A Study on Sky Radiance Distribution

The interior environment is heavily influenced by the diffuse irradiance from the sky on the earth surface. This irradiance is often measured, observed, and inspected by research workers and building engineers. The diffuse irradiance is caused by the sky radiance, as well as by the illuminance by daylight brought about by the sky luminance. Both of them originate from solar radiation. Inspection and analysis of solar radiation have been scarcely done until now, though they are absolutely necessary for the precise design of interior environment considering the orientation and inclination of the building surfaces.A sky scanner to measure the sky luminance distribution, to which a sensor was attached to measure the sky radiance, was developed for the IDMP. The first remodeled sky scanner has been set up at the IDMP station of Kyushu University, and about 10 remodeled sky scanners have been distributed to IDNIP stations in the world. They are producing an enormous amount of data every day.As the first step in the investigation on sky radiance, the relative radiance distribution by solar altitude has been examined by applying the data gathered at the IDMP station of Kyushu University in 1994 and 1995. This paper introduces the relative radiance distribution by solar altitude with a rough explanation on the circumstances of the sky radiance measurement and the remodeled sky scanner.