Exploring the effects of the spatial arrangement and leaf area density of trees on building wall temperature

Abstract

As single urban landscape elements, buildings and trees have important impacts on the urban microthermal environment. Thus, the interaction between trees and buildings requires more thorough investigation. In this study, typical residential districts in Nanjing, Jiangsu Province, China, are selected as the research area, and different evaluation indexes are established to explore the influence of trees on building surface temperature. ENVI-met simulations of the different established scenarios based on the spatial configuration analysis of buildings and trees in the study area were performed to determine the influence of the distance between individual trees, the distance between trees and walls (spatial position) and the leaf area density (LAD) value (attribute) of trees on the surface temperature of buildings. The results showed that 1) the best wall cooling times in the east, west, south and north were 12:00, 17:00, 14:00 and 16:00, respectively; 2) the best cooling effect was achieved at vertical heights of 12–14 m; 3) a compact tree arrangement reduced the shortwave radiation that reached the wall during the daytime by a large extent and thus had the best cooling effect in all scenes; and 4) trees with an LAD of 1.1 led to 20 °C greater cooling for a brick in one day than trees with an LAD of 0.3. This research attempts to reveal the influence of trees on building surface temperature and provide the corresponding decision basis for tree planning in residential areas to reduce the impact of urban heat pressure on human health and energy consumption.