Unified Glare Rating (UGR)

UGR is the CIE metric for discomfort glare from indoor lighting installations, computed from the luminance of each fixture toward the observer, background luminance, and geometry. Lower is better: office standards typically require UGR ≤ 19; industrial halls commonly accept ≤ 22–25 depending on the task. UGR belongs to the installation, not the bare fixture — the same high bay can pass at 12 m and fail at 6 m — so datasheet UGR tables state reference room assumptions. Outdoor sports and area lighting instead use the GR (Glare Rating) method of EN 12193/CIE 112. Practical glare control levers: deeper optics, diffusers, higher mounting, and aiming discipline.