Unified Glare Rating, a formula combining the luminance and apparent size of each luminaire, its position in the view and the background luminance. Values typically run from about 10 to 30 and are quoted in steps of 3: around 16 for drafting and fine work, 19 for offices and classrooms, 22 to 25 for industrial work. Manufacturers publish UGR tables for standard rooms, and calculation software computes it for real ones.
Tender calls for UGR under 19 at the workstations, and the cheap panel tables out at 22, so it's out.
Also heard as
- unified glare rating
- UGR value
Related terms
Glare
Visual discomfort or loss of visibility caused by excessive brightness or contrast in the field of view.
Luminance
The brightness of a surface or source as seen from a particular direction, measured in candelas per square meter.
Luminaire
The whole light fixture as one product: light source, optics, housing, driver or ballast and power connection.
Point-by-point
A lighting calculation that predicts illuminance at each point on a grid from every luminaire's photometric data.