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How To Reduce UGR?

Jun 17, 2020

How To Reduce UGR?

Disability glare is glare that reduces visual efficiency and visibility, and it is often accompanied by discomfort. It is mainly caused by stray light from high brightness light sources entering the eye in the field of view, scattering within the eye and reducing the image clarity and contrast of objects on the retina. Disability glare is measured by the ratio of an operation's visibility under a given lighting facility to its visibility under reference lighting conditions, called the disability glare factor. (DGF)

Discomfort glare, also known as "psychological glare", refers to glare that causes visual discomfort but does not cause a reduction in visibility.

These two types of glare are called UGR (Unified Glare Rating), or uniform glare value, which is one of the main contents of lighting quality evaluation in lighting design. These two kinds of glare can appear at the same time, or they can also appear single. The same UGR is not only a visual problem, but also a design and application problem. So how to reduce the UGR in practice is a key problem.

In general, the lamp is composed of housings, drivers, light sources, lens or glass. And at the beginning of the lamp design, there are many ways to control UGR values, such as controlling the brightness of the light sources, providing the anti-glare design on the lens, or adding the special shield to prevent the spillage.

Within the industry, it agrees that the there is no UGR if the general lighting fixture meets the following conditions.

1) VCP (visual comfort probability) is over 70.

2) When looking vertically or horizontally in the room, the ratio of the maximum lamp brightness (the brightest is 6.5 cm²) to the average brightness is 5:1 at an angle of 45deg, 55deg, 65deg, 75deg and 85deg.

3) Need to avoid the uncomfortable glare regardless of vertical or lateral viewing when the lamp and vertical line in the table at various angles of the maximum brightness can not exceed the chart below.

So in order to reduce the UGR, here are some ways for your reference.

1) To avoid installing the lamp in the interference area.

2) To use low gloss surface decoration materials.

3) To limit the brightness of the lamps.