Comparison of Physical and Psychological Aspects of Light and Heat Radiation Brought by Daylighting

This paper describes the merit of daylighting bycomparing the physical and psychologicalaspects of light and heat radiation. We preparedthree rooms: direct lighting with fluorescentlamps; indirect lighting with incandescentlamps; and daylighting alone. We conductedphysical measure-ment associated with light andheat, together with subjective experiments interms of luminous and thermal sensations.The measurement was done in August, 2006,and also in December, 2007. In summer, the airtemperature of the room with daylighting alonewas lower than two other rooms with electriclighting. On the other hand, in winter, the airtemperature of the room with daylight-ingalone was higher than two other rooms. Therewas no vote indicating either too bright or toodark in the case of daylighting. Most subjectsdid not feel heat radiation from lighting exceptdaylight in winter. More than 50% of thesubjects prefer daylighting to electric lighting.This confirms that daylighting should beretreated as one of the passive strategies becauseit creates the moderate brightness while at thesame time contributes to creating moderatecoolness in summer and moderate warmth inwinter.