Optimal lighting improves mood, task performance and sleep/wake cycles, and conversely, poorly designed lighting can cause discomfort, impede productivity and make it difficult to fall asleep at night and perk up in the morning.
To align both lighting design and lighting products with what’s best for human well-being, the idea of “human-centric lighting” has emerged. While there is no regulated definition of the term, the notion is to mimic changes in sunlight throughout the day while also providing individuals with the means to tailor lighting to their liking.
Human Centric Lighting for the Luxury Home was the title of the presentation Holly Andre of Thea Residential gave during AIA Peconic’s Procrastinator’s Delight day of education on December 6 at Twin Forks Window Company in Westhampton Beach. She shared what’s gone wrong in residential lighting and how new design ideas and new technology are fixing that.
Human-centric lighting includes dynamic tunable fixtures designed with a consciousness of what amount of light and warmth of light makes people feel comfortable at different times of day.
“We’re trying to build spaces, environments internally, that feel natural,” Andre said. “They’re warm and inviting, but they’re energized when they need to be. They have a lot of life to them, and they set the mood.”
Modern lighting technology is far more energy efficient than the incandescent light bulbs of old, the sale of which was largely banned nationally last year, but in other respects, today’s LEDs still don’t beat incandescents. A major sticking point is the ability to dim all the way down to 0.1 percent of their full brightness, something that incandescents can do. The good news is new lighting technology has come on the market that does provide this “fade to black” feature in LED fixtures as well as “soft on.”
Andre began her presentation with an overview of the evolution of electric light sources in homes.
“We ditched incandescents and we switched over to CFLs for like a hot second,” she said.
CFLs, or compact fluorescent bulbs, are more energy efficient than incandescent bulbs and last much longer but give off a harsh light — the same as fluorescent tubes that are ubiquitous in office buildings — and they contain mercury, which is toxic. When CFLs shatter, they pose a hazard.
“I learned that in Connecticut, if you drop a CFL, you have to call the hazmat team,” Andre said. “They bring your wife, your family, the dog into the front yard into a tent. They hose you down. They send somebody in a full hazmat suit to go sweep up the broken bulbs. The dustpan, the broom, everything is now biohazardous, and you get a $300 fine.”
Then came early LEDs, or light-emitting diodes.
“They were horrible. No getting around it,” Andre said. “They buzzed, they were blue, they flickered, they did all sorts of really unpredictable things, especially because incandescent is what we liked. Another hard part was figuring out color temperature, figuring out how we can match that same color that we liked with an incandescent.”
These were things that people liked about incandescent lighting without realizing it, “and we didn’t know how good we had it,” she said.
“But thankfully now we’ve worked out a lot of those kinks, and now a lot of the LEDs that are available on the market can range between the LEDs that we started with or we can have LEDs now that are going to look and feel much more like the incandescents that we all knew and loved.”
Andre noted that there is no industry-wide agreement on what “human-centric lighting” means, while use of the term “circadian lighting” is regulated by the Federal Drug Administration.
“You’ll see a lot of companies not using ‘circadian lighting,’ because if you have anything that has an effect on your circadian rhythm, which is sleep and wake cycles, it actually means that you have an FDA clearance and approval,” she explained. “And there is not a single LED out there that has FDA approval.”
Products marketed as human-centric lighting don’t imply that they are going to fix sleep deprivation, Andre noted. However, she said human-centric lighting design goes beyond what’s overhead and what’s artificial and takes the sun into consideration.
By allowing natural light to penetrate deep into homes and using artificial lighting that emulates the behavior of sunlight throughout the day, human-centric lighting can hopefully benefit the sleep/wake cycle.
Another aspect of human-centric lighting is personalized control. Rather than being stuck with a light fixture that offers one color temperature and maybe dims, human-centric lighting can be adjusted to the task at hand — work, reading, rest, etc. — and be responsive to changes in natural light.
Being able to fine tune the temperature and intensity of artificial light is also important in ensuring home finishes are appearing as intended.
When assessing finishes and fabrics, designers bring them outside or to a window to see their coloring, tonality and textures, Andre noted. “But then the problem with that is then we’re lighting it in a space that’s interiorly artificially lit,” she said.
She recalled working on a project where a client ordered a beautiful jeweled-toned blue couch, only to become livid when the couch was delivered and appeared black under artificial light.
“They didn’t build the couch wrong,” Andre said. “The couch was made of the same fabric that they saw in the showroom, but the way that the light was reflecting that back to our eyes is not the way that they expected.”
While incandescents did a great job illuminating fabrics as the sun would, LEDs, historically, have not, according to Andre.
The color rendering index, or CRI, measures how a color will appear under artificial light compared to sunlight, on a scale of 100. “The name of the game is just trying to get that number as high as possible,” she said.
A CRI of 100 matches sunlight, rendering all color correctly, and most LEDs on the market today rate between 96 and 97. “Which means that we’re getting really close,” she added.
In regards to another shortcoming of early LEDs — that they don’t dim the same way as an incandescent bulb — Andre said incandescent dims very deeply, until there is the last little bit of light on the filament. Meanwhile, most LEDs dim to 10 percent of their brightest setting before turning off completely. She said to human eyes, the lumen level appears to be 30 percent.
Reducing light from 100 percent to 80 percent is not noticeable, she said. “But when we get to that lower level, the difference between 10 percent and 1 percent is pretty wild. But 1 percent to 0.1 percent to our eyes is profound. We pick up on that much more.”
Now there are high-end LED dimming drivers that offer dimming to 0.1 percent, making it easier for eyes to adjust when an LED is turned both on and off.
“Vibrancy is a new type of feature that some LEDs are capable of,” Andre continued. “And what you’re doing here is essentially recreating the recipe for white light. White light, of course, is the culmination of all color and not the absence of color. So what some LEDs are able to do is take the white chip out of the diode set.”
By making white light from a combination of red, green and blue, LED lights with adjustable vibrancy can then be tuned to saturate specific colors to make a painting, millwork or exposed brick look its most attractive.
Another consideration in lighting design is whether to eliminate shadows or play with shadows.
“Lights can be expensive but shadows are free,” Andre said, quoting a lighting designer. “There’s a lot of drama in lighting design with playing against those shadows.”
And then there is the matter of complementing and maximizing natural light that flows through the space: “How are we playing in a way that emulates that natural light and pulls it through even the most interior spaces in the home?” she said.
The sun shifts throughout the day from high color temperature, high intensity at the height of noon, then settling to a bit more yellow, she explained. “As the sun is starting to set, that’s our body’s natural cue to start unwinding. Whether or not we actually get to do that when the sun sets is a different thing.”
