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.
Methodology: 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 simulation of the study environment in ENVI-met, the data were analyzed using the PMV index in Bio-MET.
Conclusion: Results indicate 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.