Double Skin Façades More Is Less?

DOUBLE SKIN FAADES
MORE IS LESS?
Lead Author: Brett Pollard, BLArch, BArch

Contributing Author: Mary Beatty, BS, BDes Arch
HASSELL
Level 2, 88 Cumberland Street
Sydney, NSW, 2000, Australia
bpollard@hassell.com.au
ABSTRACT
The term double skin faade covers a wide range of faade systems and types from
narrow fully sealed assemblies to systems with fully operable external louvers or
shading devices. All of them have one thing in common, the outer and usually the inner
skin is highly glazed. The use of double skin faades has increased significantly over
the last 10 to 15 years, primarily due to the benefits attributed to them in regard to
increased energy efficiency and improved day lighting.
There remains debate, however, about whether these benefits would be more effectively
provided by a well designed, traditional, single skin faade system. Indeed a German
study from 1999 1 concluded that It becomes apparent that DSFs (Double Skin
Facades) - apart from special cases - are unsuitable for our local climate (German) from
the building physic's point of view. Moreover, they are much too expensive. If they are
nevertheless designed in order to keep up with architectural fashion, building physics
support is indispensable.
This paper will survey the various types of double skin facades systems, exploring their
features and functioning followed by a review of examples, both constructed and
proposed, from North America and Australia. The paper will then assess and analyse
recent research and examples to attempt to reach a conclusion as to whether with a
double skin faade, more really is less.
from a paper written by Dr Karl Gertis, director of the Fraunhofer Institute of Building Physics in
Stuttgart, Germany. The paper is called "Sind neuere Fassadenentwicklungen bauphysikalisch sinnvoll?
Teil 2: Glas-Doppelfassaden (GDF)" published by Ernst & Sohn Bauphysik 21 (1999), Heft. A
summary of the paper in English was obtained from http://gaia.lbl.gov/hpbf/perfor_c.htm
ISES-AP - 3rd International Solar Energy Society Conference Asia Pacific Region (ISES-AP-08)
Incorporating the 46th ANZSES Conference
25-28 November 2008 Sydney Convention & Exhibition Centre
B.Pollard, M.Beatty
ATTRIBUTED BENEFITS
The primary benefits attributed to DSF are their ability to save energy and permit day
lighting of the internal spaces of the building. In regard to the reduction in energy use,
DSF are credited with the ability to mitigate the impact of the prevailing climatic and
environmental conditions on the interior of a building, allowing a reduction in the size,
extent and operation of a buildings Heating, Ventilation and Air Conditioning (HVAC)
systems. In some cases DSF have been credited with eliminating the need for air
conditioning altogether. Battle McCarthy, a United Kingdom based engineering and
landscape architectural practice, state on their website that . double skin buildings
are able to reduce energy consumption by 65%, running costs by 65% and cut CO2
emissions by 50%, in the cold temperate climatic prevalent in the United Kingdom
when compared to advanced single skin building.
Specifically, DSF are reported as achieving reductions in energy use by;
Reducing heating demand. DSF achieve this in a number of ways. Firstly, the cavity
between the inner and outer skin forms an additional layer of insulation to the building,
preventing heat loss. Secondly, warm air in the cavity can be used to preheat fresh air
being introduced into the building for ventilation. Thirdly, extensive glazing allows
sunlight to be used for passive heating of the interior of the building.
Controlling solar gain. In warmer months and climates, the cooling demand can be very
high due to solar gain through windows and the fabric of buildings. DSF can reduce the
impact of this solar gain by allowing shading devices to be installed in the cavity
between the two skins, preventing sunlight from reaching the inner skin. The shading
devices are normally adjustable to ensure that views through the highly glazed faade
are retained as much as possible. Warm air trapped within the cavity can be expelled by
natural and/or mechanical ventilation to prevent it from heating up the interior of the
building. The cavity protects the shading devices from rain and wind, especially on tall
buildings, as well as providing access for maintenance of these devices.
Allowing natural ventilation. Natural ventilation provided by operable windows in the
inner skin is believed to significantly reduce the load on the HVAC system by providing
fresh air and cooling comfort for the occupants of a building. DSF can allow for natural
ventilation even in high rise buildings by providing protection for windows in the inner
skin from wind and weather. DSFs can also be used for passive night time cooling of a
buildings structure, and a stack effect can be created within the cavity to improve cross
ventilation and purge hot air from the building.
Increased access to daylight due to DSF is a direct result of the high levels of glazing in
the skins. The specific benefits of daylight are;
Reduced artificial lighting requirement. Daylight can significantly reduce the
requirement for artificial lighting within a building. Daylight can potentially become the
major source of lighting for the perimeter of the building with artificial lighting only
being required when the sun is not shining. This results in reduced electricity demand
and therefore saves energy.
B.Pollard, M.Beatty
Improved occupant comfort. Access to daylight is seen as an important component of

occupant comfort and is believed to contribute to improved productivity, reduced eye
strain and reduced stress levels.
In addition to these two primary benefits, there are a number of other benefits ascribed
to DSF including:
Acoustic protection. DSF have been used to provide acoustic protection for buildings
located near roads and railway lines. In theory, the outer skin provides a barrier to noise
while allowing windows in the inner skin to be opened for natural ventilation.
Views. As buildings with DSFs generally have highly glazed facades, the occupants to
have increased access to views which is believed to improve wellbeing through greater
connection with the outside world and reduced eyestrain.
Enhanced security. DSF are said to improve security due to the presence of an
additional layer of building fabric that can impede illegal entry through the faade of the
building. The outer skin can also allow internal windows to be opened for natural
ventilation in high security buildings or at night when the building is unoccupied while
maintaining perimeter security. The outer skin can also be reinforced or armoured to
provide additional protection.
Futureproofing and increased building lifespan. This results from having a fully glazed
faade with a high degree of environmental control for the perimeter zone. In theory,
this allows enhanced flexibility in the arrangement of furniture and spaces within the
building as there are no blank walls or other impediments. Therefore the building can
accommodate future needs without extensive renovations or demolition.
Pollution barrier. In much the same way as the acoustic and security protection, DSF are
claimed to allow natural ventilation in polluted locations with the outer skin screening
pollutants permitting windows in the inner skin to be opened.
Emergency egress. If maintenance walkways are present in the cavity between the two
skins they can be, according to some authors, integrated into the emergency egress
paths.
Until recently double skin facades have been used as an energy saving strategy
predominantly in colder climates of Europe and North America. In recent years they
have begun to be used on buildings in warmer climates such as Australia however
research for this paper indicates that they are being used for differently in warmer
climates. In the Australian buildings researched, the external faade is primarily used to
reduce energy consumption and improve occupant comfort by reducing solar gain to the
building though the use of louvers or blinds located in the cavity and operable windows
on the internal skin to allow for natural ventilation. Another difference is that, unlike in
colder climates where air in the sealed cavity is intended to be warmed by the sun or
artificially to reduce load on the artificial heating systems, the cavities in Australian
double skin facades are more commonly designed to be well ventilated to allow warm
air to escape by creating a stack effect, thus reducing the cooling load on the buildings.
B.Pollard, M.Beatty
DOUBLE SKIN FAADE TYPES
There is no accepted standard for grouping or defining the different types of DSF. The
literature reviewed for this report found a multitude of ways to classify them. For
example, Harris Poirazis in his comprehensive review of DSF found more than six
different ways of classifying them. Bestfacade, a European Union project set up to
review and put in place best practice guidelines for DSF, has developed a classification
system for DSF based on their own extensive review of the literature and built
examples. Their system is based on three sets of criteria: the type of ventilation, the
ventilation mode of the cavity and the partitioning of the cavity. While extremely
comprehensive this system does allow for a large number of potential system variations
and too many to describe and provide examples of in this report.
Fig. 1: Bestfacade DSF Classification Diagram (VDF = DSF)

WP1 Report
Source: Bestfacade
In 2000, Lang and Herzog defined three basic types of DSF. This classification has been
adapted and developed by Terri Boake of the University of Waterloos School of
Architecture. While relatively basic, it does allow for easy understanding of the
different DSF types and was considered the most suitable classification system for this
report. The different types of DSF are:
the Buffer;
the Extract Air;
the Twin Face; and
the Hybrid System
In addition to these 4 basic types there is one additional distinction between DSF,
whether the cavity is continuous or divided into compartments, usually on a floor by
floor basis.
B.Pollard, M.Beatty
Buffer Double Skin Facade
As the name suggests this type of DSF provides a buffer between the external
conditions and the interior of the building. The cavity essentially functions as an
insulating layer with the added benefit that any heat that builds up in the cavity can be
expelled in the warmer months, usually by natural ventilation created by the stack
effect. It is suggested by Lang and Herzog that both skins of buffer facades are
typically single glazed but it has become more common for the outer skin to be single
glazed and the inner skin to have double glazed insulating panes installed. Automatic
blinds are usually installed within the cavity to reduce solar gain in summer. It is typical
for this type of DSF to run continuously for the full height to the faade with the only
interruptions being perforated or grid mesh access ways for maintaining the glass. If
narrow cavities are used, maintenance access is usually provided by making the internal
glazing operable. The disadvantage of this is the disruption that can occur when access
is required.
There are no openings in the internal skin and none in the external skin apart from
ventilation inlets at the base of the DSF and outlets at the top. Typically the ventilation
inlets are controlled by automatic dampers and exhaust fans can be installed to assist
with removal of the heated air from the cavity. There is no natural ventilation of the
interior of the building through the DSF and the buildings HVAC system is completely
separate from the DSF. However, some buildings have reclaimed the heat that is
expelled at the top of the DSF and reused it in the HVAC system.
Fig. 2: Buffer DSF
Figs. 3 & 4: Business Promotion Centre Germany
Source: Boake UW
Source: www.fosterandpartners.com
B.Pollard, M.Beatty
Extract Air Double Skin Facade
Extract Air DSF use the cavity between the two skins as an exhaust path for the return
air from the HVAC system. This allows the heat of the return air to warm the cavity
space and enhance its insulating effect. The exhaust air is expelled at the top of the
DSF, usually after the heat has been extracted for reuse in the HVAC system. In the
warmer months heat gain is moderated by the continuous extraction of the return air and
the heated air from the cavity. Additional outside air can be introduced at the base of the
DSF, if required. Solar gain to the interior of the building can be further reduced by
using shading devices mounted in the cavity. This system uses a single layer of glass in
the outer skin and double glazing for the inner skin.
As the cavity is effectively acting as duct, it tends to run continuously up the faade of
the building. The width of the cavity can be narrow or wide with similar access
provision as for the Buffer Faade type.
This type of DSF is reliant upon a buildings HVAC system and so can use more energy
than DSF that use natural ventilation during benign climatic times of the year. Although
not stated in the literature reviewed, it may be possible to use the stack effect created in
DSF to extract air from the buildings interior without use of the HVAC System
Fig. 5: Extract Air DSF
Figs. 6 & 7: Brogebude Felbermayr, Salzburg, Austria.
Source: T Boake UW
Source: www.architecten.at
B.Pollard, M.Beatty
Twin Face Double Skin Facade
These types of DSF are categorized by having two skins that are able to be opened to
permit natural ventilation of both the cavity and the buildings interior. Typically the
outer skin is single glazed and the inner skin is double glazed and contains the water, air
and vapor barriers for the building. The extent of openings in the skins can vary
significantly depending on the ventilation strategy to be employed. The outer skin can
act as a wind shield to allow the windows in the internal skin to be opened to permit
ventilation and/or night cooling of the buildings interior regardless of the wind
conditions or height of the building. If the DSF is required to assist with insulation
against the cold, the openings can be closed to make it act like a Buffer DSF. As the
range of potential options with this DSF is large, the cavities can be narrow or wide,
continuous or compartmentalized. Shading devices can also be installed within the
cavity.
The advantage of this DSF over the other two is that it is able to more easily discharge
the heat that can build up at the top of the cavity. However, if effective sealing of the
outer skin cant be achieved it may not function as well as, say a Buffer DSF, in the
colder months. Therefore this DSF tends to be built in locations without an extensive
and prolonged heating requirement unless the insulating performance of the inner skin
increased.
Fig. 8: Twin Face DSF
Figs. 9 & 10: Daimler Benz (Debis) Building, Berlin
Source: T Boake UW
Source: www.coltinfo.net
Source: www.rpbw.com
B.Pollard, M.Beatty
Hybrid Double Skin Facade
Hybrid DSFs can be a combination of, or variation on, any of the previous three DSF
types. The faade of the New York Times building, while not strictly a DSF, can be
seen as a variation of the DSF. This is on the basis that an additional layer (skin) has
been added to what is essentially a fully glazed building. Here, a layer of carefully
spaced ceramic rods have been positioned off the glazed facade to reduce solar heat
gain and glare while still admitting daylight to the interior of the building. The design
goal was to reduce the energy consumption of both the HVAC and lighting systems of
the building. Extensive studies were undertaken by the consultant team in partnership
with the Environmental Energy Technologies Division (EETD) of the Lawrence
Berkeley National Laboratory to develop both the external skin and the automated
internal blinds that make up the other half of the daylight control system. The project
has only been recently completed and will be studied by EETD to determine whether
the predicted $20,000/floor/year energy savings are achieved.
Fig. 10: New York Times Building
Fig 11: Detail of ceramic shading elements
Source:www.brianrose.com
Source: architecture.com/MID
B.Pollard, M.Beatty
DESIGN CONSIDERATIONS
As with all building systems and technologies there are a number of additional
considerations that need to be addressed other than just benefits and system functioning.
The design of DSF requires that the following issues are taken into account;
Floor area. If a building needs to use all of the available site area, for example if the site
is in an inner city location, the cavity required for the DSF can reduce the available
floor area for occupation or leasing by the owner. Alternatively, if a site is not as
constrained, the DSF cavity can lead to increased floor area and therefore increased
impact on the site.
Floor plan shape. The prevailing climatic and solar conditions primarily impact upon
the interior spaces that are located directly adjacent to the windowed facades of a
building. These spaces are commonly known as the perimeter zone and typically extend
3.5 to 4.5 meters into the building. The heating and/or cooling loads present in the
perimeter zone tend to be high but vary depending on the time of day and year. If a
building directly abuts another building or has a windowless faade, the outside
conditions have far less or no influence on the adjacent spaces. These spaces as well as
the spaces that are located away from the edge of the building are known as the centre
zone. The heating and/or cooling loads in the centre zone are relatively stable and tend
to be much lower than the perimeter zone. However, this is dependant on the type of
plant, equipment, computers, lighting and occupants located in the centre zone.
The ratio of perimeter zone floor area to centre zone floor area can affect the degree to
which external conditions influence the design and size of a buildings HVAC system
and therefore the contribution that a DSF can make to reducing HVAC energy
requirements. If a floor plan is long and narrow, the ratio of perimeter zone to centre
zone will be high and therefore the HVAC system will need to focus on the external
conditions. If the DSF can mitigate the external heating and cooling loads the capacity
or length of time the HVAC is required to run can be reduced. However, if a floor plan
is squarer, the ratio will be lower and so will be the potential contribution of DSF to
reducing overall HVAC energy use. Similarly if a building abuts others, has only one
glazed faade or limited amounts of glazing the potential benefits of a DSF will be
lower than on a building with a large amount of glazing.
Heat build up in cavity. The upper sections of a continuous DSF cavity can become quite
hot and cause overheating in the adjacent internal spaces even in the cooler months. The
DSF needs to be designed to address this potential heat build up by either providing
additional air extraction or another means to allow the heat to escape.
Glare control. As DSF are usually highly glazed, the issue of glare within and around
the building needs to be addressed. Daylight controls such as internal blinds and screens
will be required as well as consideration given to the placement and orientation of work
spaces to ensure that glare from the daylight doesnt adversely impact on the building
occupants. Similarly, potential outward reflections need to be addressed by either the
use of special coatings or films and/or careful orientation and positioning of glazing
relative to sun angles.
B.Pollard, M.Beatty
Additional faade cost. There is usually additional capital cost associated with DSF as
an additional faade(s) is required. A 2003 report by Stribling and Stigge put the
additional cost of a DSF in the United States at approximately 50% more than a
comparable single skin faade.
Maintenance requirements. DSF, especially wide cavity types, can have much higher
maintenance requirements than single skin faade. This is because there are four glass
surfaces that may require cleaning. Ventilation of the cavity also needs to be adequate
to prevent condensation and the need for additional cleaning. While maintenance
walkways can be provided within the cavity to clean the glass and maintain blinds,
access to the outer face of the glass is required, with this normally being provided by
another separate access system.
Smoke management impact. DSF can impact on the smoke management system of a
building in a number of ways. DSF make it difficult to use the faade of building to
expel smoke as the cavity will fill with smoke and may spread to other floors if their
windows are open. This can certainly occur with single facade buildings but the
situation is exacerbated in DSF buildings because the smoke is unable to be dispersed
by wind. Using the cavity of a Extract Air DSF as a smoke exhaust duct or path would
require significant fire engineering input.
Fire protection. The potential for fire spread also needs to be addressed as sprinklers
may be required within the cavity where building codes require spandrels constructed
from fire resistant materials.
CLIMACTIC STABILITY
The vast majority of DSF have been constructed in Europe, especially northern Europe,
primarily because of their high heating requirements, the high cost of energy and the
desire for increased natural light. Increasingly, examples are appearing in benign
climates were the heating requirements are not as great.
So what about hot climates? It is apparent from a review of literature on building
energy use that the biggest potential reduction in energy use can occur in buildings
located in more extreme climates (ie very cold or very hot)? Buildings in hot climates
can have very high external heat loads to deal with for all or part of year. Traditional
building techniques usually addressed this by using passive or low energy techniques
such as shading and fans to provide comfort cooling. However, the nature of modern
buildings and changed user expectations can make it difficult to implement these
strategies in office and other large buildings. The high external loads coupled with high
internal loads from computers and lighting necessitates the use of HVAC systems to
provide cooling for all or a significant portion of the year.
The use of DSF in hot climates is not nearly as extensive, with far fewer having been
constructed and reported on than in the colder areas. Of the literature found for this
report few studies and reports related to DSFs in hot climates. Hesse and Amato (2006)
have reported on the DSF that they have analysed in Hong Kong and have concluded
that ventilated Buffer DSF offer the best ability to reduce external heat loads for
buildings with HVAC system. They did not report on whether DSF have been used for
natural ventilation of interior spaces of buildings.
10
B.Pollard, M.Beatty
A Masters thesis written in 2004 by Vijaya Yellamraju investigated the suitability of
using of DSF on office buildings in India. The report was based upon building energy
simulation of theoretical buildings located in Hyderabad and New Delhi. Various
arrangements of the DSF were modelled to find the optimal solution. Unsurprisingly,
the report found that on some faces there was extensive heat build up in the cavity and
that this led to increased heat loads within the building. It did find that loads could be
slightly reduced with shading and increased ventilation of the cavity. The report
recommended that the best performing system decreased the amount of glazing to about
50% of the faade and introducing masonry for the remainder. Interestingly the cavity
of the masonry was modelled to match the cavity of the DSF which effectively made the
glazed sections of the DSF triple glazed widows
11
B.Pollard, M.Beatty
NORTH AMERICAN EXAMPLES OF DOUBLE SKIN FACADES
Museum of Contemporary Art Denver
Location:
Denver, Colorado, United States
Date:
2007
Area:
2,500 m2 (27,000 sq.ft)
Hygrothermal Zone: Cold

DSF Type:
Extract Air/ Continuous (TBC)
Architect:
Adjaye Associates & Davis Partnership Architects
Energy Analysis:
Enermodal Engineering
Description:
Approximately 50% of the faade of this newly completed building is a DSF. It

comprises an outer double glazed insulated curtain wall and an inner skin of translucent
MonoPan, which is a sandwich panel comprising a core of honeycomb polypropylene
faced with fiberglass reinforced polypropylene. The cavity between the two skins is
used as an exhaust path for internal air. Enermodal Engineering reported that the
majority of the predicted 36% energy savings were due to the design of the mechanical
systems and that the DSF functioned as well as a good double glazed insulated faade.
They also reported that the introduction of ventilation through the DSF only reduced the
heating and cooling loads by an additional 1-2%. No information could be found about
the construction of the DSF or its detailed functioning.
Fig. 12: View of 15Th and Delgany Street Facades

source: www.wallpaper.com & Ed Reeve
12
B.Pollard, M.Beatty
Seattle Justice Centre
Location:
Seattle, Washington, United States
Date:
2002
Area:
26,750 m2 (288,000 sq.ft)
Hygrothermal Zone: Marine

DSF Type:
Buffer/Continuous
Architect:
NBBJ, Seattle
M & E Engineer:
CDI Engineers
Energy Analysis:
Arup
Description:
This DSF forms the main South-Western (5th Avenue) faade of the Seattle Justice
Centre. The DSF is 9 levels high and the width of the cavity between the inner and outer
skins is 750mm (30inch). The outer skin is a single glazed curtain wall, the inner skin
has double glazed insulated low-e panes and both skins use clear glass. Automatic semi
transparent blinds are located within the cavity and fixed aluminium walkways are
provided for maintenance. Operable louvers are located at the top and bottom of the
cavity to adjust the air flow through the cavity. It is apparent from a review of the
available literature that the energy efficiency benefits of the DSF are limited due to it
being located on only one faade, the closed nature of the court rooms beyond and the
relatively benign nature of the climate. There have also been reports of glare issues
from the increased day lighting.
Fig. 13: Seattle Justice Centre - 5th Ave
Fig. 14 Detail view of DSF cavity
Source: author
Source:http://leedcasestudies.usgbc.org
13
B.Pollard, M.Beatty
Telus Building
Location:
Vancouver, British Columbia, Canada
Date:
2000
Area (gross):
12,000 m2 (129,800 sq.ft)
Hygrothermal Zone: Marine

DSF Type:
Twin Face/Continuous
Architect:
Busby & Associates (now Busby Perkins + Will)
Mech Engineer:
KEEN Engineering
Description:
This DSF is a retrofit over the face of an existing building. The outer skin is double
glazed with bands of clear and fritted glass while the inner skin is the existing concrete
and masonry structure with single glazed windows placed in the existing window
openings. The cavity is 900mm wide. The windows of the inner skin are opened
manually and the external windows are remote controlled. Ventilation to the cavity is
controlled by dampers as well by the external windows. Solar powered fans at the top
of the cavity assist with ventilation when required. It is reported that the whole building
was designed to use 30% less energy than one designed to ASRHAE 90.1 -1989.
However, no detailed information could be found that assessed the actual energy
benefits of this faade. It should be noted that the local authority agreed to allow the
DSF to be built over the footpath on the proviso that it would be removed if required.
Fig. 15 Telus Building faade
Fig. 16: Telus Building diagram
Source: www.architecture.uwaterloo.ca
Source: www.architecture.uwaterloo.ca
14
B.Pollard, M.Beatty
Biomedical Science Research Building, University of Michigan
Location:
Ann Arbor, Michigan, United States
Date:
2006
Area (gross):
40,400 m2 (435,000 sq.ft)
Hygrothermal Zone: Cold

Architect:
Polshek Partnership
DSF Type:
Buffer/Continuous
M & E Engineer:
Baro Roa + Athanas
Sustainability:
Buro Happold
DSF Modeling:
Mojyaba Navvab University of Michigan
Description:
The extensive DSF covered almost the entire southern faade of this research laboratory
and office building. The outer skin is a single glazed unitized curtain walls while the
inner skin has double glazed insulated panes. The cavity is approximately 900mm (36
inches) wide and 4 floors in height. Ventilation is provided at the top and bottom of the
DSF. Blinds are provided within the cavity as is a track mounted window cleaning
frame. The faade was subjected to extensive modelling and testing by a team from the
University of Michigan. This included construction of a full scale mock up of one floor
of the faade. The DSF is reported by the team to have made a significant contribution
in reducing the heating and cooling loads on the building. It appears from the literature
that at one stage a floor by floor DSF ventilation strategy was being considered but a
continuous DSF was constructed.
Fig. 17 Southern Elevation showing DSF

Source:http://uuis.umich.edu/cic/buildingproject/images/bsrb.jpg
15
B.Pollard, M.Beatty
AUSTRALIAN EXAMPLES OF DOUBLE SKIN FACADES
Aurora Place/Macquarie Apartments
Location:
Sydney, Australia
Date:
2005
Area:
4,262 m2
BCA Climate Zone: 5

DSF Type:
Twin Face
Architect:
Renzo Piano Building Workshop
Description:
A version of the Twin Face DSF has been used in Sydney, Australia by the Renzo Piano
Building Workshop (RPBW) for the eastern faade of the Aurora Place/ Macquarie
Apartments building. Here, the cavity of the DSF is very wide and compartmentalized
both horizontally and vertically with the cavity acting as the balcony for each
apartment. The outer face is a fully louvered glass wall and is capable of being almost
completely open to allow heat to escape and breezes to enter. Blinds are also provided
to allow for shading and glare control. The inner skin is made up of glazed sliding
windows to the apartment. The success of the DSF in reducing heat gain and energy
use is not known at the time of writing, but use of a highly glazed facades was dictated
because of the extensive harbour views to the east of the building. This faade is a
development of RBPWs Daimler Benz (Debis) building in Berlin.
Fig. 18: Aurora Place/Macquarie Sydney
Fig 19: Detail view of louvres
Source: www.rpbw.com
Source: www.pushpullbar.com.au
16
B.Pollard, M.Beatty
University of Sydney Law School Building
Location:
Sydney, Australia
Date:
Due for completion early 2009
Area:
18,250m2
BCA Climate Zone: 5

DSF Type:
Twin Face/Buffer
Architect:
FJMT
Description:
The external skin consists of panels of glass, approximately 3.3m x 2.8m which extend
approximately 1 metre from the internal faade, are supported on stainless steel arms
fixed to the floor slab. The glass panels protect the timber louvres from UV radiation
and serve as a weather barrier to the internal "skins". The intermediate skin of
automated, vertically pivoting louvres sit approximately 600mm from the internal
faade and are designed to project the internal faade from solar heat gain. The internal
skin is not fully glazed, but consists of horizontally pivoting windows, which allow for
natural ventilation and hot air escape, positioned above perforated panels with acoustic
insulation in the lower part of the faade designed to absorb noise rising through the
cavity from below . The cavity between the facades is designed to function as a thermal
chimney with hot air from internal spaces being drawn up into the cavity and released.
The bottom of the cavity is open and the top of the cavity has automated louvres with
rain sensors to allow ventilation of the cavity in fine weather. In addition to the induced
natural ventilation, each office is fitted with an individual air conditioning unit. The
cost of this faade is in the order of 3-4 times the cost of a normal single skin faade.
Fig. 21: Eastern faade
Fig. 22: Detail view of facade
Source: www.usyd.edu.au
Source: www.usyd.edu.au
17
B.Pollard, M.Beatty
Design Hub, RMIT University (proposed)
Location:
Melbourne, Australia
Date:
Construction to commence in early 2009
Area:
11,000 m2
BCA Climate Zone: 6

DSF Type:
Hybrid
Architect:
Sean Godsell & Peddle Thorp Architects in association
ESD Consultants:
Cundall
Description:
The choice of a double skin faade for this building is a site and function specific
response and appears not to refer to the function of other double skin facade buildings
either overseas or in Australia. Rather than using the external skin to reduce solar gain,
this building uses it to actively capture the solar energy.
The external faade is a translucent smart skin made up of more than 16,000
sandblasted glass cells, some of which have photovoltaic collectors to harness solar
power. The cells track the sun via the building computer automation system to help
shade and power the building. The skin has been designed to be upgraded over time to
accommodate new solar technologies as they emerge. When it rains, the sandblasted
surface becomes transparent, adding a further dimension to the dynamic nature of the
faade.
The inner skin is a high-performance, double-glazed layer, which presumed to be fixed
as the information available states that users have the option of introducing filtered
fresh air through the floor to their work area. No information was provided about the
ventilation of the cavity.
Fig. 25: View of Proposed Faade
Fig. 26: Detail View
Source: www.rmit.edu.au
Source: www.rmit.edu.au
18
B.Pollard, M.Beatty
VS1 - South Australian Water Headquarters
Location:
Adelaide, South Australia
Date:
Due late 2008
Area:
35,000 m2
BCA Climate Zone: 5

DSF Type:
Hybrid
Architect:
HASSELL
ESD Consultants:
Cundall
Description:
This 10 story building in South Australia was designed to be the headquarters of South
Australia Water. Staff surveys provided the foundation for many aspects of the design
brief and included requirements for natural light for all, openness and transparency and
a minimum 5 Green Star rating (the building has achieved a 6 Star Green Star rating).
The building is located on a relatively narrow, deep site with an exposed western
faade. The building has high performance double glazing to the north, east and south
facades and a double skin faade comprised of clear double glazing and a fritted veil on
the western side to reduce solar loads while retaining access to daylight and views.
Spandrel panels on the east and west faade reduce the area of glazing and solar loads,
horizontal shading on the northern faade reduces solar load on the glazing in the
summer and vertical fins on the southern faade (with manual blinds) control glare in
the late afternoon. Automated blinds on the north, east and south faades help to reduce
any potential glare.
Fig. 27: View of Northern & Western Facades
Fig. 28 Section
Source: HASSELL
19
B.Pollard, M.Beatty
BUILDING SCIENCE LITERATURE REVIEW
It is important when trying to determine the worth of a building system to go beyond
architectural magazines, web sites and product brochures to see what is being reported
by building specialists and scientists. As previously mentioned, back in 1999 Dr Karl
Gertis was very unsupportive of DFS in contrast to Lang and Herzog who in 2000 were
much less dismissive, suggesting that the potential return in energy savings and
improved worker productivity could make the higher cost of DSF a worthwhile
investment. To try and determine what the current engineering and building science
opinion is of DSF more recent reports and conference papers were examined and the
findings are summarized below;
John Straube & Randy van Straaten - The Technical Merit of Double Facades for
Office Buildings in Cool Humid Climates, 2001 - These authors undertook a general
technical review of DSF to determine whether they reduced heating and cooling loads,
allowed for better natural ventilations and daylighting and helped to provide improve
external noise control. After examining each of the ascribed benefits and comparing the
technical performance of alternative industry standard solutions they concluded that
DSF are merely one approach to overcoming the large energy consumption and
comfort problems that are created by excessive glazing areas of inferior
performance..The most environmentally sound solution avoids the problems that
DFs (DFS) are intended to solve by reducing glazing area and increasing the quality of
the glazing product.
Dirk Saelens, Jan Carmeliet & Hugo Hens - Energy Performance Assessment of Multiple
Skin Facades, 2003 This study was based upon computer simulations of different DSF
strategies for a hypothetical single story building in Belgium. They concluded that in
order for a DSF to reduce heating and cooling loads that the shading systems and
functioning of the cavity air flow needed to be capable of adjustment via a
sophisticated control mechanism.
Nassim Safer, Monika Woloszyn & Jean Jacques Roux - Three-Dimensional Simulation
with A CFD Tool of the Phenomena in Single Floor Double Skin Faade Equipped With a
Venetian Blind, 2004 - This study was a detailed examination of the effects of placing
blinds at different points within the cavity of a double skin faade. While the study
concluded that the blind is most useful if located near the inner skin as the air velocities
in this position are less than in the outer and middle position. The writers then indicated
that more research was required for a more conclusive position to be arrived at.
Ian Doebber & Maurya McClintock - Analysis Process for Designing Double Skin Facades
and Associated Case Study, 2006 Both of these authors are employed by the respected
engineering firm Arup which has carried out the engineering for many DSF around the
world. Indeed at least one of the study authors is understood to have worked on the
design of the DSF for the Seattle Justice Centre. In this paper, the authors described the
analytical process and computer modelling that is used to design DSF. They concluded
the paper by saying that provided DSF were carefully designed and matched to the
correct climate that a DSF can allow full height glazing to be used and still achieve
occupant expectations.
20
B.Pollard, M.Beatty
Elisabeth Gratia & Andrea De Herde - Guidelines For Improving Natural Daytime
Ventilation In An Office Building with a Double Skin Faade, 2006 This Belgian study
originally written in 2004 was aimed at determining how best to cool a building with
natural ventilation with a DSF. The study was undertaken in the context that, as
Belgiums climate is relatively benign and modern office buildings in such climates are
more likely to require cooling rather than heating, that natural ventilation should be able
to play a role in reducing energy use. Through computer simulation the hypothetical
building was modelled with a DSF orientated in different direction relative to the sun
and prevailing winds. The study concluded that by using the stack effect, enhanced by
correct positioning to the prevailing winds to allow night cooling of the building by
natural ventilation, DSF could be a successful strategy. However they also stated that
much more modelling and research was required before this approach could be applied
to a real building.
Kurt Roth, Tyson Lawrence & James Brodrick- Emerging Technologies - Double Skin
Facades - 2007 In the October 2007 edition of the ASHREA Journal these authors
reported on their review of DSF from an North American context. They were very
scathing on the ability of DSF to deliver on their stated advantages without complex
control systems and decried the lack of actual building performance assessments. They
concluded that all the benefits of a DSF can be achieved more cost effectively by using
other building systems.
CONCLUSION
So what has this review and examination of DSF found? Well firstly there is a limited
amount of literature on this subject as many of the articles and reports reviewed for this
report all had similar reference lists. This gives weight to the various authors calls for
more research into DSF including the study and reporting on their actual performance in
a range of climates. It is only through new, detailed research and study that our
knowledge and understanding of DSF will develop.
In regard to some of the ascribed benefits such as pollution barriers, emergency egress,
acoustic protection and future proofing, the effectiveness of DSF are hard to prove.
Certainly with the acoustics benefits, the author has worked on several large
infrastructure projects which required acoustic barriers to be provided to reduce the
impact from traffic noise. In all cases careful attention had to be paid to provide a
complete, uninterrupted barrier to the noise otherwise the noise attenuation properties of
the barrier would be greatly reduced. In addition the reflection of noise had to be
avoided wherever possible as it could lead to significant noise impacts for surrounding
properties. Typically the noise barriers had to be positioned by canting the panels
slightly upwards or downwards or by installing perforated panels with a backing of
sound insulation to absorb the noise. None of the examples in the literature about DSF
used to provide acoustic protection appeared to successfully address all these issues.
As to whether the energy saving benefits attributed to DSFs are correct or not, it is
certainly the case that DSF can play a role to reducing heat loss where a faade is fully
glazed. However, well designed, high performance glazing such as double and triple
glazing can achieve similar results. Fully glazed faades can definitely provide an
abundance of daylight for some of the interior spaces of a building but can also bring
21
B.Pollard, M.Beatty
glare unless the daylight is carefully controlled and moderated. It is important that we
question the desire for all glass facades and select the most appropriate design strategy
for each situation.
In regard to hotter climates, the use of DSF can be more problematic due to the need to
reduce solar heat gain as well as providing cooling for the interior of buildings. Fully
glazed facades are probably the wrong design choice in such climates if the goal is to
save energy. The recently completed Council House 2, in Melbourne Australia took the
approach that each facade needs to be separately addressed and designed to deal with
the prevailing conditions rather than adopting a uniform approach and then applying it
to all four facades. One faade uses a hybrid DSF to shield the building from unwanted
solar gain, allowing views to be gained when shading is no longer required. As the
cavity is easily able to be naturally ventilated there is little or no heat build up. It is
these types of creative responses that take building technology, examine it, understand
it, adapt it and develop it, rather than blindly replicating it. This is how we will probably
see the greatest gains made in our quest for low or zero energy buildings.
REFERENCES
DOUBLE SKIN FACADES
Aarons D M M & Glicksman L R, Double Skin, Airflow Facades: Will the Popular
European Model Work in the USA?, Building Technology Program, MIT, from
www.tjju.com/ebook/doubleskin.pdf, 2000 Draft
Battle McCarthy, Double Skin Analysis www.battlemccarthy.com, June 2000.
Blomsterberg A (Ed.), Bestfacade: Best Practice for Double Skin Facades WP5 Best
Practice Guidelines, EIE/04/135/s07.38652, from www.bestfacade.com,
Boake, T M, The Tectonics Of The Double Skin: Green Building or Just More Hi-Tech
Hi Jinx? What are Double Skin Facades and How Do They Work?, ARCC/EAAE
International Conference on Architectural Research, Montreal, May 2002 from
www.architecture.uwaterloo.ca/faculty_projects/terri/pdf/tectonic.pdf 2002
Brock L, Designing the Exterior Wall An Architectural Guide to the Building
Envelope, John Wiley & Sons, Hoboken, New Jersey, 2005
Chen A, Back to the Times: Revisiting The New York Times Headquarters Building
Upon Its Completion, web article www.lbl.gov/Science-Articles/Archive/sabl
/2007/Oct/nytimes.html, 2007.
Doebber I & McClintock M, Analysis Process for Designing Double Skin Facades and
Associated Case Study, from http://gundog.lbl.gov/dirpubs/SB06/doebber.pdf, 2006
Gonchar J & Reina P, Glass Facades Go Beyond Skin Deep Designers Stress The
Importance of Integrating With Building Systems, Engineering News Record, 2 October
2003.
Gratia E & De Herde A, Guidelines For Improving Natural Daytime Ventilation In An
Office Building with a Double Skin Faade, Solar Energy 81 (2007) p435-448,
Elsevier, 2007
22
B.Pollard, M.Beatty
Harrison K, Tectonics Of The Environmental Skin, University of Waterloo School of
Architecture, from www.architecture.uwaterloo.ca/faculty_projects/terri/ds/ double.pdf,
200?
Hesse M & Amato A, Ventilated Faade Design In Hot And Humid Climate,
presentation to the Green Room, 2006
Lang W & Herzog T, Using Multiple Glass Skins To Clad Buildings: Theyre
Sophisticated, Energy-Efficient, And Often Sparking Beautiful, But Widely Used Only
In
Europe
At
Least
For
Now,
Architectural
Record
.
http://archrecord.constrcution.com/features/green/archives/0007edit-.asp, 2000.
McClintock, M, (Arup), Faade Solar Control Strategies, unpublished, 2006
Poirazis H, Double Skin Facades for Office Buildings Literature Review, Division of
Energy & Building, Department of Construction & Architecture, Lund Institute of
Technology, Lund University, Lund, Sweden, 2004
Potvin, A, Neutralizing the Canadian Climate The Double Facade System at the New
CDP Building in Montreal (Presentation), ASES - Solar 2007, Cleveland, July 2007.
OReilly, D, Dual Skins Designs Not Popular in Canadas Harsh Climate, Daily
Commercial News and Construction Record www.dcnonl.com, 2007
Roth K, Lawrence T & Brodrick J, Emerging Technologies - Double Skin Facades,
ASHREA Journal October 2007
Saelens D, Carmeliet J & Hens H, Energy Performance Assessment of Multiple Skin
Facades, International Journal of HVAC&R Research Volume 9 NR2 pages 167 186,
2003
Safer N, Woloszyn M & Roux, J J, Three-Dimensional Simulation with A CFD Tool of
the Phenomena in Single Floor Double Skin Faade Equipped With a Venetian Blind,
Solar Energy 79 (2005) 193-203, 2004
Santamouris M, Farou I & Zerefos S, Bestfacade: Best Practice for Double Skin
Facades WP2 Report Cut Back of Non-Technological Barriers,
EIE/04/135/s07.38652, from www.bestfacade.com, 2005
Straube J & van Straaten R, The Technical Merit of Double Facades for Office
Buildings in Cool Humid Climates, www.buildingsolutions.ca , Draft White Page for
Discussion, 2001.
Streicher W (Ed.), Bestfacade: Best Practice for Double Skin Facades WP1 Report
State of the Art EIE/04/135/s07.38652, from www.bestfacade.com, 2005
Stribling D & Stigge B, A Critical Review of the Energy Savings and Cost Payback
Issues
of
Double
Facades,
CIBSE/ASHREA
Conference
2003
www.cibse.org/pdfs/8cstribling.pdf
Yellamraju V, Evaluation & Design of Double Skin Facades for Office Buildings in Hot
Climates, A Thesis - Texas A&M University, 2004.
23
B.Pollard, M.Beatty
Seattle Justice Center
Cascadia US GBC, In Depth Case Studies Seattle Justice Center, from
http://casestudies.cascadiagbc.org/lessons.cfm?ProjectID=225,
&
http://casestudies.cascadiagbc.org/energy.cfm?ProjectID=225
City of Seattle, Sustainable Building: Case Study City of Seattle Justice Center, from
dpdlNEWS, February 2003.
US Green Building Council, LEED Case Studies Seattle Justice Center, From
http://leedcasestudies.usgbc.org/overview.cfm?ProjectID=225, 2006.
Washer G, The Seattle Justice Center, Student Case Study, University of Waterloo,
from www.architecture.uwaterloo.ca/faculty_projects/terri/, 200?.
Telus Building
Boyes, Henderson, Krejcik, Sibbald, William Farrell Building Telus, Student
Powerpoint
Study,
University
of
Waterloo,
from
www.architecture.uwaterloo.ca/faculty_projects/terri/, 200?.
Boake T, M Harrison K & Chatham A, The Tectonics Of The Double Skin: Green
Building or Just More Hi-Tech Hi Jinx? North American Case Studies, University of
Waterloo
School
of
Architecture,
from
www.architecture.uwaterloo.ca/faculty_projects/terri/ds/tectcase.pdf, 200?
Kujawski Canadian best practices in sustainable retrofit design,
www.greenbuilding.ca/down/bc/retrofit_3case_studies_canada.doc, 200?
from
Museum of Contemporary Art, Denver

Pappas A, Energy Performance of a Double Skin Faade Analysis for the Museum of
Contemporary
Art,
Denver,
Solar2006,
from
www.solar2006.org/presentations/tech_sessions/t45-p201.pdf, 2006.
Navvad M, Full Scale Testing & Computer Simulation of a Double Skin Faade
Building (Paper) , Building Simulation 2005 - Ninth International IBSPA Conference,
Montreal 2005.
Navvad M & Varodompun J, Thermal Performance of a Double Skin Faade Using Full
Scale Testing & Computer Simulation and Actual Building (Presentation), ISES - Solar
2006
Australian Building References
University of Sydney Law School
building.shtml
Building:
www.usyd.edu.au/about/new-
VS1: David Clark, Director, Cundal, ARIAH Conference Melbourne - Nov 2007
,www.cundall.com.au
RMIT, Design Hub Vision, from www.rmit.edu.au/propertyservices/designhub
24
B.Pollard, M.Beatty
BRIEF BIOGRAPHY OF PRESENTER
Brett is an Architect and Landscape Architect with extensive experience in Australia nd
Europe and has played a key role in some significant, long running projects such as the
infrastructure projects at Homebush Bay fro the Sydney 2000 Olympics, the Cross City
Tunnel and the award winning North Sydney Olympic Pool.
As well as working a Senior Associate in the Sustainable Futures Unit at HASSELL,
Brett will soon take his Masters in Design Science (Sustainable Design) from the
University of Sydney. He has recently returned from five months at Vancouver's
University of British Columbia where he was researching various aspects of
sustainability including building energy performance and sustainable housing
initiatives.
HASSELL has supported Brett through his studies, which aim to build upon the firm's
already considerable strength in sustainable design. Brett is also a Green Star
Accredited Professional of the Green Building Council of Australia.
25

Double Skin Façades More Is Less?

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DOUBLE SKIN FAADES

Lead Author: Brett Pollard, BLArch, BArch

Improved occupant comfort. Access to daylight is seen as an important component of

Fig. 1: Bestfacade DSF Classification Diagram (VDF = DSF)

the Extract Air;

the Twin Face; and

the Hybrid System

Fig. 2: Buffer DSF

Figs. 3 & 4: Business Promotion Centre Germany

Fig. 5: Extract Air DSF

Figs. 6 & 7: Brogebude Felbermayr, Salzburg, Austria.

Fig. 8: Twin Face DSF

Figs. 9 & 10: Daimler Benz (Debis) Building, Berlin

Fig. 10: New York Times Building

Fig 11: Detail of ceramic shading elements

2,500 m2 (27,000 sq.ft)

Hygrothermal Zone: Cold

Extract Air/ Continuous (TBC)

Adjaye Associates & Davis Partnership Architects

Approximately 50% of the faade of this newly completed building is a DSF. It

Fig. 12: View of 15Th and Delgany Street Facades

26,750 m2 (288,000 sq.ft)

Hygrothermal Zone: Marine

Fig. 13: Seattle Justice Centre - 5th Ave

Fig. 14 Detail view of DSF cavity

Vancouver, British Columbia, Canada

12,000 m2 (129,800 sq.ft)

Hygrothermal Zone: Marine

Busby & Associates (now Busby Perkins + Will)

Fig. 15 Telus Building faade

Fig. 16: Telus Building diagram

40,400 m2 (435,000 sq.ft)

Hygrothermal Zone: Cold

Baro Roa + Athanas

Mojyaba Navvab University of Michigan

Fig. 17 Southern Elevation showing DSF

BCA Climate Zone: 5

Renzo Piano Building Workshop

Fig. 18: Aurora Place/Macquarie Sydney

Fig 19: Detail view of louvres

Due for completion early 2009

BCA Climate Zone: 5

Fig. 21: Eastern faade

Fig. 22: Detail view of facade

Construction to commence in early 2009

BCA Climate Zone: 6

Sean Godsell & Peddle Thorp Architects in association

Fig. 25: View of Proposed Faade

Fig. 26: Detail View

Due late 2008

BCA Climate Zone: 5

Fig. 27: View of Northern & Western Facades

Museum of Contemporary Art, Denver

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