Daylight Predicting Program of Tropical Climate Zone

This paper presents light calculation program is composed of natural lighting or day lighting prediction and artificial lighting or lamp lighting. Natural lighting calculation use CIE overcast sky to be an luminance calculation method and artificial lighting use lumen method to calculate number of luminaires for appropriate illuminance. By inspection illuminance in each points of area, point by point calculation use to inspect illuminance from daylight and lamp lighting in Isolux diagram. In line graph shows the result of program show that illuminance between 6.00am - 6.00pm of Thailand to use daylight to decrease energy. From this point, this program is very useful for lighting control to be designed lighting system for energy saving in the way of dimmer or appropriate the number of luminaries