Balancing the Benefits of Emerging LED Technology
Color changing LED technology has potential to be adopted for architectural lighting
LEDs are a highly efficient way to light a home or office space, and they can also be designed to allow the user to change the color of the light. This feature is of growing interest in the lighting industry, and has possible applications in offices, schools, hospitals, assisted living, and other settings. However, some styles of these “color tunable” lights consume more energy than what is typically expected from LED products.
As part of the DOE sponsored Solid State Lighting Program, PNNL staff conducted an initial investigation on color-tunable LED luminaires. Completed under the CALiPER Program, these studies provide unbiased solid-state lighting product performance information and reveal LED product issues related to lighting quality, alignment with performance claims, and energy efficiency.
The two goals of the CALiPER Report 23: Photometric Testing of White-Tunable LED Luminaries study were to understand the technology behind these products, evaluate the amount of testing required to characterize a white-tunable LED product, and to test the performance of currently available white-tunable LED products. The report describes energy use, power quality, light output, color appearance, and color rendering at various dimming and color settings.
Scenarios and Settings
Because white-tunable LEDs are capable of running at a variety of settings—they can dim to different light outputs and change the white light appearance from “warmer”, golden tones to “cooler” bluer tones—it is important to measure their performance in multiple scenarios. The question is, how many scenarios? With no industry standard test procedures or guidelines for this new product category, the study explored possible testing scenarios.
The study focused on the testing of eight different white-tunable LED product types: two troffers, one ceiling luminaire, and five downlights. All of these fixture-types are commonly used in commercial spaces and represent the current state of market-available white-tunable LED luminaires. Having found large differences in performance variation over the color-tuning ranges of the luminaires tested, the research team suggests a minimum of five to seven measurement points in order to accurately capture performance.
Potential benefits of color tuning, such as a retailer’s ability to change light color according to the season or merchandise displayed; increased focus, alertness or calmness in a classroom; occupant productivity in an office; and faster patient recovery times and improved sleep in hospital patient rooms, are driving user and manufacturer interest in this emerging category of lighting products, which will continue to mature.
The testing done for this study is part of a larger effort to better understand white-tunable LED products’ performance. To keep up with upcoming reports in this series, check the CALiPER website.
PNNL Research Team: Michael Royer, Naomi Miller, Tracy Beeson, and Massine Merzouk