Glare - UGR Concept
What is UGR?
The UGR (Unified Glare Rating) is a method for evaluating user glare.
It is a complex formula, defined by CIE technical report 117-1995, which allows calculating a glare level for a given luminaire in a given environment. The calculation compares the luminance contrast between the environment and the luminaires: the greater the contrast, the more glare the user experiences, and thus the higher the UGR.
UGR is therefore a concept relative to the luminaire's installation environment.
Example 1: The user will experience more glare in a dark environment with a single luminaire than if the light is more uniformly distributed.
Example 2: For two rooms with identical dimensions and luminaire layout, the UGR will be higher if the walls are black than if they are white.
To allow for UGR estimation of a luminaire outside its actual context (in pre-project), CIE technical report 190: 2010 defines the concept of comparative UGR.
The comparative UGR is calculated:
- In a standardized fictional room
- With a fixed user position
- For a standardized luminaire output flux
These standardized calculation conditions allow comparing luminaires with each other to preselect the most appropriate one for a given project.
UGR in practice for your lighting projects:
Case n°1: Luminaire selection based on its technical datasheet:
All CLAREO technical datasheets present the comparative UGR, defined according to CIE technical report 190: 2010. You can thus select the right luminaire for your project directly from its technical datasheet.
Case n°2: Luminaire selection based on a DIALUX study:
Don't hesitate to contact CLAREO for any DIALUX study request, which will allow you to verify the UGR at all requested points.
→ Contact our DIALux experts to calculate the actual UGR for your lighting project.
Sources:
CIE Technical Report 117-1995 by the International Commission on Illumination
CIE Technical Report 190-2010 by the International Commission on Illumination