In this paper we describe a simplified prediction model of the vertical air temperature distribution in a large space. This calculation model has the following characteristics ; (a) The large space is divided into multiple vertical zones. (b) Air flows caused by heat loss or heat gain through walls can be evaluated. (c) Air streams from outlets are calculated as nonisothermal jets. These results can be used to evaluate air flow rates between the upper zones and the lower zones of the large space. (d) Equations of heat flow and air flow volume of each zone are derived and the vertical air temperature distribution are calculated. The results of a study on the accuracy of this calculation model are presented along with the experiment results.