武汉市居住用地绿地降温效应研究

Study on Cooling Effect of Residential Green Space in Wuhan

从人们生活最密切的居住用地入手,利用三维微气候模型模拟居住区中不同绿地率、乔木覆盖率下226个绿地情景,研究武汉夏季15:00时,绿地对场地平均空气温度的调节作用。研究发现草地面积变化与场地空气温度呈现线性负相关,相同绿地率时,乔木降温效果优于草地7℃;随着场地中乔木覆盖率的增加,场地平均空气温度降低越显著,但乔木覆盖率持续增加时,单位乔木降温能力在减弱,一、二类居住用地中,发挥乔木最佳降温效能的乔木覆盖率是25%~30%。研究也表明绿地对场地温度调节作用受场地建筑高度、建筑密度、容积率等因素影响。

The residential thermal environment governs human comfort for living and recreation. This research examined the impact of the amount and composition of green space on the thermal environment in residential areas using the ENVI-met model V4. The simulation was based on 4 typical blocks representing general spatial characteristics of residential areas in Wuhan. In total, 226 scenarios with different types of vegetation configurations and compositions were simulated. The research focused on air temperature at 3 pm, when both outdoor air temperature and human activity were high. Average air temperatures（Tm） at the pedestrian level（1.5 meters above the ground） were compared for hundreds of scenarios in 4 typical residential layouts. The present study revealed that vegetation coverage is negatively correlated with air temperature, and that trees have a greater temperature-mitigation effect（7℃） than grass does. The average air temperature decreases dramatically with increasing tree canopy. However, with an increasing tree coverage rate, the added cooling capacity per unittree-increment decreases. For R1 and R2, when the tree coverage was between 25% and 30%. The study also found that the effect of green space on site temperature regulation is affected by the height of buildings, building density and floor area ratio.