Energy efficiency and sustainability

Is more heat in a home or office a good thing? It depends on the season, of course. As more people turn to solar and geothermal systems to heat and cool their homes and places of business, ambient heat gain can be a challenge—one that can, to some extent, be addressed by well-designed shade structures.Duvall Design completed a residential installation to expand the fabric structure over a roof in Cushing, Maine, in August 2013. The client’s cooling system didn’t perform well due to heat gain through the metal roof, so Duvall installed a two-layer shade structure 60 by 30 feet, over the roof and extending over the 16-foot-wide deck below. “The client cut his heat by 15 degrees [Fahrenheit] in the summer after we installed the structure,” owner Charles Duvall says.

Duvall performs dynamic shade studies prior to settling on a design so the client can see the impact of the time of day on the structure. “I try to organize the structure so it’s functional over the course of a year,” he says. “You can think you’re solving a problem by putting fabric over a large area but if you don’t pay attention to the angles, it’s ineffective. You can move a flashlight over a physical model to act as the sun, or you can use software to see where shadows and sun are cast at any given time of day.”

On the cutting edge of fabric structures with light transmission properties is ETFE—Ethylene Tetra Fluoro Ethylene. “A core part of our business is designing, manufacturing and installing ETFE systems,” Jason Smith says. “It’s a totally different kind of system than woven-base cloth fabrics, such as PVC or PTFE. The ETFE copolymer is extruded into thin films (or foils), which are used to form either a single-layer membrane or multi-layer air-filled cushion. A lot of our clients want ETFE because of its light transmission—up to 95 percent as a single layer.”

ETFE weighs 1 percent that of glass and has similar light transmission capabilities. It’s popular with general contractors because the steel work and foundations normally used for support can be dramatically reduced to support ETFE. The product can be specified in up to five layers. The space between layers is filled with air from an air handling unit that requires about the same amount of electricity it takes to power a 100-watt light bulb for one day.

With Landrell’s Intelligent Printing option, end users can manage the amount of light that enters a space by increasing or decreasing pressure in the cushions. The top and middle layers are printed with an opposing pattern. As the air pressure decreases, the printed layers come together, reducing the light transmissions; as it’s increased, the patterns “open up,” allowing light in.

Sigrid Tornquist is a freelance author and editor based in St. Paul, Minn. She is also the associate editor of InTents magazine, a publication of the Industrial Fabrics Association International.