Evaluating the vertical cooling performances of urban vegetation scenarios in a residential environment

Vegetation is one of the effective measures to mitigate urban heat island (UHI) and improve thermal comfort. Many existing studies have investigated the cooling performance of vegetation on the pedestrian level. However, no study explores the cooling effect of vegetation on other heights. In this research, we evaluate the vertical cooling performance of different vegetation species (grass, shrubs, trees) in the residential quarter using the ENVI-met model. The results show that different vegetation types have important effects on the thermal environment based on the same green coverage rate, and different vertical cooling performance of different vegetation types are also different. The study found that among the three common vegetation types (trees, shrubs, and grass), the cooling effect of trees is the most significant, and the vertical cooling performance is the best, followed by shrubs. The maximum cooling value of the tree to Ta and MRT is 0.49 degrees C and 17.7 degrees C respectively. The presence and increase of shade have a direct effect on improving the local and even the overall thermal environment. Therefore, when designing residential green space, this study suggests that designers should not only focus on the green coverage rate but also pay attention to controlling the shaded area. This research provides a new perspective for investigating the cooling effect of vegetation and provides scientific guidance for the design of residential quarters.