In order to design more efficient and comfortable atriums, it is important to comprehend the factors that affect their indoor climate. We have carried out a long term observation for the indoor climate of a real-scale atrium. The boundary conditions were clear and well measured. The results are as follows. (1) The differences of envelope materials result in clear differences of the indoor climate. (2) The vertical temperature distribution is not significant because of natural convection driven by the solar heated floor and the cold glass. (3) The solar heated steel frames in the atrium affect the indoor climate greatly.
