Modified calculation of solar heat gain coefficient in glazing façade buildings

Abstract In the building's cooling load calculation, solar heat gain through the transparent envelope is calculated using the solar heat gain coefficient. In traditional buildings, the window-wall ratio is small so it is assumed that the incoming solar radiation cannot escape through the window. But this hypothesis is not suitable for buildings with glazing facades. Modified calculation of SHGC is carried out on the basis of the Radiosity-Irradiation Method and ISO 15099 algorithms using the commercial software Matlab. The impact of room geometric dimensioning and absorptance of interior surfaces is evaluated. The results of numerical calculation show that at 12:00 on June 21th, the escaped solar energy ratio is 8.85% and the modified SHGC is 0.67, which is smaller than the original, 0.71. In room geometric dimensioning, the depth and height affect SHGC significantly, while in internal surfaces’ absorptance, the floor has greater impact on the modified SHGC than other internal surfaces.