of H2O.
Wind Speed: Magnitude of the wind velocity.
Wind Direction: Direction from which the wind blows as measured in degrees clockwise from
true north.
Day Type: This is the type of day you want to use when performing a simulation with steady
airflows and no weather file. The Day Type corresponds to one of the twelve day schedules that
you can create.
Weather and Wind Location Properties
Longitude, latitude, and time zone are currently not used by CONTAM. They have been
included for potential use in the future if heat transfer analysis is implemented within the
program.
Altitude: ContamW uses the site altitude to determine a default absolute barometric pressure for
the steady state weather data.
Weather and Wind Wind Pressure Display Properties
The wind pressure display values are used to calculate the wind pressures displayed on the
screen in wind pressure display mode. You activate the wind pressure display mode by selecting
Wind Pressure from the View menu.
NOTE: These values are not used by ContamX when performing a simulation. To display the
wind pressure results use the Wind Pressure selection of the View menu. This feature is
provided so that you can verify the wind speed and direction information visually on the
SketchPad. (see Checking Wind Pressure Data in the Defining Steady State Weather and Wind
section)
Ambient Temperature: The ambient temperature is used to calculate outside air density and
building stack effects.
Absolute Pressure: Be sure to enter the absolute barometric pressure instead of pressure
corrected to sea level.
Wind Speed/Direction: Enter the wind speed for the site. The wind direction is calculated in
degrees clockwise from true north.
143
Day Type: This is the day type as defined in the Week Schedule .
144
145
If using an external editor, you can use the Create WPC File dialog box to generate a list
of path location data that contains the locations of all the building envelope openings. You
can also have ContamW call your EWC File Converter program via the Create WPC File
dialog box that is presented later in this section and activated via the WeatherCreate
WPC File... menu command.
3. Set the simulation to utilize the WPC file (see Simultion Weather Properties in the
Working with Simulations section).
4. Verify WPC file
If you have created the WPC file using an external editor, you should verify that its
contents match that of the project file. You can do this using the View Wind Pressure
Mode to display the WPC wind pressure type (see Checking Wind in the Defining
Weather and Wind section) or initiating the pre-simulation checks by selecting either the
Run Simulation or Create ContamX Input File from the Simulation menu.Either option
will compare the WPC and PLD files and provide notification of discrepancies between
them including location data and contaminant data that do not match. If you use and
EWC file converter program, then the verification step will occur automatically. If there
are any flow paths that do not map to a location in the WPC file, they will be highlighted
on the SketchPad and a list of these locations will be written to the CONTAMW2.LOG
file. Look for list of Paths/Terminals/Junctions not found in WPC file.
5. Run simulation
If there are errors between the WPC file and the PLD file, then ContamX will not be able
to run a simulation. ContamW will not initiate ContamX. If ContamX is run from the
command line on a project having discrepancies, it will also exit with an error message.
Generate PLD File: Use this button to manually generate a PLD file. The PLD file will be
stored in the same location as the PRJ file and have the same name as the PRJ file but a PLD
extension. This file is useful for creating a WPC file with an external editor.
148
The first line of the WPC file is used to identify the type of file. For a 2.1 format WPC file it is
exactly:
WPCFile ContamW 2.1
//
//
//
//
The file description may not begin with a "!". The StartDate and EndDate are used to verify that
the file data covers the entire period to be simulated. The StartDate may not be later than the
EndDate.
The data must start at time 00:00:00 on the StartDate and end at 24:00:00 on the EndDate. The
times must be in consecutive order, but the difference between successive times need not be
constant.
Example:
WPCfile ContamW 2.1
For WPCtest3.prj
2 ! flowpaths
1 ! contaminants
1 ! use pressure flag
0 ! time step
01/01 ! start date
01/01 ! end date
C1
!nr X Y Z map
1 0.000 4.000 1.500 0
2 8.000 4.000 1.500 0
01/01 00:00:00 101325 1.204
101308.30 101306.30
0.0 1.0e-6
01/01 24:00:00 101325 1.2041
101308.30 101306.30
0.0 1.5e-6
The simulation time step provides a recommendation to the EWC File Converter for reducing the
size of the WPC file, so that only the time steps that coincide with the simulation time step could
be included (which could reduce interpolation required).
Each flow path is uniquely identified by a combination of flow path type and flow path ID
values.
Comments begin with an exclamation point (!) and may begin at the start of any line (so that
the entire line will be ignored) or after all fields of a line (so that the remainder of the line will be
ignored).
For user readability, fields should be commented whenever possible.
The format of R4 data types may be interpreted similar to a C scanf() statements conversion
specification.
Header Section:
First three lines:
EWC filename
// (I1 full path)
WPC filename
// (I1 full path)
desc[] // file description (I1)
Xref
Yref
angle
Xmax
Ymin
Ymax
Zmin
Zmax
//
//
//
//
//
//
(R4
(R4
(R4
(R4
(R4
(R4
%7.3f)
%7.3f)
%7.3f)
%7.3f)
%7.3f)
%7.3f)
shift
start
end
//
//
//
//
(I4) [s]
(hh:mm:ss I4) start time for EWC when converted to WPC
(mm/dd IX)
(mm/dd IX)
m.wt
The next (number of flow paths) lines contain for each airflow path:
path number
x-coordinate
y-coordinate
z-coordinate
//
//
//
//
(IX)
(R4) [m]
(R4) [m]
(R4) [m]
Example:
C:\Program Files\Contamw2\Prjs\WPCcube.ewc ! EWC file
C:\Program Files\Contamw2\Prjs\WPCcube1.wpc ! WPC file
WPC description
! Xref
Xref
Yref
angle
0.000
0.000
0.000
0.00
0.0000 0.0000 ! no latitude/longitude
! Xmin
Xmax
Ymin
Ymax
Zmin
Zmax
0.000
5.000
2.500
10.000
1.000
1.000
! step shift
start
end
0
00:00:00 1/1
1/1
1
2
0.01 ! pressures flag, # species, mapping tolerance
! name m.wt
CO
28.00
CO2
44.00
4
1.00 ! number of flow paths and mapping tolerance
! id#
X
Y
Z
1
5.000
10.000 1.000
2
0.000
7.500
1.000
3
0.000
5.000
1.000
4
0.000
2.500
1.000
-999
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Creating Schedules
You can create schedules using either the CONTAMW Library Manager (see Working with Data
and Libraries) or wherever a "New Schedule" button is provided when working with various
building component property sheets (e.g. airflow paths, ducts, source/sinks, and occupant icons).
Non-occupancy Schedules
You create non-occupant schedules by first selecting to create a new week schedule to display
the Week Schedule dialog box. You must then define one or more day schedules that you then
associate with each day of the week schedule. Each week schedule consists of 12 days one for
each day of the week and five more days that you can use for special situations such as holidays.
These are refered to as the 12 day types. New day schedules are created from the Week Schedule
dialog box by clicking on the "New Schedule" button. This will display the Day Schedule dialog
box whose features are explained below.
Temperature Schedules
Temperature schedules are a type of non-occupant schedule. Unlike other non-occupant
schedules they have units associated with them. Temperature schedules are only associated with
zones and duct junctions and are considered separately from other non-occupant schedules when
creating and editing. For instance, when displaying a list of temperature schedules, only those
non-occupancy schedules having temperature units will be displayed (unitless schedules will not
be displayed).
153
Occupancy Schedules
You create occupant schedules by first creating an occupant exposure icon (see Creating
Occupants). You then click on the "Edit Occupancy Schedule" button that is provided on the
Occupant Data property page of the "Occupant Exposure Properties" property sheet.
Modifying Schedules
You modify existing non-occupancy week and day schedules through the Week Schedule and
Day Schedule dialog boxes respectively. Edit occupancy schedules by editing the properties of
existing occupant exposure icons. The details of editing schedules are presented in the following
sections.
Deleting Schedules
You can only delete occupancy week schedules by deleting the associated occupant exposure
icon. Deleting all other schedules can only be accomplished using the CONTAMW Library
Manager (see Working with Data and Libraries) which will only allow you to delete those
schedules that are no longer associated with any occupants, zones or other building components.
Description: Field for entering a more detailed description of the specific schedule.
Shape: Use this check box to set how CONTAMW interprets values between the data points you
define.
Rectangular: characterized by a step function between the data points
Trapezoidal: characterized by linear interpolation between the data points.
Schedule Data: These are the time/multiplier pairs that you set to define a day schedule. The
times are entered in the hh:mm:ss format.
For unitless schedules, the value is a multiplier between 0.0 and 1.0 used to adjust down the
maximum design values of various schedulable building components, e.g., constant volume flow
rate of a fan flow element.
To insert a new data point
Enter the new time/multiplier pair in the "Time" and "Value" edit boxes in the Edit Schedule
Value Section of the dialog box and press the "<< Insert <<" button. The data point will be
inserted into the schedule in the correct sequence.
To modify an existing data point
Select the data point that you wish to modify from the list, enter the revised data, and press the
"<< Insert <<" button to overwrite the previously entered data point.
To delete an existing data point
Select the data point you want to delete from the list and click the "Delete" button. You can not
delete 00:00:00 or 24:00:00.
consists of a level and zone in which the occupant resides for the indicated time period. Select a
value of "null" from the zone list to indicate the occupant is not in the building for a given time
period.
Location data will also include zone coordinates if the occupant enters a 1D convection diffusion
zone. For such cases, enter the X, Y and Relative Elevation (Z) coordinates and units for each 1D
zone the occupant enters. X and Y are absolute coordinates and Rel Elevation is relative to the
level of each1D zone that the occupant enters.
To insert a new data point
Enter the new time and location data in the "Modify Data" block, press the "<< Insert <<" button
and the data point will be inserted into the schedule in the correct sequence.
To modify an existing data point
Select the data point that you wish to modify from the list, enter the revised data, and press the
"<< Insert <<" button to overwrite the previously entered data point.
To delete an existing data point
Select the data point you want to delete from the list and click the "Delete" button. You can not
delete 00:00:00 or 24:00:00.
156
157
Airflow
Contaminant
Simulation Simulation
Purpose
None
158
To perform a simulation, you set the simulation parameters, run the simulation, and view
simulation results. Simulation parameters are categorized by run control, numerics, and output
properties. Run control properties include the simulation methods, simulation dates and times,
type of weather to use (steady or transient), and simulation time step. Output properties are used
to set the type and amount of data you wish to have sent to the simulation results files. Numerics
properties include convergence criteria, maximum iterations and relaxation coefficients for both
airflow and contaminant equation solvers. ContamW provides default settings for these
parameters. However, you will probably work more with the run control and output parameters
than the numerics parameters.
Setting Simulation Parameters
To set simulation parameters you use the Set Simulation Parameters selection of the
Simulation menu or the F4 keyboard shortcut. This will display the "Simulation Parameters"
property sheet. Detailed descriptions of all simulation properties are given in the Simulation
Parameters section of this documentation.
Running Simulations via ContamW
Once you have set the simulation parameters, you can run the simulation. To run a simulation
select Run Simulation from the Simulation menu. This actually launches a separate program,
ContamX, which in turn displays the "CONTAMX Simulation Control" dialog box.
While there are many factors that can affect the ability of ContamX to quickly and successfully
obtain a solution (converge), there are situations that can cause the simulation to not converge or
to converge very slowly. The relative magnitudes of the flow coefficients have some effect on
the convergence of the nonlinear equation solver of ContamX [Wray and Yuill 1993]. Airflow
networks containing paths whose resistances differ by many orders of magnitude will typically
require more iterations than networks with paths of similar resistances. Reducing the relaxation
coefficient from its default value of 0.75 to a value nearer one-half can often help convergence of
these more difficult cases. The maximum number of iterations can also be increased. However,
the most effective way to improve convergence is to remove those very low resistance paths that
are not likely to effect the computed airflow rates. For example, when simulating a shaft (see
Shafts), represent a shaft using phantom zones as opposed to using airflow elements with large
cross-sectional areas between zones on adjacent levels.
Running Simulations via Command Line
CONTAM utilizes the ContamX stand-alone simulation engine, contamx3.exe. ContamX utilizes
the same .PRJ file that you create using ContamW. With the ContamX program, you can perform
batch mode operations to process multiple project files. Or you can create your own file
processor to modify project files in order to perform sensitivity analysis by performing multiple
runs while varying desired building parameters. If you wish to modify the .PRJ file in such a
manner, you should become familiar with the .PRJ file format that is now annotated with
comment lines to improve the legibility of the file. (see Appendix A - PRJ File Format)
You can simply save project files in the usual manner using ContamW or use the Run Building
Check selection of the Simulation menu. The recommended course of action would be to
perform a simulation by activating ContamX from within ContamW before implementing the
batch process. This will provide some building check routines that insure your project is "well
formed."
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Building Check
Note this building check is also performed prior to initiating a simulation from within ContamW
via the Simulation Run Simulation menu command. If during the building check routine
ContamW detects problems with your project, it will provide you with feedback to assist you in
correcting the problems. This feedback will be provided by displaying the Building Check
dialog box which will display a list problems found and allow you to highlight problematic icons
on the SketchPad as necessary.
Viewing Simulation Results
Once you have successfully run a simulation, you can use ContamW to view simulation results
or to create files that can be imported into a spreadsheet. These capabilities are explained in the
Working with Results section.
Simulation Parameters
Simulation parameters are those used to control the type of simulation that you wish ContamX to
perform and the type of results output you wish ContamX to provide. This section provides
detailed descriptions of the specific simulation parameters.
Simulation Run Control Properties
Simulation Method
Set the type of simulation you wish to perform for both Airflows and Contaminants by checking
the appropriate radio buttons. Refer to the Working with Simulations section for a table of
allowable combinations of simulation method settings.
Airflows: You can use one of the following airflow calculation methods.
Steady: A steady state simulation will utilize the weather set by pressing the Edit Weather
Button on the Run Control property page. This will calculate a single set of airflows. If any
building components have schedules associated with them, then schedule values will be
160
determined by the Day Type set in the Steady State Weather Data (see Weather Properties
under Working with Weather and Wind) and the Steady Simulation Time.
Duct Balance: Use this feature when working with detailed duct systems to have CONTAM
adjust terminal duct balancing coefficients to provide user-defined airflow rates at the duct
terminals. See Working with Ducts.
Building Airflow Test: The building airflow test method performs calculations that aid in
verifying data input to your building model. Use this test prior to performing analysis with
your building model to verify system and total airflow rates to each zone, zone temperatures
and whole building air change rate. You must have only one contaminant set to be used in the
simulation, and it must be a trace contaminant, when you run this test. Results of the test will
be written to the validation file having the same name as the project file and the .val
extension (see Working with Results). This file will be overwritten each time either the
Building Airflow Test or Building Pressurization Test is performed.
When you perform a simulation using this method, ContamX will perform a steady state
airflow calculation under the above conditions and calculate the total airflow rate between
conditioned and unconditioned zones of the project. Results of the test will be written to the
validation file having the same name as the project file and the .val extension (see Working
with Results). This file will be overwritten each time either the Building Airflow Test or
Building Pressurization Test is performed.
161
Contaminants: You can choose one of the following contaminant simulation options:
Steady: The steady contaminant option can only be used in conjunction with steady airflows
and will run until the system reaches equilibrium. Contaminant sources are modeled as
continuous sources with a constant generation rate. If any sources have schedules associated
with them, then schedule values will be determined by the Day Type set in the Steady State
Weather Data (see Weather Properties under Working with Weather and Wind) and the
Steady Simulation Time. Burst sources will be ignored. Ambient contaminant concentrations
will be the Default Concentration values of each contaminant.
Transient: Transient simulations performs calculations over a user-defined period of time and
at a regular time interval referred to as the calculation time step. When performing a transient
simulation CONTAM can use either constant ambient concentrations as given by default
contaminant concentrations or dynamic concentrations from external contaminant files. See
Contaminant Files and Working with WPC Files.
Cyclic: A cyclic simulation repeats a 24h cycle until steady-periodic conditions are achieved.
As with transient simulations, cyclic simulations can implement either steady state or
dynamic weather and contaminant data. If using dynamic weather or contaminant data files
(CTM and WTH), data will be obtained from the file for the date indicated by Steady &
Cyclic Simulations date.
Transient Integration Method: Select the type of transient or cyclic simulation to perform
from the available options. More detailed options are available via the Contaminant
Numerics simulation parameters.
o Default Solver (Implicit Euler): This is the traditional, fixed time step solver now
distinguished from the explicit Euler solver (short time step, STS) and the variable time
step solver (VODE). Note that this method can be made semi-implicit via the
Contaminant Numerics properties.
o Short Time Step (Explicit Euler): You can use this method with either the Transient or
Cyclic contaminant simulation methods. This method is required to perform simulations
of one-dimensional convection diffusion zones and/or ducts. See Contaminant Numerics
Properties for specific control in applying the short time step method to 1D ducts and 1D
zones.
NOTE: This is an explicit solution method that should only be used for short time steps,
therefore there are some checks performed to help avoid known stability problems.
ContamX will check the zone airflow rates (of all zones having non-zero volumes) during
airflow simulation to ensure that they do not exceed one air change per time step. If this
limitation is exceeded for any zone, then the simulation will be terminated with an error
message indicating the offending zone(s). The problem could also manifest itself with an
error message indicating an invalid zone density was calculated due to the calculation of
a negative absolute pressure.
o CVODE: This is a variable time step ordinary differential equation solver [Hindmarsh
and Serban 2012]. It may provide a more accurate solution especially in cases with stiff
contaminant transport systems. Stiff systems are those with wide variations in system
dynamics, e.g., air change rates or kinetic reactions.
NOTE: This solver is currently limited in that it will not handle projects that contain 1D
zones, CFD zones, occupant exposure, burst sources or zones (nodes) with zero volume.
162
Further, the CVODE solver does not support the bridge mode (socket communication
capabilities).
Reset initial contaminant concentrations to: Use this feature to reset the initial
contaminant concentrations of all zones, including the implicit supply and return zones of
simple air handling systems, prior to running a simulation. You can reset initial
concentrations to Zero, Ambient or Current Results Concentrations. If you do not check one
of these boxes, ContamX uses the Initial Concentrations indicated on the Contaminant
Property page for each zone (See Contaminant Data under the Working with Zones section).
Checking one of these boxes causes the Initial Concentration values for each zone to be
overwritten.
o Zero: This option sets the initial contaminant concentrations to zero.
o Ambient Concentrations: This option sets the initial contaminant concentrations to the
default contaminant concentrations as set when defining Project Species (See Species
Properties).
o Current Results Concentrations: This option sets the initial contaminant concentrations to
be the same as the concentrations in each zone at the time step for which ContamW is
currently displaying results on the SketchPad. You must be in the results viewing mode
to utilize this feature. The current time step is displayed in the middle pane of the Status
Bar (See the Status Bar section). This option is especially useful for cyclic simulation,
where you may continue a simulation that has been interrupted before convergence,
continue simulation with tighter convergence criteria, or create a project file for archive
which can be rerun as a one-day transient simulation to quickly compute cyclic results.
Simulation Dates and Times
These dates and times are used to set the date and time labels put on steady state simulation
results and to control the duration of transient simulations by allowing you to set the start and
stop dates and times. Depending on the simulation method chosen different simulation "Dates
and Times" fields will be enabled or disabled.
Steady & Cyclic Simulations: For steady simulations, the date field is only used to label the
simulation results, however, the time field is used to obtain schedule values from the day
schedules based on the day type which the simulation is set to utilize. You set the Day Type
via the steady state Weather and Wind Parameters property sheet (see Weather Properties
under Working with Weather and Wind). ContamX will then utilize the Day Type and time to
select schedule values for items that have schedules associated with them. The value of Day
Type will be from 1 to 12 and will be used to select from the twelve day schedules associated
with each week schedule in use during a simulation.
For cyclic simulations with steady airflows, the date field is only used to label the simulation
results, and the day type of the steady state data is used to determine schedule values. For
cyclic simulation with transient airflows, the date field is used to determine schedule values
and obtain data from weather and contaminant files if being used, otherwise steady state data
is used. Cyclic simulations always begin at time 00:00:00 and end at time 24:00:00, so the
time field is irrelevant.
Transient Simulation, Start and Stop: These date and time fields are used to set the
starting and stopping date and time of transient simulations. You should be sure to use only
those dates available in both the weather and ambient contaminant files. The available dates
in these files will be displayed in the Transient Weather Data and Transient Contaminant
163
Data sections below. Each day of the WTH file contains a Day Type field which will be used
to determine which of each week schedule's twelve day schedules should be used for each
day of simulation.
NOTE: If using steady state weather with a transient simulation, simulation will begin with
the Day Type set in the steady state weather and cycle through the first seven day schedules if
simulating more than one day.
Use restart file: Each transient and cyclic simulation produces a restart file that contains the
status of the simulation at midnight for each day of the simulation and the last time step of a
simulation if it does not end at midnight. The restart file will have the same name as the PRJ
file but have the RST extension. If a restart file is available that has the same name as the
project file, the dates for which restart data is available will be listed as "Restart data from
___ to ___" below the "Use restart file" check box. Enter the date in the edit box labeled
Restart data beginning. If a restart file is used in a simulation, the existing restart file will
be overwritten.
This feature can be useful when running long multi-day simulations with the potential for
generating impractically large detailed simulation results files. You can avoid the generation
of large results files by running the multi-day simulation outputting only summary data files,
reviewing the results to determine days of interest, e.g., highest concentration, then rerunning
the simulation for the days of interest using the restart file and outputting detailed results.
You can also use this feature to load boundary layer and deposition/resuspension
source/sinks by first running a cyclic simulation for a single day, then using the restart file to
run a transient simulation for the desired period of time.
Simulation Time Steps
These are the time increments that CONTAM uses when performing transient and cyclic
simulations.
Calculation: The calculation time step is that used by ContamX when performing transient
airflow and contaminant calculations for the transient and cyclic simulations. Shorter time
steps provide for greater accuracy of results but require more computation time. There must
be an integral number of calculation time steps in an hour. The minimum allowable time step
is 1 second and the maximum is 1 hour.
Selecting a time step can also affect the ability to capture scheduled events. CONTAM
provides the means to schedule events via day/week schedules and multiple time-based input
files including WTH, CTM, WPC, CVF and DVF files. You can have ContamW help you to
choose this time step by selecting Time Step Analysis... from the Simulation menu.
ContamW will review all schedules and input files to determine the maximum recommended
time step required to capture all of the scheduled events. This will display a dialog box that
will provide you with a list of day schedules and input files along with the limiting time step
for each and an overall limiting time step.
Output: Simulation results are written to results files (see Working with Results) at the
output time step which must be an even multiple of the calculation time step. Shorter time
steps allow you to see the results in more detail, but also create larger results files. Utilizing
an output time step that is longer than the calculation time step can still retain relatively high
accuracy while reducing the size of the results files. Using these parameters you can refine
your simulation period to provide detailed simulation results where needed.
164
Status: CONTAM uses the status time step to determine how often the simulation progress is
updated on the CONTAMX Simulation Control dialog box. The status time step must be a
multiple of the calculation time step.
If using wind pressures from a WPC file, you may not use a WTH file.
If using contaminant concentrations from a WPC file, you may not use a CTM file.
If the simulation is set to use a WPC file then schedule values will be obtained by cycling
through the first seven days of schedules beginning on the day type provided by the steady state
weather data.
When performing a cyclic simulation and using a WPC file, the WPC file must contain only one
day having the same date as indicated for Steady & Cyclic Simulations.
Simulation Output Properties
When you run a simulation, results are saved to files as the simulation proceeds. Detailed results
for airflows and/or zone contaminant concentrations are saved to the SIM file that is created
when ever a simulation is run. The SIM file is a binary file which is not "human-readable" as
opposed to human-readable text files. The data in the SIM file will be used by ContamW to
display airflow results on the SketchPad, to display contaminant concentrations in the results
display window, to create export and report files, and to generate charts of transient simulation
results. Output is created at every output time step. Shorter time steps allow you to see the results
in more detail, but lead to larger simulation result files. ContamX can create several result files in
addition to the SIM file (See Working with Results), and you can control the data that will be
saved during a simulation with the following parameters.
In most cases, ContamX can generate both detailed and/or box-whisker results. Detailed results
are written to the corresponding file at each output time step. Box-whisker results include daily
average, standard deviation, maximum and minimum values. Maximum and minimums are also
accompanied by the time of day at which they occur for daily results, or the day on which they
occur for the simulation summary results. Note that box-whisker data is based on calculations
performed at the calculation time step but can require significantly less storage space. They can
be of use when performing long simulations to find days and times of particular interest which
can then be simulated in greater detail in conjunction with the restart (RST) file.
Airflow Simulation Results: These are the results available related to airflow calculations.
Airflow Rates: Output airflows through and pressure differences across each flow link
(airflow paths, duct segments, duct leakage paths, airflow terminals and simple air handler
supplies and returns) to the SIM file. This data is necessary to display or export results of
airflow and pressures including those presented as SketchPad results and charts.
Building Air Change Rate: Output the whole building air change rate to the ACH file.
Select Use Standard Density to have ContamX use standard air density for the incoming
outdoor air in the air change rate calculations, otherwise the outdoor air density will be based
on the outdoor temperature.
Ages of Air: Output age of air for each zone to the AGE file.
WARNING: This calculation involves the inversion of the flow matrix and could be quite
demanding on computational resources for projects involving a large number of zones.
Contaminant Simulation Results: These are the results available related to contaminant
calculations.
for 1D zones the average concentrations of all sub-cells will be saved to the SIM file. You
can use zone sensors and report control nodes within 1D zones to obtain concentration time
histories at specific locations within 1D zones to output to the Controls LOG file (see Results
Files).
Occupant Exposure: Output occupant exposure data to the EBW file. This data is necessary
to display occupant exposure summary information when you highlight an exposure icon.
You can still plot transient exposure data without this summary information.
Short Time Step Results: These are the results when using the Short Time Step contaminant
simulation method and the project contains one-dimensional convection diffusion zones (see
Working with Zones). Four results files can be created, each having the same name as the PRJ
file but with a different extension. Thes files are all binary files. NIST provides two utilities that
you can use to "view" these files: ContamRV and 1DZRead. ContamRV is the results viewer that
can provide a colorized view of the contaminant concentrations within the zones including the
variations of concentrations within 1D convection/diffusion zones, and 1DZRead is a commandline program that can convert the 1D results files to tab-delimitted files. File formats are
provided in the Working with Results section.
RXR File: This is a cross reference file that is created anytime at least one of the others is
created.
RZF File: This file contains the temperature, gage pressure and density of the zones.
RZM File: This file contains the average mass fractions of each contaminants in each zone.
RZ1 File: This file contains the mass fractions of each contaminant in each cell of each 1D
zone.
Building Airflow Test Results: These options control which sections of data are written to the
VAL file when you run the Building Airflow Tests simulation mode. See the Results Files section
in the Working with Simulation Results section for detailed description of the VAL file.
Zones: Write the "Zones" section that provides various air change rates for each zone to the
VAL file.
Ducts: Write the "Junctions" section that provides information related to the duct junctions
and terminals to the VAL file.
Classified Flows: Write the "Classified Zone Airflows" section to the VAL file. This section
provides detailed mass flow rates to and from all zones categorized by various types of
airflow sources, e.g., duct system, outdoor air, etc.
CONTAMX Display and Logging Options: These properties control the manner in which the
simulation engine, ContamX, appears during execution and the amount of data written to the
CONTAMX.LOG file during a simulation.
CONTAMX Display Mode: Select whether you want to interact with ContamX via a
Windows dialog box or Console window (DOS window). The dialog box method is the
typical choice, but you might want to run it in a console window if you have trouble with
ContamX executing properly particularly for large project files.
CONTAMX Log Mode: Select the level of detail to output to the CONTAMX.LOG file.
This is provided mainly for diagnostic purposes (for program developers) in the event that a
problem is occurring during simulation (see Getting Help).
167
Echo .PRJ as read to .LOG: Check this box to output the project file to the
CONTAMX.LOG file. This is mainly provided for diagnostic purposes.
Maximum Iterations: Use this value to prevent endless calculations if the flow iterations are
not converging. This should not be a problem with an appropriate relaxation coefficient.
Relaxation Coefficient: This coefficient modifies the adjustment of the pure N-R method.
Tests have found values near 0.75 to work well. Values near 1.0 may lead to non-convergent
solutions. Values closer to 0.5 may be more reliable but take longer to solve. This coefficient
is not used with the simple trust region method
Relative Convergence Factor: The flow iterations are determined to have converged when
the sum of all flows in and out of the zone are less than the relative convergence factor times
the sum of the absolute values of those flows.
Absolute Convergence Factor: A test is also provided in the event of very low flows to
insure that the sum of the absolute values of the flows is less than the absolute convergence
factor based on a very small zone air change rate entered here.
Linear Equation Solver: Select the method for solving the linear equations generated by the NR method. ContamX uses either the Skyline algorithm (also called the profile method), which is
a direct solution of the equations, or the Pre-conditioned Conjugate Gradient algorithm (PCG),
which is the iterative biconjugate gradient algorithm. The execution time of the skyline method
is determined by the sparsity and fill pattern of the solution matrix.
Maximum Iterations: Use this value to prevent endless calculations if the flow iterations are
not converging. This is only available for the PCG method.
Relative Convergence Factor: The flow iterations are determined to have converged when
the sum of all flows in and out of the zone are less than the relative convergence factor times
the sum of the absolute values of those flows. This is only available for the PCG method.
Resequence Linear Equations: The default is to resequence the linear equations in order to
speed the solution by reducing the sparsity of the solution matrix. ContamX determines
whether or not the resequencing actually improves the matrix. A failure in the resequencing
algorithm is not a serious error because it will not change the numerical results. The
resequencing uses algorithm 582, Collected Algorithms from ACM [ACM 1982].
NOTE: If ContamX "crashes" during execution, it might work if you select not to
resequence the equations or to select the Console window ContamX Display Option.
168
Linear Airflow Initialization: An initial estimate of the pressures and flows is needed to
start the non-linear equation solver. The linear initialization is usually faster than starting
from zero.
Density Control Parameters: These parameters relate to the treatment of air density during
simulations. Allowing for the variation of zone air density can provide transient analysis as
opposed to quasi-steady analysis that does not provide for non-flow processes to take place (see
Basic Equations of the Theoretical Background section). Variation in zone density can be
realized when using non-trace contaminants, e.g., water vapor, or when system flows are
relatively large with respect to zone leakage. Typically, these parameters should be kept as their
defaults, but they do allow for some more advanced treatment if desired.
Vary density with zone pressure and Use advanced hydrostatic equation: Zone density is
computed using the gas law relationship = P / RT, where by default, P is the barometric
pressure. If this box is checked, then P is the actual zone pressure which is generally only
likely to be a factor if the zone pressure varies significantly from barometric pressure.
Typically the stack calculation is based on the incompressible hydrostatic equation of the
form Ps = -gh. The advanced equation accounts for the change in density with the local
zone reference pressure as well, and has the form Ps = Pref(e-gh/RT-1). These values are
calculated for the inlet and outlets of each airflow path (and duct segment), and the difference
is used to determine the contribution of the stack pressure to the overall pressure difference
across the flow paths.
Vary density during time-step: Allows the zone density to vary within the pressure
calculation of each time step of a transient simulation until they have converged along with
the pressures and airflow rates. This feature is not implemented when using the short time
step method.
Max Time Step Iterations: This is the maximum number of iterations for convergence of
the density values.
Adjust temperatures in flow elements: This modifies the element flow coefficients to
account for the actual properties of the air flowing through the elements. This may change
the computed flows by a few percent.
Include dM/dt in transient simulation: Set this option to account for transient flow
processes that could account for accumulation or removal of significant amounts of air within
a zone. This term is negligible for buildings with typical leakage and/or time steps greater
than a few seconds.
Linear Contaminant Solver: Both the default solver and the CVODE solver require the use of a
linear solution method. The default solver implements the linear solver directly to solve the
linearized system of equations as detailed in the Contaminant Analysis section. The
CVODE Solver utilizes the linear solver when factoring the adaptive step-size matrix
formulations.
For each zone there is an equation for each contaminant species that you may have selected to be
either trace or non-trace contaminants. The mass fractions of the non-trace contaminants are
solved within an iterative loop that also determines the airflows because the non-trace
contaminants affect the zone air densities and pressures. The mass fractions of the trace
contaminants are solved after the flows have been computed since they do not affect the zone air
densities. These calculations require the solution of simultaneous, non-symmetric, linear
algebraic equations. Four methods are provided two direct and two iterative. The iterative
algorithms are successive over relaxation (SOR) and biconjugate gradient (BCG). The direct
methods are a skyline (or profile) algorithm and a Gaussian LU-decomposition method. These
four methods have been listed in order of increasing memory use. The iterative methods may or
may not be faster than the more reliable direct methods. Before doing a long transient simulation
of a large project, it may be useful to test the different methods to determine which will give
optimum performance.
Skyline: The skyline algorithm is the most reliable solution, and it is very fast for small
problems but can be slow for large problems.
BCG: Try the iterative biconjugate gradient algorithm for problems having a large number of
zones for which the SOR algorithm might not converge.
SOR: The successive over-relaxation algorithm requires much less memory and is faster than
the Skyline method unless there are convergence problems.
LU: LU decomposition using a full (non-sparse) matrix and is for verifying the solutions of
the other methods rather than general usage.
The following properties apply to the linear solver:
o Maximum Iterations: Used to prevent endless calculations if the iterations are not
converging for the BCG method.
o Convergence Factors: The SOR iterations are assumed converged when the relative
difference between the values on successive iterations are less than the relative
convergence, e1. The BCG method is determined to have converged when
.
o Relaxation Coefficient: An optimum over-relaxation coefficient, , speeds the
convergence of the SOR algorithm. Determination of an optimum will require some
experimentation with different values (usually near the low end of the range 1.0 to 2.0).
o The Trapezoidal Integration Factor: Determines the relative portions of the explicit
and implicit terms in the solution of the differential equations. This is the parameter
presented in the Contaminant Analysis section of the Theoretical Background.
o Resequence Linear Equations: The default is to do this in order to speed the solution by
reducing the sparsity of the solution matrix.
CVODE Non-Linear Contaminant Solver: Select the method and associated parameters to use
when implementing the CVODE solver.
170
Backward Differentiation Formulas: The BDF method is recommended for stiff systems.
Convergence for Cyclic Simulations: Convergence is assumed when the relative difference in
the peak concentrations (for all contaminants in all zones) is less than the relative convergence,
e1. The absolute convergence, e2, is used to keep zones and contaminants with negligible mass
fractions from dominating the solution.
1D Options: These options provide control over the 1D simulation capabilities that can be
implemented when using the Short Time Step Method to perform contaminant simulation.
1D Zone Model: Select this method to implement the explicit one-dimensional
convection/diffusion cell solution method for zones that have been defined as 1D zones. This
will subdivide the zones into cells along user-specified 1D axes.
1D Duct Model: Select this method to implement the explicit one-dimensional
convection/diffusion cell solution method for ducts. This will subdivide all duct segments
into cells along their length based on the flow rate through the duct segment. Effective
diffusion coefficient will be based upon the Reynolds number and the molecular diffusion
coefficients of the contaminants.
If the product of the velocity u and the time step t in a given duct segment is less than the
Cell Size parameter, then an Eularian method is used with a cell size equal to that of the Cell
Size parameter, otherwise a Lagrangian method is implemented with an effective cell size of
ut leading to the solution of fewer simultaneous equations as the velocity increases.
Variable Junction Temperatures: When using the 1D Duct Model, you can have
CONTAM implement variable junction temperatures to account for the convective heat
transfer of the air within the duct system based on inlet terminal temperatures. When using
this option, the junction temperature properties are ignored and terminal inlet temperatures
are obtained from the zones in which they are located.
Simulation - CFD Numerics
These parameters are used to control the multizone+CFD coupling method.
Number of Coupled Zones: This shows the number of CFD Zones in the project. This version
of CONTAM only allows for one such zone.
Coupling Method:
CONTAM -> CFD: Run multizone calculation then provide the results as boundary
conditions for the CFD calculation. No information is passed back from the CFD calculation
to the multizone calculation.
171
CONTAM -> CFD -> CONTAM: The same as above, but the CFD results are passed back
for use as boundary conditions for the multizone calculation. The data is exchanged in each
direction only once.
CONTAM <-> CFD: This is the fully dynamic coupling method. The multizone and CFD
calculations provide boundary conditions iteratively to each other during each time step until
they either reach convergence with each other at the multizone-CFD boundaries or the
Maximum Coupling Iterations is exceeded. The begins and ends with a multizone
calculation.
Numerical Parameters:
Maximum Coupling Iterations: This is the maximum number of time per time step that
boundary conditions will be exchanged between the multizone and CFD calculations.
Output Frequency of Coupling Results: Controls how often the coupled simulation results
are saved to the .CMO file. This file is useful for monitoring the progression of the coupled
simulation. These results are also output to the console during simulation.
Convergence Factor for Airflow Coupling: Convergence criteria for the dynamic coupling
method.
Restart Coupling: Whenever a CFD airflow simulation is performed, a .VAR file will be
saved in the same location as the PRJ file. The VAR file contains the airflow results of the
last time step for which a CFD calculation was performed. Check this option to run a
contaminant simulation using the steady airflow results contained in the VAR file.
172
Results Files
When ContamX performs a simulation, it creates a set of results files within the same directory
that the project file is stored. These results files have the same file name as the project file with
different extensions appended to indicate the type of results file. The following table lists the
different file extensions and gives a brief description of the files. Details of each file are provided
following the table.
173
Extension Type
.ACH
.AGE
.BAL
.CBW
.CSM
.EBW
.LOG
.RST
.RXR
.RZF
.RZM
.RZ1
.SIM
.SRF
.VAL
File Description
Whole building air change rate - broken down into airflow path and ventilation
Text system components and the combined value. This file can contain results for
each time step and/or daily box-whisker results.
Age of air - age of air results for each zone at each time step and/or daily boxText
whisker results.
Text Balance - results of duct balancing calculation.
Text Contaminant box whisker results - only created for daily box-whisker results.
Contaminant source/sink summation - total mass of contaminants generated
Text
and/or accumulated by source/sinks and filters during a simulation.
Occupant exposure results - average exposure of each occupant to each
Text
contaminant for each time step and/or daily box-whisker results.
Text Controls log file - contains the output of all Report control nodes.
Simulation restart file - only for use by ContamX for restarting simulations at
Binary
the beginning of intermediate days of a simulation.
Binary Short time step simulation results cross reference data
Binary Short time step simulation results zone environmental properties
Binary Short time step simulation results zone mass fractions
Binary Short time step simulation results 1D zone cell mass fractions
Detailed simulation results - airflow rates and pressure difference of flow
links, reference pressures and temperatures of airflow nodes, and contaminant
concentrations of contaminant nodes at each time step. This is the file from
Binary
which SketchPad results and graphs are produced and displayed using
ContamW. It is also the file from which Export and Report files can be
generated.
Surface result file - contains contaminant concentrations for source/sinks that
Text include a reversible storage node. Currently there are two types: boundary
layer diffusion (BLS) deposition/resuspension (DVR).
Model "validation" test results file - contains the results of either the Building
Text
Airflow Test or Building Pressurization Test airflow simulation methods.
174
where
ACR = whole building air change rate [h-1]
= mass flow rate into the conditioned space [kg/s]
air = density of incoming air [kg/m3]
Vbldg = volume of conditioned space [m3]
If there is a mass-imbalance for any airflow zone, ContamX will generate a warning message
indicating the zone in question.
File Format (tab-delimited text):
The first line of the ACH file contains:
StartDate // first date of simulation (mm/dd IX)
EndDate // last date of simulation (mm/dd IX)
SimStep // simulation time step [s](IX)
achsave // save detailed results flag [0/1] (IX)
abwsave // save box-whisker results flag [0/1] (IX)
Vcond // volume of conditioned space [m^3] (R4)
time
path
duct
total"
If abwsave is 1, then three lines of daily box-whisker data are written - one for paths, ducts
and total respectively. Each line contains:
date // date (mm/dd IX)
type // "path" "duct" or "total"
avg // average value for day (R4)
dev // standard deviation (R4)
175
At the end:
If abwsave is 1, then three lines of summary box-whisker data for the entire simulation one for paths, ducts and total respectively. Each line contains:
"final"
type // "path" "duct" or "total"
avg // average value for simulation (R4)
dev // standard deviation for sim (R4)
dmin // date on which min occurs (mm/dd IX)
min // minimum value for simulation (R4)
dmax // date on which max occurs (mm/dd IX)
max // maximum value for simulation (R4)
Example File:
1/1
day
1/1
1/1
//
//
//
//
zone
avg
dev
min
min
max
max"
176
If zbwsave is 1, then a line of daily box-whisker data is written for each zone. Each line
contains:
date // date (mm/dd IX)
zone // zone number (IX)
avg // average value for day (R4)
dev // standard deviation (R4)
tmin // time at which min occurs (hh:mm:ss I4)
min // minimum value for day (R4)
tmax // time at which max occurs (hh:mm:ss I4)
max // maximum value for day (R4)
At the end:
If zbwsave is 1, a line of summary box-whisker data is written for each zone for the entire
simulation. Each line contains:
"final"
zone // zone number (IX)
avg // average value for simulation (R4)
dev // standard deviation for sim (R4)
dmin // date on which min occurs (mm/dd IX)
min // minimum value for simulation (R4)
dmax // date on which max occurs (mm/dd IX)
max // maximum value for simulation (R4)
Example File:
3 1/1 1/1 300 0 1
day zone avg dev min min max max
1/1 1 1.000 0.000 00:05:00 1.000 00:05:00 1.000
1/1 2 2.000 0.000 00:05:00 2.000 00:05:00 2.000
1/1 3 3.000 0.000 00:05:00 3.000 00:05:00 3.000
final 1 1.000 0.000 1/1 1.000 1/1 1.000
final 2 2.000 0.000 1/1 2.000 1/1 2.000
final 3 3.000 0.000 1/1 3.000 1/1 3.000
The next two lines are headers for fan and terminal data:
!fan duct # flow [kg/s] Prise [Pa] RPMratio
!trm jctn # rel-flow [-] Cb [-]
If fan:
"fan" // indicates fan data
duct // duct segment number of fan(IX)
flow // total fan flow (R4)
prise // pressure rise across fan (R4)
Example File:
0 ! Flow balance iterations converged
!fan duct # flow [kg/s] Prise [Pa] RPMratio
!trm jctn # rel-flow [-] Cb [-]
fan 4 0.334472 68.0745
trm 1 1.000025 4.38419
trm 2 0.999974 4.2013
fan 8 0.334472 107.938 0.78357
trm 11 1.000007 7.76847
trm 12 0.999991 7.58544
end
zone
ctm
avg
dev
min
min
max
max"
After all daily values comes the summary for the entire simulation
for each zone
for each contaminant:
"final"
zone // zone number (IX)
ctm // contaminant number (IX)
avg // average value for simulation (R4)
dev // standard deviation for sim (R4)
min // minimum value for simulation (R4)
dmin // date on which min occurs (mm/dd IX)
max // maximum value for simulation (R4)
dmax // date on which max occurs (mm/dd IX)
Example File:
2 1 1/1 1/1
day zone ctm avg dev min min max max
1/1 0 1 0.000e+000 0.000e+000 00:05:00 0.000e+000 00:05:00 0.000e+000
1/1 1 1 1.036e-004 0.000e+000 00:05:00 1.036e-004 00:05:00 1.036e-004
1/1 2 1 6.839e-005 4.049e-005 00:05:00 0.000e+000 24:00:00 1.019e-004
final 0 1 0.000e+000 0.000e+000 1/1 0.000e+000 1/1 0.000e+000
final 1 1 1.036e-004 0.000e+000 1/1 1.036e-004 1/1 1.036e-004
final 2 1 6.839e-005 4.049e-005 1/1 0.000e+000 1/1 1.019e-004
179
Interactions with ambient - This section provides the mass of each contaminant that enters and
exits the building volume, i.e., those that are set to be included in the building volume.
Simulation time - This section provides information on the duration of the simulation.
File Format (tab-delimited text):
The first two lines of the CSM file display the PRJ file name and the date and time the simulation
was run:
"Project:" FilePath[] // the full path of the PRJ file (I1)
"Time:"
SimTime[]
// PC time the simulation was started (I1)
-- Blank line -This is followed by the number of contaminants simulated.
NumCont "contaminants" // number of contaminants (I4)
-- Blank line --
zn#
species
released
removed
stored
[kg]
//
//
//
//
//
//
//
// mass released(R4)
// mass removed [kg] (R4)
// mass accumulated including previous storage (R4)
//
//
MassUp[nc] //
Name[]
//
// number
// and
// filter
// number
Name[]
nc
Then a line of data for each contaminant for which breakthrough is specified.
Each line contains:
"--" // indicates continuation of filter
Ctm[] // contaminant name (I1)
If breakthrough occurred:
Date[] // date on which breakthrough occurs (MMMDD I4)
Time // time at which breakthrough occurs (hh:mm:ss I4)
bkeff // breakthrough efficiency
Example File:
Project: C:\CONTAM96\samples\.4\Filters\TestBK3.prj
Time: Mon Jul 18 10:17:22 2005
5 contaminants
Contaminant source/sink summary.
4 source/sinks
s/s# type species zn# As mult Xmin Xmax Ymin Ymax Zmin Zmax released removed
stored [kg]
1 ccf CO 3 0 1 0 0 0 0 0 0 7.20E-01 0.00E+00 0
2 brs Cl2 3 0 1 0 0 0 0 0 0 1.00E-04 0.00E+00 0
182
1.204e-001
7.389e-002
1.204e-001
7.389e-002
7.388e-002
7.388e-002
Both
downstream
MERV10
downstream
GF0
downstream
4.652e-002
4.652e-002
0.000e+000
4.651e-002
0.000e+000
Both 2
MERV10 0
GF0 0
MERV10 0
GF0 0
part1.00 element ns
1.282e-001 1.649e-002
0.000e+000 1.649e-002
1.282e-001 0.000e+000
0.000e+000 1.648e-002
1.282e-001 0.000e+000
(or cells) are determined based on the associated occupancy schedules. The exposure is
determined by integrating the concentration vs. time using the mean-value of the contaminant
concentrations to which the occupant is exposed during each simulation time step. The resultant
integral is divided by the output time step then written to the file in units of kg_cont/kg_air.
File Format (tab-delimited text):
The first line of the EBW file is a header describing the data in the file:
NumExps // number of exposure icons (IX)
NumCont // number of contaminants (IX)
StartDate // first date of simulation (mm/dd IX)
EndDate
SimStep
expsave
ebwsave
//
//
//
//
time
ctm"
exp[]
pexp
ctm
avg
dev
min
min
max
max"
If ebwsave is 1, then a line of daily box-whisker data is written for each exposure icon:
date // date (mm/dd IX)
exp // exposure icon number (IX)
ctm // contaminant number (IX)
avg // average value for day (R4)
dev // standard deviation (R4)
tmin // time at which min occurs (hh:mm:ss I4)
min // minimum value for day (R4)
tmax // time at which max occurs (hh:mm:ss I4)
max // maximum value for day (R4)
At the end:
If ebwsave is 1, a line of summary box-whisker data is written for each exposure icon and for
each contaminant for the entire simulation. Each line contains:
"final"
exp // exposure icon number (IX)
ctm // contaminant number (IX)
avg // average value for simulation (R4)
dev // standard deviation for sim (R4)
dmin // date on which min occurs (mm/dd IX)
min // minimum value for simulation (R4)
dmax // date on which max occurs (mm/dd IX)
184
Example File:
1 2 1/1 1/1 300 1 1
day time ctm 1
day pexp ctm avg dev min min max max
1/1 01:00:00 1 2.811e-007
1/1 01:00:00 2 9.970e-008
1/1 02:00:00 1 2.571e-007
1/1 02:00:00 2 6.109e-008
1/1 1 1 3.021e-007 0.000e+000 02:00:00 2.571e-007 00:05:00 3.592e-007
1/1 1 2 1.061e-007 1.945e-008 02:00:00 6.109e-008 00:05:00 1.562e-007
final 1 1 3.021e-007 0.000e+000 1/1 2.571e-007 1/1 3.592e-007
final 1 2 1.061e-007 1.945e-008 1/1 6.109e-008 1/1 1.562e-007
<project name>.LOG
If you perform a transient simulation and implement report control elements, ContamX will
create a file in the same directory as your project file with the name of your project file and the
.LOG extension appended (See Control Element Type: Report a Value). This file will contain a
line of data at each output time step and a column of signal values for each report control
element.
<project name>.RST - Simulation Restart File
Restart is an alternative to normal initialization of a simulation. It contains the state of all airflow
and contaminant nodes, flow rates and pressure differences for all flow paths, contaminant
storage terms for sinks, and signal values of various control node types. State data will be stored
at 24:00:00 of all days simulated.
File Format (binary):
Header data:
m[0] = 0L; /* TURBO C++ messes up the first bytes written; */
m[1] = (I4)_nzone; /* therefore, send 4 unused bytes. */
m[2] = (I4)_npath;
m[3] = (I4)_nctm;
m[4] = (I4)_njct;
m[5] = (I4)_ndct;
m[6] = (I4)_ncss;
m[7] = (I4)_nctrl;
m[8] = (I4)_rcdat.date_0;
m[9] = (I4)_rcdat.date_1;
m[10] = (I4)_rSizeData;
m[11] = (not set)
m[1] thru m[7] allow ContamW to check for some changes in the project.
m[8] and m[9] are the date limits displayed to the user.
m[11] will allow reading all dates on the file -- could be used to create a
selection box of available dates.
RESTART DATA:
For all AF_NODEs:
R8 T - temperature
R8 P - pressure
185
R8 M - mass
R4 Mf[_nctm] - mass fractions
For all AF_PATHs:
R8 Flow[0] - primary flow
R8 Flow[1] - secondary flow
R8 dP - pressure drop
For CSS_DSC:
CSE_EDS (I4)pss->local (stored as R4, converted to I4 in simulation)
CSE_BLS (R4)pss->local
For CT_NODEs:
SNSDAT: R4 oldsig
PICDAT: R4 oldsig, R4 olderr
HYSDAT: R4 oldsig
If _nZ1D > 0, then the following data is written for each 1-D zone:
nr
nc
X1
Y1
Z1
X2
//
//
//
//
//
//
the
the
the
the
the
the
SimReadW is a Windows program that can also generate user-selected output from the SIM file.
SimReadW also provides the added capability of performing averaging of values over time
and/or groups of building components, e.g., zones. It also enables the selection of either columnwise or row-wise orientation of the output.
The CONTAM Results Viewer, ContamRV, enables the visualization of contaminant
concentrations on a color-coded image of the SketchPad. The program provides you with a
color-coded display of zone contaminant concentrations, enables the animation of transient
simulation results and displays zone concentrations in numerical format. A whole-building view
is provided along with the ability to select individual levels of a project for detailed review.
File Format (binary):
Items that appear in red are those whose data size has been increased from 2-bytes to 4-bytes to
allow for an increased number of building components. This change took place between versions
2.3 and 2.4.
The first 16 lines of the simulation results file contain data (32-bit integers) to help assure that
the results apply to the project file currently in ContamW and to set the array sizes necessary to
process the results.
24 // CONTAM version number id (I4)
_nzone // number of airflow zones (excluding ambient) (I4)
_npath // number of airflow paths (I4)
_nctm // number of contaminants (I4)
_njct // number of junctions and terminals (I4)
_ndct // number of duct segments (I4)
_time_list // listing time steps [s](I4)
_date_0 // start of simulation - day of year (I4)
_time_0 // start of simulation - time of day (I4)
_date_1 // end of simulation - day of year (I4)
_time_1 // end of simulation - time of day (I4)
_pfsave // if true, write path flow results (I4)
_zfsave // if true, write zone flow results (I4)
_zcsave // if true, write zone contaminant results (I4)
_nafnd // number of airflow nodes (zones + junctions) (I4)
_nccnd // number of contaminant nodes (zones + junctions) (I4)
_nafpt // number of airflow paths (paths + ducts) (I4)
The next _nafnd lines give the contaminant node cross-reference data:
typ // source of node [zone or junction] (I4)
nr // zone, junction or terminal number (I4)
The next _nafpt lines give the airflow path cross-reference data:
typ // source of path [path, duct, or leak] (I4)
nr // path, duct, or leak number (I4)
The time step data is followed by summary data for the day.
It begins with the following line of ambient data:
dayofy // day of year [1 to 365] (I2)
daytyp // type of day [1 to 12] (I2)
Tamax // maximum ambient temperature [k] (R4)
Tamin // minimum ambient temperature [k] (R4)
Pavg // average barometric pressure [Pa] (R4)
Wsmax // maximum wind speed [m/s] (R4)
Wsavg // average wind speed [m/s] (R4)
CC[0] // maximum ambient mass fraction of species 0 [kg/kg] (R4)
...
CC[n] // maximum ambient mass fraction of species n [kg/kg] (R4)
Programmer's Note: this file requires that the structures in ContamW and ContamX be
compiled using no greater than 2-byte member alignment (under Visual C++). The file is
unreadable if the default structure member alignment is used.
<project file>.SRF
The SRF file contains contaminant concentrations for source/sinks that include a reversible
storage node. Unlike most source/sinks, these contribute a contaminant node to the system of
contaminant equations. Currently there are two types: boundary layer diffusion (BLS) and
deposition/resuspension (DVR). The units for BLS nodes are kg of contaminant/kg of surface
and those of DVR nodes are kg/m2.
Surface Result File - File Format (tab-delimited text):
The first line of the file is a header providing the name of the PRJ file:
"Project:" file[] // PRJ file name (I1)
-- Blank line --
zone
type
species
units trace/non-trace"
<project file>.VAL
The VAL file contains the results of either the Building Airflow Tests or Building Pressurization
Test airflow simulation methods. The file will be created or overwritten each time you perform
one of these tests on a project file, so be sure to rename or copy any files you wish to keep.
If you perform a Building Airflow Test calculation, the data written to this file will be divided
into five sections: Building info and ACH, Zones, Junctions, Classified Flows and Volumes. The
first and last sections are always written, but the other three are controlled by the simulation
output parameters for the Airflow Test simulation method.
Building Airflow Test - File Format (tab-delimited text):
190
The first line of the file is a header providing the name of the PRJ file:
"Airflow Summary for" file[] // PRJ file name (I1)
-- Blank line --
"Time:" time day[] // sim time (hh:mm:ss I4) day of week (I1)
-- Blank line --
Whole building air change rate - total flow from conditioned to unconditioned zones divided by
the total volume of conditioned zones. Air change rate is calculated as ACH = F *
3600/(ZoneDensity * ZoneVol). ACH can be calculated from data provided in the Classified
Flow section :
"Bldg ACH:" ach
-- Blank line --
Zones section:
This section is only written to the file if the simulation output parameter BldgFlowZ is equal to 1.
"Zones: nZones "flows [ACH]"// number of zones (I4) plus header
Data header:
zone C/U Supply Ret/Exh OA sys OA tot Circ tot P [Pa] T [C] Vol [m^3]
A line of data for each zone (excluding implicit zones of simple air handling systems, i.e., cu = S)
- all flows provided as air changes per hour, ACH [1/hr]:
nr
cu
Qs
Junctions section:
191
This section is only written to the file if the simulation output parameter BldgFlowD is equal to
1.
"Junctions:" nJct // number of junctions (I4)
Data header:
junction J/T
Data header:
"zone C/U Vol [m^3] Dens [kg/m^3] fmTerm fmLeak fmAHS fmFan fmCzone fmUzone
fmAmbt toTerm toLeak toAHS toFan toCzone toUzone toAmbt oaTerm oaLeak oaAHS
oaFan"
A line of data for each zone (excluding implicit zones of simple air handling systems, i.e., cu = S)
- all flows provided in kg/s:
nr
cu
V
//
//
//
//
FoaFan // Outdoor airflow rate into zone from forced flow elements
-- Blank line --
Volume section:
"Volumes:"
"Conditioned zones"
VZCm "m^3" // Total conditioned zone volume [m3]
VZCft "cuft" // Total conditioned zone volume [ft3]
"Ducts & AHS (conditioned)"
VDCm "m^3" // Total system volume [m3]
VDCft "cuft" // Total system volume [ft3]
"Unconditioned zones"
VZUm "m^3" // Total unconditioned zone volume [m3]
VZUft "cuft" // Total unconditioned zone volume [ft3]
Example File:
Airflow Summary for DEMO7_AirflowTest.prj
Ambient T: 20.00 C
Pressure: 101325.00 Pa
Wind spd: 0.00 m/s
Wind dir: 0.00 deg
Time: 00:00:00 Sunday
Bldg ACH: 0.450
Zones: 5
flows [ACH]
zone C/U Supply Ret/Exh OA sys OA tot Circ tot P [Pa] T [C] Vol [m^3]
1 C 0.78505 0 0.18038 0.18038 0.79 949.0 20.0 216.0
2 C 3.1401 0 0.7215 0.7215 3.14 949.0 20.0 54.0
3 C 1.5702 6.0457 0.36079 0.36079 7.85 949.0 20.0 108.0
4 C 9.4165 0 2.1636 2.1636 9.42 949.0 20.0 18.0
5 C 4.7083 0 1.0818 1.0818 4.71 949.0 20.0 36.0
Junctions: 12
junction J/T OA [%] Flow [kg/s] P [Pa] T [C] Vol [m^3]
1 T 23.0 0.056717 78.0 20.0 0.00
2 T 23.0 0.056715 63.3 20.0 0.01
3 T 23.0 0.056721 20.3 20.0 0.01
4 T 23.0 0.056692 0.0 20.0 0.01
5 T 100.0 0.065148 -0.0 20.0 0.00
6 J 23.0 0.28354 -0.2 20.0 0.11
7 J 23.0 0.28354 79.3 20.0 0.05
8 J 23.0 0.22682 64.5 20.0 0.06
9 J 23.0 0.17011 21.4 20.0 0.09
10 J 23.0 0.11338 1.1 20.0 0.07
11 T 0.0 0.21839 -880.2 20.0 0.04
12 T 23.0 0.056692 0.0 20.0 0.01
Classified Zone Airflows for DEMO7_AirflowTest.prj
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Zones: 6
flows [kg/s]
zone C/U Vol [m^3] Dens [kg/m^3] fmTerm fmLeak fmAHS . . . oaLeak oaAHS oaFan
0 A 432.45 1.2041 0 0 0 . . . 0 0 0
1 C 216 1.2041 0.056717 0 0 . . . 0 0 0
2 C 54 1.2041 0.056715 0 0 . . . 0 0 0
3 C 108 1.2041 0.056721 0 0 . . . 0 0 0
4 C 18 1.2041 0.056692 0 0 . . . 0 0 0
5 C 36 1.2041 0.056692 0 0 . . . 0 0 0
Volumes:
Conditioned zones
432.00 m^3
15255.9 cuft
Ducts & AHS (conditioned)
0.45 m^3
15.8 cuft
Unconditioned zones
0.00 m^3
0.0 cuft
"Volumes:"
"Conditioned zones"
VZC "m^3" // Total volume of conditioned zones
VZC "cuft"
"Ducts & AHS (conditioned)"
VD "m^3" // Total volume of ducts and AHS
VD "cuft"
"Unconditioned zones"
VZU "m^3" // Total volume of conditioned zones
VZU "cuft"
-- Blank line -"Airflow details:"
"Path Czone Uzone dP [Pa] [in.H2O] F [kg/s] [kg/h] [scfm] Q [L/s] [m^3/h]
[cfm]"
A line of data for each flow path contains airflow details. All flows and pressure differences are
absolute values. If test is pressurization test, then all flows are from conditioned to
unconditioned zones. If a depressurization test, then flows are from unconditioned to conditioned
zones.
nr // path number
Czone
// number of conditioned zone
Uzone
// number of unconditioned zone
dP_Pa
// pressure difference across path [Pa]
dP_iH20 // [in.H20]
F_kgs
// mass flow through path [kg/s]
F_kgh
// [kg/h]
F_scfm // [scfm]
Q_Ls
// volume flow through path [L/s]
Q_m3h
// [m^3/h]
Q_cfm
// [cfm]
Example File:
Building Pressurization Test for Test2_BldgPress_Auto.prj
Pressurization:
50.0 Pa
0.201 in.H2O
Mass flow rate:
0.4674 kg/s
1683 kg/h
822.6 scfm
Volume flow rate:
388.2 L/s
1398 m^3/h
822.6 cfm
Ambient conditions:
Pressure
101320 Pa
29.920 in.H2O
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Temperature
20 C
68 F
Air Density
1.2040 kg/m^3
0.07517 lb/ft^3
Volumes:
Conditioned zones
445.44 m^3
15730.6 cuft
Ducts & AHS (conditioned)
17.11 m^3
604.3 cuft
Unconditioned zones
384.89 m^3
13592.3 cuft
Airflow Details:
Path Czone Uzone dP [Pa] [in.H2O] F [kg/s] [kg/h] [scfm] Q
[L/s] [m^3/h] [cfm]
3 4 1 49.95 0.2007 0.01077 38.78 18.95 0.008946 32.21 18.96
4 2 1 49.95 0.2007 0.009482 34.14 16.69 0.007875 28.35 16.69
5 3 1 49.95 0.2007 0.009482 34.14 16.69 0.007875 28.35 16.69
. . .
205 16 0 50.00 0.2009 0.009616 34.62 16.92 0.007987 28.75 16.92
206 16 0 50.00 0.2009 0.001923 6.924 3.384 0.001597 5.75 3.385
Viewing Results
This section describes how to activate the results display mode of ContamW and to display the
results at different time-steps upon the SketchPad of transient simulations.
Results Display Mode
To view results using ContamW you activate the results display mode by checking either the
SketchPad Results or the Results Display Window selection of the View menu. This will occur
automatically after the successful completion of a simulation or after opening a project file that
has simulation result files associated with it. Once the results display mode is activated, the
status bar will display result-related information (See Status Bar) and you will be able to utilize
all of the Results Display Methods outlined below.
Time Step
If you have performed a transient simulation, results will be available for each time step.
However, the SketchPad results (as described in the following section) can only be displayed for
a single time-step at a time. You can change the time-step for which results are currently
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displayed upon the SketchPad using the following menu and keyboard shortcut commands
available under the View Results Navigation menu.
Show Next Time Step
Menu Command: Next Time Step
Keyboard Shortcut: End
Show Previous Time StepMenu Command: Previous Time Step
Keyboard Shortcut: Home
Show Last Time Step (of the day)
Menu Command: Last Time Step
Keyboard Shortcut: Ctrl+End
Show First Time Step (of the day)
Menu Command: First Time Step
Keyboard Shortcut: Ctrl+Home
The increment for the following "Jump" commands can be set via the Results Display properties
of the Project Configuration.
Jump Ahead (n time steps)
Menu Command: Jump Ahead
Keyboard Shortcut: Shift+End
Jump Back (n time steps)
Menu Command: Jump Back
Keyboard Shortcut: Shift+Home
Go to Date/Time
Menu Command: Go to Date/Time
Keyboard Shortcut: Ctrl+G
SketchPad Results
ContamW will display color-coded bars indicating the relative airflow rates and pressure drops
associated with each airflow path, duct terminal, or the supplies and returns of simple airhandling systems for the current time-step on the current level of the SketchPad. By default,
Airflow rates are displayed with green lines and pressure differences with red lines. Display
colors are user-selectable (See Configuring ContamW). These result-bars will only appear if you
have selected the Airflows option on the Output page of the Simulation Parameters property
sheet. If you have set flow or pressure limits for a given airflow path (see Airflow Path
Properties), and they have been exceeded, the icon will be highlighted in red as a warning
indicator.
You can also highlight individual icons on the SketchPad to display results related to the specific
icon. Results can be viewed in the ContamW Status Bar and Floating Status Bar (See Status Bar
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in the Getting Started section of the documentation). The following is a brief explanation of the
results displayed for each building component.
Airflow path pressure difference, airflow rate and direction of pressure drop and airflow
Duct segment pressure difference, airflow rate, velocity and direction of pressure drop
and airflow where velocity is calculated from the area of the duct segment
Simple air handling system outdoor, recirculation and exhaust airflow rate
Supply and return of simple air handling system airflow rate
Zone zone temperature and reference pressure, i.e., the absolute pressure of the zone
relative to the absolute pressure of the ambient at the elevation of the level on which the
zone is located. Prior to CONTAM 2.4, this pressure was relative to the ambient pressure
at the reference elevation of the building. So now these pressures more closely resemble a
gage pressure.
Duct junction junction temperature and static pressure relative to the pressure at the
height of the junction in the zone in which the junction is located
Duct terminal airflow rate and velocity based on the terminal free face area, temperature
and static pressure relative to the pressure at the height of the terminal in the zone in which
the terminal is located
Plotting Results
ContamW provides you with some charting features for plotting transient simulation results. You
can plot airflow, contaminant and exposure results using these features. Charting is only
available for transient simulation results of the currently loaded CONTAM project. You can plot
results for airflows and pressure differences, contaminant concentrations, and occupant exposure
and potential dosage. You access these charting features from the Simulation menu when in the
results mode.
NOTE: If you select a plot menu item when the ContamW caret is highlighting an icon, that
item will appear in the list of items to plot when the associated Chart Control dialog box is
displayed. This feature allows you to plot results for a particular item by highlighting it on the
SketchPad as opposed to finding it in the list of items to plot on the Chart Control dialog box.
Plotting Airflow Results
Menu Command: Simulation Plot Airflow Results
Plot airflow and pressure difference results for airflow paths. You can plot two-way flow rates
for those flow paths that implement two-way airflow elements. If you select not to show twoway flows, ContamW will plot the net flow rate for airflow paths that implement two-way
airflow elements.
Plotting Contaminant Results
Menu Command: Simulation Plot Contaminant Results
Plot the time-history of contaminant concentrations of zones.
Plotting Exposure Results
Menu Command: Simulation Plot Exposure Results
Plot the time-history of occupant exposure to contaminants.
Plotting Particle Results
Menu Command: Simulation Plot Particle Results
Plot the time-history of particle size distribution for a single zone.
Plotting Temperature Results
Menu Command: Simulation Plot Temperature Results
Plot the time-history of temperatures for multiple zones/junctions.
Chart Control: Transient Airflow Results
Use this dialog box to control how transient airflow and pressure results are plotted.
Paths to Plot/Paths Available: The plotted data for each airflow element will appear as a
separate trace, the "Paths to Plot" lists the airflow elements that will be graphed. To add an item
to this list select the appropriate airflow element type (paths, ducts, or junctions), scroll through
the list of available elements or enter the element number directly if known, then press the "
Add" button. To remove an item from the Paths to Plot field select the zone to be deleted and
then press the "Remove" button.
Date(s) to Plot: This field allows the you to select the dates of data you wish to plot on the
graph. The available dates for the given simulation file are shown for your reference. You must
set the dates to fall within this range of dates. Enter dates in the following format:
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MMMDD - the first 3 letters of the month and then the day of the month with or without
spaces
Data to Plot: You can plot airflow rates, pressure differences, or both. If you plot both airflow
and pressure difference, then ContamW will produce a graph with two vertical axis - one for
airflow and one for pressure difference. You can select the units of these axis using the "Airflow
Units" and "Pressure Units" drop-down combo boxes on this dialog box.
You can also show two-way flows for flow elements that utilize two-way flow models. If you
leave "Show two-way flows" unchecked, then ContamW will plot the net flow rate for all flow
paths. If you check "Show two-way flows," then a zero component will be plotted for all flow
paths that do not implement two-way models.
Comment for chart title: Enter a comment you want to appear at the top of the chart to help
distinguish various plots from one another.
Chart Control: Transient Contaminant Results
Use this dialog box to control how transient contaminant results are plotted.
Contaminant to Plot: This lists all the currently defined project contaminants. Select the
contaminant for which you want results plotted.
Moisture Units: If the contaminant to plot is "H2O," then this section will be activated to
provide the ability to plot moisture in units of mass fraction, humidity ratio, or % relative
humidity. Mass fraction is the same units in which all other contaminants are reported, i.e., mass
of contaminant per mass of air. Humidity ratio is in units of mass of water vapor per mass of dry
air, i.e., mass of air less the mass of water vapor. %RH will utilize the equations presented in
Chapter 6 of ASHRAE 2005 Fundamentals [ASHRAE 2005] to calculate the relative humidity
based upon the mass fraction of H2O, temperature and absolute pressure in each of the Zones to
Plot. If you select Mass Fraction or Humidity Ratio you can select from the set of units available
in the Units list. When plotting humidity ratio, you should only plot in units of kg/kg, g/kg or
lb/lb and not in volumetric units as the conversion will not be correct due to the assumed
standard air density in CONTAMs conversion routines.
Zones to Plot/Zones Available: The plotted contaminant data for each zone will appear as a
separate trace, the "Zones to Plot" lists the zones that will be graphed. To add an item to this list
select the appropriate level and zone name from the drop down boxes in the Zones Available
field and then press the "Add" button. To remove an item from the Zones to Plot field first
select the zone to be deleted and then press the "Remove" button.
Date(s) to Plot: This field allows the user to plot the contaminant results from a specified date
range within the simulations results file. The available dates for the given simulation file are
given, the user provided date range must fall between these dates. The dates are entered in the
form: the first 3 letters of the month and then the day of the month with or without spaces.
Comment for chart title: Enter a comment you want to appear at the top of the chart to help
distinguish various plots from one another.
Chart Control: Transient Exposure Results
Use this dialog box to control how transient exposure results are plotted.
Occupant to Plot: This is a list of the occupants for which you want to plot exposure results.
Use the "Occupants Available" section to select occupants to add to this list and click the
"Add" button or highlight an occupant in this list and remove it using the "Remove" button.
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Contaminant to Plot: This lists all the currently defined project contaminants. Select the
contaminant for which you want results plotted.
Date(s) to Plot: This field allows the user to plot the contaminant results from a specified date
range within the simulations results file. The available dates for the given simulation file are
given, the user provided date range must fall between these dates. The dates are entered in the
form: the first 3 letters of the month and then the day of the month with or without spaces.
Comment for chart title: Enter a comment you want to appear at the top of the chart to help
distinguish various plots from one another.
Exporting Results
ContamW provides you with the ability to export results to external files. You can either
generate report files or export files. Report files are text files that are formatted for ease of
reading. Export files are tab-delimited, so you can easily import them into a spreadsheet. This
feature provides you with greater charting flexibility as well as the ability to perform more
sophisticated data analysis of your simulation results. You access this feature of ContamW by
selecting Export Results from the Simulation menu or use the F5 shortcut key when the
results-display mode is active. This will display the "Export Data" dialog box as described in the
following section.
Export Data
This section provides detailed descriptions of the specific properties associated with generating
result reports and exporting results to external files.
Transient Results:
Results available from/to: This shows the range of dates/times for which results are
available in the simulation results file (.SIM) of the latest simulation.
Export transient results from/to: Select the range for the data to be exported. Enter the date
as the first 3 letters of the month followed by the day of the month with or without spaces,
e.g., Jan01, followed by the time in the following format HH:MM:SS.
Airflow Data: Options for reporting/exporting airflow data. Airflow rates will be reported in the
Default Units of Flow as selected via the Project Configuration properties (See Configuring
ContamW).
Report airflows of all paths for date/time: Create a text file formatted for ease of reading
that lists the airflows and pressure differences for all paths, zone pressures and temperatures
at the selected date and time.
Export airflows of all zones for date/time: Create a tab-delimitted file containing a table of
the total airflows between each zone of the building. The leftmost column lists the level and
name of the zones from which airflows and the topmost row lists the level and names of the
zones into which air flows. Therefore, all airflows are listed as positive values.
Export transient flow for airflow path number: Create a tab-delimitted file listing all the
airflow data for a specific airflow path. Select the airflow path number(s) for which you want
to output the airflow and pressure drop data for the range of time you select in the "Export
transient results from/to" dates and times indicated above.
Export average transient flow for each zone between export result times: Create a tabdelimitted file listing the average airflow rates between zones averaged over the range of
time you select in the "Export transient results from/to" dates and times indicated above.
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Contaminant Concentration Data: Options for reporting and exporting contaminant results.
Concentrations will be reported in the units associated with the default concentration of each
species/contaminant (See Species Properties).
Report transient concentrations of all zones for date/time: Create a text file formatted for
ease of reading that lists the contaminant concentrations for all zones and contaminants at the
selected date and time.
Report transient concentrations of all zones: Create a text file formatted for ease of
reading that lists the contaminant concentrations for all zones at the selected date and time.
Export transient concentrations of all zones: Create a tab-delimitted file listing the
transient contaminant concentrations for all zones and contaminants for the range of time you
select in the "Export transient results from/to" dates and times indicated above.
Export transient concentrations for zone: Create a tab-delimitted file listing the transient
contaminant concentrations for each contaminant in the selected zone for the range of time
you select in the "Export transient results from/to" dates and times indicated above.
Shaft Report
CONTAM is well suited for the analysis of smoke control systems. Because of the importance of
shafts for some smoke control systems [Klote and Milke 2002], ContamW provides a special
reporting feature for shafts.
Defining Shafts
You define shafts during the drawing phase of project development by placing zone icons
directly below one another (in the same column and row) on adjacent levels of a building. If
there is a zone icon in the same position on the level above or below the current level, those
zones are part of the shaft when ContamW generates a shaft report. The shaft consists of zones
that exist on contiguous levels having a zone icon in the same location on the SketchPad.
You create the shaft report by selecting Generate Shaft Report from the Simulation menu.
This will display a dialog box prompting you to execute the following three steps to define the
shaft zone icon and primary and secondary flow paths associated with the shaft across which you
want ContamW to report the airflows and pressure drops. The zone icon would typically
represent a stairwell, and the primary flow path would typically represent a stairwell door.
Steps to select a shaft for a shaft report:
1) Left-click on the zone icon that defines the shaft
2) Left-click on the primary airflow path icon
3) Left-click on the secondary airflow path icon
NOTE: Click the right mouse button to cancel the shaft report generation process.
Once you have completed the above steps, the shaft report will be displayed in a dialog box. The
report will display pressure drop, airflow rates and direction of airflow on every level of the shaft
where there are airflow path icons in the same location on the SketchPad as that of the primary
and secondary airflow paths. You can use the Shaft Report dialog box to select the units in which
the airflow rate and pressure drops are reported, and you can save a copy of the report to a text
file.
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Prior to performing these tests, you should make a copy of the project file, so you do not have to
reverse the changes to restore the original project file.
SHAFTS
Buildings contain several architectural features which offer very low resistance to airflow
between building levels. These features include atria, elevator shafts, and stairwells. CONTAM
provides two ways of modeling such a low resistance path: the phantom zone and the lowresistance (or large) opening. Select the most appropriate model based on how this path interacts
with the rest of the model.
This interaction can be understood by using three flow resistances in series to model a shaft
between two levels. There is a resistance to flow through the shaft and resistances representing
the paths (doors) connecting the shaft to the two different levels. Using the powerlaw
relationship, Q = C(P)0.5, and assuming C = 3.10 for the shaft, 1.55 for an open door, and 0.01
for a closed door, the following equivalent flow coefficients, Ce = ( 1/Ci2)-0.5, are computed for
four different assumptions:
1. both doors closed, ignore shaft resistance: Ce = 0.007070
2. both doors closed, include shaft resistance: Ce = 0.007066
3. both doors open, ignore shaft resistance: Ce = 1.096
4. both doors open, include shaft resistance: Ce = 0.984
Cases (1) and (2) show that when flow resistance is dominated by the closed doors, it is not
necessary to include the shaft flow resistance. Cases (3) and (4) show that when the resistances at
the (open) doors is of the same order as the shaft resistance, it is important to include the shaft
resistance in the model. For a quick estimate of relative flow coefficients, remember that the
flow coefficient is usually roughly proportional to the opening area.
Atria
If an atrium were modeled as individual zones on each level, the inter-level flow resistances
would be very low. A cursory comparison of the inter-level opening areas to the sum of all
openings from the atrium to other zones will usually indicate that an atrium should be modeled
using phantom zones. This is done by placing a standard zone icon at the atrium's lowest level.
You use this zone icon to define the atrium temperature and total volume. You should ignore the
floor area of the normal zone icon that is used to define the atrium zone. Place a phantom zone
icon at all higher levels which contain parts of the atrium. A phantom zone icon indicates that the
region within the walls on this level are actually part of the zone on the level below the icon. If it
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Stairwells
Data to describe the airflow characteristics of a stairwell in terms of an equivalent orifice is
provided in [Achakji and Tamura 1988]. This representation is very well suited to being
implemented by CONTAM, which allows you to create a powerlaw flow element from the
physical characteristics of the stairwell. Stairwell characteristics include the cross-sectional
(horizontal) area of the stairwell shaft, whether the fronts of the stair treads are open or closed,
and the number of people on the stairs. This last item might be important in an evacuation
scenario. Since the equivalent orifice area of the shaft is on the same order as it's cross-sectional
area, and this area is likely to be smaller than the sum of the areas of the doors entering the
stairwell, it is generally best to model a stairwell as individual zones on each level connected by
openings which have been defined using the CONTAM stairwell airflow element that
implements the Achakji/Tamura model.
Elevator Shafts
Elevator shafts (hoistways) will generally lie in some modeling regime that falls between
stairwells and atria. Measured data for the flow resistance of an elevator shaft have not yet been
identified. CONTAM provides a powerlaw flow element based on flow resistance from the
Darcy/ Colebrook model of a conduit or duct. A significant difference between an elevator shaft
and a stairwell is that the door between the shaft and the building is never fully open because,
when it is open, air must flow through openings in the elevator car to pass between the building
and the shaft. Table 6.1 of [Klote and Milke 2002] presents orifice areas for closed elevator
doors which tend to be fairly small compared to the cross-sectional area of the shaft, especially
for hoistways with multiple cars, so it is likely that the airflow in most elevator shafts can be
modeled with sufficient accuracy by phantom zones. However, it may be necessary to split the
shaft into several sections to achieve sufficient accuracy in modeling contaminant transport.
Chimneys
You can use a duct to create a simple chimney model. At its simplest this will involve only a
single duct connecting the inside of the building to the outside with the Darcy-Colebrook duct
element used to model the flow resistance of the chimney. The height of the duct terminal points
must reflect the height of the chimney and a special high temperature zone must be created
around the inside terminal point so that the proper stack effect will result. Be sure to allow an
appropriate low resistance path from this special zone to the rest of the building.
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b. The CONTAM model should be drawn to scale using a scaling factor. Using the scaling
factor should result in 3D geometry for each zone that will produce a zone volume that
matches the zone volume entered into CONTAM.
c. Click the Save Trnsys3D IDF button
This will create a Trnsys3d compatible idf file [test_T3D.idf]
d. (Optional) Edit the idf file with Google SketchUp using the Trnsys3d plugin. For
example you may want to add missing parts of the building like windows or change the
shape of a zone. Also you can inspect the building model for problems with surfaces.
3. Open the TRNSYS SimulationStudio program
a. Select the File -> New menu command
b. Select 3D Building Project (multizone) and click Next ->
c. Select the idf file that was created in step 2 above [test_T3D.idf] and click Open. A
prompt will appear to create a BUI file. This will also create a TRNSYS 17 building file
[test_T3D.b17]. SimulationStudio will now display a Type56-based project in the
Assembly Window.
d. Save the TRNSYS project [test_T3D_imported.tpf]
e. Exit SimulationStudio
4. Open the Type56-98Coupler program
a. Select the CONTAM project file from step 1 above [test.prj].
b. Select the b17 file produced in step 3 above [test_T3D.b17] and click Open.
c. Click the Create Files button to create an updated building file [test_T3D_coupled.b17].
This new file has the following additions: airflow connections between zones,
infiltrations added to zones with a connection to ambient, ventilation flows for duct
terminals, AHS supply paths and duct leaks and inputs for these airflows. Also a
proforma for Type 98 is created [test_T3D_coupled.tmf].
NOTE: This proforma is referred to as a dynamic-static proforma. It takes the place of the
dynamic proforma for the previous Type 97. This is likely to be replaced in the future
with a new dynamic proforma for Type 98. In the meantime, each project you create will
implement its own dynamic-static proforma.
5. Establish the new proforma for use with TRNSYS
a. Copy the proforma [test_T3D_coupled.tmf] to the following sub directory of the Trnsys\
directory: Studio\Proformas\Utility\Calling External Programs\CONTAM\, or you can
create your own directory for your CONTAM proformas under the Proformas directory.
b. Additionally, you can copy the Type98.bmp file located in the Trnsys\CONTAM\
directory and give it the same name as that of the proforma but leave the bmp extension.
This enables TRNSYS to display the new proforma in the Assembly Area with the
Type98 icon.
6. Open the TRNSYS SimulationStudio program
a. Open the tpf file that was created in step 3 above [test_T3D_imported.tpf]
b. Change the Type56 unit to use the new building file from step 4 [test_T3D_coupled.b17].
i. Double click the Type56 icon; select the External Files tab and Browse to select the
b17 file.
ii. The automatic OUTPUTS of Type98 should now be listed as INPUTS for Type56
under the Inputs tab. These are the inter-zone airflows or connections established for
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coupling. You should also see any manual outputs from Type98 that you created
using ContamW in the list of available INPUTS.
7. Add the project-specific Type98 proforma to the TRNSYS project
a. Select the newly created Type98 proforma [test_T3D_coupled.tmf] from the Direct
Access Toolbar and drag it onto the Assembly Area.
b. Edit the Type98 unit to set the air file parameter to [test.air].
c. The inputs and outputs listed in the air [test.air] file should all be available via the
Variables window of the unit (accessed by double clicking the icon).
8. Create a TRNSYS input deck file
a. The name of the deck file is determined by the Global Infos properties. You can change
the name via the Assembly -> Control cards menu command, scroll down to the Deck
file name item and change the file name as desired. The default name is default.dck, but
you can change it to anything you like, e.g., [test_T3D_imported.dck].
b. Select the Calculate -> Create input file menu command to create the deck file.
9. Update the TRNSYS deck file using the Type56-98Coupler program.
a. Click the Select the deck file button and Open the deck file [test_T3D_imported.dck] that
was created in step 8.
b. If you closed the Type56-98Coupler program you also need to select the CONTAM
project file again.
c. Click the Change Deck Name button to set the name of the updated deck file [test_T3D
coupled.dck].
d. Click the Save New Deck File button to create the new deck file. This deck file will have
the connections between Type56 and Type98 established.
10. Import the new deck file back into the TRNSYS project.
a. In Simulation Studio use the File -> Import TRNSYS Input File menu command to
open the newly created coupled deck file [test_T3D coupled.dck].
b. You might need to reestablish the [test.air] file in the Type 98 unit as outlined above.
c. You should see the Links between Type56 and Type98 (test_T3D_coupled) and the
Inputs and Outputs will be connected. If there is a weather file type reader, e.g., Type109
or Type15, present then that type will be coupled to Type98s ambient condition inputs.
If there is more than one of these types then the first one found in the deck file will be
used. Type15 is given preference over Type109 so Type15 will be coupled before any
Type109. Be sure to select the proper file reader type for the weather file format being
used, e.g., Type15-3 for EPW files.
After following these steps you will have a TRNSYS project that has the temperature and flow
connections made between Type56 and Type98 and possibly ambient condition connections
between Type98 and Type15. You can then proceed with making any other desire connections,
e.g., manual inputs/outputs established as described above.
NOTE: To run a simulation, the time step and the beginning and ending dates must be the same
in both the CONTAM prj file and the TRNSYS simulation control cards. ContamW can be used
to view/plot temperature results.
211
212
213
Second Line:
nZones
nPaths
nAhsPaths
nTerminals
nLeaks
nJunctions
nConns
of
nInputCtrls
names
nOutputCtrls // (I) "report" type control nodes with names
Third Line:
PrjPath[_MAX_PATH] // [char] absolute path of project file from which this
AIR file was created
The ZONES section contains a line of data for each of the nZones.
214
The PATHS section contains a line of data for each of the nPaths.
Each line contains:
nr
fromZone
toZone
posCon
negCon
//
//
//
//
//
(I)
(I)
(I)
(I)
(I)
path number
positive flow
positive flow
positive flow
negative flow
"from" zone nr
"to" zone nr
connection nr
connection nr
The AHSPATHS section contains a line of data for each of the nAhsPaths.
Each line contains:
nr
// (I) AHS path number
type // (I) 0=return, 1=supply, 2=implicit
The JUNCTIONS section contains a line of data for each of the nJunctions.
Each line contains:
nr
// (I) junction number
zone // (I) nr of zone in which junction is located
The CONNECTIONS section contains a line of data for each of the nConnections.
Each line contains:
nr
// (I) connection number
fromZone // (I) nr of zone from which flow is positive
toZone
// (I) nr of zone to which flow is positive
The following data is similar to that used by the dynamic proforma for Type97. It is provided
here for informational purposes.
The REQUIRED INPUTS section begins with the following header:
215
"Ambient Temperature"
"Barometric Pressure"
"Wind Speed"
"Wind Direction"
It then contains a line of data for each available OUTPUT. There are flow rates available as
OUTPUTS for each connection as well as for each "ventilation flow", i.e., simple AHS supply
and duct terminal along with the zone in which they are located.
nr
// (I) output number
name[] // (char) name identification string, e.g.,
<lev1>/<zone1>"_"<lev2>/<zone2>. Flow path identification
// string indicating from and to level/zone
219
GETTING HELP
This help manual is available in both printed form and accompanying the ContamW program as
"on-line" help. There are several ways to access the on-line help system. You can either use the
Help Contents selection of the Help menu to display the contents of the help manual or use
the context-sensitive feature to access help.
Help Contents
You can browse the contents or index of the help system to view the topic of your choice and use
the search feature to display a list of help topics that contain the keyword in which you are
interested.
Context-Sensitive Help
The context-sensitive help feature is designed to provide you with specific information related to
the currently active ContamW window or dialog box. To activate the context-sensitive help
system, press the F1 key.
Help Index and Search
Be sure to use the on-line help index and search features if you are having trouble locating a
specific topic.
Obtaining Technical Support
If you need to contact the CONTAM developers for guidance on using the program or to report a
technical problem with the program you can do so via email at the addresses below. If you
encounter an error while working with CONTAM, and you require assistance solving the
problem, you should immediately (before running ContamW or ContamX again) make copies of
the CONTAMW2.LOG, PROJECT.BKP and WEATHER.BKP located in the ContamW
application data directory (C:\Documents and Settings\<User Account>\Application
Data\NIST\ContamW\) and the .XLOG file located alongside the PRJ file. You can email these
files to NIST so that we may be better equipped to address your particular problem.
NIST Contact Information
IAQ and Ventilation Group 301-975-6431
220
THEORETICAL BACKGROUND
This section provides theoretical background of the CONTAM program. There are basically
three subsections: the first provides a summary of underlying assumptions of the model and the
others address the contaminant and airflow analysis respectively.
MODEL ASSUMPTIONS
CONTAM is a powerful tool that models airflow and contaminant dispersal in buildings. It is
important to realize that this tool implements mathematical relationships to model airflow and
contaminant related phenomenon and therefore incorporates assumptions that simplify the model
from that of the modeled phenomenon. The following is a brief description of these modeling
assumptions.
Well-mixed zones This assumption refers to the treatment of each zone as a single node,
wherein the air has uniform (well-mixed) conditions throughout. These conditions include
temperature, pressure and contaminant concentrations. Therefore, localized effects within a
given zone cannot be accounted for using CONTAM. For example, if you utilize a contaminant
source that introduces a mass of contaminant into a zone at a certain time (burst source), the
contaminant will be diluted to the entire volume of the zone within a single time step.
One-Dimensional Convection/Diffusion Zones In versions prior to CONTAM 2.3 all zones
were considered to be well-mixed, i.e., having a uniform concentration. However, beginning with
version 2.3, zones can be preconfigured by the user to be one-dimensional convection/diffusion
zones in which contaminants can be allowed to vary along a user-defined axis. When operating
under the newly added short time step method ContamX will provide for the ability of
contaminant concentration gradients to occur in the direction of the convection/diffusion axis by
programatically sub-dividing the zone into a series of well-mixed cells along the axis.
Duct Systems Typically, during contaminant simulation, there are similarities between duct
junctions and well-mixed zones and between duct segments and airflow paths. In this case the
volumes of the duct junctions are determined from the duct segments to which they are
connected. However, in CONTAM 2.4 the entire duct system can modeled to account for onedimensional convection/diffusion flow through the system. This feature is available as an option
under the new short time step contaminant simulation method.
Conservation of mass When performing a steady-state simulation, the mass of air within each
zone is conserved by the model. This implies that air can neither be created nor destroyed within
a zone. However, when performing a transient simulation, CONTAM now provides the option of
allowing the accumulation or reduction of mass within a zone due to the variation of zone
density/pressure and the implementation of non-trace contaminants within a simulation. This is
further addressed in this Theory section (see Airflow Analysis and Contaminant Analysis), as
well as in a previous section addressing simulation settings (see Airflow Numerics Properties).
Trace contaminants Trace contaminants are those that are found in low enough levels that they
do not affect the density of air within a zone. You must be careful not to rely on the model to
handle contaminant concentrations that would cause a change in the density of air. The program
will allow for contaminants to reach levels that would, in actuality, affect the density, but the
program will still treat them as if they were trace contaminants.
Non-trace contaminants Non-trace contaminants are those that are present in such quantities
that they can influence the air density, e.g., water vapor. In CONTAM you define those
contaminants that are components of the air within the building. CONTAM will treat them as a
mixture of ideal gases.
221
Thermal effects The model does not handle heat transfer phenomenon per se, but does provide
for the scheduling of zone temperatures. Zone temperatures can be either constant or allowed to
change during transient simulations according to user-defined temperature schedules. CONTAM
will determine airflows and non-trace contaminant mass fractions induced by temperature
differences between zones including ambient (e.g., as caused by the stack effect). You can also
vary the outdoor temperature for transient simulations using weather files.
Airflow paths Airflow through various airflow elements provided by CONTAM is modeled
using either a powerlaw or quadratic relationship between airflow and pressure difference across
the flow path. These relationships are models themselves, and care should be taken when
implementing them to represent building features within your idealized buildings. See Airflow
Elements for detailed explanations of these models.
Source/sink models CONTAM provides several different source/sink elements or
representations of contaminant generation/removal processes. These elements are based upon
models found throughout the literature. You should be sure to utilize models that are appropriate
for the contaminant source/sink that you want to represent. See Contaminant Source/Sink
Elements for detailed explanations of these models.
The previous assumptions relate to the mathematical representations utilized by CONTAM in
performing analysis. These assumptions should be distinguished from assumptions made by you,
the user, when creating a model of a building referred to as a building idealization (see User
Tasks in the Getting Started section). Engineering judgment is required on your part to insure
that your building representation is adequate for the purposes of your analysis.
222
CONTAMINANT ANALYSIS
The CONTAM contaminant dispersal model is an implementation of Axley's methods [Axley
1987 and 1988]. He states: "The central concern of indoor air quality analysis is the prediction of
airborne contaminant dispersal in buildings. Airborne contaminants disperse throughout
buildings in a complex manner that depends on the nature of air movements in-to, out-of, and
within the building system; the influence of the heating, ventilating, and air-conditioning
(HVAC) systems; the possibility of removal, by filtration, or contribution, by generation, of
contaminants; and the possibility of chemical reaction, radio-chemical decay, settling, or sorption
of contaminants. In indoor air quality analysis we seek to comprehensively model all of these
phenomena."
The basis for contaminant dispersal analysis is the application of conservation of mass for all
species in a control volume (c.v.). A c.v. is a volume of air which may correspond to a single
room, a portion of a room, or several well-coupled rooms (a CONTAM zone) or the ductwork
(where a junction, under the well-mixed assumption, has half the volume of each of the adjacent
duct seg ments). The representation of building spaces as CONTAM zones is a matter of
engineering judgment.
CONTAM 2.3 added the capability to model convection-diffusion in the ductwork and userselected zones instead of treating them as well-mixed control volumes. In CONTAM this is done
with the new short time step method.
Properties of Air
In CONTAM air is treated as an ideal gas with properties computed from the ideal gas law. The
density of air is given by
= m/V = P/(RT)
(1)
where
m = the mass of air in
V = a given volume,
P = the absolute pressure,
R = the gas constant for air, and
T = the absolute temperature.
The mass of air in c.v. i is the sum of the masses of the individual contaminants, , in the c.v.
(2)
In CONTAM concentration refers to a mass ratio rather than a volumetric ratio unless otherwise
specified.
Air is a mixture of several different species. The value of the gas constant for the air in a c.v. is
given by:
(4)
where Ri = the gas constant of species which equals the universal gas constant, 8 314.41
J/(kmolK), divided by the molar mass of (kg/kmol). Similarly, for thermal calculations (an
223
option in CONTAM for duct flow under short-time-step method only), the specific heat of air in
a duct segment is given by the weighted sum of the specific heats of the individual species:
(5)
Under typical conditions only water vapor has an impact on the properties of air and even that
can be ignored as an initial approximation. There is a standard definition of species
concentrations for dry air which yields an effective molar mass of 28.9645 kg/kmol and a gas
constant of 287.055 J/(kgK). ASHRAE often refers to dry air at standard conditions which are
101.325 kPa and 20 C and notes the density of such air is 1.20 kg/m3 [ASHRAE 2004 p 18.4].
More precisely, the density is 1.20410 kg/m3 as computed by equation (1).
NOTE: ASHRAE considers water vapor in terms of humidity ratio instead of mass
concentration. The humidity ratio, W, is defined as the ratio of the mass of water vapor to the
mass of dry air in the volume: W = mw / mda [ASHRAE 2005 p 6.8]. The CONTAM mass
concentration, which ASHRAE refers to as specific humidity, is: Cw = mw / (mw + mda). The
conversions between humidity ratio and mass concentration are Cw = W / (1+W) and
W = Cw / (1Cw).
In many cases we are interested in species concentrations that are too small to signif icantly
affect the air density (or specific heat). These are referred to as trace concen trations. When a
simulation involves only trace contaminants, CONTAM uses dry air to compute the air
properties.
Contaminant Concentrations
Within CONTAM a contaminant may be added to c.v. i by:
inward airflows through one or more paths at the rate
the rate of air mass flow from c.v. j to c.v. i and
species generation at the rate
where
is
where
224
(6)
All concentrations
at time t+t are functions of various other concentrations also at t+t.
This is the standard implicit method, and it requires that a full set of equations (8) must be solved
simultaneously.
The number of equations, N, equals the number of species times the number of control volumes.
In a traditional Gauss elimination (or LU decomposition) solution the computation time is
proportional to N3, making it impractical for large problems. CONTAM offers three solution
methods which take advantage of matrix sparsity to handle cases with large numbers of
equations. These are a direct skyline algorithm, an iterative biconjugate gradient (BCG)
algorithm, and an iterative successive over relaxation (SOR) algorithm. (LU decomposition is
provided only for testing and benchmarking.) The skyline algo rithm is very fast for problems of
intermediate size but can be slow for large problems. The SOR algorithm requires much less
memory and may be faster for large problems unless there are convergence difficulties. In such
cases try the BCG solution, although it may also experience convergence difficulties. It can be
useful to test the different methods to determine which will give optimum performance before
doing a long transient simulation.
A more accurate solution can be obtained by choosing t = t /2 which means average
conditions during the time step. This has been implemented in CONTAM by a trapezoidal
integration which still requires solving the full set of simultaneous equations.
We can also choose t = 0. In this case equation (7) becomes:
(9)
Every concentration
at time t+t is a function of various other known concentrations at time
t. This is the standard explicit method which has the computational advantage of not requiring
the solution of simultaneous equations. That advantage is offset by instability under some
225
conditions. That is, the concentrations at successive time steps may diverge wildly from the
analytically correct solution. Stability is determined by the magnitudes of the coefficients in
equations (7). For example, when the sum of the flows into or out of the c.v. in one time step is
greater than the mass of air in the c.v., the solution becomes unstable, that is, values at successive
time steps begin to oscillate around the true solution and eventually reach impossible values.
Instability will also result when
or
implicit method is stable at all time steps.
The stability question is so important that it is useful to review the time scales that can be
expected in the normal operation of buildings. ASHRAE indicates that the air exchange rate to
condition and ventilate rooms should be less than 12 air changes per hour in nearly all
commercial applications. [ASHRAE 1999b, p. 3.2 Table 1 - General Design Criteria] This
corresponds to a stability limit for the explicit method of 1/12 h, or 5 min. In CONTAM the
volume of a junction is half the sum of the volumes of the duct segments meeting at the junction.
A junction between two 2 m long duct segments where the air is flowing at a velocity of 2 m/s
would have a stability limit of 1 second. Smaller limits are likely to occur because of shorter duct
segments or higher velocities.
In early versions of CONTAM it was anticipated that the processes being modeled would require
time steps down to about 5 minutes. The very short stability limit for modeling the ductwork
drove CONTAM to use an implicit solution where the execution time for relatively few time
steps was less than doing many shorter times steps using the explicit solution. The recent
addition of control system modeling and the need to track quick contaminant releases both
require time steps no longer than a few seconds. We will therefore reconsider use of the explicit
model for the ducts.
The following figure shows a CONTAM sketchpad representation of the typical features of a
very simple building and its air handling system. The duct icons indicate the normal direction of
flow. The ductwork consists of a return duct with terminals (R) in each room, an exhaust to
ambient (X), a path for recirculation, an outdoor air intake (OA), and a supply duct with
terminals (S) in each room.
The process begins by computing all airflows based on conditions known at time t. The
contaminant calculation sequence then begins by using a modification of equation (9) to compute
the concentrations
In equation (10) the flows out of the zone are divided into two parts
, flows to other zones, and
, flows into duct junctions through return terminals or leaks,
to conserve contaminant mass when computing concentrations at the return terminals.
The concentrations in the return terminals (R and OA) are then computed with a simplified form
of equation (8), because sources, sinks, and reactions are not modeled in ducts, although these
features could be added in the future.
(11)
This calculation is particularly simple for terminals because there is only one airflow into each
return terminal and an equal airflow out into the duct network. The concentration in the flow into
the terminal,
at time t+t, comes from equation (10) for the surrounding zone, j. Once all
return terminal concentrations have been computed the upstream concentrations are known for
both ducts meeting at the left-most junction (# 1) in the return duct, and equation (11) can be
solved directly because all concentrations on the right side of the equation are known. Once the
junction #1 concentrations have been computed all upstream concentrations are known for the
next junction to the right (# 2) along the return duct and its concentrations can then be computed.
This process contin ues around the ductwork until the concentrations at all junctions and all
supply terminals have been computed. This implicit calculation of the concentrations in the duct
junctions is unconditionally stable, so overall stability is determined by conditions in the zones.
CONTAM 2.4 adds this process calling it the short time step method (STS).
Reactions may include coefficients that lead to instabilities for an explicit simulation. Very fast
reactions would produce such coefficients. Therefore, the STS method processes reactions by an
implicit calculation involving only the contaminants in the c.v. after all other calculations have
been performed for the time step.
mass of air) everywhere in the zone, even at the far end 10 m from the source, and begins
entering the adjacent zone within one time step.
The well-mixed zone model is appropriate when the time step is longer than the mixing time of
the zone. Conventional HVAC systems attempt to produce well mixed zones, but the mixing
time is on the order of a few minutes rather than seconds.
The standard numerical solution to this problem is to create smaller control volumes whose size
is similar to the distance traveled in one time step. This is done in the computational fluid
dynamics (CFD) models that consider mass, momentum, and energy in computing the flow field
in a space that has been divided into many control volumes. Conventional CFD might divide a
volume into 30 cells along each of the three directions. This increases the computation effort
from one large "cell" per zone to 27,000 (=303030) cells per zone. This analysis approach is
not practical for a building containing many zones.
One-dimensional convection-diffusion flow has been introduced to CONTAM as a compromise
between simple, and fast, well-mixed zones and a full CFD simulation. CONTAM 2.4 includes
the option of modeling detailed contaminant migration in one, user-defined direction through a
zone and or an entire duct system. This one-dimensional model is obviously appropriate for flow
through a duct and reasonably appropriate for a long hallway or a zone using a displacement
ventilation system. Its use in more conventional well-mixed zones is problematic because of the
presence of supply air jets and areas of recirculation.
Contaminant flow in one direction consists of a mixture of convection, the bulk move ment of
air, and diffusion, the mixing of the contaminant within the air. CONTAMs primary 1-D
convection diffusion model is taken directly from the finite volume method developed by
Patankar [Patankar 1980] and described in more detail by Versteeg and Malalasekera [Versteeg
and Malalasekera 1995]. This model divides the zone into a number of equal-length cells and
uses an implicit method (with a fast tri-diagonal equation solver) to guarantee stability in
computing the contaminant concentrations. It has been observed that the accuracy of this method
declines as the ratio of the flow velocity time step to the length of the cell increases.
This loss of accuracy is a particular problem in the ducts where flow velocities can be quite high.
CONTAM uses a Lagrangian model to handle high speed flows in ducts. In the Lagrangian
model, air flowing at velocity u will create a cell ut long at the inlet end of the duct segment
and cause the cell at xj to move to xj + ut during a time step of t. The length of the cell, xj, is
unchanged. This process of adding cells at the inlet end of the duct and deleting cells at the outlet
end handles convection exactly. During that time step the contaminant will diffuse between
adjacent cells due to molecular diffusion and turbulent mixing. That diffusion is solved by a
standard implicit method using a tri-diagonal equation solver.
The cell at the outlet end of the duct segment will not necessarily have an edge at x = L in which
case an interpolation is necessary to compute the concentration at x = L, which becomes the
input concentration to the next duct segment downstream. When two or more duct segments
merge at a junction the contaminant concentration at the junction is the flow-weighted average of
the concentrations at the end of each incoming duct.
High velocities produce long cells and, therefore, relatively few equations to be solved in a duct
segment. At lower velocities more cells are required, and as the velocity approaches zero the
number of cells approaches infinity. To prevent this, ContamX automatically switches to the
Eulerian finite volume model when ut is less than the user specified minimum cell length. This
corresponds to the flow regime where the finite volume is most accurate.
228
The axial dispersion coefficient in ducts is computed from the following relations. For laminar
flow (Re < 2000) the Taylor-Aris relation is used [Wen & Fan 1975, p. 127]:
(12)
where
E = axial dispersion coefficient [m2/s],
Dm = molecular diffusion coefficient [m2/s],
= average fluid velocity [m/s],
d = duct diameter [m], and
L = length of duct [m].
The condition refers to a minimum length of duct for full development of laminar flow. Until
another relation is found for undeveloped flow, equation (12) will be used for all laminar flows.
For turbulent flow E depends only on the Reynolds number, Re [Wen and Fan 1975, p. 149]:
(13)
where
Cpi = specific heat of c.v. i, and
Ti = temperature of c.v. i.
This is done only for ducts because the energy in the moving air dominants the solution in a well
designed and well built duct system. That is not the case for zones where conductive and airflow
heat transfers are of a similar scale. This model ignores heat exchange with the ductwork and its
transient impact. However, the model should still be a useful help in computing the draft of a
chimney.
(15)
where S is called the contaminant "source strength". The CONTAM internal units for the
terms in equation (16) are: C [kg / kgair], G, S [kg / s], and R [kgair / s]. You may express
these values in a large number of units with automatic conversion to the internal values.
For a room air filtering device, G = 0.0 and R = fe where f is the flow rate of the room air
passing through the filter and e is the single pass removal efficiency of the device.
Pressure Driven Model
The pressure driven source/sink model is intended to model contaminant sources which are
governed by the inside-outside pressure difference, such as radon or soil gas entry into a
basement. In this case the source equation is:
(16)
where
S = the contaminant source strength,
G = the initial emission rate,
t = the time since the start of emission, and
tc = the decay time constant.
Boundary Layer Diffusion Controlled Model
The boundary layer diffusion controlled reversible source/sink model follows the descriptions
presented by Axley 1991. The rate at which a contaminant is transferred into the sink is
(19)
where
h = average film mass transfer coefficient over the sink,
= film density of air, average of bulk & surface densities,
A = surface area of the adsorbent,
Ci = concentration in the air,
Cs = concentration in the adsorbent, and
k = Henry adsorption constant or partition coefficient.
230
where
R(t) = removal rate at time t
d = deposition velocity
As = deposition surface area
m = element multiplier
air(t) = density of air in the source zone at time t
C(t) = concentration of contaminant at time t [M / Mair]
s(t) = schedule or control signal value at time t [-]
Deposition Rate Sink Model
The deposition rate model provides for the input of a sinks characteristic in the familiar term of
deposition or removal rate. The deposition rate model equation is:
(21)
where
kd = Deposition rate [1/T]
Vz = Zone volume [M3]
other terms are the same as for the Deposition Velocity Sink Model.
231
AIRFLOW ANALYSIS
Over the years many methods have been developed to compute the building airflows which are
necessary for the contaminant analysis. Feustel and Dieris report 50 different computer programs
for multizone airflow analysis [Feustal and Dieris 1992]. Note that "zones" go by many other
names in these programs, e.g., nodes, cells, and rooms are common alternatives. The airflow
calculations in CONTAM are based on the algorithms developed in AIRNET [Walton 1989a and
1989b].
Basic Equations
The air flow rate from zone j to zone i, Fj,i[kg/s], is some function of the pressure drop along the
flow path, Pj - Pi:
(1)
The mass of air, mi [kg], in zone i is given by the ideal gas law
(2)
where
Vi = zone volume [m3],
Pi= zone pressure [Pa],
Ti= zone temperature [K], and
R= 287.055 [J/kgK] (gas constant for air).
For a transient solution the principle of conservation of mass states that
(3)
(4)
where
mi= mass of air in zone i,
Fj,i= airflow rate [kg/s] between zones j and zone i: positive values indicate flows from j to i
and negative values indicate flows from i to j, and
Fi>= non-flow processes that could add or remove significant quantities of air from the zone.
CONTAM 1.0 did not provide for such non-flow processes and flows were evaluated by
assuming quasi-steady conditions leading to the following equation
(5)
CONTAM can now provide for such non-flow processes by allowing the density to vary during
time steps when performing transient simulations.
232
You can activate this option with the Vary Density During Time Step setting under the Airflow
Numerics Simulation Parameters. If this parameter is set then, equation 3 is implemented when
performing airflow calculations; otherwise equation 5 is used.
(6)
(7)
and [J] is the square (i.e. N by N for a network of N zones) Jacobian matrix whose elements are
given by
(9)
In equations (8) and (9) Fj,i and Fj,i/Pj are evaluated using the current estimate of pressure {P}.
The ContamX program contains subroutines for each airflow element which return the mass flow
rates and the partial derivative values for a given pressure difference input.
Equation (7) represents a set of linear equations which must be set up and solved for each
iteration until a convergent solution of the set of zone pressures is achieved. In its full form [J]
requires computer memory for N2 values, and a standard Gauss elimination solution has
execution time proportional to N3. Sparse matrix methods can be used to reduce both the storage
and execution time requirements. A skyline solution process following the method presented in
[Dhatt 1984] was chosen. This method can be used to solve equations with symmetric or
asymmetric matrices. It stores no zero values above the highest nonzero element in the columns
above the diagonal and no zero values to the left of the first nonzero value in each row below the
diagonal. In this case the Jacobian matrix is symmetric. CONTAM provides two solution
methods for the linear equations: Skyline (also called profile method) and Pre-conditioned
Conjugate Gradient (PCG). PCG may be useful for problems with many zones and junctions.
Analysis of the element models will show that
(10)
This condition allows a solution without pivoting, although scaling may be useful. Note that the
degree of sparsity of the Jacobian matrix after factoring is dependent on the ordering of the
zones. Ordering can be improved by various algorithms or rules-of-thumb. In AIRNET it was
easy to define an airflow network which had no unique solution. The ContamW user interface
insures the correct interconnection of the airflow elements in the network.
233
CONTAM allows zones with either known or unknown pressures. The constant pressure zones
are included in the system of equations and equation (7) is processed so as to not change those
zone pressures. This gives flexibility in defining the airflow network while maintaining the
symmetric set of equations. A sufficient condition for the Jacobian to be nonsingular [Axley
1987] is that all of the unknown pressure zones be linked by pressure dependent flow paths to (a)
constant pressure zone(s). In CONTAM the ambient (or outdoor) air is treated as a constant
pressure zone. The ambient zone pressure is assumed to be zero for the flow calculation causing
the computed zone pressures to be values relative to the true ambient pressure and helping to
maintain numerical significance in calculating P.
Conservation of mass at each zone provides the convergence criterion for the N-R iterations.
That is, when equation (4) is satisfied for all zones for the current system pressure estimate, the
solution has converged. Sufficient accuracy is attained by testing for relative convergence at each
zone:
(11)
with a test (Fj,i < 1, the absolute convergence factor) to prevent division by zero. The
magnitude of can be established by considering the use of the calculated airflows, such as in an
energy balance. In any case, round-off errors may prevent perfect convergence ( = 0).
Numerical tests of the N-R method solution indicated occasional instances of very slow
convergence as the iterations almost oscillate between two different sets of values. In AIRNET,
this was handled by a Steffensen acceleration process. More recent tests by the author and by
Wray [Wray 1993] indicate that the use of a simpler constant under-relaxation coefficient
produces a faster, reliable convergence acceleration process. Equation (6) for the iteration
process becomes
{P}* = {P} - {C}
(12)
where is the relaxation coefficient. A relaxation coefficient of 0.75 has been found to be usable
for a broad range of airflow networks. This value is not a true optimum but appears to work quite
well without the computational cost of finding the theoretically optimum value.
When convergence is progressing rapidly, under-relaxation ( < 1) slows convergence compared
to no relaxation. To prevent this a global convergence value is computed:
(13)
When * < , is set to 1. Currently CONTAM uses = 30%. This often reduces the number
of iterations. This is simple under-relaxation. CONTAM also may alternatively use a simple trust
region method implemented by David M. Lorenzetti based on [Dennis and Schnabel 1996].
Newton's method requires an initial set of values for the zone pressures. These may be obtained
by including in each airflow element model a linear approximation relating the flow to the
pressure drop:
234
(14)
Conservation of mass at each zone leads to a set of linear equations of the form
[A]{P} = {B}
(15)
Matrix [A] in equation (15) has the same sparsity pattern as [J] in equation (7) allowing use of
the same sparse matrix solution process for both equations. This initialization handles stack
effects very well and tends to establish the proper directions for the flows. The linear
approximation is conveniently provided by the laminar regime of the element models used by
CONTAM. When solving a set of similar problems, as when approximating a transient solution
by successive steady-state solutions, it tends to be preferable to use the previous solution for the
zone pressures as the initial values for the new problem.
Airflow Elements
Infiltration is the result of air flowing through openings, large and small, intentional and
accidental, in the building envelope. Simulation programs require a mathematical model of the
flow characteristics of the openings. For a general introduction see Chapter 27 of [ASHRAE
2005] and section 2.2 of [Feustel 1990].
Flow within each airflow element is assumed to be governed by Bernoulli's equation:
(16)
where
P= total pressure drop between points 1 and 2
P1, P2= entry and exit static pressures
V1, V2= entry and exit velocities
= air density
g= acceleration of gravity (9.81 m/s2)
z1, z2= entry and exit elevations.
The following parameters apply to the zones: pressure, temperature (to compute density and
viscosity), and elevation. The zone elevation values are used to determine stack effect pressures.
When the zone represents a room, the airflow elements may connect with the room at other than
its reference elevation. The hydrostatic equation is used to relate the pressure difference across a
flow element to the elevations of the element ends and the zone elevations, assuming the air in
the room is at constant temperature. Pressure terms can be rearranged and a possible wind
pressure for building envelope openings added to give
(17)
where
Pi, Pj= total pressures at zones i and j
PS= pressure difference due to density and elevation differences, and
PW= pressure difference due to wind.
Equation (17) establishes a sign convention for direction of flow: positive is from zone j to zone
i. Since the airflow elements will be described by a relationship of the form w = f(P), the partial
derivatives needed for [J] in equation (9) are related by w/Pj = -w/Pi which establishes the
relation in equation (10). Many forms of airflow elements are available in CONTAM.
235
The volumetric flow rate, Q [m3/s], is a simple function of the pressure drop, P [Pa], across the
opening. A common variation of the powerlaw equation is:
(19)
where the mass flow rate, F [kg/s], is a simple function of the pressure drop. A third variation is
related to the orifice equation:
(20)
where
Cd= discharge coefficient, and
A= orifice opening area.
Theoretically, the value of the flow exponent should lie between 0.5 and 1.0. Large openings are
characterized by values very close to 0.5, while values near 0.65 have been found for small
crack-like openings.
The primary advantage of equations (18-20) for describing airflow components is the simple
calculation of the partial derivatives for the Newton's method solution of the simultaneous
equations:
(21)
and
The sign in equations (21) will agree with the sign of F. However, there is also a problem with
equations (21): the derivatives become unbounded as the pressure drop (and the flow) go to zero.
A simple way to avoid this problem is suggested by what physically happens at low flow rates:
the physical character of the flow (and the form of the equation) changes. It goes from turbulent
to laminar. Equations (18-20) can be replaced by
(22)
where
Ck= laminar flow coefficient, and
= viscosity.
The partial derivatives are simple constants:
(23)
and
The origin of this laminar relationship is shown by the duct equations in the next section. This
technique has been independently discovered and used by several researchers [Axley 1987] and
236
[Isaacs 1980]. Although there is physical reason for using equation (22) at low pressure drops, its
purpose here is to assure convergence of the equations when P approaches zero for one of the
many flow paths in a complex network, instead of accurately representing airflows which are too
small to be of interest. Because the linear flow expression is not used as a true flow model but as
a mathematical artifice, it is not necessary to adjust its flow coefficient. Given the uncertainty in
estimating the temperature of the air as it flows through an opening, especially a crack, this
additional detail is of debatable usefulness.
The CONTAM functions for powerlaw elements calculate flows using both the laminar and the
turbulent models and select the method giving the smaller magnitude flow. There is a
discontinuity in the derivative of the F(P) curve where the two equations intersect. This
discontinuity is a violation of one of the sufficient conditions for convergence of Newton's
method [Conte and de Boor 1972, p. 86]. However, numerical tests conducted by the author for
flows at that point using a small airflow network have shown no convergence problem.
Temperature Dependence
It is useful to think of the coefficient C as a simple constant, C, evaluated at a particular set of
conditions (0, 0 and 0=0/0) multiplied by a correction factor to account for actual air
properties. Equations (18-20) are converted to a common form and summarized below with their
appropriate temperature correction factors.
Correction Factor
(24)
If n is known or can be assumed, Cb, in equation (24), can be computed from the inverse of
equation (25)
(26)
When two points (F1, P1) and (F2, P2), are known, n can be computed from:
237
(27)
where
L= equivalent or effective leakage area [m2],
Pr= reference pressure difference [Pa],
Qr= predicted airflow rate at Pr (from curve fit to pressurization test data) [m3/s], and
Cd= discharge coefficient.
There are two common sets of reference conditions:
Cd = 1.0 and Pr = 4 Pa
or
Cd = 0.6 and Pr = 10 Pa.
A leakage area can be converted to the flow coefficient by
(29)
This equation requires a value for n. If it is not reported with the test results, a value between 0.6
and 0.7 is reasonable.
Stairwells
A stairwell will normally be modeled as a vertical series of zones connected by low resistance
openings through the floors. The CONTAM model for airflow in stairwells is based on a fit to
experimental data [Achakji and Tamura 1988]. They expressed the airflow resistance per floor as
an effective area Ae in the orifice equation (20) with a 0.6 discharge coefficient. The effective
area is expressed in terms of the area of the shaft AS, the distance between floors h, the density of
people on the stairs d, and whether the treads are open or closed. A large number of people on
the stairs, as in an evacuation scenario, influences the flow resistance. The experiment used
densities of 0, 1, and 2 persons/m2. For open treads the effective area is approximately
(30)
(32)
Cracks
A relationship for flow through cracks that can be converted directly into a powerlaw airflow
element is presented in [Clarke 1985, p. 204] as:
(33)
where
(34)
and
(35)
with
W = crack width (mm), and
a = crack length (m).
Therefore, the coefficients in the powerlaw equation (19) are given by n in equation (34) and
(36)
(37)
This form can be used as an airflow element by solving the quadratic equation for F (= Q).
Letting a = A/ and b = B/2 allows equations (37) to be rewritten as
(38)
Equations (39) require that b be nonzero to prevent a division by zero and equations (40) requires
that a be nonzero to prevent a division by zero as F goes to zero. There are contrary opinions that
the powerlaw relationship is better.
239
Temperature Dependence
It is useful to think of the coefficients a and b as simple constants evaluated at a particular set of
conditions (0, 0 and 0=0/0) multiplied by correction factors to account for actual air
properties as was done for the powerlaw equations. That is
(41)
and
(42)
(43)
and
(44)
The main advantage of the quadratic model over the powerlaw model is computation speed
achieved by avoiding the slow power function. (Tests have shown pow(x) four to eight times
slower than sqrt(x). This performance is hardware and software dependent.) It must still be
determined which model is the most accurate representation for a particular airflow element. For
example, it has been found that the powerlaw model is a better approximation for smooth ducts
while the quadratic model is a better approximation for rough ducts. However, for very large
openings the derivatives (40) can become quite large leading to slow convergence of the
simultaneous mass balance equations.
Crack Description
Theoretical relationships have been developed between the coefficients A and B of the quadratic
airflow element model and the physical characteristics of the openings [Baker 1987]. These are
(45)
where
= viscosity,
= density,
z= distance along the direction of flow,
d= crack width,
L= crack length, and
C= 1.5 + number of bends in the flow path.
240
For the mass flow form of the equations (38) the coefficients are
(46)
Ducts
The theory of flows in ducts (and pipes) is well established and summarized in Chapter 35 of the
2005 ASHRAE Fundamentals Handbook [ASHRAE 2005] and treated more extensively in
[Blevins 1984] in a chapter on pipe and duct flow. See the Duct Fitting Database [ASHRAE
2002] for extensive data on dynamic losses in duct fittings. Analysis is based on Bernoulli's
equation and its assumptions. The friction losses in a section of duct or pipe are given by
(47)
where
f = friction factor,
L = duct length, and
D = hydraulic diameter.
The dynamic losses due to fittings and so forth are given by
(48)
CONTAM calculates the friction factor using the nonlinear Colebrook equation [ASHRAE 2001,
p 2.9, eqn. 29b]:
(51)
where
= roughness dimension, and
Re = Reynolds number = VD/ = FD/A.
This nonlinear equation may be readily solved using the following iterative expression derived
from equation (51) by Newton's method:
(52)
where
241
g = f -1/2,
= 1.14 - ln(/D),
= 9.3/(Re/D), and
= 2log(e) = 0.868589.
The convergent solution is achieved in 2 or 3 iterations of equation (52) using g = as a starting
value. If the value of g has been saved from the previous time it was computed for a particular
duct element, and the flow rate has not changed greatly, only one iteration of equation (52) will
be needed to compute the friction factor.
The exact derivatives of equation (50) are difficult to compute, so CONTAM uses a secant
approximation. The derivatives suffer the standard problem of powerlaw equations, i.e., they go
undefined as P approaches zero. This is solved in CONTAM by the linear approximation (22)
with the coefficient computed to give the same flow as equation (50) at the user specified
transition Reynolds number (default = 2000). A more detailed description of the flow in the
laminar region could be developed, but that would probably exceed the level of detail with which
the rest of the problem is described in CONTAM.
Terminal Loss Calculation
In CONTAM, duct terminals are essentially zero-length ducts characterized by an equivalent loss
coefficient that is determined during simulation from the properties of the terminal, Ct and Cb,
and the schedule or control signal (S) acting upon the terminal.
Ce = Ct + Cb + (1-S)/S
where
Ct = terminal loss coefficient
Cb= terminal balance coefficient
Sc = schedule or control signal acting upon the terminal
S = max(1x10-6, Sc1)
Sc1= min(1, Sc)
Using this technique, an input signal Sc of 0.0 will effect a very high loss coefficient, that of 1.0
will simply provide the loss determined by the combination of Ct and Cb, Scbetween 1x10-6 and 1
will be used to increase the value of (Ct + Cb) according to the equation above, and Sc less than
0.0 will equate to 1.0, i.e., the loss can not be reduced below (Ct + Cb). The value Ce will then be
used as the dynamic loss coefficient in the duct flow equations presented above.
Fans
This section describes the theory of how forced flow elements are modeled with CONTAM.
Forced flow elements include constant flow fans and variable flow fans. Constant flow fans
include both constant volume and constant mass flow. Variable flow fans are modeled based on
the input of a fan performance curve that relates pressure drop to airflow through the fan flow
element.
Constant Flow Fans
One particularly simple but useful airflow element sets a constant flow between two nodes. Since
the flow is constant, the partial derivatives of flow with respect to the node pressures must be
zero. The constant flow element does not contribute to the Jacobian, [A], but it does add to the
right side vector, {B}.
242
Constant flow elements do not mathematically link the pressures of the adjacent nodes. It is
necessary that all node in the network be linked to constant pressure nodes in order to have a
unique solution. Violation of this restriction will produce a division by zero somewhere in the
solution of the equations. Consider the following simple network:
|----C1----|----F1----|----C2----|----F2----|----C3----|
P1
P2
P3
P4
P5
P6
where P1 and P6 are known pressures, and F1 and F2 are known flows. Since the flow through C2
is determined by P3 - P4, and no other flow is related to those pressures, there are not enough
equations to determine P3and P4 uniquely. This is a mathematical expression of the fact that it is
possible for F1 and F2 to be assigned different flows, which produces a physically impossible
condition.
CONTAM provides two constant flow elements: one for constant mass flow and one for
constant volumetric flow.
Variable Flow Fans
The theory of flows induced by fans is summarized in Chapter 18 of the 2000 ASHRAE HVAC
Systems and Equipment Handbook [ASHRAE 2004]. More extensive treatment is given in
[Osborne 1977]. Fan performance is normally characterized by a performance curve which
relates the total pressure rise to the flow rate for a given fan speed and air density. Conversion to
another fan speed or density is done with the fan laws.
(53)
or
(54)
and
(55)
where
Q = volume flow rate,
F = mass flow rate,
P = total pressure rise,
= density,
N = rotational speed, and
subscript 0 indicates values at the rating conditions for the fan.
These laws are valid if all flow conditions at the two speeds are similar. In particular, they will
not apply at very low flows where fully turbulent conditions have not been developed.
In CONTAM the fan performance curve is represented by a cubic polynomial:
(56)
with
243
(57)
The polynomial coefficients are developed with air density and fan speed at the rating
conditions. Therefore, when N and are not at the rating conditions, convert the actual pressure
rise P to P0.
(58)
Solve (56) for F0using iterative or analytic solution and (57) for P0. Convert these values to
current conditions.
(59)
and
(60)
There are two important factors to note on the shape of the fan performance curve. First, it is
described by a relationship of the form P(F) instead of F(P) which would be more appropriate
for the calculation of flow and partial derivatives for the Jacobian. The basic shape of the
performance curve cannot be well represented by a simple polynomial with P as the independent
variable. CONTAM uses an analytic solution of the cubic polynomial (56) to determine F as a
function of P.
Second, it is common for the performance curve to contain points of contraflecture (where P =
0) creating up to three different flow rates at certain values of fan pressure rise. This causes
difficulty in solving for the flow rate and has points where dF/dP goes to infinity. However, it is
usually not recommended that the fan operate in the region of the contraflecture points.
Therefore, the fan can be modeled with a performance curve that does include the contraflecture
so long as you make sure that the air distribution system has not operated in that region.
You can identify the points of contraflecture from the coefficients of the polynomial. Solving
equation (56) for F gives:
(62)
244
where b is approximately 0.5 and C lies between 0.22 and 0.33 depending on the temperature
difference used for the correlation. It has been shown that such a heat transfer is equivalent to an
airflow which can be modeled by powerlaw elements by dividing the total opening into several
smaller openings having the same total area but configured to properly account for the magnitude
and direction of airflows at different heights in the opening.
An alternative approach is to create a single airflow element which accounts for the flow over the
entire opening. A simple theory which estimates the stack induced air flow through a large
opening in a vertical partition is given in [Brown and Solvason 1962]. This model of a doorway
tends to be faster than the multiple opening approach. However, it also complicates the assembly
process for the Jacobian matrix because one or two flows may exist. More importantly,
development of the doorway element model requires knowledge of the vertical temperature
profile used in the node model (here assumed to be constant) in order to compute the pressure
difference as a function of height across the opening. This requirement compromises the
independence of the modularity of airflow network program.
Multiple Opening Model
By assuming that the air density in each room is constant, the hydrostatic equation is used to
relate pressures at various heights in each room:
(64)
(65)
where
P0j, P0ipressure in zones j and i at y = 0, the reference elevation of the opening,
j, iair densities of zones j and i,
Pj, Pireference pressures of zones j and i,
hj, hireference elevations of zones j and i, and
h0elevation of the center of the opening.
Following [Brown and Solvason 1962] it is assumed that the velocity of the airflow as a function
of height is given by the orifice equation:
(66)
where
245
The coefficient for the powerlaw model (20) for each sub-opening is thus given by
(68)
(a simple orifice with one half the total opening area) placed at an elevation of y = 2H/9. The two
opening model is completed with an identical opening at y = -2H/9 elevation allowing an equal
flow in the opposite direction. Since the orifice is being modeled with simple orifice openings,
any additional pressure drop between the zones due to other forces is included in the two opening
model. The model becomes less accurate as the neutral plane shifts from the center of the
opening.
Single Opening Model
A third approach is to create a single airflow element which accounts for the flow over the entire
opening. Begin by defining the neutral height, Y, where the velocity of the air is zero. From
equation (66) this must occur when Pj(y) = Pi(y). From equations (65) this must be
(71)
If |Y| < H/2, there is two-way airflow through the opening. If j = i, the neutral height cannot be
computed, but, since there is no possibility of two-way flow, the opening can be considered a
simple orifice opening.
Define j - i and a transformed height coordinate z y - Y. Then the pressure difference
across the opening is given by
(72)
The mass flow through the opening above the neutral height is given by
246
(73)
(75)
< 0
< 0
(76)
(77)
(78)
(79)
247
REFERENCES
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Achakji, G.Y. & G.T. Tamura, 1988. "Pressure Drop Characteristics of Typical Stairshafts in
High rise Buildings," ASHRAE Transactions, 94(1): 1223-1236.
AIVC 1991. Technical Note AIVC 34 Airflow Patterns within Buildings: Measurement
Techniquies, Coventry UK.
ASHRAE 1993. ASHRAE Handbook - 1993 Fundamentals, Atlanta GA.
ASHRAE 1999a. Method of Testing General Ventilation Air-Cleaning Devices for Removal
Efficiency by Particle Size (ANSI approved). Standard 52.2-1999. Atlanta, GA.
ASHRAE 1999b. ASHRAE Handbook - HVAC Applications, Atlanta GA.
ASHRAE 2001. ASHRAE Handbook - 2001 Fundamentals, Atlanta GA.
ASHRAE 2002. Duct Fitting Database, v. 2.2.5, Atlanta GA.
ASHRAE 2004. ASHRAE Handbook - HVAC Systems and Equipment, Atlanta GA.
ASHRAE 2005. ASHRAE Handbook - 2005 Fundamentals, Atlanta GA.
ASTM 1999. Standard Test Method for Determining Air Leakage Rate by Fan Pressurization.
Standard E779-99. American Society for Testing and Materials, West Conshohocken, PA.
Axley, J.W. 1987. "Indoor Air Quality Modeling Phase II Report", NBSIR 87-3661, National
Bureau of Standards (U.S.).
Axley, J.W. 1988. "Progress Toward a General Analytical Method for Predicting Indoor Air
Pollution in Buildings, Indoor Air Quality Modeling Phase III Report", NBSIR 88-3814,
National Bureau of Standards (U.S.).
Axley, J.W. 1991. "Adsorption Modeling for Building Contaminant Dispersal Analysis", Indoor
Air, 1:147-171.
Axley, J.W. 1995. "New Mass Transport Elements and Components for the NIST IAQ Model",
NIST GCR 95-676, National Institute of Standards and Technology(U.S.).
Axley, J. W. 2001. Residential Passive Ventilation Systems: Evaluation and Design. AIVC
Technical Note 54. International Energy Agency, Coventry.
Baker, P.H., S. Sharples, & I.C. Ward. 1987. "Air Flow through Cracks," Building and
Environment, Pergamon, 22(4): 293-304.
Barakat, S.A. 1987. "Inter-zone Convective Heat Transfer in Buildings: a Review," ASME
Journal of Solar Engineering, Vol. 109, May.
Blevins, R.D. 1984. Applied Fluid Dynamics Handbook, New York: Van Nostrand Reinhold.
Brown, W.G., & K.R. Solvason. 1962. "Natural Convection through Rectangular Openings in
Partitions - 1: Vertical Partitions," International Journal of Heat and Mass Transfer, Vol. 5, pp.
859-867.
Clarke, J.A. 1985. Energy Simulation in Building Design, Adam Hilger Ltd., Briston and Boston,
p 204.
Conte, S.D. and C. de Boor. 1972. Elementary Numerical Analysis, McGraw Hill, New York
NY.
248
Dennis, J.E., Jr. and R.B. Schnabel. 1996. Numerical Methods for Unconstrained Optimization
and Nonlinear Equations, Society for Industrial and Applied Mathematics, Philadelphia.
Dhatt, G., G. Touzot, & G. Catin. 1984. The Finite Element Method Displayed, John Wiley &
Sons, New York.
Dols, W.S., Walton G.N., & Denton, K.R. 2000. "CONTAMW 1.0 User Manual", NISTIR 6476,
National Institute of Standards and Technology.
Emmerich, S.J. and A.K. Persily. 1996. "Multizone Modeling of Three Residential Indoor Air
Quality Control Options", NISTIR 5801, National Institute of Standards and Technology.
Emmerich, S.J. and A.K. Persily. 1998. "Energy Impacts of Infiltration and Ventilation in U.S.
Office Buildings Using Multizone Airflow Simulation" Proceeding of IAQ and Energy 98. New
Orleans, Louisiana: ASHRAE.
Emmerich, S.J. and S.J. Nabinger. 2000. "Measurement and Simulation of the IAQ Impact of
Particle Air Cleaners in a Single-Zone Building", NISTIR 6461, National Institute of Standards
and Technology.
Emmerich, S.J., JE Gorfain, M. Huang, C. Howard-Reed. 2003. "Air and Pollutant Transport
from Attached Garages to Residential LivingSpaces," NISTIR 7072, National Institute of
Standards and Technology, Gaithersburg, MD. December 2003.
Fang, J.B. and A.K. Persily. 1995. "Computer Simulations of Airflow and Radon Transport in
Four Large Buildings", NISTIR 5611, National Institute of Standards and Technology.
EPA 1989. Exposure Factors Handbook. Publication number EPA/600/8 89/043.
Feustel, H.E. and A. Rayner-Hooson (Eds). 1990. "COMIS Fundamentals", Lawrence Berkeley
Laboratory, report LBL-28560.
Feustel, H.E. and J. Dieris. 1992. "A survey of airflow models for multizone structures", Energy
and Buildings, Vol 18, pp. 79-100.
Hindmarsh, Alan C., Radu Serban. 2012. User Documentation for CVOD v2.7.0. UCRL-SM20818. Lawrence Livermore National Laboratory.
Howard-Reed, C., Begley, E., Polidoro, B., Dols, W.S. "VOC Source Emission Rate Databases:
Model Input and Data Format Issues," ASTM Conference on Indoor Emissions Testing: Methods
and Interpretation, October 2004.
Howard-Reed, C. and Polidoro, B. "Database Development for Modeling Emissions and Control
of Air Pollutants from Consumer Products, Cooking, and Combustion," NISTIR 7364, 2006.
Isaacs, L.T. and K.G. Mills. 1980. "Linear Theory Methods for Pipe Network Analysis", Journal
of the Hydraulics Division, Proceedings ASCE, Vol. 106, pp. 1191-1201. (See also author's
closure, 1982, Vol. 108, p. 153).
Klote, J.H. 1982. "A Computer Program for Analysis of Smoke Control Systems", NBSIR 822512, National Bureau of Standards (U.S.).
Klote, J.H. and J.A. Milke. 2002. Principles of Smoke Management, ASHRAE, Atlanta GA.
Musser, A. and G. Yuill. 1999. "Comparison of Residential Air Infiltration Rates Predicted by
Single-Zone and Multizone Models," ASHRAE Transactions, 1999. Vol. 105(Part 1).
Musser, A. 2000. "Multizone Modeling as an Indoor Air Quality Design Tool", Proceedings of
Healty Buildings 2000. Espoo, Finland.
249
250
251
The next line defines the weather (WTHDAT) for steady-state simulation in ContamX:
Tambt // ambient temperature [K] (R4)
barpres // barometric pressure [Pa] NOT corrected to sea level (R4)
windspd // wind speed [m/s] (R4)
winddir // wind direction: 0 = N, 90 = E, 180 = S, ...; (R4)
relhum // relative humidity: 0.0 to 1.0 (R4)
daytyp // type of day (1-12) (I2)
uTa // units for Tambt (I2) {W}
ubP // units for barpres (I2) {W}
uws // units for windspd (I2) {W}
uwd // units for winddir (I2) {W}
The next line defines weather data (WTHDAT) for the wind pressure test in ContamW:
Tambt // ambient temperature [K] (R4) {W}
barpres // barometric pressure [Pa] NOT corrected to sea level (R4) {W}
windspd // wind speed [m/s] (R4) {W}
winddir // wind direction: 0 = N, 90 = E, 180 = S, ...; (R4) {W}
relhum // relative humidity: 0.0 to 1.0 (R4) {W}
daytyp // type of day (1-12) (I2) {W}
uTa // units for Tambt (I2) {W}
ubP // units for barpres (I2) {W}
uws // units for windspd (I2) {W}
uwd // units for winddir (I2) {W}
The next four lines define the weather, contaminant and controls files, respectively:
_WTHpath[_MAX_PATH]
_CTMpath[_MAX_PATH]
_CVFpath[_MAX_PATH]
_DVFpath[_MAX_PATH]
//
//
//
//
full
full
full
full
name
name
name
name
of
of
of
of
The following lines define path location data (PLDDAT) for the creating the WPC file:
three lines for file paths and WPC description:
WPCfile[_MAX_PATH] // full name of WPC file (I1)
EWCfile[_MAX_PATH] // full name of EWC data source file (I1) {W}
WPCdesc[] // WPC description (I1) {W}
The next line defines the location (LOCDAT) (for future use with thermal simulation):
latd // latitude (degrees: north +, south -) (R4)
lgtd // longitude (degrees: east +, west -) (R4)
Tznr // time zone (Greenwich = 0, Eastern = -5, etc.) (R4)
altd // elevation above sea level [m] (R4)
Tgrnd // ground temperature [K] (R4)
utg // units for ground temperatures (I2)
u_a // units for elevation (I2)
The remaining data is stored in the run control (RCDAT) structure. In ContamX some
values may be transferred to other variables before being used. The next two lines
control the airflow simulation first the nonlinear part:
sim_af // airflow simulation: 0 = steady, 1 = dynamic (I2)
afcalc // N-R method for non-linear eqns: 0 = SUR, 1 = STR (I2)
afmaxi // maximum number of N-R iterations (I2)
afrcnvg // relative airflow convergence factor (R4)
afacnvg // absolute airflow convergence factor [1/s] (R4)
afrelax // flow under-relaxation coefficient (for SUR) (R4)
uac2 // units for afacnvg (I2)
Pres // pressure test pressure (R4) {Contam 2.4}
uPres // units of Pres (I2) {Contam 2.4}
The next four lines control the linear solver for contaminant calculations:
first for cyclic simulation:
sim_mf // mass fraction (contaminant) simulation:
// 0 = none, 1 = steady, 2 = transient, 3 = cyclic (I2)
ccmaxi // simulation: maximum number of cyclic iterations (I2)
ccrcnvg // relative convergence factor (R4)
ccacnvg // absolute convergence factor [kg/kg] (R4)
254
The next line sets the integration method and short time step contaminant calculation
parameters:
mf_solver // mass fraction integration method: {3.1 }
// 0=trapezoid, 1=STS, 2=CVODE (I2)
sim_1dz // if true, use 1D zones (I2)
sim_1dd // if true, use 1D ducts (I2)
celldx // default length of duct cells for C-D model [m] (R4)
sim_vjt // if true, compute variable junction temperatures (I2)
udx // units of celldx (I2)
The next line contains CVODE contaminant solver parameters: {CONTAM 3.1}
cvode_mth // 0
cvode_rcnvg //
cvode_acnvg //
cvode_dtmax //
tsmaxi
cnvgSS
densZP
stackD
dodMdt
//
//
//
//
//
The next line sets the dates, times, and time steps for simulation:
date_st // day-of-year to start steady simulation (mmmdd IX)
time_st // time-of-day to start steady simulation (hh:mm:ss I4)
date_0 // day-of-year to start transient simulation (mmmdd IX)
time_0 // time-of-day to start transient simulation (hh:mm:ss I4)
date_1 // day-of-year to end transient simulation (mmmdd IX)
time_1 // time-of-day to end transient simulation (hh:mm:ss I4)
time_step // simulation time step [s] (hh:mm:ss IX)
time_list // simulation output (results) time step [s] (hh:mm:ss IX)
time_scrn // simulation status time step [s] (up to 1 day) (hh:mm:ss
I4)
The next line controls output of more simulation result files: {CONTAM 3.1}
rzfsave
rzmsave
rz1save
csmsave
srfsave
logsave
//
//
//
//
//
//
(0/1)
(0/1)
(0/1)
(0/1)
(0/1)
(0/1)
save
save
save
save
save
save
256
The next line provides a set of integers that are used for development purposes:
{CONTAM 3.1}
save[0-15] // (unused by CONTAM; subject to change without notice) (I1)
The next two lines contain a list of real values provided for PRJ file flexibility. They are
stored in the rvals[] vector {CONTAM 2.4b}
nrvals // number of real values in the vector (I2)
rvals[0] // standard density for air change calculation
rvals[1] // acceleration due to gravity [m/s2](R4)
[kg/m3](R4)
The next line controls which sections are output to the .val file: {CONTAM 2.4a}
BldgFlowZ // output building airflow test (zones) (IX)
BldgFlowD // output building airflow test (ducts) (IX)
BldgFlowC // output building airflow test (classified flows) (IX)
The next line controls cfd calculations and coupling: {CONTAM 3.0}
cfd_ctype // (0=no cfd, 1=post, 2=quasi, 3=dynamic) cfd coupling method
(I2)
cfd_convcpl // convergence factor for dynamic coupling (R4)
cfd_var // (0/1) use .var file (I2)
cfd_zref // currently not used (I2)
cfd_imax // max number of dynamic coupling iterations (I2)
cfd_dtcmo // number of iterations between outputs to .cmo file (I2)
Note on outputs: _pfsave and _zfsave always have the same value 0 or 1.
Section 2: Species and Contaminants
Species/contaminant data are read by the spcs_read( ) function and saved by the
spcs_save( ) function in ContamW. They are read by ctm_read( ) in ContamX.
The species/contaminant section starts with:
_nctm // total number of species simulated (= contaminants) (I2)
The next line lists the numbers of the _nctm species treated as contaminants. The
ordering of the contaminants is important, and is set in ContamW.
_ctm[i] // i = 0 to nctm-1
This is followed by a header line and then two lines of data for each species:
The first line of species data consists of:
nr // species number (IX), in order from 1 to _nspcs
sflag // 1 = simulated, 0 = unsimulated species (I2) {W}
ntflag // 1 = non-trace, 0 = trace species (I2) {W}
molwt // molar mass [kg/kmol] - gas (R4)
mdiam // mean diameter particle [m] (R4)
edens // effective densiity particle [kg/m^3] (R4)
decay // decay constant [1/s] (R4) {W}
257
This is followed by a data header comment line and then data for all nlev levels.
Each level has a data line that includes:
nr // level number (IX), in order from 1 to nlev
refht // reference elevation of level [m] (R4)
delht // delta elevation to next level [m] (R4) {W}
nicon // number of icons on this level (IX)
u_rfht // units of reference elevation (I2) {W}
u_dlht // units of delta elevation (I2) {W}
name[] // level name (I1)
This line is followed by a comment line and then data for nicon icons.
Each icon has a data line consisting of:
icon // icon type see special symbols in contam.h (I2) {W}
row // row position on the SketchPad (I2) {W}
col // column position on the SketchPad (I2) {W}
nr // zone, path, duct, etc., number (I2) {W}
258
This is followed by a data header comment line and then data for all _ndsch schedules.
For each schedule the first data line includes:
nr // schedule number (IX); in order from 1 to _ndsch
npts // number of data points (I2)
shape // 0 = rectangular; 1 = trapezoidal (I2)
utyp // type of units (I2) {W}
ucnv // units conversion (I2) {W}
name[] // schedule name (I1) {W}
This is followed by a data header comment line and then data for all _nwsch schedules.
For each week schedule the first data line includes:
nr // schedule number (IX); in order from 1 to _nwsch
utyp // type of units (I2) {W}
ucnv // units conversion (I2) {W}
name[] // schedule name (I1) {W}
This is followed by a data header comment line and then data for all _nwpf profiles.
For each wind pressure profile the first data line includes:
nr // profile number (IX); in order from 1 to _nwpf
npts // number of data points (I2)
type // 1 = linear; 2 = cubic spline; 3 = trigonometric (I2)
name[] // schedule name (I1) {W}
This is followed by a line for each of the npts data points that are used to compute
the cubic spline or trigonometric coefficients for wind pressure profiles:
azm[] // wind azimuth value {R4} [degrees]
coef[] // normalized wind pressure coefficients {R4} [-]
This is followed by a data header comment line and then data for all _nkinr reactions.
For each reaction the first data line includes:
nr // reaction number (IX); in order from 1 to _nkinr
nkrd // number of reactions (I2)
name[] // reaction name (I1) {W}
260
This is followed by lines of data that depend on the element data type.
The introductory lines that follow give the type number, the program macro defined as
that number, the type name from _flte_names, and the data structures to hold the data.
The data structures are defined in celmts.h in ContamW and selmts.h in ContamX. Type
numbers can change as long as the ordering in _flte_names and related arrays reflect
that order.
Element type 0 [FL_CEF] "cef" stored in structure CEF_DAT.
The constant efficiency filter data consist of:
nspcs // number of species (IX)
Then a line of data containing a list of the number of each sub-element in flow
order:
elmt[] // sub-element numbers (IX) converted to pointers
This is followed by nload lines of species loading data: [not yet used; nsload =
0]
spcs[]
load
262
This is followed by a data header comment line and then data for all _ncse elements.
For each element the first data line includes:
nr // element number (IX); in order from 1 to _ncse
spcs[] // species name (I1)
ctype // element data type (string ? I2)
element type names are stored in _cse_dnames in ctype order.
name[] // element name (I1) {W}
This is followed by one or more lines of data that depend on the element data type.
The introductory lines that follow give the type number, the program macro defined as
that number, the type name from_cse_dnames, and the data structures to hold the data.
The data structures are defined in celmts.h in ContamW and selmts.h in ContamX. Type
numbers can change as long as the ordering in _csse_names and related arrays reflect
that order.
Element type 0 [CS_CCF] "ccf" stored in structure CSE_CCF.
The constant coefficient source model data:
G // generation
D // deposition
u_G // units of
u_D // units of
//
//
//
//
//
//
//
//
//
//
264
u_dA
u_dR
This is followed by a data header comment line and then data for all _nafe elements.
For each element the first data line includes:
nr // element number (IX); in order from 1 to _nafe
icon // icon used to represent flow path (R4) {W}
dtype // element data type (string ? I2)
// element type names are stored in _afe_dnames in dtype order.
name[] // element name (I1) {W}
This is followed by one or more lines of data that depend on the element data type.
The introductory lines that follow give the type number, the program macro defined as
that number, the type name from _afe_dnames, and the data structures to hold the data.
The data structures are defined in celmts.h in ContamW and selmts.h in ContamX. Type
numbers can change as long as the ordering in _afe_dnames and related arrays reflect
that order.
Element type 0 [PL_ORFC] "plr_orfc" stored in structure PLR_ORF.
The orifice data consist of:
lam // laminar flow coefficient (R4)
turb // turbulent flow coefficient (R4)
expt // pressure exponent (R4)
area // actual area [m^2] (R4) {X}
dia // hydraulic diameter [m] (R4) {X}
coef // flow coefficient (R4) {X}
Re // laminar/turbulet transition Reynolds number [-](R4) {X}
u_A // units of area (I2) {X}
u_D // units of diameter (I2) {X}
266
268
b // {R4}
269
270
x
y
This is followed by a data header comment line and then data for all _ndfe elements.
For each element the first data line includes:
nr // element number (IX); in order from 1 to _nafe
icon // icon used to represent flow path ((R4) {W}
dtype // element data type (string ? I2)
// element type names are stored in _afe_dnames in dtype order.
name[] // element name (I1) {W}
This is followed by two or more lines of data that depend on the element data type.
The introductory lines that follow give the type number, the program macro defined as
that number, the type name from _afe_dnames, and the data structures to hold the data.
The data structures are defined in celmts.h in ContamW and selmts.h in ContamX. Type
numbers can change as long as the ordering in _afe_dnames and related arrays reflect
that order.
Element type 23 [DD_DWC] "dct_dwc" stored in structure DEF_DWC.
271
After each element comes the following geometry and leakage data stored in structure
DUCT.
The first line of duct geometry data consists of:
hdia // hydraulic diameter [m] {R4}
perim // perimeter [m] {R4}
area // cross sectional area [m^2] {R4}
major // major dimension of rectangular or oval duct [m] {R4}
minor // minor dimension of rectangular or oval duct [m] {R4}
As // duct segment surface area [m^2] {R4} (not used)
Qr // duct leakage rate at Pr [L/s/m^2] {R4}
Pr // dPstatic for leakage rate [Pa] {R4}
273
This is followed by a section that contains sub-node data of the Super Element. This will
be very similar to the "control nodes:" section of the project file (see Section 12b below)
and repeated within section 12b for each super node that is instantiated from a super
element. However, the actual parameters of the instantiated super nodes may vary from
those of the super element sub-nodes.
This is followed by lines of data that contain the SketchPad icon parameters of the Super
Element sketch and will follow the "levels plus icon data:" section of the project
file but only for a single "level" of data that represents the Super Element sub-node icons
(see Section 3).
The Super Elements section is terminated with:
274
-999
This is followed by a data header comment line and then data for all _nctrl control
nodes.
For each control node the first data line includes:
nr // node (SketchPad) number (IX); in order from
type // node data type (string ? I2)
Node type names are stored in _ctrl_names in type
seqnr // computation sequence number (IX); set in
flags // flags for offset & scale, time constant,
(U2)
inreq // number of required inputs (I2) {W}
n1 // SketchPad number of input node #1 (IX)
n2 // SketchPad number of input node #2 (IX)
name[] // element name (I1) {W}
1 to _nctrl
order.
ContamW
and 1D sensor
This may be followed by one more line of data that depends on the node type.
Node type 0 [CT_SNS] "sns" stored in structure SENSOR {W} or SNSDAT {X}.
offset // offset value (R4)
scale // scale value (R4)
tau // time constant (R4)
oldsig // signal at last time step - for restart (R4)
source // index of source (source not defined at read time) (IX)
type // type of source: 1=zone, 2=path, 3=junction, 4=duct,
// 5=exp, 6=term (I2)
measure // 0=contaminant, 1=temperature, 2=flow rate, 3=dP,
// 4=Pgage, 5=zone occupancy (I2)
X // X-coordinate of sensor [m] (R4)
Y // Y-coordinate of sensor [m] (R4)
relHt // relative height of sensor [m] (R4)
units[] // units of coordinates {W} (I1)
species[] // species name [I1]; convert to pointer
275
Node type 36 [CT_SEN] this is only a placeholder value for use with the type dialog.
Node type 37 [CT_SPH] "sph" has no additional data.
The control nodes section is terminated with:
-999 // used to check for a read error in the above data
This is followed by a data header comment line and then data for all _nahs systems.
For each AHS the first data line includes:
277
nr // AHS
zone_r //
zone_s //
path_r //
path_s //
path_x //
This is followed by a data header comment line and then data for all _nzone zones.
For each zone the data line includes:
nr // zone number (IX); in order from 1 to _nzone
flags // zone flags bits defined in contam.h (U2)
ps // week schedule index (IX); converted to pointer
pc // control node index (IX); converted to pointer
pk // kinetic reaction index (IX); converted to pointer
pl // building level index (IX); converted to pointer
relHt // zone height [m] (R4)
Vol // zone volume [m^3] (R4)
T0 // initial zone temperature [K] (R4)
P0 // initial zone pressure [Pa] (R4)
name[] // zone name (I1) {W}
color // zone fill color (I2) {W} {Contam 2.4}
u_Ht // units of height (I2) {W}
u_V // units of volume (I2) {W}
u_T // units of temperature (I2) {W}
u_P // units of pressure (I2) {W}
cdaxis // conv/diff axis (0=no cd, 1-4 => cd axis direction)
(I2)
cfd // cfd zone (0=no, 1=yes) (I2)
H1
// Relative Height
"
X2
// X coordinate of other end of cdaxis
Y2
// Y
"
"
H2
// Relative Height
"
celldx // length of c/d cell [m] (R4)
axialD // axial diffusion coeff [m^2/s] (R4)
u_aD // units of axial diffusion (I2)
u_L // units of c/d axis limits (I2)
This is followed by a data header comment line and then data for all _npath paths.
For each path the data line includes:
nr // path number (IX); in order from 1 to _npath
flags // airflow path flag values (I2)
pzn // zone N index (IX); converted to pointer
pzm // zone M index (IX); converted to pointer
pe // flow element index (IX); converted to pointer
pf // filter index (IX); converted to pointer
279
This is followed by a data header comment line and then data for all _njct junctions.
For each junction the data line includes:
nr // junction number (I2); in order from 1 to _njct
flags // junction flags bits defined in contam.h (U2)
jtype // junction type flag: 0=jct, 1=term, 3=term w/ wind {Contam
2.1}
pzn // surrounding zone index (I2); converted to pointer
280
nn should equal _njct * _nctm. This is followed by _njct lines in order from junction 1 to
junction _njct.
281
Each data line contains _nctm mass fractions (R4) in contaminant order.
The initial junction concentrations section is terminated with:
-999 // used to check for a read error in the above data
This is followed by a data header comment line and then data for all _ndct ducts.
For each duct the data line includes:
nr // duct number (IX); in order from 1 to _ndct
flags // duct flag values (I2)
pjn // junction n index (IX); converted to pointer
pjm // junction m index (IX); converted to pointer
pe // duct flow element index (IX); converted to pointer
pf // filter index (IX); converted to pointer
ps // schedule index (IX); converted to pointer
pc // control node index (IX); converted to pointer
dir // positive flow direction on sketchpad (U1) {W}
length // length of the duct segment [m] (R4)
Ain // flow area at inlet end [m^2] - future (R4)
Aout // flow area at outlet end [m^2] - future (R4)
sllc // sum of local loss coefficients (R4)
color // icon color (I2) {W} {Contam 2.4}
u_L // units for length (I2) {W}
u_A // units for flow area (I2) {W}
This is followed by a data header comment line and then data for all _ncss source/sinks.
For each source/sink the data line includes:
nr // source/sink number (IX); in order from 1 to _ncss
pz // zone index (IX); converted to pointer
pe // source/sink element index (IX); converted to pointer
282
(R4)
(R4)
(R4)
(R4)
This is followed by a data header comment line and then data for all _nosch schedules.
For each schedule the first data line includes:
nr // schedule number (IX); in order from 1 to _nosch
npts // number of points (I2)
u_XYZ // units of location coordinates (I2)
name[] // schedule name (I1) {W}
283
285
286
PROGRAM EXECUTION
In order to activate the socket communication capabilities of ContamX, the program must
be run with the following command line structure.
contamx3 <project> b [-wp][-vf] <address> : <port>
After ContamX starts, it will attempt to make contact with the controlling application and
establish a socket connection. Once a connection has been established, ContamX will
send the project information messages (types 1 13) to the server to provide information
on the contents of the project file. These project information messages will be sent in
numerical order. ContamX will then perform the steady state initialization calculation and
send all of the simulation result messages (_UPDATE_MSGTYPE) followed by the
CX_READY_MSGTYPE. At this point the server can begin interacting with ContamX in
the bridge mode via the execution control and project modification messages detailed
below. ContamX will respond with the requested _UPDATE_MSGTYPE messages and
indicate when it is ready to receive more messages by sending the
CX_READY_MSGTYPE message.
287
288
110
120
130
140
150
160
BLDG_INFO_MSGTYPE
Provides the name of the CONTAM project file.
Message Header;
char* building_name; // CONTAM project file name without .PRJ extension
SIMPARM_INFO_MSGTYPE
Provides simulation control parameters.
Message Header;
int date0; // simulation start date
int date1; // simulation end date
int time0; // simulation start time
int time1; // simulation end time
int timestep; // simulation time step [s]
AGENT_INFO_MSGTYPE
Provides information related to the contaminants, i.e., only those species that are being
used in the simulation.
Message Header;
int num_agents; // number of contaminants in the PRJ file
int id[num_agents]; // index of contaminants according to ContamX
char *name[num_agents]; // contaminant names (null-terminated strings)
ELEMENT_INFO_MSGTYPE
Provides a list of airflow elements in the order in which they occur in the project file.
This provides the ability to change the airflow element, via the
289
INPUT_CTRL_INFO_MSGTYPE
Provides number of control input nodes and the initial value of each node at the start of
the simulation. Control input nodes are defined via ContamW by providing Constant
type control nodes with a name. The values of these control nodes can be modified during
simulation via the Control Input Message.
Message Header;
int num_nodes; // number of control input nodes in the PRJ file
int id[num_nodes]; // index of control nodes according to ContamX
float init_vals[num_nodes]; // initial values of control input nodes
char* name[num_nodes]; // input node names (null-terminated strings)
OUTPUT_CTRL_INFO_MSGTYPE
Provides initial values of control output nodes at the start of the simulation. Control
output nodes are defined via ContamW by providing Signal Split type control nodes with
a name. Values can be obtained during simulation via the
CTRL_NODE_UPDATE_MSGTYPE.
Message Header;
int num_nodes; // number of control output nodes in the PRJ file
int id[num_nodes]; // index of control nodes according to ContamX
float init_vals[num_nodes]; // initial values of control input nodes
char* name[num_nodes]; // output node names (null-terminated strings)
AHSP_INFO_MSGTYPE
Provides information related to simple air handling system airflow paths. AHS paths
include return, supply and implicit airflow paths (recirculation, outdoor air and exhaust)
of simple air handling systems. Supply and return airflow paths will come before all of
the implicit airflow paths which will come in groups of three: recirculation, outdoor air
and exhaust flow paths for each air handler. This is apparent when viewing the ContamW
airflow plotting dialog box. The id[] array provides the order in which airflows will be
provided by ContamX via the AHSP_FLOW_UPDATE_MSGTYPE. If the
ambient_index is 0, the path is not a building envelope path. Otherwise, the
ambient_index specifies the order in which path concentrations are to be sent using the
ADJ_WPC_MSGTYPE. Only implicit outdoor air intake paths can be considered envelope
paths.
Message Header;
int num_ahsp; // number of AHS airflow paths in the PRJ file
int id[num_ahsp]; // index of each AHS path according to ContamX
int ambient_flag[num_paths] // 0 = not connected to ambient
float x[num_paths]; // x coordinate [m]
float y[num_paths]; // y coordinate [m]
290
ZONE_INFO_MSGTYPE
Provides zone names in the order in which concentrations will be sent back by ContamX
via the CONC_UPDATE_MSGTYPE. This list of zone names includes those of the two
implicit zones (supply and return) of each simple air handling system.
Message Header;
int num_zones; // number of zones in the PRJ file
int level[num_zones]; // level number on which zone is located
char *name[num_zones]; // zone names (null-terminated strings)
PATH_INFO_MSGTYPE
Provides information related to "standard" airflow paths (as opposed to AHS paths). The
id[] array provides the order in which airflows will be provided by ContamX via the
PATH_FLOW_UPDATE_MSGTYPE. If the ambient_index is 0, the path is not an
envelope infiltration point. Otherwise, the ambient_index specifies the order in which
path concentrations are to be sent using the ADJ_WPC_MSGTYPE.
Message Header;
int num_paths; // number of airflow paths in the PRJ
int id[num_paths]; // index according to ContamX
int ambient_index[num_paths] // 0 = not connected to ambient
int element_index[num_paths]; // index of initial airflow element
float x[num_paths]; // x coordinate [m]
float y[num_paths]; // y coordinate [m]
float z[num_paths]; // if ambient_index > 0 then absolute height, else
relative to level [m]
JCT_INFO_MSGTYPE
Provides the number of junctions and the type of each junction. The index of the
type[] array is used to set the temperature of the junctions via the
ADJ_JCT_TEMP_MSGTYPE.
Message Header;
int num_jcts; // number of junctions in the PRJ file
int type[num_jcts]; // junction type: 0=junction, 1=terminal
TERM_INFO_MSGTYPE
Provides information on those junctions that are terminal types. The id[] array provides
the order in which airflow rates will be provided by ContamX via
TERM_FLOW_UPDATE_MSGTYPE. If the ambient_index is 0, this terminal is not an
infiltration point. Otherwise, ambient_index specifies the order in which terminal
concentrations are to be sent to ContamX using ADJ_WPC_MSGTYPE.
Message Header;
int num_terms; // number of duct terminals in the PRJ
int id[num_terms]; // for each terminal: index according to ContamX
int ambient_index[num_terms] // for each terminal: 0/1 = not connected
/ connected to ambient
291
LEAK_INFO_MSGTYPE
Provides a list of only those duct junctions which have been defined via ContamW to
have leakage. The id[] array provides the order in which airflow rates will be provided
by ContamX via LEAK_FLOW_UPDATE_MSGTYPE. Currently leaks are not included
when using ADJ_WPC_MSGTYPE., so ambient_index will be zero for all leaks.
Message Header;
int num_leaks;
// number of junctions with leaks in the PRJ
int id[num_leaks]; // index according to ContamX
DUCT_INFO_MSGTYPE
Provides the number of duct segments that will correspond to the number of and the order
in which duct segment airflow rates will be sent by ContamX via
DUCT_FLOW_UPDATE_MSGTYPE.
Message Header;
int num_ducts; // number of duct segments in the PRJ file
int id[num_ducts]; // for each duct segment: index according to ContamX
CX_READY_MSGTYPE
This message will be sent by ContamX to indicate that it has entered the ready mode and
is prepared to receive messages through the bridge, i.e., in the ready mode. This will
occur for the first time after ContamX has finished sending all of the project information
messages, performed the steady state initialization calculation and sent all of the
simulation result messages (_UPDATE_MSGTYPE). It will be sent again after each
CX_ADVANCE_MSGTYPE has been handled and the simulation result messages have
been sent as requested via the option flag of CX_ADVANCE_MSGTYPE.
Message Header;
int time; // time in seconds at which ContamX performed its most recent
calculation
CX_ADVANCE_MSGTYPE
This message is received by ContamX at any time while in the ready mode to notify
ContamX to run until the simulation time specified in seconds. An option field is used to
indicate whether or not ContamX should send back concentration data in the
Concentration Update Message after it reaches the time specified.
Message Header;
int option; // bitwise flag controls which _UPDATE_MSGTYPES ContamX
will send once time has been reached
o
bit 1: iterative advance message (currently not used)
o
CX_ERROR_MSGTYPE
This message may be received by ContamX at any time while in the ready mode and
terminates execution of ContamX. This message is not required to terminate the program
if it is allowed to run until the end of a simulation as determined by the simulation stop
time in the PRJ file.
Message Header;
char error_type; // 0 = terminate ContamX
ADJ_ZONE_CONC_MSGTYPE
This message may be received by ContamX at any time while in the ready mode.
Contaminant concentrations or masses should be sent in order of zones specified in the
list of zone_ids. Each message can be used to set the concentration/mass of multiple
zones, but when dealing with multiple agents, a separate message must be sent for each
agent. The zone and agent ids used here are those provided by AGENT_INFO_MSGTYPE
and ZONE_INFO_MSGTYPE respectively.
Message Header;
int option; // 0 = add mass [kg], 1 = set concentration [kg/kg]
int num_zones; // number of zones to set
int agent_id; // contaminant index
int zone_ids[num_zones]; // list of zone indexes
float values[num_zones]; // list of masses or- concentrations
ADJ_ZONE_TEMP_MSGTYPE
This message may be received by ContamX at any time while in the ready mode. Each
message can be used to set the temperature of multiple zones. The ids used here are those
provided by ZONE_INFO_MSGTYPE.
Message Header;
int num_zones; // number of zones to set
int id[num_zones]; // list of zone indexes
float value[num_zones]; // temperatures [K]
ADJ_ELEMENT_MSGTYPE
This message can be received by ContamX at any time while in the ready mode. It is used
to change the airflow element of an airflow path from one element to another. This could
be useful, for example, to change a closed door element to a two-way open door element.
Message Header;
int path_id; // id of air flow path
int element_index; // index of the new element the path is to reference
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ADJ_CONTROL_NODE_MSGTYPE
This message can be received by ContamX at any time while in the ready mode. It is used
to set the value of a Constant (Set type, CT_SET) control node where node_id is the
identifier assigned to the control node by ContamX and provided by
INPUT_CTRL_INFO_MSGTYPE. Note that the node_id will not likely correspond to
the control node number shown on the ContamW SketchPad for the corresponding
control icon. However, node names are provided by INPUT_CTRL_INFO_MSGTYPE.
Message Header;
int node_id; // id of the control node
float value; // value to which node should be changed
ADJ_WTH_MSGTYPE
This message may be received by ContamX at any time while in the ready mode. Each
message can be used to set the weather conditions which include temperature, barometric
pressure, wind speed, and wind direction. See the Program Execution section for
information related to the use of this message.
Message Header;
float temperature; // ambient dry bulb temperature [K]
float pressure; // atmospheric pressure at PRJ reference height [Pa]
float wind speed; // wind speed [m/s]
float wind direction; // direction from which wind is blowing [degrees]
ADJ_WPC_MSGTYPE
This message can be received by ContamX at any time while in the ready mode. It may
be used to set either the ambient concentrations or pressures at envelope airflow paths
(including outdoor air intakes of simple air handling systems) and duct terminals.
Concentrations for paths are transmitted in the order specified by the ambient indexes
provided by PATH_INFO_MSGTYPE followed by those of terminals as specified by the
TERM_INFO_MSGTYPE. If multiple agents need to be transmitted, the order is:
[all
...
[all
[all
...
[all
[all
...
[all
If num_agents is 0, then instead of concentrations, the message should provide one set
of pressures corresponding to the pressures at the envelope locations. Currently pressures
must conform to the 2.1 format of the WPC file as specified in the WPC File Format
section of the documentation.
Message Header;
int time; // simulation time at which to apply data
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CONC_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received and
ContamX has advanced to the time indicated. ContamX will only send this message if the
associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set.
Values are sent in the order provided by ZONE_INFO_MSGTYPE.
Message Header;
int time; // simulation time to which data corresponds [s]
int agent_id; // contaminant index of agent being updated
float concentrations[num_zones]; // contaminant concentrations [kg/kg]
PATH_FLOW_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received and
ContamX has advanced to the time indicated. ContamX will only send this message if the
associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set. Each
path has two flow rates associated with it (flow0, flow1) to handle two-way airflow
elements. flow0 and flow1 are sent consecutively for each path in the order provided by
PATH_INFO_MSGTYPE. See the Program Execution section for information related to
the units utilized by this message.
Message Header;
int time; // simulation time to which data corresponds [s]
float value[num_paths * 2]; // airflow rate for each airflow path
[kg/s] or [m3/s]
TERM_FLOW_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received and
ContamX has advanced to the time indicated. ContamX will only send this message if the
associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set.
Values are sent in the order provided by TERM_INFO_MSGTYPE. See the Program
Execution section for information related to the units utilized by this message.
Message Header;
int time; // simulation time to which data corresponds [s]
float value[num_terms]; // airflow rate for each duct terminal [kg/s]
or [m3/s]
AHSP_FLOW_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received and
ContamX has advanced to the time indicated. ContamX will only send this message if the
associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set.
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Values are sent in the order provided by AHSP_INFO_MSGTYPE. See the Program
Execution section for information related to the units utilized by this message.
Message Header;
int time; // simulation time to which data corresponds [s]
float value[num_ahsp]; // airflow rate for each simple air handler path
[kg/s] or [m3/s]
DUCT_FLOW_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received and
ContamX has advanced to the time indicated. ContamX will only send this message if the
associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set.
Values are sent in the order provided by DUCT_INFO_MSGTYPE. See the Program
Execution section for information related to the units utilized by this message.
Message Header;
int time; // simulation time to which data corresponds [s]
float values[num_ducts]; // airflow rate for each duct segment [kg/s]
or [m3/s]
LEAK_FLOW_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received and
ContamX has advanced to the time indicated. ContamX will only send this message if the
associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set.
Values are sent in the order provided by LEAK_INFO_MSGTYPE. See the Program
Execution section for information related to the units utilized by this message.
Message Header;
int time; // simulation time to which data corresponds [s]
float values[num_leaks]; // airflow rate for each duct leak [kg/s] or
[m3/s]
CTRL_NODE_UPDATE_MSGTYPE
This message may be sent by ContamX after CX_ADVANCE_MSGTYPE is received
and ContamX has advanced to the time indicated. ContamX will only send this message
if the associated bit of the option flag of the previous CX_ADVANCE_MSGTYPE is set.
Values are sent in the order provided by OUTPUT_CTRL_INFO_MSGTYPE. Units
depend on the control network.
Message Header;
int time; // simulation time to which data corresponds [s]
float values[num_outnodes]; // value of each control output node [-]
296