This paper describes how to calculate a volumetric solar heat collection with our-own separation method of direct-scattered component of solar radiation measured by a proving test at experimental site. In the case of calculation, using a simple model for real transparent hot house, firstly solar radiation incident on an each surface which consists of surfaces of the hot house was calculated, next the solar heat collected on the surface was calculated producing 0.6 times of collection rate of the house surfaces. Consequently, the calculations were well applied to the experimental results when proving test on a fully passive solar lumber drying house was executed, it was made clearly the rate of volumetric solar heat collection to the horizontal solar radiation incident on a floor reached to 2.2〜3.5 which corresponds to the collection efficiency of 130%〜210%.
