Screening of Native Evergreen and Deciduous Trees for Outdoor Human Thermal Comfort in Urban Parks: A Case of Panagal Park, Chennai, India

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IJEP 45(10): 948-956 : Vol. 45 Issue. 10 (October 2025)

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Parisutha Rajan* and Swetha Sekhar

Dr. MGR Educational and Research Institute, Faculty of Architecture, Chennai – 600 095, Tamil Nadu, India

Abstract

Cities in warm, humid climates should plan tree planting in green infrastructure to reduce microclimate effects and improve outdoor human thermal comfort during hot summer days. Tree cooling potential depends on tree parameters, such as morphological traits and environmental conditions within urban parks. Morphological traits include average crown diameter, tree height, breast height, crown volume, crown base height and leaf area. This technical paper is based on a literature review and field study of tree morphological traits of two native evergreens (perennials), Azadirachta indica and Pongamia pinnata, as well as one native deciduous, Terminalia catappa and one naturalized deciduous, Delonix regia. Data on environmental parameters were collected at Panagal park. The study aims to correlate the mean radiant temperature (Tmrt) and outdoor thermal indices, physiologically equivalent temperature (PET) and modified PET (mPET), using RayMan Pro. The PET neutral was calibrated for thermal sensation in natural shade at 26.8°C. The data from four selected trees were analyzed using hierarchical cluster analysis in SPSS software to identify which trees and their traits influence cooling effects and enhance outdoor human thermal comfort. This analysis revealed that native evergreen species Pongamia pinnata and Azadirachta indica provided a cool shade with an ambient air temperature difference of approximately +2.1°C and +1.6°C, respectively, demonstrating effective cooling for a more comfortable outdoor thermal environment.

Keywords

Average crown diameter, Physiologically equivalent temperature, Skyview factor, Outdoor thermal comfort

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