Abstract
Outside walls of a building receive not only direct and diffuse solar radiations coming from the sky but also solar radiation reflected from the ground and the opposite buildings. In an area exposed with high air temperature and strong solar radiation, such as Japan in summer, the reflected solar radiation may have quite significant effect on the thermal environment in houses. To measure the reflected solar radiation with a pyranometer, an upper half cover was used. The measured data showed that the amount of the reflected solar radiation incident on the outside wall was a half of that of the diffuse solar radiation. The variation of the reflected solar radiation depended on that of the direct solar radiation. The reflected solar radiation can be calculated, using the data of direct and horizontal diffuse solar radiation, photoes taken by a fish eye lens, and albedoes of the ground and building surfaces. The north wall opposite the northern building accepts the amount of solar radiation as much as the horizontal diffuse solar radiation, except the lower part of the wall, disregarding winter and summer. The higher story wall, the more reflected solar radiation is increased in both of winter and summer. The reflected solar radiation coming from the opposite buildings is quite large in winter.
