Estimation of Illuminance on the South Facing Surfaces for Clear Skies in Iran

Background: daylight availability data are essential for designing effectively day lighted buildings. in respect to no available daylight availability data in iran, illuminance data on the south facing vertical surfaces were estimated using a proper method. methods: an illuminance measuring set was designed for measuring vertical illuminances for standard times over 15 days at one hour intervals from 9 a.m. to 3 p.m. at three measuring stations (hamadan, eshtehard and kerman). measuring data were used to confirm predicted by the iesna method. results: measurement of respective illuminances on the south vertical surfaces resulted in minimum values of 10.5 klx, mean values of 33.59 klx and maximum values of 79.6 klx. conclusion: in this study was developed a regression model between measured and calculated data of south facing vertical illuminance. this model, have a good linear correlation between measured and calculated values (r= 0.892).