EVALUATION OF VISUAL ENVIRONMENT IN GYMNASIUMS (PART 2) : EXPERIMENT OF GLARE EVALUATION

Abstract

　LED lighting technology has been advancing quite rapidly and it has been used in sports facilities. LED lighting has characteristics such as a small light emitting part and high directionality, which may cause glare. JIS recommendation for sports lighting does not provide the recommended value for glare in gymnasiums. In Part 1 of this paper, measurements of illuminance and luminance distribution were carried out in eleven gymnasiums (six with LED lighting and five with HID lighting). In this paper (Part 2), subjective experiments were carried out in eleven gymnasiums described in Part 1. The variables that affect glare were extracted based on the subjective experiments

　The subjects looked at a badminton shuttlecock in front of the lighting, assuming that he/she was playing badminton. The position of the subject and the shuttlecock were arranged so that the subject’s eyes, the shuttlecock and the luminaire were in a straight line. Subjects evaluated visibility of a visual target, glare from luminaire, acceptability of the visual environment for playing badminton and so on. At the same time, measurement of luminance distribution in subject’s visual field was carried out.

　From the result of the subjective experiments, it was identified that glare from luminaire (the subject’s eyes focused on the luminaire) mostly influences acceptability of the visual environment. The results showed that glare evaluation increased as the elevation angle of the subject’s sight increased and the average horizontal illuminance increased. The area with higher than 1,000 cd/m² of luminance is defined as the light emitting part in this study and the average luminance of the light emitting part increased as the elevation angle of the subject’s sight increased.

　Multiple regression analysis was performed to extract the variables that determine the evaluation of glare. The glare evaluation was taken as the objective variable. While the explanation variables are the average luminance of the light emitting part, the solid angle of the light emitting part, the background luminance, UGR and UGR’. The result of multiple regression analysis showed that the average luminance of the light emitting part with higher than 10,000 cd/m², the solid angle of an area with higher than 10,000 cd/m² and the average luminance of the background with lower than 1,000 cd/m² are effective valuables to predict glare evaluation. It was suggested that the average luminance of light emitting part with higher than 10,000 cd/m² should be decreased to reduce glare.