Thermal Effects of Architecture Surface in Kunming and Beijing

Urban architecture and the urban heat island intensity is extremely closely related. The buildings' outside surface exhibits unique thermal energy characteristic because it absorbs the solar radiation and thermal energy from people's daily life influences buildings. The atmospheric thermal energy condition around buildings is affected inevitably, then the urban climate is affected. The observational data of buildings' external walls' surface temperature, rooftop surface temperature and the air temperature near the buildings' external surfaces in three different cities of Kunming, Beijing utilized. The vertical distribution rule of buildings' external surface temperature and air temperature near the buildings' external surfaces, the thermal effect features of the wall, and the rooftop between the nearby atmosphere are analyzed. The comparative analysis on two cities buildings thermal conditions is conducted. The following preliminary conclusions are drawn. In the same area, buildings' external walls' surface temperature and the air temperature near the buildings' external surfaces are different respectively from different directions, seasons, and heights. The influence of solar radiation on buildings' external walls surface temperature is greater than on the air temperature near the buildings' external surfaces. Generally speaking, the wall's surface is a heat source in daytime, and a heat sink at night. In different areas, there are many similarities and many differences in the thermal energy affect on buildings' external walls. The heat flux of the buildings' external walls basically is positive in daytime, is negative at night, and there is an extreme small value just before sunrise in Kunming. While in summer of Beijing, the heat flux of the buildings' external walls is basically negative in daytime and positive at night. This indicates that the influence of climate and people's activity is great to the thermal energy effect on the urban buildings' external walls in different cities. The average heat fluxes between the buildings' rooftop and its nearby air are basically positive in different areas and seasons. Buildings' rooftop displays the strong heat source effect. The thermal energy effect intensity and the solar radiation show a positive correlation. In summary, the urban building external surfaces (external wall surfaces, the surface of rooftop) are different from the ground in the urban region, and is noticeably influential thermal active surface in the formation of urban climate.