19K5 (1900K/50 CRI) Offers New Opportunity to Limit Blue Light at Night
As LED technology has evolved, so has industry guidance, favoring warmer color temperatures to reduce blue light in our outdoor environment. Cree Lighting’s new 19K5 (1900K/50 CRI) option dramatically reduces blue light, but without the significant economic constraints that often accompany such solutions.
In its nearly twenty-year history as a light source in luminaire design, LEDs have primarily relied on phosphor converted blue light to deliver significant energy savings over the legacy light sources it has effectively replaced. Early generation products, which were much more expensive than today’s luminaires, relied on cooler color temperatures to deliver the needed efficacies and economic value required to move projects forward. The result, economic constraints limited warmer color temperature solutions from being deployed by earlier adopters.
(2007) Half of parking lot converted to 6000K LED (left) from 2200K HPS (right).
Lower CCTs were much less energy efficient in early LED products resulting in cooler color temperatures being widely installed by early adopters.
(2010) Cree Lighting’s Area EDGE luminaire was only offered in 6000K or 4300K, cool color temperatures by today’s standards. The 4300K version required more LEDs (higher luminaire price), as well as additional watts to offset the reduced efficacy of its warmer LEDs. The economics of higher luminaire prices and higher energy costs for warmer CCTs continued to slant product decisions towards cooler CCTs.
In more recent history, the LED chip makers have dramatically reduced, and in some cases eliminated the potential economic pain of warmer color temperatures. With efficacies of warmer CCTs now rivaling their cooler CCT counterparts, preference, rather than economics can determine the color of the light source we wish to deploy at night.
(2025) Cree Lighting’s OSQ-C Area Light is offered in much warmer CCTs. With little-to-no difference in efficacy for its 5700K, 4000K and 3000K versions. In addition, all units are priced the same and consume the same amount of energy. Economics no longer influence the CCT decision.
Industry Guidance on CCT
In April 2020, the IES and DarkSky released their Five Lighting Principles for Responsible Outdoor Lighting. One of the principles in this collaborative document was to “use warmer color lights where possible.” The guidance goes on to say, “limit the amount of shorter wavelength (blue-violet) light to the least amount needed.” Much of the blue light concern here, as well as from other stakeholders that we will also discuss, relates to the increased amount of light scatter that occurs with blue light compared to other wavelengths. This increased scatter has a negative effect because it also increases light pollution – something the industry has grown increasingly sensitive to.
While the collaborated 5Ps document stops short of providing specific guidance on what CCTs we should use, DarkSky, through its Fixture Seal of Approval program, does have specific requirements. As it relates to CCT, its approved products must be 3000K or lower. Design Lights Consortium (DLC), through its LUNA (Light Usage for Night Applications) program, has a similar CCT requirement, that also excludes CCTs above 3000K.
CCT as a Proxy for Blue Light Content
All things being equal, the warmer the CCT, the more blue light from the LED that needs to be converted. Therefore, we’d expect less blue light present in a 3000K product than in a 4000K product.
Spectral Power Distribution (SPD) curves visually illustrate how blue light content decreases when moving from 4000K to 3000K.
Blue Light Concerns Beyond Light Pollution
As previously discussed, blue light scatters, making it a disproportionately larger contributor to light pollution than other portions of the visible spectrum. But beyond light pollution, blue light can also have other negative effects. For example, blue light can also be harmful to wildlife.
Defining and Limiting Blue Light
For communities looking to reduce light pollution and/or the negative effects of blue light on natural habitats, there is a way forward. Beyond using CCT to predict blue light content, defining blue light and then setting strict guidelines to limit it provides more precise results. For example, if we define blue light as light being produced between 400 and 500 nanometers and define only light being produced between 400 and 700 nanometers as the spectrum of interest, you can set limits on how much blue light is acceptable…perhaps we say, less than 2%.
The mathematical equation becomes:
(Light Produced Between 400-500nm) ÷ (Light Produced Between 400-700nm).
To qualify in this example, the answer to the equation above must be less than 2%.
Enter Cree Lighting’s 19K5 Products
Recently we expanded our CCT offerings across all products utilizing our popular NanoComfort® Technology optical system to include a 1900K/50 CRI (19K5) option. These products meet the less than 2% blue light in the example above.
(Left) Spectral Power Distribution of a Cree Lighting product utilizing our NEW 19K5 option that meets less than 2% blue light from example above.
(Right) 19K5 version of our Guideway® Series shown in one of our onsite integrating spheres.
Meets the Less Than 2% Blue Light from the Example Above
Although a much warmer color temperature than the LED products earlier adopters installed, Cree Lighting’s 19K5 products deliver competitive efficacies compared to its cooler CCT counterparts, significantly reducing the economic constraints that might have deterred previous customers from implementing such a solution. While our 19K5 products deliver a much closer visual color appearance to a High Pressure Sodium (HPS) light source, historically the dominant legacy light source used to light our roads across the country pre-LED streetlights, our 19K5 products do so with much better color quality – roughly 50 CRI versus ~20 CRI for HPS. The result, similar visual appearance to HPS, but with much better color accuracy.
Decisions, Decisions
Today, selecting the highest value CCT for your outdoor lighting application can seem like a challenging task. Depending on the application, answers can and will vary. For example, in retail applications where color accuracy is more critical, 19K5 likely delivers less value than if deployed in a residential area or in habitat sensitive areas. At Cree Lighting, we understand that lighting isn’t a one-size-fits-all business. That’s why we offer a broad range of CCTs and products to deliver the highest value lighting solutions to you and your community.