Proposing a Method Reducing UGR Calculations for LED Luminaires with Diffusers in Indoor Applications

Abstract

This paper studies discomfort glare in indoor LED lighting systems and proposes a method reducing UGR calculations. There are several methods for expressing discomfort glare, among which the unified glare rating (UGR) method is one of the most popular. It is safe to indicate that the UGR method was introduced before LED lighting became popular in indoor applications. Thus, the UGR method is not versatile currently. In this paper, key limitations of the UGR method are discussed. A method for reducing UGR calculations based on UGR tables for both LED luminaires with diffusers (uniform luminous intensity distribution) and with lenses is proposed. The method is mathematically discussed and its applicability for luminaires is discussed. Also, the luminaires are put through a test and the results from the tests are presented and the feasibility of the method separately from mathematical proofs is examined. The proof and case studies both indicate that the method can be used accurately for luminaires with diffusers. They also illustrate that the accuracy of applying the proposed method to the LED luminaires with lenses is not satisfactory. Simulations are carried out using DIALux lighting design software.

Keywords

• indoor lighting
• LED (light emitting diode)
• UGR (unified glare rating)
• UGR calculation tabular method
• LED luminaires with diffusers
• LED luminaires with lenses