The U.S. Department of Energy’s Gateway program has released a new report on a tunable lighting system installed in the new Swedish Medical Behavioral Health Unit in Seattle that sought to leverage biophilic design tenets. The unit incorporates color-tunable luminaires in common areas, and the lighting system uses advanced controls for dimming and color tuning, with the goal of providing a better environment for staff and patients.
The report reviews the design of the tunable lighting system, summarizes two sets of measurements, and discusses the circadian, energy and commissioning implications as well as lessons learned from the project.
Among the key takeaways:
- Tunable LED systems can provide significant energy savings compared to non-tunable alternatives, based on the dimming typically incorporated into tunable applications.
- Achieving design goals related to circadian and other biological and behavioral effects of lighting sometimes requires higher illuminances than those recommended for visual tasks, and consequently may increase energy use during the hours when those high illuminances are needed.
- Allowing the building occupant some degree of manual control can increase energy savings.
- Commissioning of tunable systems remains a challenge.
Scientific evidence continues to emerge, relating the medical effects of tunable lighting to proposed lighting metrics, but none of the metrics have been formally adopted for use in lighting practice.
For a closer look at the findings, download the full report.