With the acceleration of the urbanization process, the impact of the city on local thermal environment became more and more obvious. In order to quantitatively analyse the effect of urban buildings and greening on the outdoor temperature, wind speed and thermal comfort during the summer season, this paper used a three-dimensional non-hydrostatic model, ENVI-met, to analyse the local thermal environment in Zhongshan with considering a real and a non-vegetation scenario. The analyses showed that the simulated results of ENVI-met model were close to the actual conditions. The tree shadows and building shades could reduce outdoor pedestrian-level temperature in a range between 2.6℃ and 3℃. The pedestrian-level temperature difference of lawns and asphalt pavements were noticeably different between 11:00 and 17:00 in summer season, the hourly maxima was up to 1.7℃. PMV value of building shades and trees was two grades lower than that of asphalt pavements. The non-vegetation scenario showed that the area of high temperature increased by 10%, the average wind speed increased by 24%, and the area of PMV≥4 (very hot) increased by 13% compared to those under the real scenario. In the vertical layer, the heating effect on the urban street under the non-vegetation scenario extended to the height of 10meters, and the most significant effect could be found at the height of 0.6meters. Thus, urban vegetation can reduce temperature and improve human comfort in hot weather.%随着城市化进程的加快,城市对局地热环境的影响越来越明显,为定量分析城市建筑物和绿化设施对夏日室外温度、风速和热舒适度的影响,运用三维非静力模式ENVI-met对中山市典型街区建立实际和无植被两种方案进行模拟研究.结果表明,ENVI-met模式模拟结果与实况接近,能较好反映实际情况.建筑物阴影和树阴可降低行人高度的环境气温2.6~3℃;草坪和沥青路面行人高度(1.5m)的温差在11:00~17:00较大,逐时最大的温差达1.7℃.建筑物背阳面和树木附近PMV值(表征人体热反应(冷热感)的评价指标)比沥青路面低2个等级.无植被方案下,行人高度的高温面积比实际方案增加最大可达10%,平均风速增加24%,PMV≥4(非常热)面积增加最大可达13%.在垂直方向上,无植被方案街区的加热效应可伸展到10m高度,在0.6m高度上该效应最显著.由此可见,在炎热的天气下,城市的绿化可以显著降低温度,有效提高人体舒适度.
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