The steady state heat and moisture transfer from a dry or wet heated plate is used to simulate the human body's relation to the environment through clothing materials. The heat transfer without perspiration was discussed by a simple model which was constructed from the radiative, conductive and convective resistances for the case of air impermeable clothing materials. The calculated value was accurately corresponded with the measured value under various wind velocities with the temperature of the heated plate set 10°C higher than that of the environment. In the case of air permeable fabrics, an experimental equation was also derived by the modification of the model cited above using some assumptions. The effects of air resistance, thermal resistance of fabrics, air gap and wind velocity on heat transfer can be estimated by this equation. Moisture transfer, and simultaneous heat and moisture transfer in a state of perspiration will be discussed in the next paper.