Healthy Daylight and Healthy Darkness: What Our Bodies Need

Nancy Clanton is one of the country's most respected lighting designers. She's also an electrical engineer—with an exceptional sense of humor. I had the recent pleasure of hearing Nancy speak at the U.S. Green Building Council's Greenbuild conference in Portland, Ore. She lectured on a subject that often gets lost in the lighting design shuffle: the human element.


Nancy Clanton is one of the country's most respected lighting designers. She's also an electrical engineer—with an exceptional sense of humor. I had the recent pleasure of hearing Nancy speak at the U.S. Green Building Council's Greenbuild conference in Portland, Ore. She lectured on a subject that often gets lost in the lighting design shuffle: the human element.

Earlier at the conference I was introduced to a new term, "biophilia," which more or less means our innate need to connect with nature. Access to natural light and our outside environs, says Clanton, is a big part of this bodily need, yet most people in buildings have little or no access to windows.

This situation is bad enough, but it's still being propagated—even in "green" buildings. Clanton points out there are a number of LEED-certified buildings—structures held up as models of what is environmentally outstanding—but that earned this certification with no credits for daylighting. "My question is how?" she asks.

To put it in perspective, Clanton looks back to the old fashioned, multi-story schools—the kind right out of Jean Shepherd's A Christmas Story —pointing out the significant amount of natural light that penetrated these buildings. Orientation, of course, was the key, as light always came in over a student's left shoulder so as not to cause glare or distract from the teacher or blackboard. But she adds that the success of those old buildings was due even more to a minimal amount of electric light. So what changed? Ceilings.

"It's all because architects hate duct work," she says. "So they started hiding them under drop ceilings so that light now only comes from one place—above."

In fact, says Clanton, this is one of the worst things a lighting designer can do. Clearly, engineers are the most guilty of practicing what she calls "RCP"—design by reflected ceiling plan. In other words, it's the practice of laying out row after row of 2-ft. by 4-ft. fluorescent trouffers.

"Don't light volumes, light surfaces," she implores. After all, when one paints the inside of a home, they start with the walls, not the ceiling or the floor.

"And please stop putting parabolics in. That's about the worst thing in lighting," she continues, explaining the strategy originated to prevent computer glare. But new monitors, she says, have already overcome this problem. Instead, she suggests a mix of direct and indirect pendant lighting.

Part of the RCP mindset is the notion that the overall illumination level, especially for classrooms, has to be 50 footcandles. But there is nothing magical about that number. In fact, if anything, Clanton says, it's often too much.

"It's like [BNIM Architects principal] Bob Berkebile [a Greenbuild keynote speaker and sustainable design expert] says. 'We have to stop designing for fear—in this case, the fear that a student might not be able to see properly.' And how about considering the teacher?"

So why more daylight? Consider these statistics, says Clanton: Kids in a daylighted environment have scored 20% higher in math and 26% higher on reading tests; retail sales have been shown to increase as much as 40% with the use of daylighting; workers with the best views are significantly more productive (as they don't feel the need to get up and move around as much to get coffee and such); and surgery patients in hospitals with views of nature require 20% less medication.

OK, how about some non-anecdotal evidence? Retail: On one project for Stop and Shop, Clanton was called in to bring down energy consumption. "Our goal was to achieve 30% energy savings, but that was the byproduct. The real goal was better sales," she explains.

In the store were metal-halide downlights, with the light going mainly to the floor. "But we're like moths. We like to look up at the lights, but the light really should be on the products."

The solution: a combination of skylights, fluorescents and accent lighting. The new system consumes 1.8 watts per sq. ft.—two watts less than the old system—and of course, the store looked light-years better. Clanton also presented a case study of a dimly lit courthouse where judges complained that they couldn't see the prisoners being escorted down the hallway. There, overhead "glowy" luminaires were replaced with wall sconces that made an immediate improvement.

So what tips does Clanton offer? First, don't duplicate daylight, supplement it. Again, light surfaces, not floors, and support the objective. Also, try not to create glare and don't make a space too bright or too dark. Finally, "controls, controls and more controls."

"Motion sensors, daylighting sensors, dimming and a reduction of fixtures can offer huge savings," she argues.

In fact, according to the Federal Energy Management Program, 25% to 50% energy savings can be achieved with advanced lighting equipment and that number can be cut in half again when daylighting is added to a project.

"Lighting really does impact the whole building and certainly the whole LEED checklist," says Clanton.

So how about some LEED secrets?

  1. Bring in quality daylight throughout the building, but avoid sunlight on task areas.

  2. Electric lighting should be for task/ambient/accent purposes.

  3. Make sure the building is properly oriented.

  4. Work with the architect and interior designer to use light-colored surfaces and incorporate higher ceilings where possible. "Architects, get your teams involved early. We're really not bad guys," she says.

  5. Use energy-effective lighting equipment.

  6. Employ a combination of automatic and electronic lighting controls, "but don't do anything automatic in a private space like an individual office."

For exterior lighting, Clanton offers these tips: Keep lights away from places where people sleep. Not only is it annoying, but even the slightest amount of light at night prohibits the brain's production of melatonin, the hormone that produces antioxidants that help fight off cancer and other ailments.

For health-care designers, she suggests incorporating red light—possibly LEDs—in patient rooms where nurses are required to check on their charges. This is because of red light's frequency characteristics. Conversely, nurses and other people on night shifts need blasts of blue light or "light showers" to maintain their alertness levels.

"In the end," Clanton concludes, "it's really about how our buildings are able to respond to our bodily needs."

For more resources visit the websites of the Illuminating Engineer's Society of North America ( ) and the Federal Energy Management Program ( ).

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