Sky glow, light trespass and glare remain significant issues in outdoor lighting design. Over the past few decades, numerous jurisdictions have addressed them by passing local ordinances and bylaws.

In May 2023, the DesignLights Consortium (DLC) introduced “Sample Language for Light Pollution Mitigation Bylaws and Ordinances.” The DLC created this resource to offer communities sample language to write or update policies.

Skyglow is light emitted or reflected skyward that obscures a view of the stars while wasting energy. Light trespass is light falling on adjacent properties. Glare is high brightness that can impair or disable vision. Light pollution encompasses all of these issues.

In recent years, spectral emission and its impact on human circadian health has emerged as another concern, leading to the American Medical Association issuing community guidelines in 2016 that recommended 3,000K light sources.

Providing high-quality, energy-efficient outdoor lighting that minimizes light pollution can be achieved by adhering to the “Five Principles for Responsible Outdoor Lighting,” jointly developed by the Illuminating Engineering Society (IES) and the International Dark-Sky Association (IDA).

Light requirements 

These principles define responsible lighting as useful, targeted (directed only where needed), appropriate (not brighter or of a higher level than necessary), controlled (produced in the needed amount only when needed) and using warmer shades of white light where possible.

The DLC analyzed more than 400 outdoor lighting ordinances and found  inconsistency. About half focus on light trespass. The most common performance requirement was for “shielded” or “full-cutoff” luminaires, though there are no standard definitions for these terms, and they have been superseded by the Backlight, Uplight, Glare rating system (IES-TM-15). Less than a fourth set a maximum color temperature, and almost none required dimming.

In 2011, the IES and IDA published a Model Lighting Ordinance (MLO) to provide sample language. The LEED building rating system incorporated requirements based on these guidelines, while the WELL rating system went beyond by requiring 2,700K to 3,000K light sources.

Enter the DLC, an organization representing some 100 utilities and energy-efficiency organizations administering lighting rebate programs. In December 2021, the DLC launched LUNA version 1.0, which identifies outdoor LED luminaires that save energy and promote responsible outdoor lighting. As of July 2023, 65 products gained listing in this subset of the DLC’s SSL Qualified Products List (QPL), with more in review.

“We learned that incentives are not driving adoption of energy-efficient, night sky-friendly lighting because end-users are unaware that they should be prioritizing outdoor lighting that is both energy-efficient and mitigates light pollution,” said Andrew Antares, DLC’s project manager of technical development. “So, we are working to provide easy-to-understand and easy-to-implement resources, and at the same time learning what is needed to drive additional change.”

He said the DLC sample ordinance is essentially the LUNA Technical Requirements, but phrased and formatted for municipalities, offering them two approaches for implementation.

“The simple approach is for them to say, ‘You can only get light fixtures for this project from the LUNA QPL,’” he said. “This means they don’t have to review any additional performance requirements beyond those already in place. But if they don’t feel comfortable doing that, the sample language provides a second approach that spells out the performance requirements so municipalities can review products themselves.”

The sample language is fairly simple, focusing on installed luminaires rather than the site, as the IES-IDA MLO does. It includes a statement of purpose, definitions, requirements for a lighting plan and permitted exemptions. It requires all installed outdoor lighting (new luminaires, not replacement lamps or retrofit kits) to satisfy technical requirements for limited uplight, continuous dimming capability to a maximum 20% of power, limited tilting (if featured) and at least one shielding option or accessory available. 

All luminaires must be installed with whatever optics and accessories are needed to eliminate light trespass and glare. Luminaires used to light freestanding surfaces must be mounted above and aimed down and focused only on the surface. Luminaires must be automatically dimmed to 20% or lower between midnight and dawn or be controlled by occupant sensors.

The sample language does not address nonwhite (amber or red) light sources that may be desirable for environmentally sensitive applications where typical outdoor lighting might affect wildlife. Antares said the DLC may address this in the future if standards are created.

“Communities and business owners rely on electrical contractors as experts,” Antares said. “You’ve got to be a catalog, designer, and these days, a programmer. For outdoor lighting projects, the LUNA QPL gives you an ‘easy’ button. You have a growing list to choose from, and you know that any product on the QPL is going to check important boxes like rebate eligibility, low color temperature, minimal uplight, shielding options and controllability.”

Download the DLC sample language at https://tinyurl.com/mr3jr9jh.

stock.adobe.com / christophe