Investigating the Effect of Changing the Transmitted Light's Color on Thermal and Visual Comfort

Thermal comfort is one of the key factors for achieving energy saving in the buildings. In the survey of thermal comfort, psychological aspects are as important as the physical parameters such as temperature and relative humidity. If thermal comfort could be achieved by using non–physical parameters, a significant energy and cost would be saved. The aim of this study is to investigate the effect of changing the color of inward daylight (into cool/warm), on sensation of thermal and visual comfort. This study was conducted to answer these questions: to what extent can the lights, which are traditionally called cool and warm, cause the real sensation of cold and heat? What is their influence on thermal and visual comfort? And what is the effect of changing the color of transmitted light on the occupant’s sensation of illumination? Research method is descriptive–analytical; in this study, thermal and visual effects of changing the color of inward light from the windows is surveyed, by using questionnaires, in three naturally ventilated high–schools; and the results were compared with the outputs of PMV simulation analysis. The results show that changing the inward light to a cool color (blue) and a warm color (red) resulted in a difference of 0.33°C in the sensation of thermal comfort. Moreover, the AMV in all cases had a neutral temperature below the PMV’s neutral temperature which was simulated by the software. In lower illuminance levels (lower than 300 lux) blue light aroused more visual satisfaction; but in higher illuminance levels (more than 300 lux), simple windows produced the best visual satisfaction. Red light produced the least visual satisfaction amongst these three. While, blue and red glazing generated better distribution of light in the room, than the witness group.