LED how to anti-glare UGR value ?
May 05, 2022
First of all, let's explain: glare is a visual condition that causes visual discomfort and reduces the visibility of objects due to unsuitable luminance distribution in the visual field or the existence of extreme luminance contrast in space or time. The visual field produces a light sensation to which the human eye cannot adapt, which may cause disgust, discomfort, or even loss of visual acuity. Excessive brightness in a local part of the visual field or excessive brightness changes before and after. Glare is one of the most important causes of visual fatigue.
In order to get a comfortable, high-quality lighting environment, it is necessary to suppress glare by improving the lamps. In recent years, indoor luminaires exported to the European Union have an anti-glare standard, i.e. UGR <19, or even lower. In fact, as early as 1995, CIE (International Commission on Illumination) has put forward the concept of anti-glare lamps, and UGR (Unified Glare Rating) as an indicator to evaluate the indoor lighting environment uncomfortable glare. With the development of LED chip technology, LED lamps and lanterns are getting brighter and brighter, and the uncomfortable glare is getting more and more serious. So in 2014, the EU made the UGR limit value as a mandatory standard for luminaires, not just as a reference as before.
The following table lists the UGR limits for several types of locations as specified by CIE.
| Application | UGR limit value |
| Factories, power stations, monitoring rooms | 16 |
| Office space, design and drawing room | 16 |
| Airport, control tower | 16 |
| Daily office space | 19 |
| Meeting room | 19 |
| School,classroom | 19 |
| Hospital, ward | 19 |
| Convenience stores, sales areas | 22 |
| Restaurants, hotels, dining areas, banquet halls | 22 |
Use
UGR < 19" is usually used to meet the basic glare requirements of schools and offices. In fact, in actual use, customers still prefer luminaires with smaller UGR. If you look at the following table of UGR value and the degree of uncomfortable glare, you will understand: UGR=19, in fact, means uncomfortable. The lower the UGR for work and study places, the better.
Many people have a misunderstanding of UGR, thinking that it is a parameter of the luminaire itself, like power and luminous efficiency. In fact, the meaning of UGR is the uncomfortability of the lighting environment for the human eye. It is a value that characterizes the uncomfortable glare level of the entire lighting space, calculated by various parameters related to glare generation. In simple terms, the UGR value is not only related to the luminaire, but also to the size of the room, the reflectivity of the room, and the observer's direction of observation.
