基于热环境模拟的城市水体缓热研究

Urban Water Body Cooling Based on Thermal Environment Simulation

城市化进程的加快导致城市热岛效应增强,室外环境热舒适下降。城市水体作为城市冷岛,其缓热效果已被研究证实。使用微气候模拟软件ENVI-met对水体及滨水区热环境进行24 h动态微气候模拟,参考夏热冬冷地区城市南京的气象参数设置模拟气象条件,依据不同影响因素建立简化的水体及滨水区模型,选取空气温Ta和生理等效温度PET为评价指标分析不同宽度、风向、季节和时间条件下的城市河流型水体缓热效果的差异,进而探讨不同滨水区建筑空间形态对水体缓热效果的影响,最终从城市物理环境角度对城市滨水区建设提供指导意见。结果表明,水体的缓热效果随水体宽度的增加而增强,随离水岸距离的增加而减弱,100 m宽度水体较10 m宽度水体滨水区空气温度降低0.75℃,风向垂直于水体时下风向滨水区热环境更优;使建筑平均高度较低,行列之间形成风廊,临水界面保持开敞时水体缓热效果更好。

The acceleration of urbanization leads to the enhancement of urban heat island effect and the decline of outdoor thermal comfort. As a cold island in the city, the cooling effect of urban water body has been confirmed by research. The micro-climate simulation software ENVI-met is used to simulate the 24-hour dynamic micro-climate of water and waterfront. The simulated meteorological conditions are set by referring to the meteorological parameters of Nanjing, a city with hot summer and cold winter, and a simplified model of water and waterfront is established according to different influencing factors. The difference of the cooling effect of urban river water under different width, wind direction, season and time conditions is analyzed by taking air temperature(Ta) and physiological equivalent temperature(PET) as evaluation indexes, and then the influence of different waterfront architectural space forms on the cooling effect of water is discussed. Finally, from the perspective of urban physical environment, the results show that the water body’s heat-slowing effect increases with the increase of water body width, but decreases with the increase of distance from the water bank. The air temperature in the waterfront of 100 m-wide water body is 0.75 ℃lower than that in 10 m-wide water body, and the thermal environment in the waterfront is better when the wind direction is perpendicular to the water body. Make the average height of the building low, form a wind corridor between the rows and columns, and keep the water interface open, which can make better use of the water body’s slow heating effect.