An Analysis of Thermal Comfort in a School’s Outdoor Space: A Case Study of a Typical School, Dubai, UAE

Lana Isam Abu-Qulbain ¹, Hanan M. Taleb ^2,*

1. Sustainable Design of Built Environment, Faculty of Engineering, British University, Dubai, UAE

2. Faculty of Engineering, British University, Dubai, UAE

* Correspondence: Hanan M. Taleb

Academic Editor: Cheng Siew Goh

Special Issue: Sustainable Built Environment

Received: October 29, 2024 | Accepted: February 24, 2025 | Published: April 01, 2025

Adv Environ Eng Res 2025, Volume 6, Issue 2, doi:10.21926/aeer.2502015

Recommended citation: Abu-Qulbain LI, Taleb HM. An Analysis of Thermal Comfort in a School’s Outdoor Space: A Case Study of a Typical School, Dubai, UAE. Adv Environ Eng Res 2025; 6(2): 015; doi:10.21926/aeer.2502015.

© 2025 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

1. Introduction

The outdoor environment is a place of great dynamism because it continuously changes, giving an excellent opportunity for us humans to learn, interpret and understand it. Children, who according to the United Nations Convention on the Right of the Child, are young people whose age is below 18 years, can greatly benefit from the outdoor environment because their healthy development and enhanced wellbeing is highly associated with it. They greatly benefit from an outdoor environment: their physical, mental, social, emotional, and academic wellbeing can be improved when spending quality outdoor time [1]. Accordingly, the American Academy of Pediatrics and the U.S. National Wildlife Federation advise that children spend at least one hour physically active outdoors [2].

A recent study on a representative sample of students in the UAE revealed that they are more inclined to spend time indoors, where only 16% of the participating students achieved the moderate-to-vigorous recommended activity intensity level [3,4]. Consequently, the move towards staying indoors results in a global phenomenon: “Nature Deficit Disorder” [5]. As a result, the new generation of children prefer being indoors over being outside in the natural environment [6].

Schools, particularly, represent an opportunity to tackle the issue of “Nature Deficit Disorder”. Yearly, children spend almost 175 to 220 days at school, impacting multiple facets, such as cognitive, physical and mental development [7,8]. As such, enhancing the thermal comfort of outdoor school spaces provides students with equal opportunities for outdoor exposure [9]. The design of outdoor spaces first received attention in the 2000s, with Moogk-Soulis investigating the thermal conditions of outdoor school spaces [10] by studying 275 schoolyards, revealing the “Schoolyard heat island” effect. Owing to a lack of trees and the presence of artificial materials of high heat capacity - such as cement, asphalt, and synthetic turf, it tended to have a hotter microclimate compared to its surroundings [11,12,13].

Although research shows that the most critical aspect of designing outdoor spaces in schools should be ensuring thermal comfort, little attention has been given to this factor [14], as no study combines different strategies for outdoor school spaces and analyzes their impact. Consequently, schools should maximize the benefits of their outdoor spaces, and investigations into the status of these spaces in the UAE are limited as a result. The current study will investigate their status by assessing them and providing solutions by analyzing a typical school in Dubai.

2. Literature Review

Schools’ outdoor spaces are primarily used for break-time, occurring at midday, during high sun intensity [15]. As schools are usually built around or inside existing residential compounds, priority is given to the school buildings’ design along with outdoor sports fields, which results in fragmented spaces for free play [16]. Considering numerous articles dated from 2018 to 2022 using Google Scholar, Science Direct, and bibliographies of articles, twelve research papers regarding school outdoor spaces were found. Five studies revealed that increased tree planting was the optimum solution for heat mitigation in the outdoor spaces of educational buildings as it improves outdoor thermal comfort and reduces Physiological Equivalent Temperature (PET) [17,18,19,20,21].

The impact of vegetation in school courtyards revealed that a vegetal façade acted as a fundamental enhancer of outdoor thermal conditions, up to 11°C [19]; whilst [18], which looked into evaluating and improving student thermal perception of the outdoor space, concluded that increasing tree density and greenery reduced heat stress and resulted in a significant reduction in PMV. Meanwhile, some studies found that adding shading had the most critical effect on the area under the shade, reducing its heat conditions [22,23]. Moreover, a study that explored the impact of several sun-sail shading coverage canopies on a courtyard revealed that 60% or more sun-sail shading resulted in a reduction of 0.5°C in air temperature and 0.6 in the PMV scale [23].

However, little research has been done on the outdoor comfort of schools compared to other buildings, such as office buildings. The significance of such research stems from the fact that students, especially the young ones, do not know how to express themselves; they may come wearing a jacket in the morning and may keep it on all day as temperatures rise and as they go out to occupy their outdoor spaces especially in hot climates [24].

Therefore, whilst many studies have investigated varying factors affecting thermal comfort, there are still limitations regarding the extent of the current research available. As such, this study aims to fill that gap by identifying and investigating the multifaceted role of thermal comfort and its impact on students in schools’ outdoor locations.

3. Methodology

To investigate the current conditions of a typical school’s outdoor spaces and improve them, a survey, design workshops, and simulation analysis will be combined, strengthening the conclusion by merging both qualitative and quantitative data [25]. ENVI-met version 5.2/5.3 will be used to simulate the outdoor thermal conditions of the base case and to analyze the improvements [23,26]. ‘LEONARDO’, the imaging software of ENVI-met, will aid in visualizing the data [10]. Moreover, thermal indices will be calculated through ‘BioMet’ software from ENVI-met using the output files from LEONARDO to give an overview of human thermal perception [27].

For this study and its location in Dubai, UAE, the PET thermal index will be used since it is one of the most detailed indices available for the outdoor environment, incorporating meteorological factors and personal factors [23]. Also, it is recommended by ENVI-met to use PET as a thermal comfort indicator, rather than PMV and UTCI [27].

3.1 Case Study

The case study school is located in Nad Al Sheba, Dubai, and has 433 students. The school’s site comprises three buildings that share outdoor spaces, as shown in Figure 1, and the total area of the plot is 46,155.54 m² [28,29]. The case study building is one of the three buildings and is labeled Phase 1 in Figure 1. Figure 2 shows an image of the case study building [30,31,32].

Figure 1 School Site Plan (Authors 2023).

Figure 2 Phase 1: School Case Study [32].

The schools’ outdoor spaces have several palm trees and a few other varieties, such as Conocarpus Dilver and Ficus Panda, and shrubs like Tecoma Stans, Tecomaria Capensis and Jatropha Pandurifolia [31]. The outdoor areas are shown in Figure 3 where large green circles represent palm trees of 5 m height, and small green circles represent smaller trees, 2-3 m high [28].

Figure 3 Outdoor spaces with vegetation (Authors 2023).

3.2 Study Domain

The focus of the study will be primary school children aged 7 to 11 from the phase 1 building. After having obtained the consent of parents, these students will be participating in the workshop and the questionnaire. This smaller sample was chosen due to ethical considerations, as well as to provide a more concise examination of school students. However, investigating outdoor spaces will include all outdoor spaces since students from the three buildings share them. The temporal range of this study will be break-time which occurs for 25 minutes, twice, between 9:00 and 10:00 a.m. and 12:00 and 1:00 p.m. Consequently, inspired by the research workflow map by Zhang et al., Figure 4 represents the current research workflow process.

Figure 4 Workflow Process inspired by workflow map by Zhang et al. [16].

3.3 Building the Base Case on ENVI-Met

Architectural drawings of the buildings, in addition to specific materials identified by the engineering firm, were used to construct the school on ENVI-met. Materials used for the outdoor spaces in the software include artificial turf, PVC, grey concrete, asphalt and a running track.

Table 1, similar to a table done by Galal et al., provides more details that represent the simulation settings of the ENVI-met model [33].

Table 1 Parameters for ENVI-met model (Authors 2023).

Moreover, the existing trees were constructed using the ‘Albero’ software of ENVI-met depending on their type, height, and features. Furthermore, for weather conditions’ settings and simulation, full forcing was used, incorporating the Energy-Plus weather file (.epw) file, specific to the longitude and latitude of the school’s location. Finally, after all the above was set up, the base-case model was built, as shown in Figure 5.

Figure 5 School Model on ENVI-met (Authors 2023).

4. Results

Six scenarios were set up for simulation, where October represented autumn conditions, February represented winter, and June represented summer conditions. The scenarios for analysis are shown in Table 2.

Table 2 Simulation scenarios through month, date and time (Authors 2023).

Later, the six variables were investigated and extracted from ‘Leonardo’ ENVI-met. The variables are listed in Table 3 below, as those related to the microclimate of the outdoor spaces or the thermal perception of students.

Table 3 Thermal features’ variables of comparison (Authors 2023).

4.1 Local Microclimate Variables

4.1.1 Potential Air Temperature

Figure 6 shows this variable for all scenarios. It is crucial to note that colors in the images correspond to different values depending on their scale. Like Antoniadis et al., shaded areas had lower temperatures than non-shaded areas [10]. Moreover, the courtyard highlighted with a black circle in (f) has more solar radiation at noon than (b) of the same space, thus higher temperatures, due to the sun’s more perpendicular position. However, like Zhang et al., the other courtyard highlighted using a grey circle in (a) is within the lower temperature range because of light-colored sun sails [16].

Figure 6 Potential air temperature for the six scenarios (Authors 2023).

Additionally, the central, most open space in the school, referred to as Zone I in the image (a), displays higher temperatures in October and June due to the lack of vegetation and shading. Lastly, Figure 7 shows a graph with maximum and minimum temperature values, revealing that temperatures in October and June are beyond the comfort range.

Figure 7 Graph showing max. And min. Temperature ranges for the different scenarios, where the red bar defines the comfort range of PET at 18°C to 27°C (Authors 2023).

4.1.2 Humidity

ASHRAE recommends that this variable be maintained below 60% in indoor spaces [35]. However, vegetation or water bodies can highly impact humidity in outdoor dynamic spaces. Considering the climate of Dubai, conditions become muggy from mid-April to mid-November, with humidity reaching levels of 80% and more. Figure 8 shows that relative humidity is high and gets lower around noon. However, in the case of the simulation for June, image (f) reveals that minimum moisture reaches 28%. This observation can be attributed to minimal vegetation that cannot raise humidity to an adequate level and add moisture to the air [10]. Figure 9 shows a graph of the minimum and maximum values of relative humidity, where in their maximum conditions, all scenarios exhibit humidity higher than the comfort range, and the minimum relative humidity in scenario (f) is low and is almost out of the comfort range [36].

Figure 8 Relative humidity of the six scenarios (Authors 2023).

Figure 9 Minimum and maximum values for relative humidity where the red bar represents comfort range (Authors 2023).

4.1.3 Direct Solar Radiation

Figure 10 reveals a pattern of reduced solar radiation in areas surrounding trees by 400 to 500 W/m², due to the geometry of trees that allows for shading [12]. Additionally, similar to the study by El-Bardisy et al., and as seen in images (b), (e) and (f), marked using a black circle in Figure 9, solar radiation falls directly into the courtyard due to a lack of shade, especially in June [12].

Figure 10 Direct solar radiation of the six scenarios (Authors 2023).

Comparing the images on the left to those on the right, the noon simulation reveals that Zone I is always exposed to the sun and lacks any form of shading except for the two play areas situated around the green field, resulting in increased temperatures, as previously observed in Figure 5. Figure 11 below shows that the maximum solar radiation values exist in October and June at noon.

Figure 11 Solar radiation maximum values (Authors 2023).

4.1.4 Ground Surface Temperature

The school is mainly covered with grey pavement, as shown in Figure 12. However, there is an existing sandpit shown in Figure 13, a large green turf field and a red rubber running track shown in Figure 14.

Figure 12 Gray pavement at ASCS (Authors 2023).

Figure 13 Sandpit at ASCS courtyard (Authors 2023).

Figure 14 Rubber running track and green turf field (Authors 2023).

Figure 15 shows that ground surface temperatures increase exponentially around noon due to direct solar radiation, similar to the study by Antoniadis et al. [10]. Ground materials of higher albedo had lower temperatures, visible in the sandpit annotated using a black circle in the image (b). On the other hand, those with lower albedo, like asphalt, which is color-coded orange and yellow in most of the images, and artificial turf and the rubber running track, color-coded red and magenta, exhibit surface temperatures on the higher range of the scale. Areas of shade exhibited the least ground surface temperatures regardless of their material. These areas are mainly color-coded green, having temperatures within 30°C.

Figure 15 Ground surface temperature variable (Authors 2023).

Figure 16 shows the running track surface temperature under shade and direct sun, revealing that shade is essential to ensure thermal comfort, because surfaces exposed to the sun can easily exceed their burn threshold contact time, thus leading to heat injuries. Appendix B shows the burn thresholds for some materials [37]. Finally, Figure 17 shows the minimum and maximum temperature ranges for this variable, also revealing that the maximum temperatures occurred in October and June.

Figure 16 Running track surface temperature in the shade and the sun (Authors 2023).

Figure 17 Maximum and minimum ground surface temperatures (Authors 2023).

4.1.5 Wind

The analysis here gives an insight into wind behavior and areas of faster speed rather than the speed value itself, because wind speed was set to 2 m/s from the west to reduce model instability. 2 m/s, which allows for natural ventilation in hot and humid climates, is within the comfort range according to Lawson’s comfort criteria, as shown in Figure 18 [38,39].

Figure 18 Lawson wind comfort range [38].

Areas adjacent to buildings are more likely to be impacted by variations in wind, and this can be seen in Figure 19 and Figure 20, for the two scenarios in October [16]. Additionally, in all scenarios, from Figures 19 to 24, the wind movement in courtyards is minimal.

Figure 19 Scenario 1 wind analysis (Authors 2023).

Figure 20 Scenario 2 wind analysis (Authors 2023).

Figure 21 Scenario 3 wind analysis (Authors 2023).

Figure 22 Scenario 4 wind analysis (Authors 2023).

Figure 23 Scenario 5 wind analysis (Authors 2023).

Figure 24 Scenario 6 wind analysis (Authors 2023).

4.2 Thermal Perception Variable: PET

PET is an index that considers internal heat production within the human body and the energy exchange between the human body and surrounding surfaces. Thus, the result is an ‘energy balance model’ that is quantified, based on research, into categories of comfort or discomfort. Figure 25 shows the thermal comfort range for PET bearing in mind that the comfort range can extend beyond what is shown to include 18°C up to 27°C [11,40].

Figure 25 PET thermal comfort range [40].

Figure 26 shows the set-up applied for the personal human parameters of the PET simulation in the ‘Biomet’ of ENVI-met, highlighted using a red rectangle. The settings were set to the minimum accepted by ‘Biomet’ to get closer to the parameters of students from grades two to five.

Figure 26 Human parameter for PET calculation in 'Biomet' of ENVI-met (Authors 2023).

Looking into PET in Figure 27, most outdoor spaces display high PET values, corresponding to extreme heat stress [17]. These spaces share several characteristics: they are unshaded, they are distant from trees or vegetation, and they are covered by low albedo materials.

Figure 27 PET variable (Authors 2023).

Moreover, courtyard spaces show high levels of PET, as discussed by Zhang et al.; the enclosed spaces of courtyards result in less wind circulation and, thus, higher PET. Moreover, the open space of Zone I allows wind to mitigate heat stress, as mentioned in the wind analysis, thus allowing for a lower PET [16]. Furthermore, it is noticed that most of the areas adjacent to the south facades of the buildings display the highest PET range, because the façade is subject to intense solar radiation, increasing the temperature of the air surrounding it. Finally, Figure 28 below shows the minimum and maximum values of PET obtained from the analysis, revealing that the 9 a.m. February scenario is the only one with maximum values that fall within the comfort range of PET.

Figure 28 Minimum and maximum PET values (Authors 2023).

4.3 Analysis of the Surveys

With parental consent, children aged 7 and above can independently participate in surveys, but the questions provided must be literal and precise and focus on feelings [41]. To make the survey more understandable to young students, answers will be supplemented with pictures similar to a questionnaire designed for the thermal perception of children by Huang et al. [37]. Question Pro was used to design the survey, as Appendix A shows.

The students participated in the questionnaire, comprising 17 questions, and took an average of 7 minutes to complete. During the survey, similar to the study by Vanos et al., students were asked to focus on their overall feeling of thermal sensation [15]. On the other hand, unlike the survey by Shih et al. that occurred once in summer and once in winter, the period of the current survey took place between the 31st of January to the 3rd of February 2022, where the weather was comfortable, ranging between 17°C to 25°C [42]. For that, students were asked to think of their thermal sensations all year long.

Table 4 shows the participants' gender and, similar to the surveys by Shih et al. and Dunzeli et al., there was an almost equal number of male and female participants [13,43].

Table 4 Gender of the participants (Authors 2023).

Figure 29 shows bar graphs that represent the survey answers, where the green bar highlights the answer most often chosen per question.

Figure 29 Students’ survey answers (Authors 2023).

For the research, a few questions will be focused on. For example, in the fifth question, 77% of the students preferred spending time outside, highlighting the importance of enhancing these spaces, and when asked about their favorite school spaces in the seventh question, using Figure 30, most of the participants chose space 6 followed by 5. The choice of students here was similar to the choice of students in the study by Mokhtarmanesh et al., where participants preferred school playgrounds followed by schoolyards [7].

Figure 30 Diagram used during the survey (Authors 2023).

In the eighth question, students were asked why they preferred these spaces, as shown in Appendix A, question 8, where ‘The kind of play area’ was the choice most chosen. The answer here is similar to the answer in the survey by Duzenli et al., where most of the participants chose playing games outside as their favorite activity in school [43]. Moreover, in the study by Shih et al., 20% of the participants selected playgrounds as the areas of most thermal comfort compared to other school spaces, revealing the significance of play for students, as suggested in the answers of the current survey [13]. Furthermore, ‘size of space’ was selected by 22% of the participants, especially those who chose space 5 (the green field) as their favorite space. Open spaces like the green field are less restrictive for students, allowing them more interaction opportunities [43]. Moreover, 22% of students chose to write why they chose their spaces, and the answers are shown in Appendix C. Most of the reasons were related to space five being ‘big’. The findings here are similar to the study by Mokhtarmanesh et al., where participants preferred ‘big yards’ at schools [7].

In the ninth question, students were asked to choose their least favorite space, if any, and most students chose space 9, followed by 8, as shown in Figure 29, and when they were asked why in question 10, more than half of the students chose to write their answer. Appendix C displays the different answers depending on the space, revealing that specifically for spaces 9 and 8, students were aware of clutter, preferred clean organized spaces and did not prefer spaces filled with sand.

For question 11, students were asked to rate their thermal sensation when occupying their school’s outdoor spaces. The results showed that 25%, of whom 6 were girls and 2 were boys, felt neutral. This is similar to the study by Huang et al., where females seemed to have less thermal sensitivity in hot conditions [37]. However, most students chose conditions that signal thermal discomfort, with 16% feeling slightly warm, 16% feeling warm, and 22.5% feeling hot, thus shedding light on the fact that there is a varying sense of outdoor discomfort [15]. Moreover, the students' answers here are related to the PET conditions investigated, revealing an overlap between data obtained through the simulation and survey analysis. Moving on, in question 12, 93.55% of the students expressed a desire for more time outdoors in their school, shedding light on the importance of refurbishing these spaces, because (as the study by Duzenli et al. showed) post Covid-19, students missed spending time in their schoolyards [43].

Next, in question 13, as shown in Appendix A, looking into different outdoor activities they can engage with, students chose playing and physical activities the most, as shown in Figure 29. The option of having outdoor learning and lessons came next, giving an insight into the more excellent value of extending the classroom to the outside [44]. For question 14, students selected ideas that would enhance their outdoor spaces, allowing them to take part in the process of enhancing their schools’ spaces. As shown in Figure 29, most students chose to add more play areas and larger spaces, followed by ‘more seating areas’ and ‘more trees and vegetation’; the option of more trees and vegetation can impact the outdoor thermal conditions.

4.4 Analyzing Students’ Drawings

According to the study by Elgheznawy, improved academic performance is positively related to student satisfaction. Thus, it is important to include students in all decisions that impact them directly [23]. Therefore, as the surveys were taking place, other participating students drew what they would like to change in their school outdoor spaces. Using the same diagram with numbered outdoor locations, students were asked to pick one location whose number they wrote on the A4 supplied to them, and they were given 20 minutes to draw and/or write the changes they wanted to see in that location. Appendix D displays the 29 drawings. Figure 31 demonstrates how often outdoor spaces were picked as areas to be changed.

Figure 31 Frequency of choosing school outdoor spaces for the workshop drawing session (Authors 2023).

The location most often chosen by students was space 6, shown in Figure 32, followed by space 5, shown in Figure 33. Likewise, in the survey, location 6 was chosen as the favorite area, followed by space 5. It seems that students chose their favorite space to push it further, so they could spend more time playing in it. As for suggestions for space 6, they included some elements that could enhance thermal comfort: more shade, benches, chairs, and more trees.

Figure 32 Space 6, the most frequently chosen space for the workshop drawing session (Authors 2023).

Figure 33 Space 5, the green field (Authors 2023).

For space 5 specifically, most students asked for a shading structure over the green field, benches, and a seating mat to relax. Moreover, two drawings had a small structure that represented a shelf to store water bottles safely. These suggestions reflect the students’ needs based on their interaction with their spaces. Similar to the study by Nordstrom and Wales, child inclusion in urban planning challenges the existing adult-child relationship and provides unprecedented perspectives that broaden the existing one [45].

Considering existing literature, and analysis, the strategies shown in Figure 34 will be combined to enhance the existing conditions. The PET index of the base case will be compared to the enhanced case to analyze the improvement made.

Figure 34 Strategies for enhancing ASCS outdoor spaces (Authors 2023).

Figure 35 represents the base case, while Figure 36 shows the enhanced case. Figure 37 shows the simulation results of PET for the base-case and Figure 38 shows that of the enhanced case. The comparison of PET will focus on spaces 3, 4, 5, 6, and 9 in image (a) of Figure 37 and Figure 38 due to their significance to the children, as inferred from the workshop and the questionnaires.

Figure 35 ASCS base-case ENVI-Met model (Authors 2023).

Figure 36 Cumulative strategies improved ASCS ENVI-met model (Authors 2023).

Figure 37 PET of ASCS Base-case (Authors 2023).

Figure 38 PET for ASCS improved case (Authors 2023).

Table 5 below summarizes the PET improvements resulting from the strategies for the separate locations numbered in Figure 36 and Figure 37. Moreover, Table 6 shows the minimum and maximum PET of the locations too.

Table 5 Cumulative PET comparison to Base-case of ASCS depending on location (Authors 2023).

Table 6 Maximum and minimum PET values comparison between Base-case and improved case of ASCS (Authors 2023).

Looking at Table 5, the noon scenarios show more PET reduction when comparing the base case to the enhanced case. Play area 3 has the most PET improvements, with a 21% to 25% reduction in the scenarios of noon, October, and February. Figure 39 shows the space in its current condition with an existing canopy that shades it, but still allows sun penetration from the south. Consequently, trees were added to shade the play area from the south. Moreover, a green wall was added, as pointed out in Figure 35. In addition to shading the green field, area 5 also aided in shielding the play area from direct sunlight.

Figure 39 Play area 3, ASCS (Authors 2023).

The combination of strategies of a green façade, increased trees and shade, and the location of the play area that would allow for wind to tunnel through resulted in better PET for this space that was favored by 10.53% of students, as noted by the survey. After the enhancements, the space falls almost within the higher PET comfort range, for the scenarios of 9 a.m. for October and June, and for the 9 a.m. and 12 p.m. for February.

Space 4, shown in Figure 40, exhibits the second highest PET reduction, as shown in Table 5, accounting for a 16% reduction at noon, October 14th. Comparing the same space for the 12 p.m. scenarios of the base-case in Figure 36, compared to the improved case in Figure 38, reveals that in the base-case, play area 4 always had worse PET conditions than the mirrored play area facing it, space 6. Even though the play area is shaded, there is direct solar radiation from the south, as noted in Figure 40. However, the PET of play area 4 was improved and became similar to that of play area 6, as shown in the 12 p.m. simulations (b), (d) and (f) of Figure 38, because of the shading over the green field. Shading around the green field will cast a shadow over the adjacent play area, thus reducing PET. After the enhancements, the space falls almost within a higher PET comfort range for the scenarios of 9 a.m. for October and June, and for both scenarios in February.

Figure 40 Play area 4, ASCS (Authors 2023).

As for the green field, space 5, shown in Figure 41, is unshaded, with direct solar radiation. However, this space was the second most favored space as the questionnaire and workshop showed; 19.30% of students favored its ‘big size’. At the same time, space 5 was often chosen during the workshop, where students spoke of needing shading, benches and resting spaces. Due to this, 4 m wide shading canopies were added around the periphery of the football field. Moreover, several trees were equally spaced next to the surrounding rubber running track around the green field. Zhao, Sailor & Wentz [46] found that trees arranged at equal intervals exhibited slightly lower PET values than the other arrangements, which aligns with the findings of this study; by equally spacing trees next to the surrounding rubber running track, as well as changing artificial grass to natural grass, the combined strategy resulted in a PET reduction of 7% to 15%.

Figure 41 Space 5, the Green Field, ASCS (Authors 2023).

Nonetheless, comparing space 5 in the base-case scenarios to the improved case reveals that in Figure 37, the green field always had PET levels similar to the surrounding area. In contrast, after the strategies were added, the space always exhibited lower PET levels, as shown in Figure 38, showing that combining the strategies resulted in an enhancement of the space.

After the enhancements, the space falls almost within the higher PET comfort range, similar to spaces 3 and 4, for the scenarios of 9 a.m. for October and June, and for both scenarios in February [47].

As for space 6, the play area shown in Figure 42, there has been an overall reduction in PET ranging between 1% and 10%. The play area, which was chosen as the favorite space in school by 23% of students, generally falls within the lower range of PET values on the right-hand scale in both Figure 37 and Figure 38. In its initial condition, this space has a shading canopy. It is located next to the area that has exhibited higher wind movement, as aforementioned, in the wind analysis of the base case. As for the enhanced condition, the space would be impacted by several equally spaced trees to its south, which can help reduce the direct solar radiation and improve the surrounding thermal comfort. It would also be impacted by the shading canopy added to the adjacent green field. After the enhancements, the space falls almost within the higher PET comfort range, similar to spaces 3, 4 and 5, for the scenarios of 9 a.m. for October and June, and for both scenarios in February [47].

Figure 42 Play area 6, ASCS (Authors 2023).

Finally, for space 9, the courtyard, analysis shows that this area always exhibited PET corresponding to the higher values on the right-hand scale in Figure 37 and Figure 38. This is due to the absence of ventilation, as previously mentioned, or it might be due to the ratio of the building to the courtyard. In one investigation, researchers have concluded that a 1.2 H/W ratio was better at achieving thermal comfort than a 0.7 H/W ratio [48].

The current condition of this space is as shown in Figure 43, but children expressed, through the questionnaire, that they disliked the clutter present here and did not prefer sand. As for the improved case, adding a vegetal façade and a green roof and then transforming the sand-pit into a green area has improved the space’s PET condition by 5% to 13%. An analysis of PET shown in Figure 37 and Figure 38 reveals that the narrower areas of the courtyard almost always had worse PET values compared to the wider central area at noon. In contrast, the broader area of the courtyard was thermally more comfortable at 9 a.m., and this was due to the sun angle that penetrates most of the space by noon, but at the same time, the width of the space allows for shade to be cast onto the narrower spaces.

Figure 43 Space 9, the courtyard. ASCS (Authors 2023).

After enhancements, the space is thermally comfortable for 9 a.m., the 15th of October scenario and for the January scenarios in the base case. Nevertheless, there has also been a reduction specific to the narrower edges of the courtyard only, wherein in the base case, their PET value was 36°C compared to 32°C in the improved case, thus allowing for this space of the courtyard to fall within the larger PET comfort scale.

5. Discussion

This study used a calibrated ENVI-met simulation model to analyze and improve the existing conditions of outdoor school spaces at ASCS, guided by findings from existing literature. The primary focus was to categorize the outdoor spaces by major function to enable point-to-point PET comparisons, and the study found that it was important to divide the ASCS outdoor spaces since each space had different initial conditions and thus, different responses or reactions to the combined enhancement strategies.

Contrary to the results by Dalia et al., which concluded that covering 60% of the courtyard improved thermal comfort, this study found that doing that resulted in worse PET courtyard conditions than the base-case due to the increased enclosure, as stated by [23]. Additionally, [16], states that the enclosed space of courtyards meant less dissipation of heat through wind thus causing a rise in PET.

Moreover, the findings demonstrated that cumulative strategies resulted in better maximum and minimum reduction of PET compared to individual strategies. It is apparent that the combination of strategies from the nearby green façade, trees and vegetation, and the existing condition of shade, seclusion and location that would allow for ventilation, resulted in better PET conditions for this specific space, as it was favored by 10.53% of the students. Additionally, evenly spaced trees along the rubber running track surrounding the green field were found to lower PET values. This finding aligns with [46], who found that trees arranged at equal intervals exhibited slightly lower PET values about the other arrangements; by equally spacing trees next to the surrounding rubber running track, as well as changing artificial grass to natural grass, the combined strategy resulted in a PET reduction of 7% to 15%.

When conducting the study, parents/guardians were asked to select what they would like their children to be engaged with the most, and similar to their children’s choice, 24% selected more playing followed by more physical activities. This finding contradicts [49] who reported that parents prefer more learning opportunities inside and outside the classroom. Moreover, after implementing the proposed interventions, the play area’s PET values generally fell within the higher comfort range during the 9 a.m. scenarios for October, June, and February, consistent with the findings of [47].

6. Conclusion

This study aimed to examine the enhancement and utilization of outdoor school spaces and has developed several key strategies to optimize their functionality and thermal comfort. The identified research gaps indicate that current studies have a limited ability to examine thermal comfort, resulting in a scarcity of research connecting thermal comfort and school spaces. The findings of this study suggest that spaces facing the north consistently exhibited the lowest PET values on the, and features such as trees, vegetative façades, and green roofs were found to improve thermal comfort by reducing heat stress, and ensuring proper airflow within these spaces is crucial for maintaining it. The study also found that it was significant to study the ventilation of the courtyard space to ensure the right ratio between the H/W of the courtyard relevant to the building. Furthermore, the timing of outdoor activities also impacts students' exposure to heat stress; so, adjusting break times to earlier hours during hotter months could minimize this exposure, enhancing student well-being.

Most schools in warm regions undergo a deterioration process that renders them obsolete according to the current sustainable design standards. The following implies that schools must undergo an indoor and outdoor refurbishment process, with an action plan that is based on research, to promote feasible and practical strategies that can mitigate heat stress [20]. The current research has proven that combining strategies of vegetation, shade, green roofs and facades, and water features led to a decrease of 5% to 25% in PET of the selected outdoor spaces at the school, moreover, including the several methods of simulation, observation, survey and workshop allowed for a better understanding of the local conditions and local students’ adaptation and desires. Although the different analyses of all the strategies may seem like a limitation since each topic was discussed with a certain degree of detail, it is recommended for future studies to investigate each strategy individually to analyze conditions further to create a well-developed approach to each problem.

Additionally, future studies may investigate each strategy separately to understand its impact. Specializing in each strategy can allow for the creation of a local manual that becomes a reference for local schools. Future surveys are also advised to take place in the space being studied, allowing students to relate directly to how they feel. Besides, future surveys should span the summer and winter to understand students’ thermal sensations better. Furthermore, an additional limitation of the current study could be the sample, which is children aged 7 to 11, limiting representativeness. Due to that, it is also recommended for future studies to integrate older children of high school age into the study, since they may provide different insights. Finally, future research may consider integrating dynamic devices that can respond better to the hourly changing solar position, wind and humidity to create a comfortable thermal comfort that can last all year [37], as well as local PET indexes relative to the UAE, and adapted to children.

There is ground for future contributions regarding the local outdoor school spaces, as the locations investigated in this paper had various thermal features and provided diverse thermal comfort. Therefore, depending on the child’s adaptive thermal behavior, different strategies suggest various points that the students may choose to find comfortable thermal ranges [37].

Author Contributions

Lana AbuQulbain, responsible for project development, data collection, data analysis and recommendations. Dr Hanan Taleb, responsible for data analysis and report review.

Competing Interests

The authors have declared that no competing interests exist.

Additional Materials

The following additional materials are uploaded at the page of this paper.

1. Appendix A: Shows the questionnaire used for students.
2. Appendix B: Shows burn thresholds for some materials.
3. Appendix C: Shows notes for choosing the favorite outdoor school spaces.
4. Appendix D: Shows notes for choosing the least favorite outdoor school spaces.
5. Appendix E: Students’ workshop drawings of changes or additions they want to apply to their outdoor school spaces.