There’s no doubt that light affects our health and well-being. Plenty of studies prove the impact of daylighting and access to views on the health, productivity and safety of building occupants. And yes, medical and educational outcomes can be improved. “But the question is, whether or not we’re able to use electric lighting in buildings to provide the same health benefits that we know daylight provides. And that question, I don’t think, has a defined answer yet,” said Brent Protzman, director of building science and standards development at Lutron Electronics. We can carefully time changes in spectrum and intensity of lighting in buildings, but we have limitations of space, equipment, and energy and safety codes; not to mention accommodations for visual tasks.
Beyond issues of health and worker productivity, there are great applications for dimming combined with color tuning of white light. These primarily relate to creating the appropriate ambiance in changeable venues, or setting different moods throughout the day in otherwise static interiors. “If you play with color and distribution, you can do things like make a space appear festive or somber or add melancholy to environments; make it appear more public or more private,” said Protzman, citing the research of John Flynn. “Nobody knows that better than a theatrical lighting designer.”
Retailers set the scene and draw the eye of the buyer to seasonal merchandise using differences in color temperature to reinforce differences in light levels. To change the traffic flow in a retail space, tuning CCTs to increase contrast can, in fact, be more impactful than dumping more light on a display. In smaller retail settings, a nail spa this year could turn into an accountant’s office in the spring. In these spaces, a flexible dimming and color-tuning solution may have more value than standard troffers. The coworking market is booming, with increasing competition for amenities like direct dimming and direct color tuning.
Tunable white lighting systems can help in matching color temperatures among luminaires from different manufacturers, and in simplifying specifications by selecting color temperatures on-site. In cases where an installation calls for an unexpected look or corporate branding: “Even if it’s just once, you can tune the fixtures in the space to make sure that the finishes appear the way you wanted them in the space, and you’re getting the feeling you’re looking for,” Protzman said.
Any spaces that adapt to different uses or decors are primary candidates for the benefits of combining dimming and tunable white lighting. Hotel lobbies change their decor seasonally, or even more often. Ballrooms and other multipurpose spaces host all kinds of events from deskwork meetings to AV presentations to high-end weddings and awards dinners. Those types of spaces can undergo dramatic transformation in their visual appearance and functionality just by changing light levels and color temperatures.
Dim to warm is not always the answer, as we’ve seen in daylight harvesting systems. An art gallery or any museum space with rotating exhibits may be required to provide a variety of moods, color schemes and contrasts. A classroom may require low light levels for a presentation, but still benefit from a higher CCT more appropriate to that time of day.
Diurnal dimming and color tuning
This appropriateness to time of day is a primary driver for tunable white lighting systems, whether they get a lot of daylight or little or no daylight. Regardless of any health effects, many spaces benefit from dimming that tracks with dynamic CCTs, correlating generally with the cycle of daylight. “You have a better connection to the time of day and to the outdoors. There’s value in that,” Protzman said.
There’s a startling abruptness to walking into a dimly lit steakhouse on a sunny lunch hour. And a painful abruptness to walking back out after an hour being exposed to 25 fc at 2500K. Ketra markets its Natural Light lighting and controls system as a solution. “In any of the retail spaces that we’ve done, we can shift that Kelvin temperature and intensity throughout the day,” said Meg Pirouz, regional sales manager, West. “Having a space that is warm and inviting in the morning when you go get a cup of coffee is nice. And then having one that’s crisp and white and clean in the middle of the day; it mimics the same Kelvin temperatures you would expect outside.”
Ketra systems use an RGBW LED (actually the white is more of a green, according to Priouz) and on-board wireless mesh controls in every fixture. Programmed dimming and tunable white cycles are actuated by fixed or astronomical timeclock. Saturated colors off the blackbody curve are available for special events.
McCray & Co. designed Ramen Tatsu-Ya in Austin, TX, with a Ketra system; cycling a CCT and dimming program to deliver different lighting designs appropriate to time of day. “Reducing the Kelvin temperature and reducing the intensity make that space feel appropriate for a dinnertime ambiance,” she said. “I absolutely tie the emotional impact to appropriate lighting. I think there’s an aesthetic and emotional response to lighting design that happens unconsciously for most people.”
AES Engineering employed a similar strategy for different reasons at the Museum of Anthropology at the University of British Columbia. The Gallery of Northwest Coast Masterworks opened this summer in the Arthur Erickson–designed museum, which is rich in daylighting. AES Lighting Designer Doug McMillan worked with architect Noel Best of Stantec and the museum’s Exhibition Designer Skooker Broome to convert a former theater space to expanded exhibits. “In this new gallery, there is only a small little window in the corner,” said McMillan. “The curator wanted to have that feeling that you have natural light coming in. It needed to work within the context of the rest of the museum.”
McMillan and the project team worked collaboratively to develop a solution of backlit fabric, which runs around the borders of the gallery, with LED track lighting in the center dropped ceiling. The 4 ft–wide perimeter “skylight” is backlit by LED strips that crossfade a mix of 2700K, 4000K and 6500K LEDs to mimic the quality of light outdoors. AES worked with CDm2 LIGHTWORKS to develop a custom photocell and controller that measures, real time, the color temperature and intensity of exterior daylighting and sends this information to a standard DMX controller that, in turn, controls the luminaires’ color and intensity.
“We mounted the strips as far away from the fabric ceiling as possible to give the LEDs some space to mix together, in order to provide an even glow on the fabric,” McMillan said.
I just adore a penthouse view.
Whether it’s just to save energy or part of a larger green initiative, upgrades to LED lighting are attractive to hoteliers. But a quick payback is dependent on guest satisfaction: maintaining or upgrading the atmosphere and quality of the space. The luxurious penthouse of the Quin Hotel is a three-floor “sanctuary” with breathtaking views of Central Park in New York City. According to Beatrice Witzgall, founder and CEO of LumiFi, the Quin explored the use of tunable-white technology to maintain the high-end “incandescent experience” in an energy-efficiency upgrade of the corridor leading to the penthouse. With a program of color tuning and dimming, LumiFi achieved the light quality and color temperatures the Quin was looking for. In addition, the conversion from incandescent to LEDs had high energy savings,” Witzgall said. At night, the sconces warm significantly and dim down to 15 to 20 percent, providing an additional 50 percent savings on top of the conversion to LED.
“We ended up using also saturated colored lighting for their penthouse floor, as they have a lot of events and special occasions up there. Not only do the colors help to identify the entrance better, but they can also brand and theme the lights according to their clients and events,” she added. LumiFi offers a software-based lighting control system compatible with an array of IoT-enabled luminaires. Hospitality customers can choose pre-programmed dimming algorithms; custom programming; or direct dimming by the end-users, where personal preferences are selected and saved.
“The whole concept of personal control of lighting absolutely applies to color temperatures as well,” said Protzman. Studies of direct dimming indicate a preference for personal control of light intensity; end-users are often responding to changing daylight or tasks. In a study of one call center, end-users viewed color tuning, changing the color of the lights, as nearly as valuable as dimming.
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