Passive design can keep a comfortable thermal environment without air conditioner all year around while it needs precise thermal environment simulation to analyze the effectiveness before it has been constructed. However, large discrepancies in simulation results can exist between different programs so that it’s hard for designers and researchers to choose appropriate program for passive design from so many programs without recognition about characteristic of them. This paper compares several commonly used simulation programs in Japan, concentrating on analyzing natural temperature calculation to find out the calculation characteristic of each programs.
