Abstract
Based upon their observation data for two years in Suita City near Osaka, the authors had previously proposed standard sky luminance for lighting design. But as sky luminance is affected by solar altitude and atmospheric condition, the proposed value can not always be applicable to all other districts in Japan. In the present paper attempts are made to estimate values for other districts by making corrections in the primary data in the following two ways. 1. correction with latitude (occurrence rate of solar altitude) and meteorological data. 2. correction ditto above, neglecting the difference in meteorological condition. The results obtained in these two ways were very similar. And the differences between the upper, lower and median values in 80% and 90% ranges for almost all locations and these for Osaka were found to be within ±10% range. When this 10% allowance is acceptable, the values previously proposed for Osaka could be used in all districts in Japan irrespective of the differences in lalitude and meteorological condition. Even when the demand calls for more precise values it will be sufficient to give the standard values at 4 degrees intervals in latitude.
