Sustainability is at the forefront of the Twin Creeks Science and Education Center, a National Park Service (NPS) research facility named for two nearby trout streams and nestled in the Great Smoky Mountains National Park. A key element of the building's sustainable approach is the lighting design, which heavily relies on daylighting.

“Daylighting allows you to reduce cooling loads, fan power, and all the other things that can end up reducing capital costs in the building,” says Victor Olgyay, principal of the Rocky Mountain Institute (RMI) Built Environment Team, who worked on the project's lighting design while at architectural-engineering firm ENSAR Group before it merged with RMI. “The daylighting and electric lighting integration was a huge part of reducing the energy loads.”

Olgyay collaborated on the lighting design with Atlanta-based architectural firm Lord, Aeck & Sargent, which designed the facility to accommodate changing research activities and foster collaboration among various groups—from biologists and ecologists to universities and museums. The center includes offices, curatorial storage, and laboratory space for park employees and visiting scientists and researchers. It also supplies space for Discover Life in America's All Taxa Biodiversity Inventory project, which seeks to categorize the park's estimated 100,000 species of living organisms.

Jim Nicolow, who leads the sustainable design initiative at Lord, Aeck & Sargent, notes that one of the great things about this project is that the researchers and regional NPS staff all were involved in the early discussion of the design process. “It was a great educational opportunity for the whole team, and we were able to collaboratively identify the goals,” he says.

BUILDING BLOCKS The NPS wanted Twin Creeks to have a mountain cabin aesthetic to go along with its natural wooded location near Gatlinburg, Tennessee. But at 15,000 square feet, Nicolow says, “That's a big mountain cabin. Coming up with a way to design it to have that feel was a challenge.” The solution, he explains, was daylighting. Raising the building's center roof allowed daylight to illuminate the workspace from either side, but it also helped achieve the cabin look the client wanted.

The building interior is split into three parts: a band of offices to the west, the workroom and classroom space in the center, and support spaces to the east, including a wet lab and curatorial storage area. Orientation is key in regard to daylighting, and Olgyay says that was a challenge on this project. “If the building was turned 90 degrees so its primary apertures were facing north and south, it would have been much easier,” he explains. “But because of the site it had to face the way it did. That's why we had increased exterior overhangs and interior glare control, to ensure the daylight wouldn't interfere with the program needs.” While the western orientation of the site was not ideal for daylighting, the architects and lighting designers relied on extensive solar analysis to ensure the building maximized its daylighting potential.

“We went ahead and tried to make all the interior surfaces into light-reflecting surfaces,” Olgyay explains. “There was a lot of shading design, a lot of careful adjustment of the overhangs and specifics of the glazing to quantify the amount of light coming in so we could get the appropriate amount of light at times it could be most useful.”

The project site years ago experienced a landslide that resulted in a mix of boulders ranging in size from footballs to Volkswagen Bugs, Nicolow says. Instead of building concrete walls around the site, the boulders were used as part of the sustainable design to create a retaining wall system. “We took one bad thing and turned it into a good thing,” says Thomas Butler, staff architect at Lord, Aeck & Sargent. “It really integrates the site with the surroundings. It's a lot more natural.”

Taking advantage of the building's wooded surroundings also helped in the daylighting strategy to diffuse the incoming light. “We were very conscious about limiting disturbance and cutting down trees to get the building in,” Nicolow says. “There are trees all the way up to the building that will shade those windows and provide a benefit aside from looking nice.”

The curatorial storage area is not daylit because it has strict humidity and temperature control requirements, Nicolow explains. Natural light would compromise the collections kept there; however, all of the general workspaces and offices have some access to daylight and view. The daylighting analysis performed for the building not only looked at the amount of light brought into the space but also the quality of that light, says Vikram Sami, daylighting specialist, project designer, and energy analyst at Lord, Aeck & Sargent. “Something I don't think is stressed enough is that the quality is as important as quantity,” he adds, noting that glare and control are crucial because if the light is not controlled, “people use shades to block the light and you lose the opportunity for daylight.”