Three New Homes in Alberta Produce More Energy Than They Consume

Imagine a home that saves you more than $2,500 a year in energy bills and emits not a single kilogram of climate change-causing greenhouse gases. Sound too good to be true? It's not as farfetched as it sounds.

There are already three so-called net-zero homes in Alberta - two in Red Deer and one in Edmonton, each producing more energy, from renewable sources, than it uses each year. Two others are under construction in Calgary and Edmonton. If the Canada Mortgage and Housing Corporation has its way, these environmentally friendly pilot projects will encourage other home builders and consumers to build more net-zero houses.

Solar Thermal Collectors on the Riverdale NetZero house

The Riverdale NetZero House, for instance, is a semi-detached duplex nestled among the trees in the historic neighbourhood of Riverdale, just a block from the North Saskatchewan River. Designed and built by Peter Amerongen, president of Habitat Studio & Workshop, its boxy shape and black wall of solar collectors stand out among the neighbourhood's 1950s-era cottage-style homes, illustrating a dramatic change in thinking about the relationship between residential homes and energy use.

"Housing is responsible for a significant portion of Canada's energy use and greenhouse gas emissions," says Amerongen.  "If we learn from and repeat what we've done with these prototype houses, we'll soon be in a position to incorporate these changes on the scale we need."

Each two-storey, 2,500-square-foot home contains four bedrooms, three bathrooms, an office/den and a garage. On-site annual production from renewable energy sources includes passive and active solar heating systems and a solar photovoltaic (PV) system. The homes are highly insulated and airtight and have higher amounts of internal mass, which helps to regulate indoor temperatures and reduce heating requirements. The homes also have high-efficiency appliances.

"The key is to start with an integrated design that incorporates energy efficiency and renewable energy collection right from the beginning," says Amerongen. "If you build the best possible building envelope, you can always add renewable energy collection later if it has been planned for."

Although these homes generate all their own energy, they are still connected to Alberta's electricity grid. All surplus electricity generated by the PV system is fed back into the grid, which supplies electricity to the homes when there isn't enough solar energy, such as at night, during cloudy weather, and/or when household electrical demands are heavy.

Net-zero homes result in significant environmental benefits. At Riverdale, energy use has been reduced to 24 per cent of the average Canadian house (61 kWh/m²), and all of the heat and electricity it does use is generated on-site from renewable sources. This gives it an EnerGuide rating of 100 and virtually eliminates the 16 tonnes a year of greenhouse gases emitted by a conventional house.

The Riverdale NetZero home will keep approximately 1,000 tonnes of carbon out of the atmosphere over the first 60 years of its lifespan. Water use, too, has been reduced by 54 per cent.

There is a catch, of course. The cost of building a net-zero house can be as much as $100,000, or 25 per cent, more than a traditional home of comparable size. At the current price of electricity and natural gas, the payback period is between 16 and 35 years, but as energy prices rise and the technology improves, the price tag and the payback period of a net-zero home could shrink as fast as its carbon footprint.