不同覆盖率的草地下垫面对热环境的影响研究

Study on the Effect of Grassland Underlay Surface with Different Coverage on Thermal Environment

建筑微气候受到多种因素影响,下垫面作为影响建筑微气候的关键因素,合理规划下垫面对室外热环境的改善至关重要。本文以不同覆盖率的草地为研究对象,搭建了下垫面反射率综合测试装置,在室外自然环境中进行不同草地下垫面的反射率测量,同时检测其地表与浅层的温度变化,分析草地下垫面对周边热环境的影响机理。结果表明:裸露地表相较于草地反射率下降了50%以上,草地下垫面相较于裸露地表具有一定的降温能力,降温幅度一般在23.5%左右;草地反射率随着覆盖率的增加而降低,最大降幅仅为10.7%,而此时影响草地下垫面温度的主要因素是植物的蒸腾作用。因此随着草地覆盖率的增加,草地下垫面降温能力逐渐增加,且表面温度更加均匀,这对于提升下垫面上方热舒适性有积极作用。本研究为合理规划建筑周边下垫面提供了理论支撑。

The microclimate of the building is affected by many factors.The underlying surface is a key factor affecting the microclimate of the building,and reasonable planning of the underlying surface is essential to improve the outdoor thermal environment.This paper took grass with different coverage rates as the research object,and built a comprehensive test device for the reflectivity of the underlying surface to measure the reflectivity of the underlying surface of different grass in the outdoor natural environment.The temperature changes of the ground and shallow layers were detected,and the influence mechanism of the under-grass on the surrounding thermal environment was analyzed.The results show that the reflectivity of the bare surface is reduced by more than 50%compared with that of the grassland,and the grassland has a certain cooling capacity compared with the bare surface,the cooling rate is generally about 23.5%.The reflectivity of the grass decreases with the increase of the coverage,the maximum decrease was only 10.7%,and the main factor affecting the temperature of the grassland is the transpiration of plants.Therefore,with the increase of grass coverage,the cooling capacity of grassland gradually increases,and the surface temperature is more even,which has a positive effect on improving the thermal comfort above the underlying surface.The research provides theoretical evidence for the rational planning of the underlying surface around the building.