Abstract
It is important for planning an effect of direct solar gain to calculate the effect of surrounding environment, especially buildings around a numerical model. Therefore in this study, simulation of heating load with a boundary condition based GIS data was conducted. The result showed that solar heat gain was larger than heat loss from a window where Rss was larger than 0.4. The detail simulation were carried out for the building where Rss was larger than 0.4, and results revealed the relationship of glass size and heating load and interior design.