Tunable-white LED lighting offers highly efficient general illumination combined with dimming and the ability to tune correlated color temperature (CCT) from warm- to cool-white. A strong potential application is classrooms, where teachers can set lighting/visual conditions to support classroom activities.
In May 2019, the Department of Energy (DOE) published a Pacific Northwest National Laboratory (PNNL) report evaluating a trial installation of tunable-white lighting systems at three classrooms in an elementary school in Folsom, California. One of the three classrooms was used for general-education fifth-graders and the other two for autism spectrum disorder (ASD) students. The goal of the trial installation, which occurred in August 2017, was to gain an understanding of energy savings potential and possible effect on student health and academic performance, particularly children with ASD.
The study was conducted as part of DOE’s GATEWAY program, which evaluates solid-state lighting field installations to generate real-world data and experience. Using monitoring, the researchers found the new LED lighting generated 46 percent energy savings compared with the existing fluorescent system at full output, while producing similar light levels. Energy savings increased to 48 to 69 percent during a typical day based on how teachers used the controls. Teachers valued the ability to dim the lights and change color output via tuning.
In each classroom, recessed 2×2 tunable-white LED luminaires (furnished by Finelite, along with the controls) replaced two-lamp T8 fluorescent recessed luminaires. Additionally, a 12-ft. tunable-white LED wallwash luminaire was installed surface-mounted above the whiteboard. Teacher-controlled dimming and CCT tuning of general and whiteboard lighting was enabled by an easily accessible, touch-sensitive, wall-mounted, preset DMX512 controller. This controller offered five preset scenes that could be altered with dimming (0 to 100 percent) and color-tuning (2700K to 6500K) slider bars, in addition to featuring ON/OFF power buttons for the entire system and for the general and whiteboard luminaires separately.
Image (left) and reflected ceiling plan (right) of classrooms L1 and L2 with the new tunable-white LED system.
Monitored energy savings during a typical day throughout the school year varied from 48 to 69 percent depending on how the controls were used. (Actual savings will be somewhat less, as the DMX-controlled LED drivers draw a small amount of power in their OFF state.)
Comparison of intensity and energy consumption of the fluorescent and tunable-white LED systems on a typical day in Classroom L2.
In addition to monitoring, the manufacturer added hardware and software to log teacher use of the controls and thereby generate individual usage profiles. While the general-education teacher primarily used the default ON/OFF settings, the teachers in the ASD student classrooms frequently used the presets and slider bars to tune color output and intensity.
“The teachers viewed the preset lighting options as particularly beneficial because they were quick to implement, and noted that the presets were a way to get students’ attention or cue them to transition between certain activities,” PNNL stated in its report. “According to the teachers, the lights were more effective in getting students’ attention than any other method they had tried. They considered the lighting system’s dimmability to be particularly valuable, with color-tunability seen as a secondary benefit. The individual differences between teachers in their use of controls showed the opportunity that tunable LED lighting systems can provide for customizing the educational setting.”
Though use of the controls differed in the three classrooms, the teachers agreed that the LED lighting system provided an improved environment for both themselves and their students, while saving energy. This study is another important step in validating tunable-white lighting’s strong potential role in supporting education environments.
Check out the GATEWAY report here.
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