Evaluation of a hybrid photo-radiometer sky model compared with the Perez sky model

In this study, the HDR images within four office spaces were taken. Simultaneously, global horizontal illuminance and HDR sky images were recorded outside. Simulated luminance maps were generated under both the HPR and Perez skies. Daylight Glare Probability and vertical eye illuminance (Ev) were calculated from 112 groups of luminance maps. The simulated Ev under HPR and Perez skies presented relative RMSE of 21.3% and 23.7%, respectively. The frequencies of accurate glare prediction under HPR and Perez skies were 95.5% and 93.9%, respectively. The results indicated that both the horizontal HPR sky and the Perez sky simulate equally accurate luminance maps.