DOE Tour of Zero: Solar Residence by e2 Homes
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This custom home by e2 Homes in Winter Park, Florida, was the first home in the country certified to the strict performance criteria of the U.S. DOE Zero Energy Ready Home program.
This 4,305-square-foot Zero Energy Ready Home has almost no electric bills thanks to very high-efficiency construction and a solar electric system.
The roof design, metal roofing, and steel-reinforced autoclaved aerated concrete wall construction help make this a disaster-resistant home. Risks prevalent to Florida include pests, termites, hurricanes, high winds, and wildfires.
The water-saving landscaping design includes drought-tolerant species and pervious bark and gravel ground cover that can handle both heavy rains and drought conditions.
The 13.4-kW solar electric system forms the roof of the back porch. The panels are dual surface, meaning they produce power from any sunlight that hits the top of the panels as well as from any light reflected onto their lower surface from below, for up to 30% greater power production. All wiring is hidden within the canopy’s aluminum support beams.
The home’s porch roof consists of 69 solar panels. The panels don’t sit on top of the roof; they are the roof. The panels are fitted together into a completely water-tight 962-square-foot roof structure that blocks the rain but allows about 15% of the light to filter through to the porch area below.
A high-efficiency ceiling fan supplements the cooling provided by the home’s high-efficiency ducted heat pumps and an additional ductless heat pump for the master bedroom.
High-efficiency endless hot water is provided with two tankless propane-fired water heaters located near the master bath and the kitchen to speed hot water to faucets. An outdoor shower off the master bath helps keep heat and humidity outside. A 7,000-gallon rainwater cistern provides water for large aquariums, toilets, and landscaping irrigation.
The home’s exterior walls consist of 8-inch-thick autoclaved aerated concrete blocks. The steel-reinforced blocks are structurally solid, airtight, and provide a continuous thermal blanket insulation system around the home.
The high-efficiency autoclaved aerated concrete block walls are bug-resistant, moisture-resistant, and fire-resistant to help make this home disaster-resistant.
The ultra-efficient attic insulation consists of an R-20 layer of foam insulation sprayed on the underside of the roof decking to provide insulated attic space for the interior comfort delivery system. The roof is topped with a light-colored standing-seam metal roof that reflects radiant heat from the sun.
Autoclaved aerated concrete is made of standard concrete ingredients (sand, cement, and water) with a little bit of aluminum powder added. The aluminum reacts with the cement, causing millions of tiny bubbles to form, more than doubling the volume of the concrete. When the aerated concrete dries, it is cut into blocks or slabs, reinforced with steel, and baked. The hardened blocks are lightweight, much more insulating than concrete, and can be cut with ordinary power saws.
“We like … the use of solar to offset power costs.”
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"DOE Zero Energy Ready Home takes advantage of new technologies and materials [like aerated concrete walls] to have a more efficiently operating home, with less maintenance .… We like the indirect daylight throughout the house, the use of solar to offset power costs, the ability to reuse the rainwater. We have an outdoor shower in the master bath to keep humidity out of the house. We have less maintenance in the yard since we have drought-tolerant plants and no grass."
– e2 Homes homeowner