Gary Sharp built this home with what he calls the "best of the best" energy-saving features from Canada's Advanced House program.

If you're looking for the future of energy-efficient building, look to Canada. When the Canadian government sponsored the construction of ten Advanced Houses from 1992 to 1994, its goal was to test and promote combinations of energy-saving technologies. Now a consultant who helped run the program has taken the next step on his own. Gary Sharp is a partner in Post Harvest Development of Ottawa, Ontario, and a design evaluator for the Canadian Home Builders Association's R-2000 energy-efficient construction program. Sharp used what he learned from the Advanced Houses project to build his own 3300-sq.-ft. home that uses 75 percent less energy than a typical North American dwelling at an extra cost of 20 to 25 percent.

Sharp's strategy was simple. "All of the Advanced Houses had special features," he says. "This house combines the best of the best." He blended the standard list of energy-saving features--good solar orientation, high-performance insulation and windows--with a menu of recycled products and highly efficient mechanicals.

From the Ground Up

One of the most intriguing parts of the building envelope was its 15-in. thick foundation, which sandwiches 5-in. of rigid foam between two layers of concrete. To build this unique wall, Sharp placed the rigid foam inside the form to create two chambers, one 6-in. wide and the other 4-in. During the pour, concrete filled both chambers at the same time to equalize the pressure on both sides of the foam. The foam acts as a thermal and moisture break. Placing the foam inside the wall also shields it from insects and eliminates the need for a protective covering above grade.

The thinner wall section supports brick veneer siding, while the thicker one carries the wood-framed above grade walls. Instead of using a drainage layer of gravel beneath the basement slab, he substituted crushed glass. In Sharp's area, the recycling company was glad to get rid of the stuff, so it actually cost less than stone. In other places, it might be more expensive.

Above grade, the frame consists of 2x6's sheathed with rigid foam. Sharp insulated the walls to a super-efficient R-37.5 (the typical R-2000 wall is R-21), but instead of fiberglass, he chose rock wool insulation batts from the Milton, Ontario-based Roxul, Inc. (see page 6). According to Sharp, the dense rock wool eliminates convection currents that lower an insulation's in-place R value. And while he concedes that blown cellulose would have worked as well, his construction schedule demanded that he use batts. Rock wool is also known for its soundproofing ability, and Sharp marvels at the silence in the house. A railroad line runs next to his property, but the passing train sounds quieter than a car. (When cars pull into the driveway, he can't even hear them.)

Air tightness was also high on Sharp's priority list. He did most of his air sealing on the outside, carefully taping and caulking rigid foam sheathing to the wall framing. The only interior air barrier consisted of a polyethylene sheet on the second floor ceiling. Installing and testing the air barrier before insulating made it easy to find and fix air leaks.

The super-efficient windows, which were made by Dorwin in Winnipeg, Manitoba, have fiberglass frames and triple-glazed, argon-filled glass with insulating spacers. All windows have a positive Energy Rating, which means they bring in more energy than they lose. According to Sharp, they satisfy 30 percent of the home's heat load.

The roof is topped with recycled rubber tiles that have been cast to look like traditional slates. They're made by Crowe Industries in Hamilton, Ontario. "We basically took a flat rubber roof, made it more attractive, and put it on an incline," he says. The rubber slates have an estimated lifespan of 80 years and, because they weigh about as much as asphalt shingles, there's no need to beef up the roof frame. Sharp liked the slates so much that his company now sells them.

Mechanicals

The home is heated by a York ground-source heat pump that came with an electrically commutated (ECM) motor. The motor is self-regulating, and can be programmed to deliver a particular number of cubic feet per minute, regardless of the distribution system. This helps compensate for small errors in duct sizing and design. Not that the motor is overworked: "The high-performance envelope makes for a very small heat load," says Sharp. "The main reason for moving air isn't heating, but ventilation. And we can reduce the ventilation rate because we used healthy building materials." The home's low air-flow requirements allowed Sharp to replace the standard sheet metal ducts with 2-in. diameter, high-velocity flex duct. The narrow duct can be routed through interior 2x4 partition walls.

It's the Envelope

Sharp is using his house as a test laboratory for new energy-saving technologies. For instance, he's writing a software program that will let him control all of the home's mechanicals from his home computer. And he is wiring his security system motion sensors to turn the lights and ventilation on and off, depending on whether someone is in the room. But these features are icing on the cake. When asked what he considers his best energy investments, he points to the home's tight, well-insulated envelope. If the house is designed from the footings up to prevent heat loss and air leakage while maintaining a healthy indoor environment, then almost any type of mechanical system will do. Sharp says that if he built the house again, he would trade his highly efficient heat pump for the heat source with the lowest capital cost--even if it used the most expensive energy. The reason? "I hardly ever use it."