Evaluation of impact of vegetation on thermal comfort in public spaces (Case study: Jabal Al-Drak residential complex, Shiraz)

Subject Areas : architecture

Mohammadbagher Bigdeli ¹ , Seyedeh Sedigheh Mirgozar Langaroudi ^{2 *} , Ahmadreza Kaboli ³

1 - Ph.D Candidate, Department of Architecture, Shiraz Branch, Islamic Azad University, Shiraz, Iran
2 - Assistant Professor, Department of Architecture, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.
3 - Assistant Professor, Department of Architecture, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran.

Received: 2024-11-13 Accepted : 2025-03-17 Published : 2025-07-15

Keywords: Thermal comfort, ENVI-met, PMV thermal comfort index, neighborhood green space,

Abstract :

Urban expansion and the need for housing have led to a decrease in green spaces and vegetation, impacting thermal comfort and temperature regulation in cities, resulting in increased air temperatures and heat stress that affect urban life. Given the importance of thermal comfort, extensive research has been conducted in various fields, including plants, building
facades and forms, and urban neighborhoods. Green spaces and vegetation can improve the urban environment and thermal comfort. Vegetation cools the surrounding environment through transpiration and shade, moderating the urban heat island effect and reducing the effects of heat stress on humans. However, the ability of green spaces to mitigate the effects of heat depends on various factors, including the type and form of vegetation and, most importantly, their arrangement in the site. Therefore, proper and intelligent design of vegetation is important for improving thermal comfort and microclimate.
Numerical simulations, such as ENVI-met software, are used to estimate and improve the environmental performance of urban spaces. Studies on thermal comfort in parks and urban open spaces, especially neighborhood parks, are important because these areas are easily affected by small-scale green spaces, and with intelligent design, microclimates can be created for thermal comfort. In this study, the ENVI-met three-dimensional urban microclimate model was used to investigate the thermal environment of an open space in a high-rise residential complex in Shiraz, Iran, on a hot summer day. By examining the site, without vegetation and also to create thermal comfort in a neighborhood park, five different vegetation patterns, including grass, plane trees, cypress trees, and combined trees (plane, cypress) arranged in the direction of the prevailing wind and combined trees (plane, cypress) arranged in the opposite direction of the prevailing wind were investigated. The results showed that increasing vegetation cover leads to improved thermal conditions of the environment, and the broadleaved vegetation pattern with more shading had the best performance compared to other patterns. However, excessive plant density may lead to a decrease in cooling efficiency. Among all the components, the main factor affecting thermal comfort was the mean radiant temperature. Also, for the software validation, field data were collected by a WBGT-2010SD device in the time interval of 10 hours in a street, in four selected points, including air temperature, mean radiant temperature, relative humidity, and air temperature, and similar modeling was done in the software with the existing buildings and also the number and type of vegetation cover. After obtaining the software outputs and examining the correlation between the obtained numbers, with a correlation coefficient of 0.85 to 0.89 in four points of the selected site in the software validation, we reached an acceptable result, which shows the high accuracy of the software. The results of this study showed that proper design of vegetation, including the number, species, and also different patterns of placement in the environment, can help to improve thermal conditions in urban spaces. There is a need for more studies in this field in different seasons.

References:

1. اخلاقی نژاد، فاطمه؛ و باقری سبزوار، هادی.(1402). ارزیابی آسایش حرارتی فضای باز در فرمهای مختلف حیاط در مقیاس همسایگی؛ نمونه موردی: اقلیم سرد و نیمه خشک سبزوار ، نشریه هنرهای زیبا – معماری و شهرسازی، دوره 28 ، شماره 1، 45-61. 10.22059/JFAUP.2023.352410.672828
2. قلی‌نژاد، اسماعیل. (1390). علل گرم شدن زمین. همایش ملی تغییر اقلیم و تاثیر آن بر کشاورزی و محیط زیست.
3. سازمان مدیریت و برنامه ریزی فارس،21:1375 .
4. رجب بیگی، الهام؛و عرفانیان سلیم، رامین؛و جعفری، سید محمد.(1393). مروری بر کارایی گیاهان در تعدیل اثرات و سازگاری با تغییرات اقلیمی در محیط‌های شهری با تأکید بر صفات عملکردی گیاهان، فصلنامه علمی- پژوهشی علوم محیطی، دوره 12، شماره 4. https://envs.sbu.ac.ir/article_97449.html
5. هاشمین، ابوالفضل؛ وزرکش، افسانه؛ و گارسیا، ایستر؛و سوزنچی، کیانوش.(1401). تأثیر طرح کاشت درختان بر آسایش حرارتی انسان در مقیاس میکرواقلیم؛ نمونه موردی: محوطه دانشکده هنر دانشگاه تربیت مدرس. مطالعات نظری و فناوری های نوین معماری و شهرسازی،دوره ۱۲، شماره ۲. 138-158. http://bsnt.modares.ac.ir/article-2-61858-fa.html
6. Aboelata, A., Sodoudi, S., (2020). Evaluating the effect of trees on UHI mitigation and reduction of energy usage in different built up areas in Cairo. Build. Environ, 168, 106490. https://doi.org/10.1016/j.buildenv.2019.106490
7. Alexandri, E., Jones, P., (2008). Temperature decreases in an urban canyon due to green walls and green roofs in diverse climates, Building and Environment 43(4):480. DOI:10.1016/j.buildenv.2006.10.055
8. Álvarez-Rodríguez, C., Hernandez, E., Aracil, J,. Godini, L., Sanz, S., (2024). Interpretable extreme wind speed prediction with concept bottleneck models. Renewable Energy/ ELSEVIER /ScienceDirect.231. https://doi.org/10.1016/j.renene.2024.120935
9. Ashraee. Ashraee Standard 55: Thermal Environmental Conditionals for Human OccupanCY. Atlanta,2013.
10. Brown, R. D., Gillespie, T. J., (1995). Microclimatic Landscape Design: Creating Thermal Comfort and Energy Efficiency. New York: Wiley.
11. Carmen, J., Nappo,(2012). "Appendix A - The Hydrostatic Atmosphere". International Geophysics, Volume 102, 2012, Pages 309-321.
12. Duarte, D. H., Shinzato, P., dos Santos Gusson, C., Alves, C. A., (2015). "The Impact of Vegetation on Urban Microclimate to Counterbalance Built Density in a Subtropical Changing Climate". Urban Climate, 14, 224-239. https://doi.org/10.1007/s11356-021-13179-z ·
13. Ergonomics of the thermal environment — Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. ISO 7730:2005
14. Fanger, P.,(1973). "Assessment of man's thermal comfort in practice." Oct;30(4):313-24.doi:10.1136/oem.30.4.313.
15. Hamada, S., Ohta, T., (2010). "Seasonal Variations in the Cooling Effect of Urban Green Areas on Surrounding Urban Areas". Urban Forestry & Urban Greening, 9(1), 15-24.
16. Jamei, E., Rajagopalan, P., Seyedmahmoudian, M., Jamei, Y.,(2016). Review on the Impact of Urban Geometry and Pedestrain Level Greening on Outdoor Thermal Comfort. Renewable and Sustainable Energy Reviews, Vol.54,pp 1002-1017.
17. Jiao, M., Zhou, W., Zheng, Z., Wang, J., Qian, Y., (2017). "Patch Size of Trees Affects Its Cooling Effectiveness: A Perspective from Shading and Transpiration Processes". Agricultural and Forest Meteorology, 247, 293-299.
18. Le, D. Y., Tsui, J. K., Chen, F., Yip, W. K., Vrijmoed, L. L., Liu, C. H., (2011). "Effects of Urban Vegetation on Urban Air Quality". Landscape Research, 36(2), 173-188.
19. Lee, H., Mayer, H., Chen, L., (2016). Contribution of Trees and Grasslands to the Mitigation of Human Heat Stress in a Residential District of Freiburg, Southwest Germany. Landscape and Urban Planning, 148, 37-50.
20. Lin, T. P., Tsai, K. T., Liao, C. C., Huang, Y. C., (2013). "Effects of Thermal Comfort and Adaptation on Park Attendance Regarding Different Shading Levels and Activity Types". Building and Environment, 59, 599-611.
21. Li, Y., Song, Y., (2019). "Optimization of Vegetation Arrangement to Improve Microclimate and Thermal Comfort in an Urban Park" International review for spatial planning and sustainable development, Vol.7 No.1 (2019), 18-30 ISSN: 2187-3666 (online) DOI: http://dx.doi.org/10.14246/irspsd.7.1_18
22. Malek, N. A., Mariapan, M., Shariff, M. K. M., (2012). "The Making of a Quality Neighbourhood Park: A Path Model Approach". Procedia-Social and Behavioral Sciences, 49, 202-214.
23. Nazarian, N., Fan, J., Sin, T., Norford, L., Kleissl, J., (2017). "Predicting Outdoor Thermal Comfort in Urban Environments: A 3d Numerical Model for Standard Effective Temperature". Urban Climate, 20, 251-267.
24. Ng, E.,(2009). Designing High-density Cities: For Social and Environmental Sustainbility, Routledge.
25. Onyango, S.A., Mukundi, J.B.,(2021) Ochieng’Adimo, A.; Wesonga, J.M.; Sodoudi, S. Variability of In-Situ Plant Species Effects on Microclimatic Modification in Urban Open Spaces of Nairobi, Kenya. Curr. Urban Stud., 9, 126.
26. Park, J., Kim, J. H., Lee, D. K., Park, C. Y., Jeong, S. G., (2017). "The Influence of Small Green Space Type and Structure at the Street Level on Urban Heat Island Mitigation". Urban Forestry & Urban Greening, 21, 203-212.
27. Prasetya, N., Okur, S., (2024). Investigation of the free-base Zr-porphyrin MOFs as relative humidity sensors for an indoor setting. Sensors and Actuators: A. Physical/ ELSEVIER /ScienceDirect. 01 April 2024, Version 1
28. Ragab, A., Abdelrady, A.,(2020) Impact of green roofs on energy demand for cooling in Egyptian buildings. Sustainability, 12, 5729
29. Sun, S., Xu, X., Lao, Z., Liu, W., Li, Z., García, E. H., Zhu, J. (2017). "Evaluating the Impact of Urban Green Space and Landscape Design Parameters on Thermal Comfort in Hot Summer by Numerical Simulation". Building and Environment, 123, 277-288.
30. Taleghani, M., Sailor, D., Ban-Weiss, G.A.,(2016) Micrometeorological simulations to predict the impacts of heat mitigation strategies on pedestrian thermal comfort in a Los Angeles neighborhood. Environ. Res. Lett.11, 024003.
31. Torres JL., Martin ML.,(2008) Adaptive Control of Thermal Comfort Using Neural Networks. Argentine Symposium on Computing Technology, 1–12.
32. Trenberth K., John, T., Fasullo, Jeffrey ,(2009). "An update of the Earth's global annual mean energy budget is given in the light of new observations and analyses. Changes overtime and contributions from the land and ocean domains are also detailed.". EARTH'S GLOBAL ENERGY BUDGET, In final form 29 July 2008 ©2009 American Meteorological Society
33. Waseem Ahmad, M., Mourshed, M., Mundow, M., Sisinni, M., Rezgui, Y.,(2016). "Building energy metering and environmental monitoring – A state-of-the-art review and directions for future research