窓面のグレアが鉛直面のコンピュータ作業の視作業性に及ぼす影響

Abstract

In order to reduce global warming while maintaining occupants' health it is important to make the best use of daylight in interior spaces. To maintain comfortable interior environments while utilizing daylight it is necessary to control window luminance appropriately. To this end, many researchers have referred to discomfort glare from high-luminance windows. However, since recent office workers often perform visual tasks by using computer displays their visual performances are susceptible to high-luminance windows. Ocular light scatter covers the entire visual field of a worker, and therefore often reduces the luminance contrast of a target against its background. The purpose of this study was to investigate how a high-luminance side window impairs visual performance of a computer task. Subjects were asked to detect targets presented at the central and peripheral visual field, and the subjects' response times were measured. In order to investigate the mechanisms of how window luminance affects target detections, veiling luminance on each target caused by the window was calculated under each of the experimental conditions. The findings of the study are listed below. 1) The high-luminance window behind the computer display significantly impaired the detection performance of targets presented on the computer display. As the luminance of the window increased, the visual performance was decreased. The validity of the experimental dataset was confirmed by comparing the dataset with existing experimental data. 2) When window luminance exceeded a certain luminance between 3000 cd/m2 and 6000 cd/m2, visual performance was deteriorated significantly. This implies that window luminance should be reduced to lower than 3000 cd/m2 for computer tasks. 3) Evaluations of discomfort glare did not necessarily correspond to visual performance. Therefore, in order to design windows for efficient task environments it is important to minimize the effects of windows on discomfort glare and visual performance.