Reducing Sky Pollution – One Light Source at a Time
Written by: Dave Thomas, Gresco Lighting Specialist
Over the last several years, there has been increasing discussion about preserving the night sky, with organizations such as the International Dark-Sky Association (IDA) leading the way. Their stated mission is “To preserve and protect the nighttime environment and our heritage of dark skies through environmentally responsible outdoor lighting.” The ability to see the Milky Way or anything other than the brightest of stars has become quite challenging throughout most of the United States. An article published in Science Advances on June 10, 2016 concludes that the Milky Way is not visible to nearly 80 percent of the population in North America and that 99 percent of U.S. and European populations “live under light-polluted skies.”
Many of Gresco’s customers in various municipalities and counties have implemented codes that align with IDA’s goals, or at least have moved in the direction of helping to mitigate this issue while also meeting the needs of the community. These needs include but are not limited to: light trespass, glare, and uniformity.
Additional groups have joined the movement to focus on issues of glare and light trespass in addition to the objectives outlined by the IDA. One such organization, the Smart Outdoor Lighting Alliance (SOLA), serves to educate lighting professionals and governmental agencies on the challenges of achieving balance between design components that can, seemingly, be in conflict.
For example, to achieve uniformity and reduce the number of fixtures (and poles), a fixture may produce a wide spread, which can sometimes produce glare and/or light trespass. Because LEDs are a directional light source, reducing glare (especially direct glare) should be at the forefront of consideration in addition to illuminating the task area. Glare is a bit of a tricky issue because it is light directed from the fixture at a certain angle (referred to as zonal lumens), which is sometimes necessary (or preferred) to achieve a certain goal of lighting a particular area. However, direct glare is defined by the Illuminating Engineering Society (IES) as “Glare resulting from high luminances or insufficiently shielded light sources in the field of view. It usually is associated with bright areas, such as luminaires, ceilings, and windows, that are outside the visual task region being viewed. A direct glare source may also affect performance by distracting attention.” One way to reduce the unwanted direct glare is through better source luminance uniformity and shielded light sources.
Striking a balance between what may seem like competing objectives can feel daunting. Gresco’s Lighting Team, along with our manufacturer partners, works to provide our customers with the best lighting solutions for the specific task at hand.
How can we assist you with your next lighting project? Contact your Gresco Lighting Representative today to get started!
Featured image source: https://unsplash.com/photos/PDdG11W3khU