What is a UGR?What are the common solutions?

What is UGR?
Glare - a glare that reduces visual efficiency and visibility and is often accompanied by discomfort.It is mainly due to the high brightness source in the field of vision stray light into the eye, the scattering in the eye and the retinal image clarity and contrast decreased.Incapacitated glare is measured by the ratio of the visibility of a job under a given lighting facility to its visibility under reference lighting conditions, called the incapacitated glare factor (DGF).
The diseomfort glare, also known as "psychological glare," leads to visual discomfort but does not cause reduced visibility.
These two kinds of Glare are known as UGR(Unified Glare Rating), that is, uniform Glare value, which is one of the main contents of illumination quality evaluation in lighting design.These two kinds of glare can appear at the same time or in a single form. The same UGR is not only a visual problem, but also a problem in design and application. How to reduce UGR to within the comfort value as much as possible?
 1. Design first
Generally, lamps are composed of shell, power supply, light source, lens or glass. In the early design, there are many methods to control UGR value, such as controlling the brightness of light source, or making anti-glare design on lens and glass, as shown below:

2. Design problems
Within the industry, under the condition that general lamps and lanterns meet the following conditions, it is unanimously agreed that UGR does not exist:
Free VCP (visual comfort probability) greater than or equal to 70;
(2) when in indoor vertically or horizontally to see, with the vertical lamps and lanterns into 55 °, 45 °, 65 °, 75 ° and 85 ° Angle of maximum brightness of lamps and lanterns (6.5 cm squared the brightest) and the ratio of the average brightness of lamps and lanterns or less 5:1;
The maximum brightness of luminaires and vertical lines shall not exceed the industry regulations when viewed vertically or horizontally.

3. Late-stage control of UGR
Avoid installing the lamp in the interference area;
Low gloss surface decorative materials are used in the creaming;
Limit the luminaire brightness.
Some of the lamps designed by OKT are UGR<5, such as split downlight, Low Glare LED Linear Pendant Light. They are respectively used for shopping mall lighting and indoor lighting, giving people a very comfortable experience.Details can be found on the website：www.oktlighting.com.