Study on Evaluation of LED Lighting Glare in Pedestrian Zones

At present, there is no internationally accepted method of evaluation that converts discomfort glare in pedestrian zones into numerical form. While LED streetlights are rapidly coming into wide use, their light-emitting parts are often nonuniform in luminance compared with streetlights that employ HID lamps. This nonuniformity has been noted as a factor responsible for the emergence of glare. A subjective evaluation experiment was conducted with seven types of streetlights placed in an outdoor field that simulated a pedestrian zone. The streetlights used for the experiment were selected in consideration of the type of light source and the luminance uniformity of the light-emitting surfaces. The results showed that luminance-based photometric quantities are a better measure of discomfort glare than is the illuminance at the observer's eye for light sources with both uniform and nonuniform surfaces. Based on the experimental results, a new evaluation equation that converts discomfort glare in pedestrian zones is proposed.