The Illuminating Engineering Society defines dimming as “the ability to change the luminous flux of one or more lamps or luminaires.” In layman’s terms, the ability to dim lighting is central to providing only as much illumination as is needed at any time or place.
It’s easy to see the energy benefits of this: the more an LED fixture is dimmed, the less electricity it uses.
Common practices often lead to over-lighting since it’s easier to select a product off the shelf that seems to match the lumen output of the existing lighting – even though this doesn’t take into account the fact that many LED fixtures appear brighter than fluorescent ones due to different spectrum and improved luminaire efficiency. Nonetheless, to be on the safe side, product selection often errs on the side of ensuring there is plenty of light, rather than providing just the amount needed.
In many cases, lighting controls can help right-size light output by dimming fixtures down to 80% of full light output, and sometimes even lower, without compromising perceived light levels for occupants. With Networked Lighting Controls (NLCs), lighting can be fine-tuned (possibly with a light meter) to set the appropriate light level for a given space.
The latest version of the DesignLights Consortium’s (DLC) Solid-State Lighting (SSL)Technical Requirements stresses the importance of dimming as a way to increase energy savings, while allowing occupants of offices, conference rooms and other spaces to adjust light levels to their comfort or needs. In fact, the DLC’s SSL Qualified Products List (QPL) — a resource that guides eligibility for commercial lighting rebates in most North American utility markets — requires that nearly all indoor LED products be continuously dimmable, and that outdoor products include continuous or stepped dimming capability.
In terms of future-proofing the energy savings of lighting projects, the longevity of LED products makes it paramount to strengthen requirements for dimmability and other lighting control strategies now, since LEDs installed today are expected to work for a decade or more. For the same reason, LEDs installed now should be paired with NLCs to maximize energy savings. DLC research has shown that adding NLCs at the time of installation can increase energy savings by nearly 50% above what’s achievable with LEDs alone.
Dimming capability is a linchpin to the added savings NLCs can provide, since it’s impossible to capture the full functionality of NLCs, and therefore their full savings potential, if they are paired with non-dimmable fixtures. A luminaire’s ability to dim light is a prerequisite for other lighting control strategies as well, including high-end trim (also known as “task tuning”), which allows a fixture’s maximum light output to be set at a lower level that provides occupant comfort and is appropriate for the space.
The DLC is hardly alone in emphasizing dimming capability. Several other organizations, codes and standards also include dimming provisions, including:
- California’s non-residential Title 24 Building Energy Efficiency Standards;
- The International Energy Conservation Code (adopted by 48 states);
- LEED Building Design + Construction version 4.1;
- Energy Star Luminaires version 2.2; and
- The General Services Administration’s P-100 Facilities Standards for the Public Buildings Service.
All LEDs are inherently able to dim and nearly 100% of DLC-listed fixtures are dimmable. Expanded adoption is the necessary next step to capturing the benefits of dimming. Despite studies that support occupant preference for dimming and research that demonstrates energy savings, the capability remains limited in commercial lighting settings. The US Department of Energy reports that 70% have no controls at all beyond an on-off switch.
The DLC’s technical requirements represent a big step toward changing this paradigm. With continued education about the benefits of dimming, we look forward to supporting the commercial lighting market’s move toward broader adoption of dimmable LEDs and other lighting solutions that save money and benefit people and the environment.
