Horizontal heat impacts and shading effects of buildings on surface soil layer in Beijing,China

Abstract

Thermal condition of the surface soil layer was neglected due to much concern of the urban heat island effect, which has an important impact on cities. In this study, on-site measurements of surface soil layer temperatures were conducted between two east-west oriented buildings in the winter, spring and summer. Building shade was shown to reduce average surface soil layer temperatures to 0.33, 0.33 and 0.37°C in three seasons, respectively. The horizontal heat flux between the building and the soil was calculated and showed different intensities at various monitoring sites. Additionally, the building shade could reduce and stabilize the surface soil layer temperature. According to the analytic hierarchy process, among six energy factors only horizontal heat flux between the building and the soil was correlated significantly (p <0.05) to the different surface soil layer temperatures. This has a key or dominant role in affecting the difference in surface soil layer temperatures, which was influenced by the building shade. Moreover, the soil warming rate was reduced by the building shade (50% at most). The surface soil layer temperatures at various observation points were compared with the air temperature. The surface soil layer was found to have different roles between two sites in three seasons.