Thermal environments in reefer hold of refrigerating cargo ship and cabin during air conditioning are controlled by turbulent air flow with adequate temperature. Such an air in enclosed space has tendency to form thermal layers in such cases that most of air flow is slow in speed and the location of supplied air inlet is either lower position for cool blow or upper position for hot blow.In the case of arising this phenomenon, the gradient of air temperature in vertical direction tends to be so large that it causes heat loss, cargo damage and uncomfortable circumstance. In order to clarify the heat transfer for such case of forming thermal layers in enclosed space, flow velocity and air temperature in an air conditioned chamber of container type are measured in various conditions during heating up. Further, three dimensional analyses of heat convection in non-isotropic turbulent flow, described in 2nd report by finite element method, are carried out for models corresponding to measurements. In general, it is very complicated to solve exactly the heat convectional equations. However, it is necessary to obtain easily the distribution of air temperature in enclosed space for the prediction and optimum design of thermal environment in designing stage of ship equipment. In this paper, a new conception of heat penetrating rate in surrounding walls is introduced to constitute the thermal balance equation. And a simplified formula based on heat transfer equation is proposed for practical use to predict simply the distribution of air temperature as time proceeds. This formula is applied to the analyses of the measured value at air conditioned chamber for judging its justice. Reasonable agreement between the measured and predicted ones is shown.