Lighting University

Application Bundles - Training Tool

Measuring Light

Glare

Negative sensation caused by excessive and uncontrolled brightness in the visual field

The degree of glare not only depends on the luminaire but also the positon of the observer, the room dimensions and reflections of the surfaces.

Unified glare rating (UGR) - measure of the glare in a given environment

  • UGR data should be provided by the manufacturer of the luminaire often found in the specifications or datasheets of the luminaire (e.g. in an office, the luminaires should have an UGR ≤ 19)
Direct glare from windows and luminaires.
Reflected glare on computer screen from ceiling luminaries.

If there are no luminaire specifications available you can also observe and experience the glare:

  • Is the luminaire causing you an unpleasant feeling to your eyes?
  • Is it blinding you?

Discomfort glare – it is difficult to see an object

Disability glare – reduced visual performance

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