Research Of Urban Public Space Thermal Environment

Urban public space is the main concourse for people outdoor communion, leisure, meeting, entertainment and other social activities, so the comfortable thermal environment in the public space can easily improve city's quality and environment .The research on the thermal comfort of the public space is a good groping based on respecting the climate condition, human's physical and mental demand for a real "green public hall".This paper first introduces the status and results of urban public space thermal comfort both in domestic and foreign. Then it analysis the main factors affecting people's thermal comfort and the urban outdoor thermal comfort evaluation indicators, which lays a theoretical foundation for the estimation of urban public space thermal comfort in Xi'an.Using the way of actual measurement, this paper chooses four typicals urban public spaces in Xi'an——Xingqing Gong Park,the wild goose northern square of Buddhist pagoda,Fengqing Park and bell building square to measure the thermal environment. The results indicate that the thermal environment shows different characteristics between the parks and squares, especially in summer.Based on the test data and questionnaire, the thesis surveyed human thermal comfort of Xi'An. From the factors of climate,physiology and psychology, the thesis summarizes adaptable characters of thermal comfort of human body in winter and summer.Through the results and conclusions, with statistical methods, comprehensive analysis the main factors of the impact on public space thermal comfort, using the correlation of predicted percentage dissatisfied "PPD" and environmental factors, to establish an equation of the thermal adaptability. In summer, PPD=-1.127+ 0.049T_g-0.205V(25℃=T_g=48℃, 0.5m/s=V=5m/s) ,when People feel comfortable, the black-bulb temperature and wind speed, respectively is : Tg=29.2℃～34.6℃, V=0.5 m/s～1.8 m/s. In winter, PPD =1.137～0.098Tg (1.4=Tg=11.6℃), feeling comfortable black-bulb temperature is: 9.6=Tg=11.6℃. The establishment of this equation, provides a simple and effective methods for forecasting the public space thermal comfort.Through quantitative analysis of thermal environmental characters and studies on the thermal comfort of human body, it brings designers to pay attention to thermal environment in space. According to the static and theory, it will support the design of common space, which will benefit to the construction of comfortable space.