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Valuing Dimming in Energy Efficiency Programs

Dimmable lighting unlocks increased energy savings and gives building occupants more comfort and control over the areas where they work and live. What’s not to like? Yet, despite these positive attributes, the US Department of Energy (DOE), reports that only one percent of commercial lighting is installed with dimming capability. Through a carefully sequenced, stakeholder-informed approach, we at the DesignLights Consortium are working to change this narrative.


The Illuminating Engineering Society defines dimming as “the ability to change the luminous flux of one or more lamps or luminaires.” It’s a feature of commercial lighting that research shows office workers and others strongly prefer, despite the sparse presence of dimmable lighting in today’s commercial spaces.


One field simulation study, for example, showed that people who had dimming control reported higher ratings of lighting quality and overall satisfaction with their work environment and higher self-rated productivity. Another investigation showed that nearly 60 percent of office workers placed a “high” or “very high” value on being able to dim their lights. These metrics should be a strong motivator for installation of dimmable lights, given the high value employers place on employee satisfaction, comfort and wellbeing.


It’s the energy savings potential, however, that should generate the keenest interest among those invested in reducing electricity consumption in the face of not only business bottom lines but also local, state, and national efforts to cut carbon emissions. With that in mind, the DLC recently implemented some policy changes.


In March, the DLC removed from its Qualified Products List (QPL) luminaires that don’t meet new Solid-State Lighting Technical Requirements (SSL V5.0) announced in early 2020 – including a dimming requirements for all DLC Premium Products on the QPL, a resource relied upon by energy efficiency incentive programs across North America. We will see more dimming capability on the QPL when the second phase of this new specification, SSL V5.1, takes effect in 2022. At that time, nearly all indoor and outdoor Standard Products on the QPL must be dimmable.


These new requirements are reflective of and responsive to advances in technology and market shifts. LED luminaires are inherently dimmable, and 75 percent of products on the DLC’s QPL already had the ability to dim prior to announcement of our new requirements last year. The QPL currently comprises 77 percent dimmable products.


In the simplest terms, the importance of dimmable lighting from an energy savings perspective is clear - the more an LED fixture is dimmed, the less electricity it uses. LED lighting savings expand substantially when dimmable products are combined with networked lighting controls (NLC), achieving savings that are on average nearly 50 percent above savings possible with LEDs alone.


For context, it’s important to note the high priority the DLC places on promoting NLCs as a path to significant energy savings in the commercial and industrial lighting sector. The DOE estimates that, by 2035, annual savings from commercial lighting controls could reach 81 terawatt hours – roughly equivalent to the state of South Carolina’s annual electricity consumption – if high levels of NLC adoption are achieved.  Conversely, savings could be stranded if LED products are promoted and installed as non-dimmable, and therefore incapable of capturing these additional control savings.


The case for installing dimmable LEDs with NLCs is particularly compelling since it is, in fact, impossible to capture the full functionality of NLCs, and therefore their full savings potential, unless they are paired with dimmable fixtures. A luminaire’s ability to dim light is a prerequisite for other lighting control strategies as well, including high-end trim, 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 recognizing that dimmability is a worthwhile requirement of commercial lighting. Dimming specifications in the DLC’s SSL V5.0 and V5.1 technical requirements complement and build upon the dimming provisions of several other codes and standards. These include California’s non-residential Title 24 Building Energy Efficiency Standards, the ENERGY STAR Luminaires version 2.2 specification, the LEED Building Design + Construction v4.1, and the International Conservation Code (IECC), which has been adopted in some form by 48 states.


All these codes and standards recognize that the technology is ready and realizing its potential hinges largely on the right signals from policymakers. Adoption of dimmable LEDs has generally been limited by continued use of legacy fluorescent lighting already in place in existing buildings. Although LEDs offer improvements in both cost and performance, utilization of dimmable LEDs remains constrained by industry standard practices and lack of dimming infrastructure in existing buildings.


In advance of the next set of the DLC’s revisions (SSL V5.1), there are several steps energy efficiency administrators can take to support the transition to more dimmable and controllable LED lighting products. Some ways to promote and distinguish these products include:

  •   Communicating the energy and non-energy benefits of dimmable/controllable lighting to trade allies and customers;
  •   Sponsoring training programs in lighting control for distributors (sales strategies) and facility managers (proper programming and operation);
  •   To the extent additional energy savings can be claimed, offering higher incentives for dimmable and controllable LED products when bundled with dimming control products;
  •   Offering incentives for energy monitoring and data reporting, to verify energy savings attributable to dimming and other control strategies.


Change in requirements takes time and effort on the part of all stakeholders, and the DLC has taken a thoughtful, data-driven, and phased approach to implementing these changes to our technical requirements. In partnership with our member energy efficiency program administrators and through ongoing engagement with industry stakeholders, we are confident this shift will effectively move the C & I market toward broader adoption of lighting and control solutions that save energy costs and benefit people and the environment.


Christina Halfpenny is Executive Director and CEO of the DesignLights Consortium.

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