Understanding glare and UGR
Interpret a UGR figure in the context of the room and viewing direction.
Bright luminaires can cause discomfort even when illuminance is adequate. UGR assesses discomfort glare under defined conditions. Room dimensions, surface reflectance, mounting height and viewing direction affect the assessment.
A label such as “UGR < 19” is not a universal promise for every installation. UGR tables and photometric files must be checked against the project. Reflections on screens or glossy workpieces also need attention through layout and light distribution.
Workstation arrangement matters alongside the product data. A new luminaire in the old position may affect glare differently because its luminous surface and distribution differ. For screens and glossy workpieces, assess the real viewing directions. A sample installation can help illustrate the visual impression, but does not replace the required planning assessment.
What to clarify for your project
- Include viewing directions and screen positions in the layout.
- Request UGR tables and photometric files.
- Assess direct glare and disturbing reflections separately.
Remember: Design glare control together with viewing directions, surfaces and luminaire positions.