The US Department of Energy (DOE) has published another in its Gateway series of research reports that cover actual solid-state lighting (SSL) installations in challenging indoor and outdoor lighting settings. The "Tuning the light in senior care: Evaluating a trial LED lighting system at the ACC Care Center in Sacramento, CA" document details the installation of a programmatic, tunable LED-lighting system in resident rooms and corridors at a senior living facility. Moreover, the researchers installed additional SSL products including occupancy-controlled night lights that provide added safety for residents.
The idea of using tunable LED lighting in a variety of applications, and generally referred to as human-centric lighting (HCL), is not a new one. But some researchers believe we need to know more about the impact of tunable spectrum before trying to use lighting as almost a therapy. Generally, Europe has been more proactive in the HCL area. And we recently covered the use of tunable lighting in a dementia center in Germany.
It was very encouraging to see the DOE involved in an actual HCL trial in the US, even if the Gateway report only refers to tunable lighting and not to the HCL moniker. The project was conceived and led by the Sacramento Municipal Utility District (SMUD) working with the ACC Care Center. SMUD invited the DOE to participate and the agency's Pacific Northwest National Laboratory (PNNL) worked with SMUD in evaluating the photometric properties of the lighting and also evaluating the health and behavioral response of the residents.
The tunable elements of the project were installed in two places. SMUD installed tunable ambient lighting in one single-resident room and one double-resident room. That installation used Philips Color Kinetics iW Cove MX Powercore cove luminaires. In the corridors, nurses' station, a common area, and office, SMUD installed the Beetle tunable troffer from Samjin. But only the corridor lighting and the resident-room lighting was placed under programmatic control.
Scripts controlled the lighting in both spaces. In the corridors there were CCT and intensity changes. The standard script was:
7 AM–2 PM: 6500K at 66% output
2 PM–6 PM: 4000K at 66% output
6 PM–7 AM: 2700K at 20% output
The resident rooms only varied CCT, although the lights might be turned off at any time whereas the corridor had to remain lit. The script was:
7 AM–2 PM: 6000K
2 PM–6 PM: 4100K
6 PM–8 PM: 2700K
In both systems, there were controls that allowed for manual overrides. If an override happened, the script would resume at the next scheduled change.
There were other LED-based lighting products that were key to the project, because things such as bathroom lighting and lighting for exams in the resident rooms had to be at a warm CCT to avoid an impact on the installation of the tunable system. But those additional luminaires delivered primarily energy savings over what had been a system comprising linear fluorescent lighting with some compact fluorescent lighting (CFL).
The one exception in terms of impact of other LED fixtures was the motion-activated lighting installed for nighttime safety. That lighting was generally amber in color or 2400K CCT. The team found that night lights needed to be away from the floor to deliver the requisite safety. And the installation even included some handrail lighting, all focused on safety at night.
As mentioned earlier, the results of the project are generally positive, although privacy regulations prevent anything more than aggregate data from being published. But the report said target behaviors such as yelling, agitation, and crying were reduced by 41% for the three months of the study relative to the three months prior to the tunable LED lighting being installed. There was also a reduction of falls in the corridors.
The DOE said overall the SSL installation delivered 68% energy savings. Perhaps more significantly, illuminance levels met or exceeded current IES (Illuminating Engineering Society) levels whereas the fluorescent lighting had not. In general, the tunable features were determined to be positively impactful in controlling melatonin suppression or production to match circadian cycles. And the ambient lighting was deemed very important to safety without impacting circadian cycles.
The project also taught some tough logistic lessons. The report said installing new tunable fixtures in a retrofit fashion can be challenging. Indeed, the Color Kinetics products were difficult to install and wire without disturbing the walls in the space. Moreover, the team found that commissioning remains difficult and that it is hard to find contractors who have any experience with tunable lighting.