Development of annual daylight simulation algorithms for prediction of indoor daylight illuminance

An annual daylight simulation method (ADSM) has been developed in this study to predict daylight illuminance under diverse sky conditions. The ADSM simulation results were validated by comparing them with Radiance software simulation results and field measurements. Classroom and small private office space facing south and north were used for validation. A classroom facing north and south was used for simulation of ADSM and Raidnace. Field measurements were conducted in a small private office space. Simulation of ADSM was conducted for the conditions of measurements to examine the differences between the results The results indicated that the daylight illuminance levels computed by ADSM and by Radiance correlated strongly under various sky conditions. Daylight coefficient approach and sun-matching method of ADSM were recommended to achieve higher prediction accuracy. The ADSM simulation results were consistent with actual field measurements of illuminance, even though they varied in accuracy under various sky conditions. The illuminance levels achieved from ADSM and field measurements correlated with each other strongly. Difference ranges between illuminance levels from measurements and simulations were effectively reduced when daylight coefficient approach of ADSM for sky was used with any other computational algorithms of ADSM for the sun.