Most European suppliers publish Uncorrected UGR Tables while Photometric Toolbox generates a Corrected UGR Table (Max UGR value in AGi32 and Photometric Power Tools is derived from the Corrected UGR table). Uncorrected UGR Values are normalized to 1000 lumens while Corrected UGR Values are based on actual lumens.
From CIE-190: Calculation and Presentation of Unified Glare Rating Tables for Indoor Lighting Luminaires - Uncorrected UGR values must be corrected for application purposes.
The Indoor Tool in Photometric Toolbox (v2.5 and greater) allows you to toggle between Corrected (default) and Uncorrected UGR values which is useful when comparing with Uncorrected UGR Tables produced by others.
Here's an example how to manually convert an Uncorrected to Corrected UGR Value:
- Luminaire lumens = 4875
- Correction value = 8 * log (4875 /1000) = 5.5