Chapter 3: Literature Review
3.4 Case Studies
3.4.1 Supreme Audit Court Building in Tehran
A famous construction in Iran named “Supreme Audit Court”, is 11 levels high and has DSF on around. The 7th and 11th floors were monitored in summer and winter.
Energy Plus Version 2.1 was used to simulate the building both with and without DSF.
The two buildings' performance under the influence of thermal loads and the temperature on the exterior facade are compared with the findings of the field measurements
(Hashemi, 2010).
This Court building is located in extremely hot weather and is placed at 45ºC towards the southeast. Figure 27 shows the Supreme Audit Court building in the Tehran building, in addition, Figure 28 shows a typical floor plan and building section viewed from the south with a double facade on the east and west sides of the case study. The building cross-section is shown in Figure 29 the DSF starts from the second floor and upwards around the whole building in a square shape. This corridor facade is divided vertically at every two floors for seventeen offices on each floor with 20–25 people’s capacity. The cavity is 70 cm wide. The northeast (NE) and southeast (SE) double facades are linked to one another. The NW and SW facades share the same flaws in this respect.
Figure 27: Supreme Audit Court building in Tehran.
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Figure 28: Building a typical floor plan with DSF (Hashemi, 2010).
Figure 29: Cross-section of the case building.
57 a) Construction Properties:
Table 7 presents some Construction characteristics of the building's inner facade, which has two sections: a transparent one and an opaque one. The windows on the interior facade are 180 x 60 cm, with ledges that are 75 cm off the ground. Each office has 2-4 windows that can be opened for fresh air ventilation. Air can enter and exit the hole through 150 cm-high aluminum ports on the exterior facade. Around 9 % of the top outlets, 2.8 % of the lower, and 5.75 % of the intermediate ones make up the ratio of the vents' area to the façade area in the mid floors on each side. These ratios for the upper floors are 1 %, 5 %, and 16 % respectively.
Table 7: Properties of the building construction.
Façade type
Building elements
Construction Layer Thickness (mm)
U-Value (W/m2 K)
Solar transmit tance
Solar reflectance Double
skin façade
exterior façade
Single glazing 6 5.68 0.775 0.071
interior façade (Opaque part)
Paint on gypsum board Rockwool Paint on gypsum board
15 100 12
0.342
interior glazing façade
Single glazing 4 5.8 0.864 0.075
Double skin façade
Floor Stone
Cement grout Concrete slab Air Gap Ceiling Paint
30 30 100 700 15
2.16
Normal block wall Simulated building without DSF
External wall
Gypsum plasterboard Mineral fiber Brick
Cement mortar Granite
9.5 9 100 20 13
0.335
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b) Air Conditioning Equipment ( AC )
Fresh air and air conditioning of interior areas are provided by 5 chillers in the building and Air handling units on each floor. The working hours are from 7:30-16:00 for five days a week. This data was used in the simulation input to finalize the final results. Figure 30 shows a cross-section of the DSF and the adjacent office floor.
Figure 30: DSF section for the building.
c) Climatic Data
The simulation of the court building for the field measurements in hourly weather profile provides the actual data quantities. This data was extracted from Iranian
Meteorological Organization statistics. They comprise hourly wet and dry temperatures, dew point, relative humidity, cloud cover, wind direction, wind velocity, solar direct and diffuse reflection, and air pressure (Energy Efficiency & Renewable Energy, 2021). The summer means the maximum temperature for Tehran which is around 37°C. Table 8 shows the orientation and the temperature for the four orientations.
Table 8: Interior temperatures on July 18.
Orientation North-East South-East South-West North-West Temperature
(ºC)
23-25 20-22 23-25 22-24
59 d) Field Measurements
The temperature sensors were used to measure the inside and outside climates.
The data were collected at fifteen minutes periods. The temperatures were measured in the mid floors summer in summer and winter. On each of the building's four sides, the sensors for the outside temperature were installed on the seventh level, 50 cm from the exterior face. The interior sensors were positioned on the walls, on two sides, and 150 cm from the floor in the middle of the space.
e) Summer Measurements
The summer measurements were carried out on the mentioned periods, In a typical sunny day, mid of August the measurements demonstrate that on the NE side the maximum temperature of the cavity on the 7th floor (Tcav7) is 41°C, on the 11th floor (Tcav11) 37°C and the outside temperature at this time is about 38°C. The cavity temperature is at most 5°C more than the temperature outside. When this side is in the shade the cavity temperature will reach 7ºC less than that of the outside. On the 11th floor, these differences are 2°C more than the outside and 9°C less than that respectively.
On the SE façade, Tcav on both floors is 4–7°C. On SW from 12:00 a.m. to 6:00 p.m., the modest hours of the day, during monitoring, the maximum temperature variance on this side reached minus 12ºC.
On NW sideways at 18:00, it is 40°C, Tcav7 is around 50°C and Tcav11 is 42°C.
The reason for this is bad ventilation of the cavity on the seventh floor. The above mentioned figures reveal that the NW facade and the SW facade reach the max
temperatures respectively. On SW with the solar occurrence, T cav reaches 43°C, but when this facade is away from solar effect T cav falls 10°C below. This shows the significance of mounting shading devices in DSF throughout the hot period of the year.
The cooling system was on during summer. According to the typical thermal measures of office buildings in Iran, the adequate temperature in August is 26.7–32.5°C.
The huge variance between this range and the measured room temperatures indicates that
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the energy is heavily expended for air conditioning. Research on three DSF buildings in Germany found that Tcav in the Siemens building (a box-window DSF) is 10°C, in Victoria Insurance Co. (a multi-story DSF) 8°C, and in the RWE high-rise (a box- window DSF) 15°C ( Hashemi, 2010).
f) The Operational Profile
The HVAC system in the model buildings is operational from 6:00 am to 10:00 pm. The heating setting ranges from 21.1 to 12.8°C after 2:00 p.m. 23.9°C has been adjusted for cooling. The temperature will stay at 40°C at night. Figure 31 depicts the temperature on the NE, SE, SW, and NW in the summer.
The volume flow proportions for the stair zone is 0.068 m3/s, for offices on SE and NW, 0.15 m3/s, for NE and SW rooms, 0.17 m3/s. These values for DSF zones are 0.6 m3/s for SE, 0.05 m3/s for NW, 0.4 m3/s for SW, and 0.01 m3/s for NE. There are no shading devices in the DSF.
Figure 31: Cavity summer temperature in different orientations (Hashemi, 2010).
61 g) Modelling the Building with and without DSF
On the seventh floor, it was computed the building's energy consumption for each scenario. The average amount of heating energy used throughout the winter is around 14.6 kWh less than what would be expected under normal circumstances thanks to the DSF. In the summer, the cooling demand in the DSF decreases during the day but increases at night. The key reason for this tragedy is a lack of natural ventilation.
However, the DSF has a lower monthly cooling cost than the conventional facade. The annual savings for the 7th floor is 10.8 kWh.
h) Summer Temperatures
Both the cavity temperatures of the building with DSF and the outside interface temperatures of the outside walls of the buildings with and without DSF were calculated.
The result compares the simulated cavity temperatures to the observed values for the days that monitoring was done.
Figure 32 depicts the exterior walls' summertime temperatures on a bright
summer day. Buildings with and without DSF were subjected to the test on August 18. It is made very obvious that buildings with DSF have less heat loss via their walls. As a result, the rooms are kept warm at night. This issue won't arise due to night ventilation.
The room temperatures will stay high in the morning if there is no ventilation, which will increase energy usage. The greatest wall temperature of the typical facade is 14.8°C higher than the DSF. When compared to the normal facade, DSF may result in a reduction in cooling demand throughout the day. A typical facade has greater temperature differences between the exterior walls than the DSF (Table 9).
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Figure 32: Cavity summer temperature inside and outside temperature.
Table 9: The external walls’ surface temperature is July 18.
Facade orientation Temperature (°C) Time
DSF NE
SE SW NW
49 53.8 55.7 59.8
10:00 11:00 15:00 17:00 Normal Façade NE
SE SW NW
59 68.6 63.2 64.4
10:00 11:00 15:00 17:00
The simulation outcomes show that the cavity temperature on 18th July is at most 14.5°C which is more than the external temperature. At the same time, the NW facade was the warmest side of the building. Showing that on 18th July the variance between Tcav and To was 5–10°C and the same facade was the warmest side of the envelope surface. As shown in Figure 33 the layout for the model with DSF.
63 Figure 33: Building floor with DSF.
Figure 34 shows the monthly heating and cooling rate of the seventh floor in the simulated buildings.
Figure 34: Monthly cooling and heating for the simulated buildings.
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