城市绿地和建筑格局影响热环境的模拟研究

Simulation on the influence of green spaces and built⁃up patterns on urban thermal environment

景观类型和格局能够影响城市热环境,但是在不同小区域背景下,它们的贡献差异尚缺少定量研究。将实地监测与数值模拟技术相结合,对北京市典型景观的风速场与温度场进行模拟研究,分析天空开阔度、绿地面积与风速、地表温度之间的关系。在此基础上,探讨绿地形态与绿地温度及地表温度的关系,同时设计多种典型的城市绿地、建筑格局在计算机中进行模拟,揭示不同绿地、建筑景观配置下热环境的影响因素。结果表明:(1)天空开阔度和风速是影响城市小区域热环境的重要因素,天空开阔度与地表温度显著负相关,高风速会明显降低地表温度;(2)绿地面积和形态是影响区域地表温度与气温的重要因素,占比10%—50%的绿地降温强度为1.4—2.2℃,面积越大、形态越复杂,降温效应越明显,分散的绿地降温效应优于集中式绿地;(3)迎风向呈两端低中间高的建筑分布可显著改善热环境,较其它格局气温约低1.6℃。研究结果对于指导城市景观设计改善城市热环境具有一定的参考价值。

The impact of landscape types and patterns on the urban thermal environment has always been concerned,but there is still a lack of quantitative research on the differences in impacts under different small area backgrounds.Combining in situ observation and numerical simulation technology to simulate the wind speed and temperature of the typical landscape pattern in Beijing,we analyzed the relationship between sky view factor,green area,wind speed,and surface temperature.By discussing the relationship between green space shape and green space temperature and surface temperature,we designed a variety of typical urban green space and building patterns to model the thermal environment.Finally,the model results were used to reveal the influencing factors of temperature under different green space and landscape configurations.The results showed that:(1)sky view factor and wind speed were important factors affecting the thermal environment in urban areas.Sky view factor was negatively correlated with land surface temperature,and high wind speeds would significantly reduce land surface temperature.(2)Green space composition and configuration were important factors influencing land surface temperature and air temperature.The cooling intensity of 10%—50%of the green space was 1.4—2.2℃.Specifically,the larger the area and the more complex the shape,the more cooling effect,and the cooling effect of dispersed green space was better than that of the centralized green space.(3)The windward distribution of buildings with low ends and middle height could significantly improve the thermal environment,and the land air temperature was about 1.6℃lower than other landscape patterns.The results of the study had important implications for guiding urban landscape design to improve the urban thermal environment.