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Effect of Courtyard Height and
Proportions on Energy Performance of
Multi-Storey Air-Conditioned Desert
Buildings.
Khaled El-Deeb, PhD Ahmed Sherif, PhD Abbas El-Zafarany, PhD
[Alexandria University, Egypt.] [The Ameican University in Cairo] [Cairo University, Egypt]
[email protected] [email protected] [email protected]
ABSTR ACT
Courtyard buildings have been always recommended as a passive architectural technique in desert
environments in order to maintain indoor thermal comfort. Nowadays, an increasing number of
buildings are air-conditioned. The importance of using passive techniques, then, becomes to reduce
energy consumption. A previous study, however, showed that in desert environments, the energy
performance of two-storey residential courtyard buildings proved less efficient than other solid forms,
even when attached to neighbouring buildings from three sides in a compact urban fabric. Their
performance was relatively better in mild desert climates than in extreme hot ones. The study was
limited to a single family house with “thin” depth of zones surrounding the courtyard.
In multi-storey courtyard buildings, the courtyard results in more height and self-shading on the facades
overlooking the courtyard. This will have a direct effect on the energy consumed for cooling and
heating, as well as on that consumed by artificial lighting
This study questions the effect of courtyard height proportions and thickness of the built area
surrounding it on the energy consumption in multi-storey air-conditioned courtyard buildings and tracks
that effect under different desert climates. Courtyard buildings of 1-10storey-height were modelled using
the DesignBuilder software and simulated using EnergyPlus simulation engine for the desert climates of
Khargah, Cairo, Alexandria and for the temperate climate of Berlin for comparison. All cases were
compared to the corresponding solid building forms of the same built area.
Air-conditioned courtyard houses has not shown a significant improvement in energy savings in desert
environments, buildings with bigger depth surrounding the courtyard had a much better performance
than thinner buildings, giving small energy savings with building depth exceeding 12m
Keywords: multi-storey courtyard, air-conditioned, desert buildings, energy performance simulation.
INTRODUCTION
Courtyard buildings have been always recommended as a passive architectural technique in desert
environments in order to maintain indoor thermal comfort. Nowadays, an increasing number of buildings
are air-conditioned. The importance of using passive techniques, then, becomes to reduce energy
consumption. A previous study, however, showed that in desert environments, the energy performance
of two-storey residential courtyard buildings proved less efficient than other solid forms, even when
attached to neighbouring buildings from three sides in a compact urban fabric [1]. Their performance
was relatively better in mild desert climates than in extreme hot ones. The study was limited to a single
30th INTERNATIONAL PLEA CONFERENCE16-18 December 2014, CEPT University, Ahmedabad
1
family house with “thin” depth of zones surrounding the courtyard. Neither the effect of change in
building depth (BD) surrounding the courtyard was not studied, nor the effect of courtyard height
proportions (HP), while both are still questionable.
Review of recent literature demonstrated that the performance of a courtyard as a passive cooling
strategy was discussed in numerous publications. The effect of a naturally ventilated courtyard on
thermal performance was studied in hot arid, tropical and warm humid tropical climates [2, 3, 4]. Results
showed that a courtyard building with controlled natural ventilation, of specified opening time improved
thermal performance. However in hot arid climate, the thermal performance resulting from continuous
day and night natural ventilation was worse than keeping the building closed without natural ventilation
[2].
The shading effect of different courtyard forms [5] and that of courtyard proportions [6] were
studied. It was found that in Rome, courtyards with deep proportions were recommended over shallow
ones. However, in both studies the tested buildings were solid with no windows, and thus both the effect
of transmitted solar radiation and the energy needed for artificial lighting were not considered.
The passive effect of courtyard with plants and water pool on energy consumed for heating and
cooling was studied [7]. It was found that passive features alone could not maintain comfort during hot
summer times in Tehran, and that similar effects could be obtained through envelope components such
as insulation and double glazing. However, the energy needed for artificial lighting that compensates for
the effect of shading was not accounted for.
A study of energy performance of courtyard buildings in different climatic conditions showed that
better performance was achieved in hot-dry and hot-humid climates rather than in cold and temperate
ones [8]. The study was limited to zones overlooking the courtyard and ignored the influence of the
external perimeter walls and zones. The impact of integrating deep courtyards in mid-rise housing
buildings in Dubai was evaluated, showing that a six-storey courtyard building achieved up to 6.9%
savings [9]. The addressed heights ranged from 4 to 10 stories high, while two-storey low-rise residential
buildings that are common in some countries like Saudi Arabia were not considered.
Some studies addressed the effect of orientation on thermal performance for non-air-conditioned
buildings in a hot-humid tropical climate [10] and the implications of orientation on thermal energy
efficiency of passive buildings in mild temperate climate [11].
Literature showed that the combined effect of building depth surrounding the courtyard and the
courtyard’s height proportions on energy consumed in heating, cooling and lighting of air-conditioned
buildings in the desert needs more investigation.
OBJECTIVES
This research aims at exploring the effect of courtyard on energy consumption of heating, cooling
and lighting in air-conditioned multi-storey residential desert buildings based on two parameters: height
proportions, and the depth of built area surrounding the courtyard.
METHODOLOGY
Six courtyard buildings with fixed courtyard plan dimensions (12X12m) were tested for energy
performance in the following cases of thickness of built area surrounding the courtyard: 4, 6, 8, 10, 12,
20m. Values of thicknesses 14, 16, 18m were interpolated.Each case was tested in building heights of
1,2,4,6,8 and 10 floors. These represented courtyard section length-to-height proportions of 1:0.25,
1:0.5, 1:1, 1:1.5, 1:2, and 1:2.5 respectively. Then, for each of the six main cases, a solid square building
of the same built area and height (but with no courtyard) was tested for comparison.
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
2
The energy use intensity (EUI) of each of the courtyard BD cases was compared in different HPs in
order to detect how the building’s height affects the overall energy consumption per square meter. This
overall value in each courtyard building case was compared to its corresponding solid square case to
detect which form was more efficient in energy consumption.
Figure 1: Tested courtyard height and building depth proportions and solid square buildings.
All courtyard and solid building cases were modelled using Design Builder software and simulated
using EnergyPlus. Even at small building thickness, it was assumed the thickness is divided into two
zones one facing the courtyard and the other on the external perimeter.
Table 1: Simulation parameters of tested Buildings
Simulations were performed for four cities: Alexandria, Cairo, and Khargah located in Egypt, and
classified as hot arid according to koeppen-Geiger classification [12]. For comparison; Berlin, a
temperate city with warm summer was simulated. Despite being classified as desert, the first three cities
represent three different cases: Alexandria is a Mediterranean coastal city, Cairo is inland 220 km south
of Alex., Khargah lies in the sahara 600km south of Alex. Figure 2 shows the difference in climate.
Khargah is the highest in temperature, and out of comfort level for nearly all the year. Cairo is less in
temperature than Khargah, yet higher than Alexandria. Berlin is the lowest.
4m 6m 8m 10m 12m 20m
2
COURTYARD and SOLID SQUARE
Building Cases.
Height Proportions (HP)
1:2.5 1:2 1:1.5 1:1 1:0.5 1:0.25
Building Depth (BD)
Form Square
Courtyard Dimensions 12X12m
WWR 20% fixed for all forms
Occupancy 0.13 person/m2
Schedule Residential Type
Cooling 23 Type: Fluorescent Suspended
Heating 21
Type Split
SIMULATION PARAMETERS
BUILDING
Daylightin
g control
LIGHTING
CONSTRUCTION
External walls
HVAC
Illuminance:
300 lux
Dimming:
On/off
20cm concrete block + 2cm cement plaster each side
10cm concrete block + 2cm cement plaster each side
Insulated with 10 cm polystyrene foam
20cm concrete + 10cm flooring + 2cm plaster
Double-glazed clear
Sensor Height:
0.8m
Internal walls
Roof
Internal slab
Windows
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
3
Figure 2: Mean daily maximum and minimum temperatures in tested cities for each month.
RESULTS AND DISCUSSION
Performance simulations showed a clear difference across the tested cities.
Height proportions:
In desert climates, results showed that EUI for all forms increased by increasing height in all cities.
For example, In Khargah city, dominated by cooling loads, a courtyard building with BD 8m in different
cases of floor HPs showed that the ground floor was always of the least consumption, then the second
floor consumed more cooling energy, and starting from the third one the cooling energy at each floor
were nearly constant, then it increased again at the top floor, Figure 3. This indicated that the ground
floor was significantly lower in consumption due to the heat sink to the ground, while the top floor was
higher but with a small difference than the preceding floor despite being subjected to the solar radiation
due to the thermal insulation of the roof by 10cm. Thus in low-rise cases, the positive effect of heat sink
on minimizing the overall EUI was significant. This effect became less as height increased.
As the tested buildings are fully air-conditioned with no natural ventilation, they were not directly
affected by air temperature inside the courtyard. These results differed from what is expected in naturally
ventilated courtyard buildings where height promotes natural convection, and stack ventilation. The
decreased direct solar radiation at bottom floors increased lighting energy consumption, and its radiant
fraction; and so, minimized the expected savings in cooling loads resulting from self-shading.
Figure 3: EUI per floor in courtyard buildings, with total height 1,2,4,6 and 8 Floors in Khargah
city representing courtyard height ratios 1:0.25 to 1:2.
-5
0
5
10
15
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1 2 3 4 5 6 7 8 9 10 11 12
MAX MIN
-5
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1 2 3 4 5 6 7 8 9 10 11 12
MAX MIN
-5
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10
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1 2 3 4 5 6 7 8 9 10 11 12
MAX MIN
-5
0
5
10
15
20
25
30
35
40
45
1 2 3 4 5 6 7 8 9 10 11 12
MAX MIN
Khargah Cairo Alexandria Berlin
-5
0
5
10
15
20
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30
35
40
45
1 2 3 4 5 6 7 8 9 10 11 12
MAX MIN
-5
0
5
10
15
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30
35
40
45
1 2 3 4 5 6 7 8 9 10 11 12
MAX MINMean Daily Maximum Mean Daily Minimum
Mea
n D
ail
y T
emp
era
ture
s o
C
Lighting Heating Cooling
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
FLO
OR
01
FLO
OR
01
FLO
OR
02
FLO
OR
01
FLO
OR
02
FLO
OR
03
FLO
OR
04
FLO
OR
01
FLO
OR
02
FLO
OR
03
FLO
OR
04
FLO
OR
05
FLO
OR
06
FLO
OR
01
FLO
OR
02
FLO
OR
03
FLO
OR
04
FLO
OR
05
FLO
OR
06
FLO
OR
07
FLO
OR
08
1 2 4 6 8
ON
10 cm
COURT 1:1 - 8m
KHARGAH
Sum of FLOOR LIGHTING (Kwhr/M2) Sum of FLOOR HEATING (Kwhr/M2) Sum of FLOOR COOLING (Kwhr/M2)
1: 0.25 1: 0.5 1: 1.0 1: 1.5 1: 2.0Courtyard Height
Proportions
Floor Number
KHARGAH
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
4
The reflectance of wall paint was assumed to be 50% as the color of the accumulated dust of the desert
usually overrides the color of light paints.
In Berlin, dominated by heating loads, the contrary occurred. The heat sink lead the ground floor to
consume more heating, making the building of 1 or 2 floors consume more than a the 4-storey one, then
a gradual increase occurred as height increased, Figure 4.
Figure 4: EUI in Kwhr/m2 for courtyard building with BD 8m, in case of different building heights
in the four cities.
In Cairo and Alexandria the same pattern occurred as in Khargah, however, consumption values
differed according to climate. Figure 4 shows that increasing HPs lead to an increase in the overall
energy consumption in all tested desert cities.
Depth of Building Surrounding the Courtyard:
Forms with BD alternatives 4m-20m surrounding the courtyard were tested. Changing BD while
fixing courtyard dimensions means that the exposed surface area-to-built volume ratio (S:V) was also
changed. This ratio was also changed by changing HP at each BD.
Results showed that in both extreme hot and cold climates of Khargah and Berlin, the BD was a
determinant factor, Figures 5,6. In Khargah, as BD increased, total energy consumption decreased, in
spite of the increase in lighting energy that was overcome by greater savings in cooling loads. On the
other hand, in Berlin, the increase in BD lead to a large decrease in heating loads due to both the
increased internal area protected from external conditions, as well as the increased lighting energy and
its emitted thermal loads that help decrease heating loads, while increase cooling loads in summer. The
result was a decrease in the overall consumption.
Figure 5: Energy use intensity in Kwhr/m2 for courtyard height proportion 1:2.5 (building height 10 floors), in case of different building depths in tested cities.
0
50
100
150
200
250
300
350
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
ALEX CAIRO KHARGAH BERLIN
8m
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2)
Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
ALEX CAIRO KHARGAH BERLIN
8m
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2)
Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
ALEX CAIRO KHARGAH BERLIN
8m
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2)
Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
ALEX CAIRO KHARGAH BERLIN
8m
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2)
Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
ALEX CAIRO KHARGAH BERLIN
8m
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2)
Sum of BUILDING COOLING (Kwhr/M2)
Lighting Heating Cooling
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
BERLINKHARGAH CAIRO ALEX
0
50
100
150
200
250
300
350
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
ALEX CAIRO KHARGAH BERLIN
8m
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2)
Sum of BUILDING COOLING (Kwhr/M2)
Courtyard Height
Proportions
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
KHARGAH CAIRO ALEX BERLIN
10
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
BERLINKHARGAH
Lighting Heating Cooling
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
0
50
100
150
200
250
300
350
4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m 4m 6m 8m 10m 12m 14m 16m 18m 20m
10 10 10 10
KHARGAH CAIRO ALEX BERLIN
COURT
Sum of BUILDING LIGHTING (Kwhr/M2) Sum of BUILDING HEATING (Kwhr/M2) Sum of BUILDING COOLING (Kwhr/M2)
CAIRO ALEX
Building
Depth
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
5
In all cities, BD 4m was of the highest EUI followed by BD 6m, as their S:V ratio were much
higher than the other BDs, thus they were more liable to be affected by the outdoor climate. The S:V
ratio for BDs 4 and 6m at HP 1:1 for example were 58%, 42% respectively, while BDs 8 to 20m ranged
from 18-33% only.
In Alexandria, the climate is moderate and close to comfort levels for long annual periods. Cooling
loads were not as high as the extreme environment of Khargah because the difference in temperature
between indoor and outdoor is relatively small. For that, the effect of BD was the lowest of the four
cities. Forms of different BDs other than 4m were of close EUI values. Lighting consumption increased
uptill BD 8m then became nearly constant. Savings occured in lighting at low HPs, up to 1:1 (4 floors)
and small BDs. The courtyard building with BD 8m was the lowest in consumption at all tested building
heights. EUI of BD 6m was nearly similar to the rest of BDs starting from HP 1:0.5 (2 floors). The BD
4m case was of the highest consumption until HP 1:1.5 (6 floors), then became of similar values to BD
10-20m cases.
Figure 6: Energy use intensity in Kwhr/m2 for courtyard buildings of different building depths and
height proportions.
In Cairo, whose climate showed higher temperatures than Alexandria and lower than Kharga,
results showed some similarity to either cities. As in Khargah, BD was inversely proportional to
consumption, however, the differences in consumption between BD cases were much smaller than the
corresponding values in Khargah, while larger than those in Alexandria. At BDs 10-20m, a slight
decrease in cooling loads occured while lighting loads were nearly the same.
120
140
160
180
200
220
240
260
280
300
320
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m
ALEX - COURT 1:1 - 8m ALEX - COURT 1:1 - 10m
ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m
ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
120
140
160
180
200
220
240
260
280
300
320
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
BERLIN - COURT 1:1 - 4m BERLIN - COURT 1:1 - 6m
BERLIN - COURT 1:1 - 8m BERLIN - COURT 1:1 - 10m
BERLIN - COURT 1:1 - 12m BERLIN - COURT 1:1 - 14m
BERLIN - COURT 1:1 - 16m BERLIN - COURT 1:1 - 18m
BERLIN - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
120
140
160
180
200
220
240
260
280
300
320
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
CAIRO - COURT 1:1 - 4m CAIRO - COURT 1:1 - 6m
CAIRO - COURT 1:1 - 8m CAIRO - COURT 1:1 - 10m
CAIRO - COURT 1:1 - 12m CAIRO - COURT 1:1 - 14m
CAIRO - COURT 1:1 - 16m CAIRO - COURT 1:1 - 18m
CAIRO - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
120
140
160
180
200
220
240
260
280
300
320
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
KHARGAH - COURT 1:1 - 4m KHARGAH - COURT 1:1 - 6m
KHARGAH - COURT 1:1 - 8m KHARGAH - COURT 1:1 - 10m
KHARGAH - COURT 1:1 - 12m KHARGAH - COURT 1:1 - 14m
KHARGAH - COURT 1:1 - 16m KHARGAH - COURT 1:1 - 18m
KHARGAH - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20m
100
120
140
160
180
200
220
240
Sum of 1 Sum of 2 Sum of 4 Sum of 6 Sum of 8 Sum of 10
ALEX - COURT 1:1 - 4m ALEX - COURT 1:1 - 6m ALEX - COURT 1:1 - 8m
ALEX - COURT 1:1 - 10m ALEX - COURT 1:1 - 12m ALEX - COURT 1:1 - 14m
ALEX - COURT 1:1 - 16m ALEX - COURT 1:1 - 18m ALEX - COURT 1:1 - 20m
CITY FORM
Val...
Sum ... Sum ... Sum ... Sum ... Sum ... Sum o...
Depth 4m
10m
16m
6m
12m
18m
8m
14m
20mDEPTH
ALEX
CAIROKHARGAH
BERLIN
1:0.25 1:0.5 1:1 1:1.5 1:2 1:2.5 1:0.25 1:0.5 1:1 1:1.5 1:2 1:2.5
1:0.25 1:0.5 1:1 1:1.5 1:2 1:2.5 1:0.25 1:0.5 1:1 1:1.5 1:2 1:2.5
Kwhr/m2
Courtyard Height
Proportions
Kwhr/m2
Courtyard Height
Proportions
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
6
Courtyard or Solid Building:
In order to evaluate whether the performance of multi-storey courtyard buildings achieve savings in
comparison with solid ones without courtyard, each of the tested building forms was compared to a solid
square form with the same built area and no courtyard, Figure 7.
In Khargah, results showed that courtyard buildings did not achieve savings in any case of HPs for
BD 4-14m, moreover, it lead to a significant increase in consumption. Only at BD 16m, minor savings
occurred in case of HP 1:0.25 and 1:0.5 only. Also, minor savings were achieved in BD 18m at HPs upto
1:1. The only case where saving were achieved at all heights was in the BD 20m, especially at up to 1:1
height ratio, while up to 1:2, savings were very small.
In Berlin, courtyard buildings did not show any improvement compared to the solid square until
BD 16m, at which saving were achieved in nearly all floors. Savings increased as BD increased. In most
cases it caused a high increase in consumption that reached 40% in some cases.
In Cairo, minor savings were achieved at and some cases of BDs 8m and 16m. At BDs 18-20m,
savings upto 6-8% were achieved at low HPs. The courtyard building consumed more energy than its
corresponding solid building not exceeding 5% in most of the other cases except for BD 4m at low HPs.
In Alexandria, courtyard building achieved energy savings compared to their corresponding solid
ones in the majority of cases. In the cases that did not achieve savings, the increase in consumption was
was less than 4% except for BD 4m at low HPs. This indicated that Courtyard building is more liable to
be used in the moderate climate of Alexandria than in other tested cities.
Figure 7: Percentage of change in energy consumption of courtyard buildings compared to its corresponding solid square.
-20%
-10%
0%
10%
20%
30%
40%
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
COURT COURT COURT COURT COURT COURT COURT COURT COURT
4m 6m 8m 10m 12m 14m 16m 18m 20m
ALEX
Total
Total
-20%
-10%
0%
10%
20%
30%
40%
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
COURT COURT COURT COURT COURT COURT COURT COURT COURT
4m 6m 8m 10m 12m 14m 16m 18m 20m
KHARGAH
Total
Total
-20%
-10%
0%
10%
20%
30%
40%
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
COURT COURT COURT COURT COURT COURT COURT COURT COURT
4m 6m 8m 10m 12m 14m 16m 18m 20m
BERLIN
Total
Total
-20%
-10%
0%
10%
20%
30%
40%
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
COURT COURT COURT COURT COURT COURT COURT COURT COURT
4m 6m 8m 10m 12m 14m 16m 18m 20m
CAIRO
Total
Total
ALEX
CAIRO
KHARGAH
BERLIN
-20%
-10%
0%
10%
20%
30%
40%
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
COURT COURT COURT COURT COURT COURT COURT COURT COURT
4m 6m 8m 10m 12m 14m 16m 18m 20m
BERLIN
Total
Total
-20%
-10%
0%
10%
20%
30%
40%
1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10 1 2 4 6 8 10
COURT COURT COURT COURT COURT COURT COURT COURT COURT
4m 6m 8m 10m 12m 14m 16m 18m 20m
BERLIN
Total
Total
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
1: 0
.25
1: 0
.5
1: 1
.0
1: 1
.5
1: 2
.0
1: 2
.5
Courtyard Building
Courtyard
Proportions
Building Depth
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
7
CONCLUSION
Height proportions had a lower effect than building depth which was a key factor in the cities with
extreme cold and hot climates, Khargah and Berlin. EUI values decreased significantly by the increase in
depth due to the decrease of exposed surface area with respect to the indoor air-conditioned volume.
This BD effect was less in Cairo and nearly insignificant in Alexandria where temperature differences
between indoor and outdoor is small, thus decreasing heat transfer by conduction.
For a fixed depth, a courtyard with lower height proportions consumed less energy in desert cities
due to the effect of the heat sink to the ground which became of less impact as height increased, leading
to an increase in EUI accompanied by the increase in artificial lighting and its consequent cooling loads.
This nearly cancelled the self-shading effect of the courtyard. The opposite effect occurred in Berlin.
Compared to the corresponding solid square, the courtyard building achieved significant savings in
the moderate climate of Alexandria especially in case of medium height proportions (1:1) at small BD
and in low height at large BD. In khargah and Cairo, that are more hot cities, significant saving were
only achieved at large BD (18m-20m) and low height proportions (1:0.25 to 1:1) while a significant
increase in consumption occured especially at small BD and higher height proportions in most cases.
Further research is required to quantify the effect of courtyard house with more proportions.
ACKNOWLEDGEMENTS
This research is financially supported by King Abdullah University of Science and Technology
(KAUST) as part of the Integrated Desert Building Technologies Project IDBT (Award no.UK-C0015).
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30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
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