Are you familiar with Unified Glare Rating (UGR)? If not, then this article is for you. UGR is an objective measure of glare, which helps lighting designers minimize the risk of occupants experiencing glare from artificial lighting in a building. In this article, we will explore what UGR is, how it is calculated, and recommendations for reducing UGR in an installation.

What is UGR?

UGR stands for Unified Glare Rating. It measures the relative intensity of light from a light fitting compared to the surrounding area, as perceived by the viewer. UGR values range from 40 (extremely high glare) to 5 (very low glare). Lower UGR values are preferred in most situations as they indicate less glare and better lighting conditions.

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How is UGR Calculated?

UGR is calculated using lighting design software like Relux, Dialux, and AGi32. The software requires input such as photometric files of the fittings, room geometry, surface reflectance, and the number and spacing of the fittings. With this information, the software can calculate the UGR for a specific installation.

How Can I Reduce UGR in an Installation?

There are several steps you can take during the design of an installation to reduce UGR:

• Consider the position of the room occupants in relation to the light fittings. Avoid placing lights in the direct line of sight.

• Choose light fittings that have a narrower beam angle to reduce the perceived luminous intensity.

• Consider introducing an uplight component by projecting light onto the ceiling. This decreases the contrast and reduces UGR.

• Use fittings where the light source or diffuser is recessed behind a bezel.

• Increase the background luminance and angle the luminaires away from the viewer to avoid shining light in their eyes.

By implementing these measures, you can effectively reduce the UGR and improve the lighting quality in your installation.

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Frequently Asked Questions

Q: What is a UGR<19 light fitting?
Strictly speaking, UGR refers to an installation and not a light fitting. However, many manufacturers sell light fittings labeled as "UGR<19." This means that the fitting's light distribution is designed to assist in achieving a UGR of less than 19 when used at typical heights and spacings in the intended environment.

Q: Are specific UGR values mandatory or a legal requirement?
No, specific UGR values are not mandatory or a legal requirement. However, following the recommended UGR levels, as stated in standards like BS EN12464, is considered good practice.

Q: What are the recommended UGR levels?
BS EN12464 provides maximum UGR levels for different working environments, ranging from 16 to 28. These recommendations cover various areas such as offices, educational premises, healthcare premises, transportation areas, and more.

Remember, selecting fittings with appropriate lighting distribution and following best practices can help you achieve optimal UGR levels in your lighting installations.

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