Taking a certain housing in Guangzhou as an example,we conduct the field measurement of the microclimate at fixed points for air temperature,relative humidity,black globe temperature and wind speed,etc.We investigate the effects of manmade lake,shade of trees and ground surface character on outdoor thermal environment,and make a quantitative analysis on the weighting position of the landscape design factors in design behavior.The study intends to explore a method to improve the thermal environment of residential quarters by changing the corresponding factors.
Zhuolun CHENLihua ZHAOQinglin MENGChangshan WANGYongchao ZHAIFei WANG
Wet bulb globe temperature(WBGT)is a comprehensive index obtained mainly from three parameters:black globe temperature(Tg),wet bulb temperature(Tw),and dry bulb temperature(Ta).While in field observation and numerical simulation,black globe temperature and wet bulb temperature were not easy to obtain,so WBGT was difficult to measure and calculate directly.In order to solve this problem,air dry bulb temperature,wet bulb temperature,globe temperature,relative humidity,mean air velocity,solar radiation and wet bulb globe temperature were collected during the summer(July)in Guangzhou.Correlation analysis and regression analysis were used to get a simplified method to calculate WBGT.The results showed that dry bulb temperature,relative humidity,solar radiation and WBGT were interrelated to some extent.These three parameters could be used in the simplified method to predict WBGT,and the linear correlation and precision of this model were high.In addition,we used the measured data to verify the simplified method,and the results showed that the error of the calculated value and the measured value was all below 5%,which means the simplified calculating method is feasible and can be used in field observation and simulation research of urban thermal environment.
ZHANG Lei,MENG Qing-lin,ZHAO Li-hua,ZHANG Yu-feng(State Key Laboratory of Subtropical Building Science,South China University of Technology,Guangzhou,Guangdong 510640,China)
In order to calculate the air temperature of the near surface layer in urban environment,the surface layer air was divided into several layers in the vertical direction,and some energy balance equations were developed for each air layer,in which the heat exchange due to vertical turbulence and horizontal air flow was taken into account.Then,the vertical temperature distribution of the surface layer air was obtained through the coupled calculation using the energy balance equations of underlying surfaces and building walls.Moreover,the measured air temperatures in a small area(with a horizontal scale of less than 500 m)and a large area(with a horizontal scale of more than 1 000 m)in Guangzhou in summer were used to validate the proposed model.The calculated results agree well with the measured ones,with a maximum relative error of 4.18%.It is thus concluded that the proposed model is a high-accuracy method to theoretically analyze the urban heat island and the thermal environment.
ZHANG Lei,MENG Qing-lin(State Key Laboratory of Subtropical Building Science,South China University of Technology,Guangzhou,Guangdong 510640,China)
