In Canada, private and public interests are working on a common problem: How to build net-zero energy housing that average homebuyers can afford.
Asked by officials in the government’s ecoEnergy Innovation Initiative for some new ideas on how to encourage energy efficient building, a company called buildABILITY Corp. put together a program in which five separate builders were invited to tackle the net-zero problem in whatever way they chose. As a result, single-family homes and condominiums are going up in five cities in four provinces as builders work with their own consultants to produce affordable net-zero energy houses in their respective markets.
Natural Resources Canada chipped in $2 million from the national $278 million ecoEnergy program. (All costs in this article are in Canadian dollars.)
Owens Corning Canada provided insulation products for free, and builders themselves came up with in-kind contributions that equaled the government’s ante, says buildABILITY president Michael Lio. The net-zero houses, all of which must be completed by next March, will be sold privately after the government double-checks to make sure they really will produce as much energy as they use.
The larger goal of the Owens Corning Net Zero Housing Community Project is to help production builders figure out how net-zero building practices can become part of their regular repertoires.
“We’ve been talking about it for a long time,” Lio said recently. “There have been lots of net-zero buildings that have been constructed both in the U.S. and in Canada, but there haven’t been many activities that focused on production builders, and even fewer on affordability. So at the heart of this project is to work with large production tract builders to bring them to net-zero and have them change net-zero so it’s more affordable for their customers, to simplify it and drop it into their assembly-line processes.”
Builders find common ground
Builders are working independently. There’s no central agency directing their work, and there’s no common script they have to follow. Even so, Lio says, builders have settled on very similar approaches. “The technologies are off the shelf,” he says, “very accessible.”
Some of the common building characteristics:
- Grid-tied photovoltaic systems for on-site renewable energy, with arrays averaging about 10 kilowatts.
- Exterior walls with R-values between 38 and 44. Wood-framed walls have cavity insulation of fiberglass batts and an exterior wrap of extruded polystyrene rigid insulation between 2 and 3 inches thick.
- Airtightness, measured with a blower door, of 1.5 air changes per hour, or lower, at a pressure difference of 50 pascals.
- Triple-pane windows.
- Although some builders have chosen small-output furnaces, many others are using cold-climate air-source heat pumps.
- Heat pump water heaters.
- Interior polyethylene vapor barriers.
- Attics insulated with batts or blown in fiberglass to a range of R-50 to R-70. Roof framing consists of raised-heel trusses that allow extra insulation above perimeter walls.
Lio says the units have fairly small heating loads (most of the projects are located in Climate Zone 6). Half the 10 kW output of the PV arrays are on average used for base electric loads, Lio says, with one quarter devoted to space heating and the balance to domestic hot water.
Builders will sell the houses at market rates, Lio says, but because of program restraints they won’t be allowed to make a profit on building components that contribute to net-zero operation.
Construction costs are similar
A total of 26 housing units are underway, ranging from one-bedroom condos to single-family houses. Floor areas run from 750 to 3,000 square feet. They’re being constructed in Laval, Quebec; the Ottawa suburb of Kanata; Calgary, Alberta; Halifax, Nova Scotia; and Guelph, Ontario, just to the west of Toronto. Lio says land prices vary widely, but construction costs are similar across the country. Single-family houses will probably be listed in the $500,000 range.
The incremental cost of getting to net-zero on a single-family is looking like $60,000 to $80,000, Lio says, a 12% to 16% premium over the cost of a conventional house. Lio says it’s too soon to know whether Canadian homebuyers will be willing to pay it.
“I think that as a full-on market initiative, we’re really early,” Lio says. “I suspect there will be some homebuyers who have an eye on innovation, who want to be the very first to adopt a particular technology and will certainly buy these houses.
“We’ve seen dramatic shifts in the pricing on some of these systems, particularly on-site generation, and as some of these systems become even more affordable and builders start to adopt the technology in volume, then it would be appropriate to have a conversation about what the market would bear. Right now, it’s conjecture. Prices are high, numbers are low, and it’s really unfair to talk about would someone be willing to dish out $80,000.”
Building on a Canadian tradition
Canada has a long history of high-performance building and introduced its R-2000 program in the early 1980s. As Lio points out, standards typically become more demanding as time passes.
“The R-2000 is in many regards the springboard for these net-zero houses,” he says. “R-2000 is an energy standard but it doesn’t include on-site generation. These net-zero houses not only demonstrate the new type of energy efficiency that’s embedded in the R-2000 standard but it takes that next leap and embeds on no-site renewables.
“That’s the real difference,” he adds. “It’s a continuum. We’ve been at it for a long time and we’ve made lot of mistakes along the way, but it’s pretty obvious that there’s this continuum and these programs that are voluntary eventually become the stuff of code minimums.”
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