Craig DiLouie interviewed Leora C. Radetsky, Senior Lighting Scientist & LUNA Program Director at DesignLights Consortium (DLC), about the new SSL Technical Requirements V6.0. This interview will inform articles by DiLouie in Electrical Contractor and tED Magazine.
DiLouie: Please provide a brief history of the Qualified Products List and the Technical Requirements establishing qualification, including the process by which these requirements are developed.
Radetsky:
The DesignLights Consortium (DLC) actually began as a commercial lighting initiative of Northeast Energy Efficiency Partnerships (NEEP) in 1998. Initially, it was a working group of NEEP member energy efficiency program managers who recognized that lighting quality was a missing component of many EE programs. They created a set of lighting design guides called the “knowhow series” for various commercial spaces that highlighted up to date equipment, best practices and codes and standards for commercial lighting. In 2006, they engaged distributors in an educational and incentive campaign to promote the stocking and use of High Performance T8 (HPT8) fluorescent lighting, which resulted in making this a mainstream technology within 2 years. In 2008, when LED for general illumination was entering the market, NEEP members asked for a single, common set of requirements and list of products that met those requirements, to identify quality, efficient commercial LED lighting for incentive programs. Prior to the DLC’s Technical Requirements, each EE program was developing its own criteria and managing its own evaluations and analyses. As the QPL grew, other EE programs began to use and require it and today DLC listing is required by nearly 700 programs in North America.
The DLC uses a six-step stakeholder input process to develop our technical requirements. There is a significant amount of research and development that occurs on a regular basis including member input, data-driven analyses and outreach with industry stakeholders. This R&D informs the first draft. The DLC uses comment periods to get additional, formal stakeholder input and revises the requirements based on this input. For SSL V6.0, we received nearly 1500 comments over two comment periods. These comments had a significant impact on our technical requirements, including on eligible PUDs, efficacy thresholds, controls requirements, quality of light and LUNA.
DiLouie: What impact have the DLC’s SSL Technical Requirements historically had on commercial lighting rebate programs and setting a minimum standard for energy efficiency and performance in the lighting industry? How prevalent is use of the QPL in commercial lighting rebate programs?
Radetsky:
As a consortium, the DLC works with our members and lighting industry stakeholders to create comprehensive technical requirements that help them save energy, reduce carbon emissions and minimize light pollution. Having consistency in the requirements has allowed these programs to operate more cost effectively and align offers for the most common products without having to individually evaluate these products.
As of Q4 2025, about 70% of commercial lighting rebate programs require DLC listing.
DiLouie: Please describe the new efficacy increases in the 6.0 version of the Technical Requirements. What product types received the largest increases and what types the smallest? What was the reasoning behind this, and what impact will it have on energy efficiency programs and retrofit projects?
Radetsky:
On average, SSL V6.0 has a 14% increase in the minimum efficacy thresholds over SSL V5.1. Every category had increases with a range of 4 – 19%. Four-pin, 2G11 Base LED Replacement lamps for CFLs saw the smallest increase (4%) and several outdoor product types (or primary use designations (PUDs)) had the largest increase (19%). These increases were based on data analyses from our own listed data, as well as DOE and FEMP market data trends.
DiLouie: A useful way to evaluate LED-to-LED upgrades “back of the napkin” is to compare the efficacy requirements in the 2015 version of the technical requirements to the current requirements. How does this look?
Radetsky:
We think that outdoor retrofits, with zero uplight and low CCT (≤ 3000K) products, should continue to grow, with a focus on light pollution mitigation as well as energy efficiency. While cities often hear complaints about light trespass, outdoor lighting can also have immense, unintended, negative consequences for the environment.
DiLouie: In the last iteration of the Technical Requirements, the DLC began setting minimum standards for lighting performance in addition to energy efficiency, which was considered by some an extraordinary move. Why did the DLC take this step, and what did it accomplish?
Radetsky:
Customer satisfaction is important to utility and EE programs, and a lighting retrofit should have high quality and energy efficient lighting. At the time that DLC was developing the SSL V5.0 specification, EE programs were particularly concerned with glare. DLC introduced tabular UGR thresholds for Premium as a method for addressing this concern which, while limited, aligns with our product evaluation process. We are continuing to evaluate glare research and standards development with the intention of utilizing better glare metrics when they are standardized.
DiLouie: Please describe what’s new in terms of lighting performance requirements for the 6.0 version. Why were these changes adopted, and what impact will it have on quality of light in projects featuring DLC-listed products?
Radetsky:
There are several lighting performance changes in SSL V6.0. First, we are allowing in Amber LED and low CCT (1800 K – 2000 K) products to qualify for V6.0 with commensurate efficacy and lumen maintenance requirements. These products do not have to meet the color quality requirements we have for white light but do have to report their performance. This information (as well as efficacy) can be hard to find and is often lacking in spec sheets. To help our stakeholders, we will be listing this information on the QPL. This allows QPL users and decision makers to see how these products compare and differ. We have also capped the maximum CCT to 5000K for outdoor products to help limit light pollution.
We have eliminated UGR thresholds as a requirement for Premium for linear ambient, high-bay and low-bay products but continue to have it for troffers. The tabular method is still appropriate for troffers, but less predictive for these other product types and standards have adopted application UGR.
Finally, there are several changes with LUNA V2.0. LUNA V2.0 is now included in the SSL V6.0 technical requirements (in Part 4) and builds on the SSL V6.0 technical requirements. We are now allowing lamps and retrofit kits to list to LUNA V2.0 if they meet our more rigorous constraints on light output and CCT. We introduced three new turtle PUDs, which have maximum light output, uplight and high angle light requirements. These products must also use direct-emission Amber LEDs (sometimes known as narrowband Amber LEDs). We are also calculating and displaying more metrics for LUNA products including S/P Ratio (which is a more predictive metric than CCT for the spectral impacts of sky glow), percent blue and Hawaii code compliance.
DiLouie: The 6.0 version of the Technical Requirements includes new expanded controllability requirements. Can you describe them and why they were undertaken as changes?
Radetsky:
In SSL V5.1, controls information is shown for all possible variations available for a product. In SSL V6.0, based on feedback from members, QPL users and manufacturers, we are collecting the details of controls variations within listings to help EE Programs better connect a model number from an invoice to specific integral controls capabilities.
- We are introducing a new controls options table which has more information on listed controls and their performance attributes.
- Based on the controls options table, we will be organizing products into controls categories based on their integral controls capabilities from no integral controls: Category 0, to most controllable LLLC: Category 6.
- A new “Controls Ready” category is introduced, highlighting products with “plug and play” receptacles making it easier to add controls in the field.
- Products that are compatible with DLC-listed networked lighting controls (NLCs) on the DLC’s NLC QPL will link to NLC-listed systems.
- Controls Categories are designed to simplify incentive review applications and review processes by aligning with specific controls savings factors detailed in Technical Resource Manuals (TRMs) that govern many EE programs.
We have also revised our field adjustability requirements to enable more comprehensive reporting, allowing EE programs to verify performance for selectable product settings for field adjustable light output (FALO), color temperature (FACT) or light distribution (FALD) qualities.
DiLouie: What impact will these new controllability requirements have on retrofit projects featuring DLC-listed products?
Radetsky:
More available incentives. Using controls categories, we are helping our members provide more controls rebates, and support incentive tiers, by making it easier for EE programs to connect integral lighting controls with control savings factors.
Controls categories and the new controls options tables will also be helpful where codes or rebates require application-level controls usage, such as daylight harvesting, high-end trim, and occupancy/vacancy sensing because the specific integral control capability will be shown in the Controls Options table (including driver information, minimum dimming level, integral controller or sensor type, function and technology, and maximum mounting height).
DiLouie: Are there any other changes in the Technical Requirements that is important for the lighting industry to know about?
Radetsky:
With SSL V6.0, we are supporting innovative initiatives that have emerged with regard to sustainability and material transparency, as well as resiliency and decarbonization. As a result, we have also added new solar powered outdoor luminaire categories with additional reporting for grid, battery and solar panel performance, as well as optional sustainability reporting.
DiLouie: Why are the new Technical Requirements important to electrical contractors, what do they need to know about them, and how should they be using this knowledge in engaging with customers?
Radetsky:
The Technical Requirements set the minimum performance for products to be listed on the SSL QPL. With billions of dollars of incentives available each year, EE programs use the SSL QPL as a trusted, objective source to vet lighting products that would meet their customers’ needs. Many municipalities are also interested in responsible outdoor lighting, and have ordinances requiring light pollution mitigation, and LUNA listed products help them save energy while minimizing light pollution.
The Technical Requirements also makes it easier to identify selectable products which provide more flexibility when trying to meet customer expectations for color, light output, and distribution. By detailing the controls variations within a listed product, such as “Controls Ready” capabilities, the QPL also helps with future proofing installations so that contractors and customers can make changes as their needs change.
DiLouie: Why are the new Technical Requirements important to electrical distributors, what do they need to know about them, and how should they be using this knowledge in engaging with customers?
Radetsky:
First, distributors can, and should, identify which products qualify for rebates using the DLC QPLs. They should not rely on a logo on a product spec sheet. This ensures that their customers receive the maximum incentive. With the growth of Controls-Ready products, NLCs and selectable light output/CCT/light distribution products, we expect to see more innovative luminaires and lamps listed on the SSL QPL. By providing distributors with the comprehensive information they are looking for on the QPL (including a spec sheet, as well as all the other information discussed in this interview), the QPL can become a key resource for distributors looking to meet their customers’ needs.
DiLouie: If you could tell the entire electrical industry just one thing about the DLC V6.0 SSL Technical Requirements, what would it be?
Radetsky:
Utilities are facing growing power demand from AI and data centers while still trying to hit decarbonization goals. Improving energy efficiency continues to be a key strategy for managing and reducing increases in energy demand. SSL V6.0 and LUNA V2.0 assist EE programs by establishing clear performance requirements that are designed to lower energy consumption, expand the range of eligible products, and deliver responsible outdoor lighting solutions that meet the needs of communities.
DiLouie: Is there anything else you’d like to add about this topic?
Radetsky:
Local and state governments also have environmental, sustainability and/or climate-action goals that they need to meet. Energy efficiency and responsible outdoor lighting are key mechanisms they can use to meet their goals, and the SSL QPL provides these stakeholders with validated lighting products that can help them.
DiLouie: Thank you for sharing your expertise, Leora.
You must be logged in to post a comment.