What is UGR value?
The UGR value is a measurement defined by the International Commission on Illumination (IEC) to measure the illuminance produced by light in a given environment.
Glare is defined by the International Astronomical Union (IAU) as “a visual condition in which the contrast of a light source is so high or so poorly distributed that it interferes with or limits the observer's ability to distinguish details and objects”. Therefore, discomfort glare is measured using the CIE's Uniform Glare Rate UGR assessment method.
How is the UGR value determined?
The shape and dimensions of the room.
The visual sensation of brightness, also known as luminance, of walls, ceilings, floors and other extended surfaces,
Type of luminaire and protection,
Lamp luminance.
The distribution of luminaires in the room.
Observer position(s).
Standard EN 12464-1 gives a maximum value not to be exceeded for each application. This number, which varies from 10 (lowest) to 30 (highest), is proportional to the risk of glare.
