The U.S. Department of Energy (DOE) has released a GATEWAY report documenting the trial installation of tunable-white light-emitting diode (LED) lighting systems in three classrooms at an elementary school in Folsom Cordova Unified School District (FCUSD) in Folsom, California. Because such systems have considerable energy-saving potential, DOE evaluated their energy and photometric performance as part of a GATEWAY evaluation. The trial installation was conducted by FCUSD with the help of the Sacramento Municipal Utility District (SMUD). The goals were to explore the potential to improve student health and academic performance and to gain firsthand experience with tunable LED lighting systems. SMUD and FCUSD coordinated and completed the design and installation of the LED systems and coordinated the collection of data from teachers, students, and parents.
Tunable LED lighting systems that provide the ability to vary both intensity and spectrum offer the potential for significant energy savings relative to fluorescent systems and non-dimmable LED lighting systems. The growing use of tunable LED systems is because of both energy and non-energy benefits. The non-energy benefits can come from the effects different light spectra have on human circadian and behavioral responses. A tunable lighting system also provides teachers with an additional visual cue to promote learning and student engagement.
The LED lighting system was installed in August 2017. Without tuning the intensity, the LED system was estimated to offer a potential energy savings of 46% relative to the incumbent fluorescent system. The ability to tune the intensity resulted in significant additional energy reductions for the lighting system. Utilizing morning and afternoon default settings for the LED system, all luminaires operated at 52% intensity, resulting in a potential energy savings of 72% relative to the incumbent fluorescent system. For an operation scenario where the LED system was set with preset scene buttons based on an “active” 24 hour school day with different possible classroom activities (group work, lecturing, watching movies, etc.), the LED lighting system offered approximately 70% energy savings compared to the fluorescent system.
The control system drew more than 3 watts of power per luminaire, even when the luminaires were switched off, which accounted for more than 25% of the system’s annual energy use. This is an important concern that needs to be addressed to maximize the energy savings potential of tunable LED systems during the extended periods when the lighting is off.
Analysis of data regarding the teachers’ use of the systems, teacher and student responses to the lighting, and measured power during different times of day is ongoing and may be included in a future update to this report.