Effect of tree planting design and tree species on human thermal comfort in the tropics

• Single and clusters of trees are quantified on a quantitative manner.
• Thermal comfort conditions are strong influenced by solar radiation and wind.
• Must appropriate tree for the improvement of thermal comfort conditions are Caesalpinia pluviosa.
• Reduction of Tmrt can improve thermal comfort conditions about 16°C (PET) during summer condition.

Trees behave in different ways on microclimate due to mainly distinct features of each species and planting strategies especially in the tropics. This paper quantifies the daily and seasonal microclimate behavior of various tree species with different planting design either individual or in clusters. This specific knowledge is an important step in the development of urban design guidelines based on the shading of trees and climate adaptation in urban areas in the tropics. It focuses on human thermal comfort based on the physiologically equivalent temperature (PET) for different species. Twelve species were analyzed: Handroanthus chrysotrichus (Mart. ex A.DC.) Mattos, Jacaranda mimosaefolia D. Don., Syzygium cumini L., Mangifera indica L., Pinus palustris L., Pinus coulteri L.; Lafoensia glyptocarpa L., Caesalpinia pluviosa F., Spathodea campanulata P. Beauv., Tipuana tipu F., Delonix indica F. and Senna siamea L. The results show that shading of trees can influence significantly human thermal comfort expressed by (PET). The species C. pluviosa F. presents the best possibility in terms of PET because it can reduce between 12 and 16 °C for individual trees cluster can reduce between 12.5 and 14.5 °C. Appropriate vegetation used for shading public and private areas is essential to mitigate heat stress and can create better human thermal comfort especially in cities. The results can be seen as a possibility of improvement of outdoor thermal comfort conditions and as an important step in order to achieve sustainability in cities.