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Unfortunately, High bay lighting can come with a glaring problem…glare.

UGR Ratings and Strategies for Better Light to Reduce Glare

Glare High Bay Lighting Blog header
Published on: 10/21/2021
Updated on: 3/25/2024

You purchased a LED High Bay luminaire because it’s supposed to save you a lot on your energy bill, reduce maintenance costs and last a long time. But after the install, there was one glaring problem – glare. Did we mention these products can last a long time? If you don’t want to suffer from chronic glarlitis (OK, we made this term up), keep reading.

First, some definitions. There are two types of glare: disability glare and discomfort glare. Disability glare happens when a bright light suddenly enters your field of vision, triggering an instinct to look away and momentarily reducing your visibility. It often depends upon the geographical position of the light source (relative to the individual) as well as the contrast between the source and the area surrounding it. Discomfort glare occurs when your visibility is reduced by bright or uncontrolled light that doesn’t trigger the reaction to look away. Discomfort glare may not be as dangerous as disability glare, but it can be annoying, as well as lead to eyestrain and headaches - and should be avoided.

Now that we’ve defined glare, how do we implement high bay luminaires that limit our risk as it relates to glare in our factories, warehouses, distribution centers, gymnasiums, and retail spaces? Enter Unified Glare Rating (UGR). UGR is a metric that predicts the amount of discomfort-causing glare produced from a luminaire for a given indoor lighting application. UGR values generally range from 10 (no perceived discomfort) to 31 (intolerable discomfort). Although UGR is an unknown commodity for most, DLC uses this metric to qualify its DLC Premium troffers, linear ambient luminaires, as well as low and high bay products, to help ensure safe and comfortable work environments. Most think of DLC Premium products for their energy efficiency, and today a DLC Premium qualified high bay product must produce a minimum 135 Lumens Per Watt (LPW). What’s less known, to achieve DLC Premium status, high bay products must also have a UGR value of less than 28. For purchasers of light, buying a DLC Premium qualified high bay luminaire ensures both energy efficiency AND a minimum glare hurdle to be cleared.

Beyond DLC Premium, there are strategies to reduce glare while still meeting your illumination needs and energy goals. Some effective glare reduction strategies include masking the LED source and effectively using uplight. Cree Lighting can offer both with its KBL Series – Version C High Bay Luminaire. Available with optional aluminum, clear polycarbonate, as well as clear prismatic and white acrylic reflectors, these reflectors all mask the source from common viewing angles to effectively reduce glare (UGR Values between 11 – 24, well below DLC Premium’s 28 limit). In addition, the clear polycarbonate, clear prismatic and white acrylic reflectors are all design to redirect some of the light exiting the luminaire up at the ceiling (up to 7% with reflector and up to 10% with reflector and lens accessory). This uplight provides multiple benefits, including reducing contrast between the luminaire, where the light is being produced, and the ceiling background, to lessen glare. The ceiling also acts as a reflector, so as light hits the ceiling it bounces off and is returned to the space below, helping with light uniformity (Note: White or light-colored ceilings are more efficient “reflectors” than dark color ceilings that absorb more light).

What good is glare reduction if energy goals can’t be achieved? No problem, Cree Lighting’s KBL Series is extremely energy efficient, featuring efficacies of up to 178 LPW, well beyond DLC Premium’s 135 LPW requirement. This means you keep more money in your pocket every month when your energy bill comes due.

Lastly, Cree Lighting’s KBL Series is offered in a broad range of lumen packages (up to 35,000 lumens) and color temperatures to meet the specific illumination needs of your application. Whether you’re lighting a factory, warehouse, distribution center, gymnasium, or retail space, the KBL Series reliably meets your lighting, energy, and economic needs, while keeping chronic glarlitis at bay.

Learn more about Understanding Unified Glare Rating (UGR) here: www.designlights.org/wp-content/uploads/2021/02/DLC_UGR-Fact-Sheet.pdf

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