Energy and Buildings 119 (2016) 28–40

Contents lists available at ScienceDirect

Energy and Buildings

journal homepage: www.elsevier.com/locate/enbuild

Computational study and experimental validation of the heat

ventilation in a living room with a solar patio system
Slah Driss ∗ , Zied Driss, Imen Kallel Kammoun
Laboratory of Electro-Mechanic Systems (LASEM), National School of Engineers of Sfax (ENIS), Univrsity of Sfax, B.P. 1173, km 3.5 Soukra, 3038 Sfax, Tunisia

a r t i c l e i n f o a b s t r a c t

Article history: The numerical investigation of the heat ventilation and thermal comfort evaluation in a living room
Received 20 December 2015 with a patio system was undertaken using a validated computational fluid dynamic (CFD) model. The
Accepted 5 March 2016 Reynolds averaged Navier–Stokes (RANS) modeling approach with the k–ε turbulence model was used
Available online 9 March 2016
for the numerical investigations. The steady-state governing equations were solved using the software
SolidWorks Flow Simulation. Based on the various flow simulations, the numerical results obtained for
Keywords:
the temperature distributions, the airflow patterns and the turbulence characteristics inside the building
Living room
were presented. Using the numerical results, it was noticed that the choice of the building design can
Patio system
Heat ventilation
improve comfort conditions by modifying the microclimate of the building and by enhancing the airflow
Air flow in it. Indeed, it was found that patio system can be useful of a heat source in the building.
CFD © 2016 Elsevier B.V. All rights reserved.

1. Introduction conditioning) systems go through rigorous coupling procedures as

a result of indoor conditions, which are significantly affected by the
Solar energy utilization is one of the main strategies used to pro- outdoor environment. Hence, a traditional method for addressing
vide buildings renewable energy. In fact, buildings require energy a coupling setback in HVAC systems is to add a reheating coil. Rauf
both in the form of heat during operation, which can be provided by and Crawford [4] investigated the relationship between the service
solar thermal collectors. In this context, Han et al. [1] described the life and the life cycle embodied energy of buildings. The embod-
new designs and developments of illumination, heating and air con- ied energy of a detached residential building was calculated for a
ditioning systems and technologies for energy-efficient buildings. building service life range of 1–150 years. The results show that
Important breakthroughs in these areas include high-efficiency and variations in building service life can have a considerable effect on
reduced cost solar system components, compact combined heat- the life cycle embodied energy demand of a building. A 29% reduc-
power generation systems, and so on. To take advantage of these tion in life cycle embodied energy was found for the case study
new technologies, hybrid or cascade energy systems have been pro- building by extending its life from 50 to 150 years. Boixo et al. [5]
posed and investigated. A survey of innovative architectural and described the cool roofs which are an inexpensive method to save
building envelope designs that have the potential to considerably energy and to improve the comfort level in buildings in mild and hot
reduce the illumination and heating and cooling costs for office climates. A high scale implementation of cool roofs in Andalusia, in
buildings and residential houses is also included. Chan [2] inves- the south of Spain, could potentially save 295,000 kWh per year,
tigated an appropriate floor level of a residential building above considering only residential buildings with flat roofs using elec-
which balconies should be incorporated. A 21-story residential trical heating. Oliveira Panão et al. [6] developed a newly revised
building was modeled using Energy Plus. Simulation results indi- methodology arises including a few corrections in procedure. This
cated that, for a west facing flat, only the flats located on 15/F–20/F iterative result is sufficiently accurate to calculate the building’s
can give acceptable environmental payback periods, ranging from cooling energy needs. Secondly, results show that the required con-
58.3 years to 40.7 years, i.e., within the lifespan (60 years) of a build- ditions are insufficient to prevent overheating. The use of the gain
ing. Homod [3] proposed the HVAC (heating, ventilating and air utilization factor as an overheating risk index is suggested, accord-
ing to an adaptive comfort protocol, and is integrated in the method
used to calculate the maximum value for cooling energy needs.
Marszaland and Heiselberg [7] recognized that in the long run,
∗ Corresponding author. Fax: +216 74 275 595. the implementation of energy efficiency measures is a more cost-
E-mail addresses: slah.driss@gmail.com, face-pro@hotmail.fr (S. Driss), optimal solution in contrast to taking no action. However, the Net
Zied.Driss@enis.tn (Z. Driss).

http://dx.doi.org/10.1016/j.enbuild.2016.03.016
0378-7788/© 2016 Elsevier B.V. All rights reserved.
 S. Driss et al. / Energy and Buildings 119 (2016) 28–40 29

Munich (Muenchen) and Helsinki, whose average annual tempera-

Nomenclature ture and solar potential differ significantly. Irulegi et al. [12] studied
the building design strategies based on the full integration of active-
k–ε Turbulence model (dimensionless) passive solar technologies and passive design criteria in order to
C2ε Constant of the k–ε C1ε constant of the turbulence achieve an energy self-sufficient proposal, providing high quality of
model (dimensionless) life to its occupants. He and Hoyano [13] developed a passive cool-
C Constant of the k–ε turbulence model (dimension- ing wall (PCW) constructed of moist void bricks that are capable of
less) absorbing water and which allow wind penetration, thus reducing
e Internal energy (J kg−1 ) their surface temperatures by means of water evaporation. Pas-
Fi Force components on the i direction (N) sive cooling effects, such as solar shading, radiation cooling and
h The thermal enthalpy (J kg−1 ) ventilation cooling can be enhanced by incorporating PCWs into
Si Mass-distributed (kg m−2 s−2 ) the design of outdoor or semi-enclosed spaces in parks, pedes-
Gk Production term of turbulence (kg m−1 s−3 ) trian areas and residential courtyards. Du et al. [14] presented
H Height (m) the building microclimate in free-running buildings and the rela-
k Turbulent kinetic energy (J kg−1 ) tionship with summer thermal comfort. Field measurements were
l Length (m) conducted to investigate the microclimate in a Chinese traditional
P Pressure (Pa) vernacular house. Macias et al. [15] developed and implemented for
Pr Prandt number a new project of social housing. The passive cooling system incor-
QH Heat source or sink per unit volume (kg m−1 s−3 ) porates a solar chimney in combination with high thermal mass
qi Diffusive heat flux (J) in the building construction. The natural ventilation is enhanced
Re Reynolds number (dimensionless) with the help of the solar chimney and night fresh air cools the
t Time (s) building structure. The design of this concept was calculated by
ui Velocity components (m s−1 ) balancing energy using basic thermal equations for a summer ref-
ui Fluctuating velocity components (m s−1 ) erence day and evaluated using two simulation tools, TRNSYS and
V Magnitude velocity (m s−1 ) TAS. Luo et al. [16] studied models of cuboids obstacles to charac-
xi Cartesian coordinate (m) terize the three-dimensional responses of airflow behind obstacles
X Cartesian coordinate (m) with different shape ratios to variations in the incident flow in a
Y Cartesian coordinate (m) wind-tunnel simulation. Wind velocity was measured using parti-
Z Cartesian coordinate (m) cle image velocimetry to study the design impact of this building
ε Dissipation rate of the turbulent kinetic energy on the aerodynamic characteristics. Tamayol et al. [17] used FTC
(W kg−1 ) and PTM to study the effects of the inlet position and the baffle
 Dynamic viscosity (Pa s) configuration on the hydraulic performance of the primary settling
t Turbulent viscosity (Pa s) tanks. Shortcomings of the FTC approach were stated. The optimal
 Density (kg m−3 ) positioning of the baffles was also determined though a series of
k Constant of the k–ε turbulence model (dimension- computer simulations. Sumon et al. [18] studied the performance
less) of mixed convection in a rectangular enclosure. Four different
ε Constant of the k–ε turbulence model (dimension- placement configurations of the inlet and outlet openings were con-
less) sidered. A constant flux heat source strip is flush-mounted on the
ıij Kronecker delta function (dimensionless) vertical surface, modeling an integrated circuit chips affixed to a
 ij Viscous shear stress tensor (Pa) printed circuit board. Rahmati and Ashrafizaadeh [19] compared
the performance of proposed model, several benchmark problems,
such as a cubic lid-driven cavity flow, flow over a backward-facing
ZEB concept raises a new issue: how far should we go with energy step, and a double shear flow. Bunsri et al. [20] suggested that
efficiency measures and when should we start to apply renewable the velocity of air-releasing during a wet process was higher than
energy technologies? This analysis adopts the LCC methodology the velocity of air-entering during a dry process. The infiltration
and uses a multi-family Net ZEB to find the answer to this ques- is the most important land applications. Boixo et al. [21] consid-
tion. Sorsak et al. [8] presented an approach in the determination ered residential buildings with flat roofs using electrical heating.
of the most economically efficient building from the viewpoint of At the current energy prices, consumers can save 59 million euros
the costs of envelope’s composition, the present value of heating annually in electricity costs and the emission of 136,000 metric
costs and the costs incurred in fitting out the boiler room. Pikas tons of CO2 can be directly avoided every year from the production
et al. [9] determined the cost-optimal energy efficiency level for of that electricity. If radiative forcings are considered, Andalucía
two lately built apartment buildings in a cold climate of Estonia, can potentially offset between 9.44 and 12 Mt of CO2 . Ibrahim
and achieved low energy and nZEB (nearly zero energy build- et al. [22] proposed to capture this wasted energy available during
ing) requirement levels. The influence of high-efficiency external non-cloudy winter days and transfer it to the cooler north facade
walls, roofs, windows, ventilation units and solar collectors on through water pipes embedded in an exterior aerogel-based insu-
energy use and construction costs were studied by using multi- lating coating. The coating’s projection technique through spraying
stage methodology for reducing the number of combinations. Yang or plastering allows the easy implementation of this system. The
et al. [10] studied the natural ventilation of buildings can be closely proposed system was presented with all the mathematical equa-
related to building design. The object of this investigation is to tions and numerical model. This model is then validated against
conduct computational fluid dynamic (CFD) simulations and field experimental data found in the literature. To test its performance
measurements for studying the natural ventilation effectiveness of on a full-scale house, the MATLAB numerical model is coupled to the
office space in a common public building with a built-in central whole building energy simulation program EnergyPlus through co-
ventilation shaft (CVS). Premrov et al. [11] demonstrated possi- simulation. Nam and Chae [23] developed the energy-foundation
bleavoidance of the latter energy. The research is based on a case system by several researches which use building foundation as a
study of a one-storeytimber-frame house, taking into account the heat exchanger. In order to establish the optimum design tool of
climate data for three different European cities, those of Ljubljana, an energy-foundation system integrated with the horizontal heat
30 S. Driss et al. / Energy and Buildings 119 (2016) 28–40

exchanger, the prediction method of ground heat exchange rate

was developed with numerical simulation model. The developed
model was coupled with ground heat transfer model, ground sur-
face heat model and ground heat exchanger model. Faggianelli et al.
[24] studied the natural ventilation of buildings is a common way to
improve indoor air quality, thermal comfort in summer and reduce
energy consumption due to air conditioning. However, efficiency
of such a system is highly dependent on climatic conditions. This
paper investigates the use of thermal breezes, characterized by
moderate speeds and well-defined direction, to improve natural
cross ventilation technique on Mediterranean coastal zones. The
interest of this phenomenon is highlighted by the development of
climate indicators with meteorological data from various places
in Corsica (France). Bangalee et al. [25] studied the flow structure
of fluid-driven natural cross-ventilation using three techniques:
flow visualization, particle image velocimetry (PIV) measurement
and computational fluid dynamics (CFD). Four specific cases are
chosen to study the effect of the number of windows and the
window configuration on cross-ventilation performance. Teodo-
siu et al. [26] examined the capacity and the accuracy of a CFD
model to characterize the thermo-aeraulic behavior of a heated
room. A simplified approach was presented in order to integrate a
pure buoyancy source within the model, based on a volumetric heat
generation rate which is uniformly distributed within the heater.
Furthermore, detailed experimental–numerical comparisons are
given with regard to heat transfer to the walls as well as to heat
source behavior and plume characteristics.
According to theses anterior studies, it is clear that the use of the
renewable energy in the building application becomes very crucial.
Also, there are few researches on the design method. For thus, we
propose to integrate a solar patio system in the building design to
use the heat ventilation in a living room. The numerical simulations
Fig. 1. 3D view of the building.
achieved in this study were validated using a prototype developed
in our laboratory.

2. Geometrical apparatus
∂H ∂ui H ∂     ∂ ∂u
+ = uj ij + ijR + qi + − ijR i
Fig. 1 presents a living room prototype with a height h = 0.24 m, ∂t ∂xi ∂xi ∂t ∂xj
a width w = 0.21 m and a length l = 0.33 m. In this system, two holes
+ε + Si ui + QH (3)
placed in the same face were considered. The first hole, placed at
a distance h1 = 0.05 m from the floor, is used to stoke the air flow
(i,j = 1, 2, 3)
from the patio placed near the living room. The second hole, placed
at a distance h2 = 0.17 m from the base, permits the evacuation of u2
the air from the living room to the patio system. In fact, the air H =h+ (4)
2
flow comes from the patio located in the building center. This patio,
with transparent roofing, can stock the heat energy in winter. By where  is the density (kg m−3 ), t is the time (s), xi and xj are the
connecting this patio to the adjacent rooms, it is possible to create Cartesian coordinate, ui and uj are the velocity components (m s−1 )
a circulation of the heat flow which can be distributed according respectively on the i and j direction, p is the pressure (Pa),  is
to the building design. However, in the experimental investigation the viscosity (Pa s), ıij is the Kronecker delta function, Fi is the force
we have used an air heater to supply the living room. component on the i direction (N), Si is the mass-distributed external
force per unit mass (kg m−2 s−2 ), h is the thermal enthalpy (J kg−1 ),
3. Numerical model QH is the heat source per unit volume (kg m−1 s−3 ),  ij is the viscous
shear stress tensor (Pa), qi is the diffusive heat flux (J).
3.1. Mathematical formulation The energy equation is written as follows:
 p

The mathematical description of the present model is based ∂E ∂ui E +  ∂     ∂u
+ = uj ij + ijR + qi − ijR i
on the Navier–Stokes equations, [27–31] which in a conservative ∂t ∂xi ∂xi ∂xj
formulation are given as:
+ε + Si ui + QH (5)
∂ ∂(ui )
+ =0 (1)
∂t ∂xi
u2
∂(ui ) ∂(ui uj ) ∂p ∂   E =e+ (6)
+ + = ij + ijR + Si i = 1, 2, 3 (2) 2
∂t ∂xj ∂xi ∂xj
where e is the internal energy (J kg−1 ).
 S. Driss et al. / Energy and Buildings 119 (2016) 28–40 31

Fig. 2. Boundary conditions.

Fig. 3. Meshing of the computational domain.

For Newtonian fluids, the viscous shear stress tensor is defined here ıij is the Kronecker delta function (it is equal to unity when i = j,
as: and zero otherwise),  is the dynamic viscosity, t is the turbulent
  viscosity (Pa s) and k is the turbulent kinetic energy (J kg−1 ).
∂ui ∂ui 2 ∂uk In the frame of the k–ε turbulence model, t is defined using two
ij =  + − ıij (7)
∂xj ∂xj 3 ∂xk basic turbulence properties, namely, the turbulent kinetic energy k
(J kg−1 ) and the turbulent dissipation ε (W kg−1 ):
Following Boussinesq assumption, the Reynolds-stress tensor has
the form:
 
∂ui ∂uj 2 ∂uk 2 C k2
ijR = t + − ıij − kıij (8)
∂xj ∂xi 3 ∂xk 3 t = f (9)
ε
32 S. Driss et al. / Energy and Buildings 119 (2016) 28–40

Fig. 4. Velocity profiles.

Fig. 5. Visualization planes.

 S. Driss et al. / Energy and Buildings 119 (2016) 28–40 33

Fig. 6. Distribution of the velocity field.

here f is the turbulent viscosity factor. It is defined by the expres- here the constant  c = 0.9, Pr is the Prandt l number, and h is the
sion: thermal enthalpy (J kg−1 ). These equations describe both laminar
 20, 5
 and turbulent flows. Moreover, transitions from one case to another
f = [1 − exp(−0.025Ry)]2 1 + (10) and back are possible.
RT
For an ideal gas, the pressure is given by the state law of perfect
where gases:
k2 p = RT = ( − 1) e (14)
Rt = (11)
ε
√ Two additional transport equations are used to describe the turbu-
 ky lent kinetic energy and dissipation:
Ry = (12)
   ∂k
∂(k) ∂(ui k) ∂ t
and y is the distance from the wall. + = + + Sk (15)
∂t ∂xi ∂xi k ∂xj
The diffusive heat flux is defined as:
  ∂h   ∂ε
t ∂(ε) ∂(ui ε) ∂ t
qi = + (13) + = + + Sε (16)
Pr c ∂xi ∂t ∂xi ∂xi ε ∂xj
34 S. Driss et al. / Energy and Buildings 119 (2016) 28–40

Fig. 7. Distribution of temperature.

where the source terms Sk and Sε are defined as: Table 1

Constants of turbulence models.
∂ui
Sk = ijR − ε + t + PB (17) The constants C Cε1 Cε2 ε k
∂xj Values 0.09 1.44 1.92 1.3 1
 
ε ∂ui ε2
Sε = Cε1 f1 ijR + CB PB − Cε2 f2 (18)
k ∂uj k
CB = 1 when PB > 0, and 0 otherwise;
here PB represents the turbulent generation due to buoyancy forces  0.05 3
and can be written as: f1 = 1 + (20)
f
gi 1 ∂  
PB = − (19) f2 = 1 − exp −RT2 (21)
B  ∂xi

where gi is the component of gravitational acceleration in direction The constants C , Cε1 , Cε2 ,  k and  ε are defined empirically. In Flow
xi , the constant  B = 0.9, and the constant CB is defined as: Simulation, the following typical values are presented in Table 1.
 S. Driss et al. / Energy and Buildings 119 (2016) 28–40 35

Fig. 8. Distribution of the static pressure.

3.2. Boundary conditions been changed based on the cells number. Then, the obtained results
has been compared to the experimental velocity values collected
For the boundary conditions, we have considered that the heat from the experimental invesigation. For thus, four meshes have
flow stoke the living room from the patio with a velocity inlet equal been tested. The first case to be set corresponds to a coarse mesh
to V = 3.4 m s−1 and a temperature T = 37 ◦ C measured in the first with 3552 cells (Fig. 3a). The second case corresponds to 22,584
hole. From the second hole, the air flow is evacuated from the liv- cells (Fig. 3b). The third case corresponds to 64,656 cells (Fig. 3c).
ing room to an area of static atmospheric pressure. For thus, we The fourth case corresponds to a refined mesh with 68,446 cells
have imposed in the second hole an outlet pressure with a value of (Fig. 3d). The corresponding time calculation and number of itera-
101,325 Pa. Knowing that the living room prototype is presented in tions for these different simulation are presented in Table 2. In the
our domain, the roof and the lateral surface of the building and the considered plane X = 0.06 m containing the two holes and the super-
wall of the computational domain are considered as a wall bound- position of the velocity profiles in the differents directions defined
ary condition. A summary of the boundary conditions is given in by Z = −0.03 m, Z = −0.09 m, Z = −0.12 m and Z = −0.18 m are pre-
Fig. 2. sented in Fig. 4. The numerical results gathered from the CFD code
and the experimental results taken by the aneometer are super-
posed. The measure velocity values are made by positioning the
3.3. Meshing effect and experimental validation probe of the anemometer for each controlling point and by collect-
ing the velocity value of the air flow. According to these results,
In this section, we have interested on the mesh resolution’s it has been observed that the velocity profiles seems to have the
influence on flow simulation results. In fact, the size of the mesh has
36 S. Driss et al. / Energy and Buildings 119 (2016) 28–40

Fig. 9. Distribution of the dynamic pressure.

Table 2
Characteristic of different meshes.

Number of cells Number of the partial cells Time calculation Number of iterations

First meshing 68,446 105,270 4:10:45 654

Second meshing 64,656 95,520 2:37:2 345
Third meshing 22,584 41,768 0:31:9 321
Ford meshing 3552 6312 0:1:26 119

same appearance but the velocity values depends on the cell size. 4. Numerical results
It is clear that the velocity value obtained for the fourth case is
the closest to the experimentally measured value. Also, it has been As presented in Fig. 5, six planes defined by X = 0.06 m, X = 0.18 m,
noted that the resolution time increases with the decrease of the Y = 0.06 m, Y = 0.18 m, Z = −0.03 m, and Z = −0.18 m are considered
size of mesh cells. Indeed, the greater the cell size gets the more to visualize, the velocity field, the average velocity, the tempera-
the gap between numerical and experimental results is large. Our ture, the static pressure, the dynamic pressure, the turbulent kinetic
choice leads to a better result with regards to the precision and the energy, the turbulent viscosity, the dissipation rate of the turbulent
resolution time.
 S. Driss et al. / Energy and Buildings 119 (2016) 28–40 37

Fig. 10. Distribution of the turbulent kinetic energy.

kinetic energy and the turbulent viscosity. In these condition, the larly, a discharge area is created from the hole and continues until
Reynolds number is equal to Re = 5100. the opposite wall. While approaching to this wall, a rapid decrease
of the velocity field until V = 1.13 m s−1 has been observed. With the
direction change, this flow creates two recirculation zones in the
4.1. Velocity field
whole area of the living room. These zones are characterized by a
low speed values not exceeding V = 0.9 m s−1 . Their form depends
Fig. 6 shows the distribution of the velocity field in the planes
on the visualization planes. By approaching to the holes outlet situ-
defined by the positions X = 0.06 m, X = 0.18 m, Y = 0.06 m, Y = 0.18 m,
ated at the top of the living room, the speed increases slightly until
Z = −0.03 m and Z = −0.18 m. Based on these results, it’s clear that
reaching V = 2.8 m s−1 .
the average speed is maximal at the hole inlet situated in the con-
sidered living room. In reality, the air flow comes from the patio
located in the building center. This patio, with transparent roofing, 4.2. Temperature
can stock great heat energy in winter. By connecting this patio to the
adjacent rooms, it is possible to create a heat flow which can be dis- Fig. 7 shows the distribution of the temperature in the planes
tributed according to the building design. At this level, the average defined by the positions X = 0.06 m, X = 0.18 m, Y = 0.06 m, Y = 0.18 m,
velocity reaches a maximum value equal to V = 3.4 m s−1 . Particu- Z = −0.03 m and Z = −0.18 m. According to these results, it has been
38 S. Driss et al. / Energy and Buildings 119 (2016) 28–40

Fig. 11. Taux de distribution of the dissapation rate of the turbulent kinetic energy.

observed that the temperature is governed by the boundary con- sion zone appears in the holes inlet situated in the considered living
dition, in the hole inlet which the air flow is equal to T = 37 ◦ C. This room. During the air progress, the static pressure decreases slightly.
value decreases slightly in the computation domain and reaches After that, it increases close the opposite wall and the different cor-
the lowest value in the hole outlet. In this case, it is interesting to ners and reaches the maximum value equal to p = 101,332 Pa. In
note that the difference between the temperature values is very the holes outlet, the static pressure is governed by the atmospheric
low. This fact is due to of the flow forced convection. condition value equal to p = 101,325 Pa.

4.3. Static pressure 4.4. Dynamic pressure

Fig. 8 shows the distribution of the static pressure in planes Fig. 9 presents the dynamic pressure in the planes defined by the
defined by the positions X = 0.06 m, X = 0.18 m, Y = 0.06 m, Y = 0.18 m, positions X = 0.06 m, X = 0.18 m, Y = 0.06 m, Y = 0.18 m, Z = −0.03 m
Z = −0.03 m and Z = −0.18 m. According to these results, a compres- and Z = −0.18 m. Based on these results, we find a compression zone
 S. Driss et al. / Energy and Buildings 119 (2016) 28–40 39

Fig. 12. Distribution of the turbulent viscosity.

characteristic of the maximum value of the dynamic pressure in the kinetic energy appear in the inferior corner of the opposite wall
discharge area located between the holes inlet and the opposed and the holes outlet situated at the top of the living room. In these
wall. Outside of this zone, the dynamic pressure decreases before areas, the maximum value of the turbulent kinetic energy is about
increasing in the holes outlet. k = 0.4 J kg−1 . Outside of this area, the value of the turbulent kinetic
energy becomes very weak rapidly.
4.5. Turbulent kinetic energy
4.6. Dissipation rate of the turbulent kinetic energy
Fig. 10 shows the distribution of the turbulent kinetic energy in
the planes defined by the positions X = 0.06 m, X = 0.18 m, Y = 0.06 m, Fig. 11 presents the distribution of the dissipation rate of
Y = 0.18 m, Z = −0.03 m and Z = −0.18 m. According to these results, the turbulent kinetic energy in the planes defined by the posi-
it has been observed that the turbulent kinetic energy is low at the tions X = 0.06 m, X = 0.18 m, Y = 0.06 m, Y = 0.18 m, Z = −0.03 m and
holes inlet situated in the considered living room. While approach- Z = −0.18 m. According to these results, it’s clear that the dissipation
ing to the opposite wall, its value increases progressively. The rate of the turbulent kinetic energy is low at the holes inlet situated
wakes characteristics of the maximum values of the turbulent in the considered living room. While approaching to the opposite
40 S. Driss et al. / Energy and Buildings 119 (2016) 28–40

wall, its value increases progressively. The wakes characteristics of energy needs used to prevent the overheating of buildings in the summer,
the maximum values of the dissipation rate of the turbulent kinetic Energy 36 (2011) 3262–3271.
[7] A.J. Marszal, P. Heiselberg, Life cycle cost analysis of a multi-storey residential
energy appear in the inferior corner of the opposite wall and the net zero energy building in Denmark, Energy 36 (2011) 5600–5609.
holes outlet situated at the top of the living room. In these areas, [8] M. Sorsak, V.Z. Leskovar, M. Premrov, D. Goricanec, I. Psunder, Economical
the maximum value of the dissipation rate of the turbulent kinetic optimization of energy-efficient timber buildings: case study for single family
timber house in Slovenia, Energy 77 (2014) 57–65.
energy is about k = 2 W kg−1 . Outside of this area, the value of the [9] E. Pikas, M. Thalfeldt, J. Kurnitski, R. Liias, Extra cost analyses of two
dissipation rate of the turbulent kinetic energy is very weak. apartment buildings for achieving nearly zero and low energy buildings,
Energy 84 (2015) 623–633.
[10] A.S. Yang, C.Y. Wen, Y.H. Juan, Y.M. Su, J.H. Wu, Using the central ventilation
4.7. Turbulent viscosity
shaft design within public buildings for natural aeration enhancement,
Applied Thermal Engineering 70 (2014) 219–230.
Fig. 12 shows the distribution of the turbulent viscosity in the [11] M. Premrov, V.Z. Leskovar, K. Mihalic, Influence of the building shape on the
energy performance of timber-glass buildings in different climatic conditions,
planes defined by the positions X = 0.06 m, X = 0.18 m, Y = 0.06 m,
Energy (2015) 1–11, http://dx.doi.org/10.1016/j.energy.2015.05.027.
Y = 0.18 m, Z = −0.03 m and Z = −0.18 m. According to these results, [12] O. Iruleg, L. Torres, A. Serra, I. Mendizabal, R. Hernández, The Ekihouse: an
it has been observed that the turbulent viscosity is low at the holes energy self-sufficient house based on passive design strategies, Energy Build.
inlet situated in the considered living room. While approaching to 83 (2014) 57–69.
[13] J. He, A. Hoyano, A 3D CAD-based simulation tool for prediction and
the opposite wall, its value increases progressively. The wakes char- evaluation of the thermal improvement effect of passive cooling walls in the
acteristics of the maximum values of the turbulent viscosity appear developed urban locations, Solar Energy 83 (2009) 1064–1075.
in the inferior corner of the opposite wall and the holes outlet situ- [14] X. Du, R. Bokel, A.V.D. Dobbelsteen, Building microclimate and summer
thermal comfort in free-running buildings with diverse spaces: a Chinese
ated at the top of the living room. In these areas, the maximum value vernacular house case, Build. Environ. 822 (2014) 15–227.
of the turbulent viscosity is about t = 2 Pa s. Outside of this area, [15] M. Macias, A. Mateo, M. Schuler, E.M. Mitre, Application of night cooling
the value of the turbulent viscosity becomes very weak rapidly. concept to social housing design in dry hot climate, Energy Build. 38 (2006)
1104–1110.
[16] W. Luo, Z. Dong, G. Qian, J. Lu, Wind tunnel simulation of the
5. Conclusion three-dimensional airflow patterns behind cuboid obstacles at different
angles of wind incidence, and their significance for the formation of sand
shadows, Geomorphology 139 (140) (2012) 258–270.
In this paper, we have developed a computational study and [17] A. Tamayol, B. Firoozabadi, G. Ahmadi, Determination of settling tanks
experimental validation of the heat ventilation in a living room with performance using an Eulerian–Lagrangian method, J. Appl. Fluid Mech. 1
a solar patio system located in the building center. This patio, with (2008) 43–54.
[18] S. Sumon, M.d. Arif Hasan Mamun, M. Zakir Hossain, A.K.M. Sadrul Islam,
transparent roofing, can stock great heat energy in winter. By con-
Mixed convection in an enclosure with different inlet and exit configurations,
necting this patio to the adjacent rooms, it is possible to create a J. Appl. Fluid Mech. 1 (2008) 78–93.
heat flow which can be distributed according to the building design. [19] A.R. Rahmati, M. Ashrafizaadeh, A generalized lattice Boltzmann method for
three-dimensional incompressible fluid flow simulation, J. Appl. Fluid Mech. 2
These solutions can improve the comfort conditions by modifying
(1) (2009) 71–96.
the microclimate of the building and by enhancing the airflow in [20] T. Bunsri, M. Sivakumar, D. Hagare, Applications of hydraulic properties
it. In fact, by connecting this patio to the adjacent rooms, it is pos- models on microscopic flow in unsaturated porous media, J. Appl. Fluid Mech.
sible to create a heat flow which can be distributed according to 2 (2009) 1–11.
[21] S. Boixo, M. Diaz-Vicente, A. Colmenar, M.A. Castro, Potential energy savings
the building design. In this application, a discharge area is created from cool roofs in Spain and Andalusia, Energy 38 (2012) 425–438.
from the holes inlet and continues until the opposite wall. This flow [22] M. Ibrahim, E. Wurtz, P.H. Biwole, P. Achard, Transferring the south solar
creates two recirculation zones in the whole area of the room. By energy to the north facade through embedded water pipes, Energy 78 (2014)
834–845.
approaching to the holes outlet situated at the top of the living [23] Y. Nam, H.-B. Chae, Numerical simulation for the optimum design of ground
room, the speed increases slightly. These results present very inter- source heat pump system using building foundation as horizontal heat
esting ideas to provide buildings the heat energy by using a solar exchanger, Energy 73 (2014) 933–942.
[24] G.A. Faggianelli, A. Brun, E. Wurtz, M. Muselli, Natural cross ventilation in
patio system. buildings on Mediterranean coastal zones, Energy Build. 77 (2014) 206–218.
In the future, we propose to work on methods stored energy to [25] M.Z.I. Bangalee, J.J. Miau, S.Y. Lin, J.H. Yang, Flow visualization, PIV
assume a continuous end heating with zero energy. measurement and CFD calculation for fluid-driven natural cross-ventilation in
a scale mode, Energy Build. 66 (2013) 306–314.
[26] C. Teodosiu, F. Kuznik, R. Teodosiu, CFD modeling of buoyancy driven cavities
References with internal heat source: application to heated rooms, Energy Build. 68
(2014) 403–411.
[1] H.J. Han, Y.I. Jeon, S.H. Lim, W.W. Kim, K. Chen, New developments in [27] Z. Driss, Z.G. Bouzgarrou, W. Chtourou, H. Kchaou, M.S. Abid, Computational
illumination, heating and cooling technologies for energy-efficient buildings, studies of the pitched blade turbines design effect on the stirred tank flow
Energy 35 (2010) 2647–2653. characteristics, Eur. J. Mech. B/ Fluids (EJMF) 29 (2010) 236–245.
[2] A.L.S. Chan, Investigation on the appropriate floor level of residential building [28] M.W. Ammar Chtourou, Z. Driss, M.S. Abid, Numerical investigation of
for installing balcony, from a view point of energy and environmental turbulent flow generated in baffled stirred vessels equipped with three
performance. A case study in subtropical Hong Kong, Energy 85 (2015) different turbines in one and two-stage system, Energy 36 (8) (2011)
620–634. 5081–5093.
[3] R.Z. Homod, Assessment regarding energy saving and decoupling for different [29] S. Driss, Z. Driss, I. Kallel Kammoun, Study of the Reynolds number effect on
AHU (air handling unit) and control strategies in the hot-humid climatic the aerodynamic structure around an obstacle with inclined roof, Sustain.
region of Iraq, Energy 74 (2014) 762–774. Energy 2 (2014) 126–133.
[4] A. Rauf, Robert H. Crawford, Building service life and its effect on the life cycle [30] Z. Driss, O. Mlayeh, D. Driss, M. Maaloul, M.S. Abid, Numerical simulation and
embodied energy of buildings, Energy 79 (2015) 140–148. experimental validation of the turbulent flow around a small incurved
[5] S. Boixo, M. Diaz-Vicente, A. Colmenar, M.A. Castro, Potential energy savings Savonius wind rotor, Energy 74 (2014) 506–517.
from cool roofs in Spain and Andalusia, Energy 38 (2012) 425–438. [31] S. Driss, Z. Driss, I. Kallel Kammoun, Impact of shape of obstacle roof on the
[6] M.J.N. Oliveira Panão, S.M.L. Camelo, H.J.P. Gonçalves, Assessment of the turbulent flow in a wind tunnel, Am. J. Energy Res. 2 (4) (2014) 90–98.
Portuguese building thermal code: newly revised requirements for cooling