Abstract：
Intense urban development and high urban density cause the thermal environment in urban centers to deteriorate continuously, affecting the quality of the living environment. In this study, 707.49 hectares of land in the central area of Changsha were divided into 121 plots. 11 microclimate-related morphological indicators were comprehensively selected, and the K-means method was used for cluster analysis. Then, the relationship between morphological clusters and the thermal environment was explored by simulating the thermal environment of the study area with ENVI-met. First, five spatial types were found to characterize the area: high-level with high floor area ratio, low density, and low greenery; middle-level with high floor area ratio high density; medium-capacity with high density and small volume; low-level with low density and high greenery; and low floor area ratio, low density, and high greenery. Second, the building windward surface density, sky openness, building density, floor area ratio and green space rate affect the thermal environment. Third, Cluster3 had the highest average air temperature (Ta), followed by Cluster5, furthermore Clusters4, 1, and2 had relatively low Ta. The spatial vitality index and green space rate in Cluster1; the area-weighted building shape index, average building volume and sky openness in Cluster2; green space rate in Cluster3; indicators such as the floor area ratio and green space rate in Cluster4; indicators such as the impervious surface rate and green space rate in Cluster5 had greater influences on Ta. Fourthly, simply increasing the area of green space cannot maximize the cooling effect of green spaces. Instead, constructing an equalized greening network can better regulate the thermal environment. Fifthly, the results provide a scientific basis for the design and the regulation of urban centers.
摘要：
激烈的城市发展和高密度城市导致城市中心的热环境持续恶化,影响生活环境的质量。在这项研究中,长沙中部地区707.49公顷土地被划分为121个地块。综合选择了11个与小气候相关的形态学指标，采用K-means法进行聚类分析。然后，通过ENVI-met模拟研究区的热环境，探索了形态簇与热环境之间的关系。首先,发现了五种空间类型来表征该区域：高层和高容积率，低密度,低绿化；高容积率高密度的中层；高密度和小体积的中等容量；低密度和高绿化的低层；和低容积率，低密度,和高绿色。第二,建筑物迎风表面密度，天空开放，建筑密度,容积率和绿地率影响热环境。第三，集群3的平均气温(Ta)最高，其次是Cluster5，此外Clusters4、1和2的Ta相对较低。集群1中的空间活力指数和绿地率；面积加权建筑形状指数，集群2的平均建筑体积和天空开放度；集群3的绿地率；集群4的容积率和绿地率等指标；集群5的不透水表面率和绿地率等指标对Ta的影响较大。第四,简单地增加绿地面积并不能最大限度地提高绿地的降温效果。相反，构建均衡的绿化网络可以更好地调节热环境。第五,研究结果为城市中心区的设计和调控提供了科学依据。
