ECO-STRUCTURE recently caught up with Chelsea Royall, design director for the Solar Homestead, Appalachian State University’s entry for the U.S. Department of Energy’s 2011 Solar Decathlon.
How is your solar paneling unique?
Our solar panels are the only array that was seamlessly integrated into the architectural design. When working on the conceptual design, we knew we didn’t want to tack our panels on as an afterthought. So we created an 800-square-foot outdoor living space, covered by an 8.2-kilowatt array transmitting light throughout. This canopy is composed of Sanyo bifacial panels that collect sun from both the top and bottom of the panel, making them up to 30 percent more efficient. In addition, the integration of the panels allows users to experience solar energy as they enjoy their outdoor space.
What other sustainable features have you incorporated into your design?
Our solar thermal-evacuated tubes sit within a student-engineered and student-built C-shaped trough, making a more efficient system design. We have a 55-gallon tub with paraffin wax (a phase-change material) that replaces the hot-water heater. The line from the evacuated tubes heats the phase-change material, which in turn heats the second line providing hot water for the home. We also have a modernized Trombe wall, which uses a phase-change material to regulate the temperature of the home. We used local building material for the floors that was milled from 200-year-old trees that fell at the Biltmore Estate in Asheville, N.C. We also used poplar bark siding, a byproduct from the lumber industry which is Cradle-to-Cradle Gold certified.
What was the inspiration of your design, and does it display any regional influences?
The Solar Homestead concept was driven by local homesteads built by isolated settlers around our region in Boone, N.C. These settlers were independent and self-sufficient, as is the net-zero Solar Homestead. We took the idea of living and working compounds to create outbuilding modules (OMs). These OMs all have unique purposes similar to a traditional homestead. Previously homesteads had a springhouse or an outhouse; we reinterpreted this concept as storage OMs, main living quarters, or a flex OM. These OMs can be sold separately, working as independent modules supplying any home solar energy.
How has the new affordability criteria affected the design of your house?
Although the affordability contest does create restrictions for the design, we viewed the criteria as an opportunity to show the public how you can have an affordable, solar-powered home. These guidelines allowed us to utilize different materials and construction methods. For example, we used off-the-shelf materials and conventional building practices. One of our conventional construction methods was staggered stud framing, which uses a 2-inch-by-8-inch top and bottom plate, with 2x4s staggering 24 inches on center. This allows for two layers of batt insulation and 1 inch rigid on the exterior, to provide an R-40 wall system. Although the affordability contest may have restricted certain materials, we were able to find options still desirable by the public.
What will happen to the house after the Solar Decathlon?
We have the Solar Homestead set up on campus for visitors. Efforts are in progress to take the home on tour.