Numerical simulation studies of the different vegetation patterns' effects on outdoor pedestrian thermal comfort

Vegetation has positive effects on the outdoor pedestrian comfort and thermal environment. Throughout the three numerical simulation experiments and a presupposition of a same total leaf area for all greening cases, the differences of vegetation patterns on the pedestrian thermal comfort have been studied with an evaluation index as (Standard Effective Temperature) SET. Firstly, in comparison with grass and shrub patterns, greening with tree does not always have better effects for improving pedestrian thermal comfort in summer in all directions around buildings. The reasons include the relatively negative function of tree to decrease the wind velocity and the hourly change of the sun's location. However, if considering the average SET around the pedestrian space, greening with tree is still better than others are. Secondly, the difference for the three vegetations for pedestrian comfort is affected by the arrangements and orientation of buildings. Thirdly, there is an optimized pattern with a lower SET distribution for the configuration of trees (including the shapes and arrangements) around buildings. In this situation, the average SET in the pedestrian space has a slight difference and should be carefully compared for better outdoor pedestrian comfort. (c) 2008 Elsevier Ltd. All rights reserved.