In the cooling/heating loads simulation for buildings, it is too difficult to estimate the solar heat gain through the windows with shading devices using the detailed and complicated calculation method (e.g. JIS A 2103) and the off-normal optical characteristic parameters in each time. This paper proposed a simplified methodology for calculating hourly or daily accumulated solar heat gain through the windows with shading devices using relation between solar heat gain coefficients of glazing with and without shading devices. In addition, this paper showed the accuracy of proposed models. As the results of this study, the following conclusions were obtained;
(1) There is relationship of quadratic approximation passing through the origin between solar heat gain coefficients of the glazing with and without shading device.
(2) In the case of external roller shade, the hourly and daily accumulated solar heat gain through windows of various type of combination of glazing and external roller shade can be calculated by the simplified formula that has explanatory variables for the solar heat gain coefficients of windows without roller shade and solar transmittance and reflectance of the roller shade.
(3) In the case of internal roller shade, the hourly and daily accumulated solar heat gain through windows of various type of combination of glazing and internal roller shade can be calculated by the simplified formula that has explanatory variables for the solar heat gain coefficients of windows without roller shade and solar reflectance of the roller shade.
(4) In the case of either external or internal venetian blinds, the hourly and daily accumulated solar heat gain through windows of various type of combination of glazing and venetian blind can be calculated by the simplified formula that has explanatory variables for the solar heat gain coefficients of windows without venetian blind and solar reflectance of the blind slat. However, in the case of the slat angle of external venetian blind that there is a lot of direct transmitted solar radiation through blind layer, the daily accumulated solar heat gain cannot be calculated with high accuracy. Therefore, the model should be improved in the future.
