The effects of illuminance, color temperature and color rendering index of light sources upon comfortable visual environments

In the present experiment, the effects of illuminance upon comfortable visual environments of a room were examined by using a miniature room. The room was set to simulate an usual office. The light source was placed above the ceiling made of opaque acrylic plate. The room was lighted through the ceiling, using six kinds of lamps. Under various lighting conditions, subjects were required to rate the office according to the psycological method, which consisted of the “image” and “evaluation” tests. For each of the tests, the scale values obtained by the method of successive categories were subjected to principal components analysis. As the results of the analysis, four components were extracted for both the “image” and the “evaluation” tests, accounting for 95% and 90% respectively. The canonical correlation analysis was applied and indicated that the relation between two tests was very strong. In both tests, the first component closely related to illuminance, color temperature and color rendering, and strong depencence of the second component upon illuminance was found. The relationships between the scale values: of individual items and illuminance were discussed.