What is UGR and why has it become so important in the projects?

Currently, in numerous project tenders, project owners are increasingly demandingn testing reports indicating UGR (Unified Glare Rating) of less than 19. Moreover, some high - end office and school projects explicitly require a UGR < 16. What precisely is glare? Why has glare control become a mandatory criterion for lighting procurement? Today, we will comprehensively expound on glare control from the perspectives of procurement and engineering.

1、 What is glare? What is UGR?

Glare is a visual phenomenon within the field of view that leads to discomfort or impairs the ability to observe targets due to inappropriate brightness distribution or extreme brightness contrast. In simple terms, it is the blinding light that causes discomfort to people. UGR (Unified Glare Value) is an internationally recognized quantitative indicator for assessing the discomfort glare of indoor lighting, with values ranging from 10 to 30. The smaller the UGR value, the milder the glare and the more comfortable the visual experience. For instance, UGR<19 indicates acceptability, UGR <16 indicates comfort, and UGR <13 indicates high comfort. For procurement purposes, understanding the UGR report can help determine the anti-glare level of lighting fixtures.

2、 Why does glare occur? Why control?

In actual lighting environments, glare primarily stems from high light source brightness, an excessive contrast between the brightness of the light source and the background, and then light source being too close to the line of sight direction. The UGR calculation formula takes these factors into consideration: the higher the brightness of the light source, the darker the background, the larger the light source, and the closer it is to the line of sight, the higher the UGR value and the more severe the glare.

If glare is not controlled, it can cause:

--Visual fatigue: Working in a glare environment for a long time can cause dryness and soreness in the eyes, reducing work efficiency.

--Safety hazards: For example, glare in road lighting may cause drivers to instantly become blind.

--Decreased spatial quality: High end commercial and office spaces may appear cheap and unprofessional due to glare.

Therefore, modern lighting design must control the UGR value through lamp selection (such as hidden anti glare, grille, lens) and installation position optimization.

3、 UGR procurement requirements for different industries

In actual procurement, there are clear specifications for UGR limits in different application scenarios:

--High end offices and design studios: UGR ≤ 19 (recommended ≤ 16)

--School classrooms and reading rooms: UGR ≤ 16 (blackboard lights need to be anti glare)

--Hospital wards and consultation rooms: UGR ≤ 16

--Shopping malls and exhibition halls: UGR ≤ 19 (key lighting can be slightly higher, but direct glare should be avoided)

--Industrial plants and warehouses: UGR ≤ 22 (adjustable according to operational precision)

Purchasing personnel must request the UGR test report of the lighting fixtures when selecting, and verify whether the actual UGR value after installation meets the design requirements. At the same time, anti glare design usually means hiding the light source, using lenses or grilles, which may increase costs, but this is an inevitable investment in improving project quality.

Simply put, glare control is to improve visual comfort by reducing the UGR value. For procurement, sales, and engineering personnel, mastering UGR parameters means:

--Understand the anti glare requirements in the bidding documents

--Recommend more comfortable and high-end lighting solutions to customers

--Avoid acceptance failures and customer complaints caused by glare issues