The National Electrical Manufacturers Association (NEMA) published NEMA LS 20001-2021 White Paper on Unified Glare Rating (UGR). This new white paper explains the original intent of Unified Glare Rating (UGR), its proper uses, and common misuses.
Unified Glare Rating (UGR) is one of the few lighting metrics that practitioners use to model and design appropriate lighting to meet application and task visual needs. In the hands of a competent lighting designer, UGR can provide insight into visual comfort expectations when included as part of a complete lighting design because it incorporates room layout, luminaire layout, the task being performed, and surface reflectances.
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