Simulation experiments

A. Used simulation tools

This research used Envi-met simulation tool to conduct the main body of the simulation experiments, which included determining air temperature, MRT and air velocity. To determine the insolation in courtyards, the research used IES-VE as the used version of Envi-met does not offer to determine insolation levels. The use of Envi-met and IES-VE did not include using their results to feed the simulation of each other, but outcomes were integrated at the analysis stage (Figure 4. 7). Using two simulation tools did not affect results integrity or conclusions validity. First of all, the research ensured the simulation of identical courtyard forms and integrated simulation configurations for both of the two simulation tools, as presented in the following sections. Second, the aim of using IES-VE was only to determine the insolation levels in courtyards, not their microclimatic conditions. The results of Envi-met and IES-VE were used at the analysis stage to determine the impact of changing courtyard insolation on MRT, and the resulted globe temperature. Having these variables determined in two tools did not have a negative impact on accurately determining that correlation as each variable was determined separately using one tool. Using more than one simulation tool may generate

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inconsistency when multiple tools are used to determine the values of a single variable. The reason is that simulation tools use different assumptions and principles in their simulation

processes (Hedquist & Brazel, 2014; Malekzadeh, 2009).

Figure 4. 7. Use of Envi-met and IES-VE simulation tools in the research B. Examined courtyard configurations & urban spaces

 Courtyards: this research aimed to determine the whole range of possible thermal conditions in courtyards in Iraq and the impact of manipulating courtyard geometric configurations on their thermal conditions. However, due to limitations of time and resources, the study examined 360 geometric configurations (Figure 4. 8). Although they do not include all possible courtyard forms, the 360 configurations represent a wide range of possible courtyards. The manipulated and examined geometric properties included the following:

o Courtyard area: six different areas were examined ranging from a 10m2 _{courtyard area,}

which can be used as a private courtyard for a housing unit, to 100m2 courtyard, which

can be used as a shared courtyard for a residential building.

o Width/Length ratio: five different ratios were examined ranging from a narrow courtyard with 1:10 ratio to a square courtyard.

o Courtyard long axis orientations: four main geographic orientations were examined, which included north-south, east-west, northeast-southwest and northwest-southeast. Intermediate orientations can be extrapolated from the performance of courtyards in these four master orientations.

o Height: courtyards with 3m, 7m and 10m heights were examined, which represent the typical height of one-storey, two-storey and three-storey courtyards. This affects the ratios of Width/Height (W/H) and Periphery/Height (P/H).

The 360 options stem from exploring the variations of these effective geometric properties of courtyards on their thermal conditions:

6 areas × 5 W/L ratios × 3 heights × 4 orientations = 360

Simulation Analysis Determining the impact of courtyard geometry on its microclimatic conditions Courtyard configurations Analysing simulation data

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100m2 _{area – Orientations:(north-south, east-west, southeast-northwest, southwest-northeast) – Heights: 3m,7m,10m}

10.0mx10.0m 11.0mx9.0m 14.0mx7.0m 17.0mx6.0m 32.0mx3.2m

80m2 _{area – Orientations : (north-south, east-west, southeast-northwest, southwest-northeast) – Heights: 3m,7m,10m}

9.0mx9.0m 10.0mx8.0m 12.0mx7.0m 15.0mx5.0m 28.0mx2.8m

60m2 _{area – Orientations : (north-south, east-west, southeast-northwest, southwest-northeast) – Heights: 3m,7m,10m}

8.0mx8.0m 9.0mx7.0m 11.0mx5.0m 14.0mx4.0m 24.0mx2.4m

30m2 _{area – Orientations : (north-south, east-west, southeast-northwest, southwest-northeast)- Heights: 3m,7m,10m}

5.0mx5.0m 6.0mx5.0m 8.0mx4.0m 10.0mx3.0m 16.0mx2.0m

20m2 _{area – Orientations : (north-south, east-west, southeast-northwest, southwest-northeast)– Heights: 3m,7m,10m}

4.0mx4.0m 5.0mx4.0m 6.0mx3.0m 8.0mx2.0m 14.0mx2.0m

10m2 _{area – Orientations : (north-south, east-west, southeast-northwest, southwest-northeast)– Heights: 3m,7m,10m}

3.0mx3.0m 4.0mx3.0m 5.0mx2.0m 6.0mx2.0m 10.0mx1.0m

Figure 4. 8. Tested courtyard configurations

These 360 courtyard configurations were modelled in the simulation tools as buildings with central courtyards (Figure 4. 9). The width of the indoor space strip around the courtyard was unified in all of the examined courtyards to neutralize its possible impact on the thermal conditions of courtyards. In Envi-met the microclimatic conditions were

Width (W) 6 areas × 5 W/L ratios × 3 heights × 4 orientations = 360 options

Length (L)

Height (H) North

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observed in the middle of courtyards at 1.5m height. This location was selected to represent the average conditions in courtyards. In IES-VE, the research measured the sunlit area as a percentage to the total surface area for each of the courtyard’s four walls and the ground surface.

Figure 4. 9. An example of the modelled courtyard buildings in the simulation tools

 Urban spaces: this study compares the thermal conditions in typical residential roads, representing the thermal conditions of modern urban spaces, with conditions in courtyards. This comparison allows to determine the thermal conditions with which indoor spaces interact. For this purpose, in Envi-met simulation experiments, the study examined typical cases in Iraq, which included two modern urban fabric cases. The two simulated cases are of 9m and 12m wide streets (Figure 4. 10). Building heights were set to be between two

to three storeys, which is the typical residential building height in the country (Aladdin &

Alsdjan, 2013). The construction materials and forms of the street and the building were set to be in correspondence with the Iraqi context. The street is black asphalt and buildings were built of light-colour concrete blocks and bricks.

Figure 4. 10. Simulated modern urban fabric model in Envi-met

C. Simulated cities' climatic conditions

This study took Baghdad as a case study for the simulation experiments. The study did not include the whole country because doing such simulation work would have exponentially increased the simulation load and analyse efforts. Accordingly, for the climatic conditions of

Courtyard space Indoor space

Street

Modern non- courtyard

urban block Modern non-

courtyard urban block

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Baghdad, four days that represent the typical conditions of summer, winter, spring and autumn were identified and used in the simulation. These four days were selected following analysing

the hourly climatic conditions of Baghdad using unpublished data from the Iraqi Metrological

Organization and previous literature (Bilal, Al-Jumaily, & Habbib, 2013) (Table 4. 3). Table 4. 3. Selected simulation days' climatic conditions - Baghdad

Season / date

Climatic conditions

Air temperature (°C) Humidity (%) Wind

speed (m/s)

Direction

Min. Time Max. Time Min. Time Max. Time

Typical winter / 21st _{of January} 13.6 04:00 19.7 14:00 68.0 14:00 89.0 04:00 2.7 East Typical spring / 16th _{of March} 21.8 06:00 27.0 14:00 44.0 14:00 51.0 06:00 2.0 East Typical summer/ 1st _{of august} 31.6 06:00 46.8 16:00 26..0 16:00 41.0 06:00 1.3 East Typical autumn/ 1st _{of October} 27.0 07:00 38.0 15:00 39.0 15:00 63.0 7:00 2.6 East

In IES-VE, the research assumed a clear sky status, which is the typical status in most of the

year in Iraq (Iraqi Meteorological Organization; Al-Biaty, 2018). Assigning the other climatic

conditions in IES-VE was not relevant as the aim of using this software was only to determine courtyard insolation, which is not affected by climatic conditions, but changes according to the geographic location of the simulated place. The location was set to Baghdad. Regarding Envi- met, this software requires manual input of climatic conditions. This includes air temperature, humidity, air velocity, cloud coverage percentage and solar radiation. The climatic conditions of the defined four days were used as inputs for the software (Table 4. 3). The solar radiation was kept to its default calculated value by the software. It is recommended by the software guidelines not to modify this value unless the user has advanced relevant knowledge. The cloud cover was set to be ‘clear sky without clouds' to represents the typical weather conditions in Iraq, which corresponds with IES-VE the simulation. Neither rain nor dust storms have been considered in the simulation. These conditions do not represent the typical Iraqi climate, as

they occur only during a short period during the year (Iraqi Meteorological Organization).

The results of the simulation experiments provided the thermal conditions of various courtyards in Baghdad during the examined four days, and the impact of the geometric properties of courtyards on their thermal conditions. The resulting dataset of simulation outputs was used to develop a regression equation that can be used to interpolate the annual hourly thermal conditions of the examined courtyards. This was required to determine CTUI and assess the thermal efficiency of courtyards.

Regarding the applicability of these results to other locations, it can be said that the relative impact of courtyard geometry on thermal conditions in courtyards is applicable to other cities in Iraq, or countries of similar climate. For instance, if a deeper courtyard in Baghdad is of a lower globe temperature, then it is of a lower globe temperature in other climatically similar places. But, the specific conditions of courtyards in Baghdad are not necessarily the same as in other cities. The reason is that thermal conditions in courtyards, as an outdoor space, are affected by the detailed outdoor climatic conditions of other places. This may lead to courtyards in other cities being colder or warmer than in Baghdad. Accordingly, the thermal comfort

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assessment of Baghdad may be different from other cities of different climatic conditions. To determine the range of differences and the applicability of the results of Baghdad to other cities in Iraq, the hottest and coldest courtyard options from the 360 examined courtyards were simulated in six cities in the country: Erbil, Mosul, Duhok, Ramadi, Muthana and Basrah. These two courtyards were simulated to show a clear indication of the difference between the thermal performance of courtyards in Baghdad and other cities. The considered cities in the simulation represent the whole range of climatic conditions in Iraq (Figure 4. 11). Their typical summer and typical winter climatic conditions were used in their simulation experiments (Table 4. 4).

Figure 4. 11. Included cities in Envi-met simulation on a climate map of Iraq

Summer temperature Winter temperature

Wet climate

Dry & Semi-dry climate

Very dry climate

Mosul Al-Ramadi Erbil Muthana 2 4 4 6 6 10 8 10 12 12 8 30 28 30 34 34 34 32 32 36 36 36 36 2 28 Duhok Basrah Baghdad

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Table 4. 4. Used climatic conditions of the simulated cities in Envi-met

Season / date

Climatic conditions

Air temperature (°C) Humidity (%) Wind

speed (m/s)

Direction

Min. Time Max. Time Min. Time Max. Time

Erbil Typical winter / 21st _{of January} 3.6 04:00 14.9 14:00 42.4 14:00 98.0 04:00 0.95 East Typical summer/ 1st _{of August} 24.9 06:00 42 16:00 4.8 16:00 41.8 06:00 0.89 East Duhok Typical winter / 21st _{of January} 2.5 04:00 12.5 14:00 42.4 14:00 98.0 04:00 0.95 East Typical summer/ 1st _{of August} 23.3 06:00 40.5 16:00 4.8 16:00 41.8 06:00 0.89 East Mosul Typical winter / 21st _{of January} 6.7 04:00 18.9 14:00 42.4 14:00 98.0 04:00 0.95 East Typical summer/ 1st _{of August} 27.1 06:00 44.9 16:00 4.8 16:00 41.8 06:00 0.89 East Muthana Typical winter / 21st _{of January} 3.0 04:00 19.3 14:00 18.6 14:00 70.1 04:00 2.3 East Typical summer/ 1st _{of August} 28.2 06:00 47.8 16:00 5.2 16:00 23.5 06:00 3.4 East El-Ramadi Typical winter / 21st _{of January} 5.3 04:00 19.0 14:00 28.7 14:00 79.5 04:00 2.2 East Typical summer/ 1st _{of August} 26.1 06:00 43.9 16:00 5.4 16:00 30.2 06:00 4.5 East Basrah Typical winter / 21st _{of January} 6.2 04:00 20.5 14:00 20.9 14:00 72.8 04:00 2.4 East Typical summer/ 1st _{of August} 29.5 06:00 49.2 16:00 4.6 16:00 42.5 06:00 2.8 East D. Simulation calibration

Simulation models used in this study were calibrated to ensure accurate simulation results. This was only done for the Envi-met simulation model. Regarding IES-VE, calibration was not required as its simulation is related to accurately determining the position of the sun around the year and shadow casting, which has been validated by previous studies and scientific

organizations such as ASHRAE and CIBSE (Nikpour, Kandar, & Roshan, 2013; Yazhari

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Regarding Envi-met, it was essential to carry out a calibration experiment. This was for two reasons. First, the aim of the research was to determine, as accurately as possible, the actual thermal sensation of occupants in courtyards in Baghdad. Second, the results of Envi-met depend on a wide range of interrelated factors. Accordingly, for each specific context, the simulation model needs to be calibrated for accurate results. For this purpose, the simulation model was calibrated using actual measurements of two courtyard houses in Baghdad obtained

from third-party measurement efforts (Al-Azzawi, 1984; Salman, 2016)(Refer to Appendix E

for further details). The Baghdadi courtyard houses used for these measurements were modelled in Envi-met. The properties of courtyard surfaces were fine-tuned until the simulation results were similar to the real-life conditions. To check the validity of the calibration and the accuracy of the built simulation model, the Coefficient of Variation for the Root Mean Squared Error (CV-RMSE) statistical test was conducted. This equation gives a percentage showing the accuracy of simulation results in comparison to real-life conditions. Lower resultant values

indicate a better-calibrated model (Bagneid, 2010; Haberl & Bou-Saada, 1998). The

comparison showed that the simulation results agree strongly with the actual thermal measurements of both of the examined courtyards (Figure 4. 12). The maximum CV-RMSE indicates that there is only a 7.2% margin of error in the simulation data. According to the ASHRAE standard, for hourly data simulation, the simulation model can be declared to be

calibrated if the result of this equation is within ± 30% (Bagneid, 2010). This research used

the thermal properties of the calibrated model to ensure accurate results in simulation experiments (Table 4.5). The thermal properties used in the simulation are not claimed to be identical to the thermal properties of the actual houses; however, they lead to having similar thermal conditions in the simulation to actual houses’ conditions. The thermal conditions in the calibrated simulation model combine the interaction of various effective factors in actual courtyards, including the building thermal properties, occupants’ behaviours and courtyards interaction with surrounding indoor spaces.

CV-RMSE = ((∑ (Da – Dd)2/ P – 1))0.5/ Daa --- The validation equation

where:

Dp = the predicted data, Da = the actual data, Daa = the average value of the actual data, P = the

number of data points

Figure 4. 12. Calibrating Envi-met simulation model (Refer to Appendix E for further details)

This difference is due to the asymmetric outdoor air temperature curve in real-life conditions, which is not possible to be included in Envi-met simulation. This difference is not because of the simulation inaccuracy.

Plans have been removed due to

Copyright restrictions.

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Table 4. 5. Thermal properties used in Envi-met simulation experiments

Thermal property Value Thermal property Value

Thickness 0.30 m Emissivity 1.10 Frac

Absorption 0.80 Frac Specific heat 1300.0 J/(Kg*K)

Transmission 0.00 Frac Thermal conductivity 0.30 W/(M*K)

Reflection 0.05 Frac Density 1000.0 (Kg/M3₎

Note: The simulation period length was set to be 32 hours, starting at 00:00. The first six hours were not considered in the results as they do not include the impact of the stored heat during the daytime on the thermal conditions of courtyards.

To further validate the simulation results, the air velocity in the simulated models was compared with in-situ data measurements from the two referenced courtyard houses. It was found that simulation results and recorded measurements are highly similar. In both cases, the air velocity in the courtyard is lower than that in the urban situations. In both cases, when the average outside air velocity is around 2.0 m/s, the air velocity in courtyards is between 0.2 and 0.3 m/s. Regarding the MRT, it was not possible to validate outcomes as there are no in-situ data measurements of MRT in actual courtyards. However, this was not considered a problem as the ability of Envi-met to simulate MRT in spaces similar to courtyards had been validated in previous studies.

This calibration approach, which involves a trial and error process, has been used in

previous studies (Gusson & Duarte, 2016; Hasehzadeh Haseh, Khakzand, & Ojaghlou,

2018; Shinzato, Simon, Silva Duarte, & Bruse, 2019). Other approaches, such as the optimization-based calibration can lead to more accurate simulation models. However, it was not a feasible option for this study due to the complexity of the climatic conditions in

urban contexts and the long and time-consuming process (Maleki, Kiesel, Vuckovic, &

Mahdavi, 2014). E. Analysis approach

The data obtained from Envi-met and IES-VE were arranged in Excel sheets. IBM SPSS statistics 24 package was used to analyse the correlations between the various explored variables. The analysis included conducting regression analyses. There were two aims from doing the analysis. The first aim was to determine the impact of courtyard geometry on resulting thermal conditions in order to indicate approaches that can help to manipulate the thermal conditions in courtyards. The second aim was to develop equations that can be used to predict thermal conditions in contexts not simulated by this study but of similar climatic conditions.