Study of glaring effect from light emitting diodes via lens approach

Abstract

The purpose of this study was to evaluate the glaring effect from light-emitting diode (LED) streetlight with two different brands of lens (Lens A and Lens B). By using DIALux Evo with 70W LED luminaires, same scenarios of road lighting designs with pole distance of 35m and pole heights of 10 m on a 7 m wide road was evaluated from both the lenses. Calculation was performed on a section defined by one pole on one side of the road (single row). The pole height, light overhang and boom length were 10m, 1m and 1.5m, respectively. The light loss factor was 0.80. TracePro was used to simulate the distribution of light by tracing rays. All mounted luminaries have three zones of light output which are backlight, uplight and frontlight. Both frontlight and backlight sub-zones are factored into the glare rating. Lens B demonstrated a better threshold increment (8) and the lowest lumens for glare rating as compared to Lens A. This was due to the shape of lens. Smaller shape of lens contributes to narrower light distribution patterns as well as smaller average beam angle, suggesting that Lens B was more suitable for LED streetlights.