Nazar Research Center for Art, Architecture and Urbanism (NRC) The Monthly Scientific Journal of Bagh-e Nazar 1735-9635 23 158 2026 07 23 Investigating the Impact of Vegetation on Thermal Comfort in a Hot and Arid Climate (A Micro-Scale Study of Kholdebarin Residential Neighborhood, Shiraz, Iran) Investigating the Impact of Vegetation on Thermal Comfort in a Hot and Arid Climate (A Micro-Scale Study of Kholdebarin Residential Neighborhood, Shiraz, Iran) 19 26 243397 10.22034/bagh.2026.507504.5769 FA Fatemeh Minabian Department of Architecture, Faculty of Architectural Engineering and Urban Planning, Shahid Rajaee Teacher Training University, Tehran, Iran 0009-0007-8706-1947 Nazanin Fakhfoori Department of Urban and Regional Design and Planning, Faculty of Architecture and Urban Planning, Shahid Beheshti University of Tehran, Tehran, Iran 0009-0007-6463-460X Mohammadreza Mehrabani Golzar Faculty of Architecture, and Urban Planning, Imam Khomeini International University, Qazvin, Iran 0000-0001-9706-2723 Journal Article 2025 02 24 Problem statement: Urbanization and uncontrolled physical expansion of cities, without consideration of climatic consequences, have led to rising ambient temperatures and a subsequent decline in thermal comfort and quality of life for residents in outdoor spaces within hot and arid climates. Although vegetation can enhance thermal comfort through shading and radiation mitigation, the effectiveness of this strategy at the microscale, such as in residential alleys, remains uncertain and warrants further investigation. Research objective: This study evaluates the role of vegetation in moderating thermal comfort at the microscale in urban spaces within a hot and arid climate. Research method: Two alleys with similar physical characteristics but different vegetation conditions in the Kholdebarin neighborhood of Shiraz, Iran, were selected. Field data, including air temperature and relative humidity, were collected during peak heat hours. Following the simulation of the study environment in ENVI-met, the data were analyzed using the PMV index in Bio-MET. Conclusion: Results showed that the maximum temperature difference was approximately 2°C, while the PMV index remained in the “very hot” range. Despite the relative effect of vegetation, this degree of change is insufficient to provide thermal comfort. The findings demonstrate that tree species and canopy form play a significant role in improving thermal conditions. This study emphasizes that effective green space design incorporating trees with wide canopies is more impactful than simply planting trees with limited canopy cover. Problem statement: Urbanization and uncontrolled physical expansion of cities, without consideration of climatic consequences, have led to rising ambient temperatures and a subsequent decline in thermal comfort and quality of life for residents in outdoor spaces within hot and arid climates. Although vegetation can enhance thermal comfort through shading and radiation mitigation, the effectiveness of this strategy at the microscale, such as in residential alleys, remains uncertain and warrants further investigation. Research objective: This study evaluates the role of vegetation in moderating thermal comfort at the microscale in urban spaces within a hot and arid climate. Research method: Two alleys with similar physical characteristics but different vegetation conditions in the Kholdebarin neighborhood of Shiraz, Iran, were selected. Field data, including air temperature and relative humidity, were collected during peak heat hours. Following the simulation of the study environment in ENVI-met, the data were analyzed using the PMV index in Bio-MET. Conclusion: Results showed that the maximum temperature difference was approximately 2°C, while the PMV index remained in the “very hot” range. Despite the relative effect of vegetation, this degree of change is insufficient to provide thermal comfort. The findings demonstrate that tree species and canopy form play a significant role in improving thermal conditions. This study emphasizes that effective green space design incorporating trees with wide canopies is more impactful than simply planting trees with limited canopy cover.

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