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| Two of the subarrays of this 7.6 kW PV system do double-duty— providing renewable electricity and shading windows. | Adjustable PV awnings optimize electricity production and control solar heat gain simultaneously. | Large south-facing windows admit an abundance of natural light, significantly reducing or even eliminating the need to rely on electrical lighting during the day. |
Bob Heath’s home is another net-zero energy home located in the Belgravia area of Edmonton, Alberta, Canada. This house is a direct result of the Canada Mortgage and Housing Corporation’s EQuilibrium Sustainable Housing Demonstration Initiative. Habitat Studio & Workshop (HS&W; habitat-studio.com)—the Heath home’s contractor—was one of 12 selected by CMHC to build energy-efficient demonstration houses.
Bob’s home, the third net-zero energy house built by HS&W, takes advantage of the main lesson learned from the first two houses—keep it simple. It has no solar thermal system—a 30-gallon electric hot water tank provides domestic water heating. Electric baseboard heaters provide backup space heating. A ground-source heat pump was rejected as too expensive for the small amount of space heating required.
An unusual feature of the house is the adjustable awnings on which 24 of the 36 PV modules are installed. The awnings are adjusted in the summer to completely shade the south-facing windows. This also orients the PV modules more perpendicular to the sun. In winter, the awnings are readjusted to allow the low-angled winter sun to enter the windows. This also puts the modules at a more favorable orientation to the low-angled winter sun and facilitates snow-shedding. These seasonal tilt adjustments yield a 15% higher energy production. The awning design won 2011 Product of the Year at the Net-Zero Energy Home Coalition awards.
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| Once filled with cellulose, these 16-inch-thick double-stud walls will provide an R-56 insulation value. | One of two grid-tied inverters, which process PV power and send excess energy to the utility grid. | A standard tankstyle electric water heater is housed in its own insulated closet to reduce standby heat loss. |
