LED lighting has opened new avenues for facility managers, especially concerning energy efficiency. Newer to the field is tunable lighting, which allows users to adjust lighting color temperature for different conditions and possible improvements of occupant wellness.
As researchers understand more about this technology and manufacturers capitalize on it, a gulf in understanding is emerging about tunable lighting.
“As the day goes on into the evening hours, you go to warmer temperatures with lower blue content attempting to mimic what one might call sunrise/sunset lighting,” says Bob Karlicek.
With tunable lighting becoming a fixture in the lighting marketplace, it’s important to sort through fact and fiction. Overcome the misconceptions and identify whether tunable lighting is right for your facility.
Flexibility and LED Lighting
Color temperature has emerged as an important metric in lighting. It’s closely aligned with workplace comfort, with warmer (lower) color temperatures often used to improve relaxation and cooler (higher) color temperatures used to improve concentration. LEDs and other solid state lighting (SSL) options have unlocked a wide range of color temperatures available for use in facilities.
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“With solid state lighting, it’s possible to create LEDs with different color temperatures and corresponding spectral power distributions (a better measure than color temperature, but harder to grasp) anywhere from 2200K to 7000K,” explains Bob Karlicek, director of Lighting Enabled Systems & Applications (LESA), a National Science Foundation engineering research center at Rensselaer Polytechnic Institute.
The application of LED lighting at various color temperatures has evolved over time. Early LEDs often used high color temperature values because they were more energy-efficient, notes Karlicek. However, as LEDs became more sophisticated and LED chips and packaging materials improved, LEDs could be highly efficient over a wide range of color temperatures.
This led to tunable lighting technologies that allow facilities managers to adjust lighting style throughout the day.
“Almost all the color tunable fixtures that are available for commercial applications have different kinds of LEDs in them, and the control system can blend different color temperature LEDs in the fixture to deliver the desired color temperature,” explains Karlicek. “Depending on the number of color temperatures you put in there and the range covered, that tuning curve can be rather smooth or less smooth.”
On top of all the energy efficiency benefits LED lighting provides, the ability to control color temperatures and have a direct impact on a work environment is exciting for facility managers. However, the exact potential of tunable lighting is only partially understood.
Linking Tunable Lighting to Wellness
The differences between color temperature settings might be easy to notice in some systems, but the health benefits that many manufacturers claim are more difficult to identify.
Most lighting manufacturers aim to make tunable lighting as natural as possible by mimicking sunlight. By matching the light throughout the day, the goal is to regulate circadian rhythms and melatonin production, which both have links to health and wellness.
“What manufacturers try to do is emulate the color temperature of daylight throughout the day to be able to have higher blue concentration in the morning – so-called alerting spectral properties that also suppress melatonin formation,” says Karlicek. “As the day goes on into the evening hours, you go to warmer temperatures with lower blue content attempting to mimic what one might call sunrise/sunset lighting.”
More broadly, tunable lighting has been observed to improve attention and behavior in certain settings. For example, high color temperatures were found to have a focusing effect in classroom settings and other workplaces, according to a report from Canadian utility BC Hydro.
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“This was expected as midday conditions exhibit high level correlated color temperature (CCT) and luminance, and this is when alertness levels are at their highest and cortisol levels are also high at this time of day,” the report notes. “Under low CCT and luminance level lighting, a calming effect was seen in classrooms and hospital patients. This was also expected due to these levels of lighting simulating times of day when melatonin levels were higher and alertness levels were lower.”
By creating more natural light, it’s thought that tunable lighting will stabilize circadian rhythms and melatonin production for workers, but the scientifically supported links have yet to be proven. However, some manufacturers are equating natural to healthy, which is a gross oversimplification.
Quantitative vs. Qualitative Research
As with the results mentioned in the report, most studies of the health or behavioral effects of tunable lighting are anecdotal and observation-based. While these can provide some insights into the effects of tunable lighting, they can’t tell the whole story.
Tunable lighting in schools is a common area to study, and several studies in schools have found better student alertness and relaxation (as determined by the teacher) in lower color temperature lighting. Sometimes these findings are quantified with test scores or other student performance metrics, explains Karlicek.
On top of all the energy efficiency benefits LED lighting provides, the ability to control color temperatures and have a direct impact on a work environment is exciting for facility managers.
While these studies provide some foundation for the potential of tunable lighting, they don’t have the scientific backing to fully determine their usefulness. We lack quantitative data that provides a more scientifically based understanding of tunable lighting beyond the qualitative work often conducted by manufacturers.
“The emerging metrics are still being revised and defined, and none of these metrics have yet been adopted by standards-setting organizations,” notes the Pacific Northwest National Laboratory (PNNL). “This is not surprising, since the implementation of new technology and related new design approaches often precede the establishment of standards. But it is important to recognize that a sizable gap exists for evidence relating specific lighting metrics to biological and medical effects.”
For research on schools, Karlicek states that he isn’t aware of any really detailed quantitative measurements in the U.S. on solid state tunable lighting. Ultimately, it’s incredibly difficult and expensive to perform any quantitative research on tunable lighting, so anecdotal research is the best that facility managers can refer to when considering it. That said, it’s important to be skeptical of clear health claims made by manufacturers.
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“While a growing body of literature exists related to the benefits of biophilic design and the circadian effects of light and several new lighting metrics have been developed and used in some studies, the established evidence on the medical effects of these techniques and metrics is very limited. It hasn’t yet been widely accepted within the medical community,” states PNNL.
Thus, it’s important to be skeptical when it comes to “healthy” proclamations about tunable lighting. Despite best efforts to provide a full assessment of its impact on health and wellness, calling it healthy might be a marketing shortcut.
“Reproducing the solar spectrum and calling it healthy without clinical data is misleading, and this is a problem that a number of manufacturers of color tunable lighting have an issue with,” says Karlicek.
Energy Efficiency and Tunable Lighting
Tunable lighting adds another possible dimension to LED lighting by introducing potential health and wellness benefits. But how does that impact energy efficiency – the main draw of LED lighting?
If you are implementing tunable lighting to improve wellness and productivity, there might be an energy trade-off. The Pacific Northwest National Laboratory (PNNL) performed a study at a Seattle hospital and found that approaching lighting with goals to improve circadian and other biological and behavioral functions leads to higher energy costs because the lighting systems that do so often require higher illuminances.
“In this project, 74% of the estimated annual energy use of the tunable lighting system occurred during the six hours each day when the control settings were established based on achieving the desired circadian stimulus,” notes PNNL. “While the energy reductions that occur during the hours when the lighting was dimmed to lower intensity levels may offset the increases during these high intensity hours, it can be difficult to justify the increased cost and complexity of tunable systems while the evidence of the non-energy benefits are still emerging and not fully established.”
Find out how efficient different manufacturers’ products are to see if it’s worth the tradeoff in your facility, as LEDs may not work as efficiently when they are tuned to improve wellness and behavior.
“The bottom line is that if you have a lighting system and go from a high color temperature to a lower color temperature, the energy efficiency goes down somewhat,” says Bob Karlicek, Director of Lighting Enabled Systems & Applications, a research center at Rensselaer Polytechnic Institute. “It’s the fundamental physics of the process. Fortunately, today’s blue LEDs and phosphors have become so energy-efficient that most people don’t worry about the energy impacts of color tunable lighting.”
Working with What We Know
Despite the lack of fully detailed research about tunable lighting, some of the more qualitative work might provide a suggestion for its potential. Along with schools, healthcare facilities are being closely observed to see how tunable lighting might improve worker and patient well-being.
“They are testing tunable lighting in healthcare environments for the elderly and ordinary hospitals with patients of all ages where there’s an ability to tune the color temperature in an effort to promote circadian health and healing,” explains Karlicek. “There are small studies that have been done to show that in healthcare environments, color tunable lighting can promote sleep at night. There are also studies that show workers tend to be more satisfied with color tunable lighting because the perceived work environment seems better.”
Some smaller studies in elder care suggest that high color temperatures and brightness might help prevent falls and improve visual acuity, while lower color temperatures may improve sleep and reduce late day confusion with Alzheimer’s or dementia patients.
These are anecdotal observations not accepted in any peer-reviewed journals, but they give indication of how tunable lighting can help in healthcare facilities.
One area that requires considerably more research but is promising is the broader impact tunable lighting can have when it comes to circadian rhythm regulation. Shift work is considered to be particularly unhealthy for people, with some describing it as carcinogenic. There are higher incidents of breast cancer in women and prostate cancer in men who work second and third shifts, not to mention a number of other maladies thought to be connected to shift work and irregular scheduling, explains Karlicek.
“Melatonin produced in the body is mainly a timekeeper – it doesn’t cause people to sleep, but melatonin regulates all the other body clocks,” says Karlicek. “Constantly jerking around the primary timekeeper is thought to be related to health issues like Type II diabetes, heart disease, cancer and obesity. While these are complex health problems with many causes and factors, it is becoming increasingly clear that the wrong spectral power distribution at the wrong time of day plays a role in disrupting circadian rhythm. It is also hypothesized that disrupted circadian rhythms promote these kinds of problems in some individuals.”
Researchers are now looking at how spectral power distribution in lighting systems can impact circadian regulation.
“At a very high level, you need enough high intensity, blue-containing light to suppress melatonin during the day, and you need to have low blue levels at low intensity to generate melatonin and regulate the timing of circadian rhythms at night,” explains Karlicek.
Conducting more detailed research on these larger implications of tunable lighting is expensive and difficult, so conclusive answers aren’t possible at this time. Until then, a lot of anecdotal research looks at relaxation, workplace satisfaction of control over color temperature and other similar purported benefits.
Avoiding Misconceptions
Despite the perceived benefits of tunable lighting, there’s no ironclad evidence to demonstrate clearly whether your facility should invest in it. Anecdotal findings may be enough for some to take the plunge. Others might want to wait for that ever-elusive data. Either way, it’s important to be able to distinguish fact and fiction with tunable lighting.
Make sure the manufacturers you’re considering are doing their due diligence to ensure that their tunable lighting solutions have a data-based beneficial impact on a building’s occupants. Ask to see the research and see if it is applicable to your customer requirements. Be aware that standards and best practices are still very much in development now, and that they are subject to change.
“Lighting companies are really struggling right now to define standards for color tunable lighting, connected lighting and the Internet of Things with regards to lighting,” says Karlicek. “Demonstrating value propositions beyond energy savings for solid state lighting is creating a lot of challenges for lighting companies today.”
Finally, expect change in the understanding of tunable lighting’s potential for buildings. What may be unknown today might have a better answer later. As long as manufacturers and researchers commit to the fully detailed study of tunable lighting, those answers will come.
Justin Feit was an associate editor of BUILDINGS.
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