摘要:
本文以夏热冬冷气候的上海为研究区域,以高密度住区的中心绿地为研究对象,采用ENVI-met软件进行模拟,探讨不同绿化类型对住区热环境的影响,特别关注了绿化在夏季高温天的致凉作用,以期对住区的绿化设计或改造设计进行科学性的指导.研究表明在相同绿化覆盖率的基础上,使用不同的绿化类型对热环境有重要影响.在常见的三种绿化类型(乔木、灌木以及草地)中,乔木是影响夏季致凉最显著的绿化类型,并且树荫的存在和增加对于改善局部乃至整体的气温有直接作用.在本组案例中,与无绿化案例相比,乔木引起的最大降温幅度能达到4.8 °C(15:00),而地面层的草地对热环境的影响有限,平均降温仅为0.3°C;同时,乔木挡风作用明显,1.5m高度各点风速平均下降29%,最大降幅达44%.此外,乔木与水体的合理搭配在改善热环境方面效果较好.因此,在住区中心绿地设计时,不能只关注绿化覆盖率,应注意控制区域遮蔽率,尤其是使用者逗留区域.%This paper describes work that carried out in Shanghai,researched the central green area in high-density residential districts,and identified the influence of vegetation species on thermal environment by using ENVI-met software,especially emphasizing vegetation cooling effect in hot days.The study is expected to provide scientific directions for the greening design or reformation design of residential districts.The research shows that based on the same green coverage,using different vegetation species will affect thermal environment greatly.Among the three common species of vegetation (tree,shrub and grass),tree is the most effective type for cooling effect,and the existence and enlargement of tree shade can directly improve the local even the overall air temperature.In the study,compared to case without vegetation,the cooling effect of trees can be up to 4.8 °C (15:00),while grass has the limited effect to thermal environment with only 0.3 °C cooling,meanwhile trees blocks wind obviously by lowering down wind velocity by 29% in average and 44% in max case.Moreover,trees matching with water may have better effect in improving thermal environment.Finally,residential planners should not only focus on green coverage,but also control the covering rate,especially the areas for users' activities.