What exactly is UGR?


UGR is a calculation method that assists lighting designers in developing schemes to avoid the discomfort caused by misplaced light.

The Unified Glare Rating (UGR) is an indicative glare rating based on a predetermined set of circumstances in a lit environment. Within a typical field of vision on a lit environment, glare sources can be numerous, including daylight from windows and internal lighting. The UGR value is calculated using a complex equation that takes into account the luminaire’s luminance value, the background luminance value, the solid angle of the luminaire as seen by the viewer, and several other values.


UGR references can be found in lighting application guides such as The Chartered Institution of Building Services Engineers (CIBSE) Light Guide 7, which recommends that office environments not exceed a UGR of 19. It should be noted at this point that UGR is a function of the installation environment, not the individual luminaire. A professional lighting design is required to accurately assess the level of glare. It should be noted that UGR is not a product criterion. No product-based standards impose any restrictions.


All UGR19 Integral LED products are tested in our lighting lab and proven to be rated as less than 19 at 4H/8H for reflectance at 70/50/20 on both visual axes.

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