What can we learn from net zero homes like Harmony House?
Out of reach for most, net zero homes use materials and ideas we can use
Going net zero is still a bit outside the expectations (and budget) of the average home buyer, and outside the experience of the average home builder. But net zero homes, which produce as much energy as they use over the course of the year, offer valuable lessons.
Homes like Harmony House, a demonstration net zero home in Burnaby, influence building practices while offering builders ways to prepare for the demands of the future.
Sponsored by CMHC's EQuilibrium Sustainable Housing Demonstration Initiative,Harmony House has helped put new ideas and materials into use. The home was built by Arthur Lo of Insightful Healthy Homes, with collaboration from a diverse project team.
Arthur Lo offers his thoughts on what we can learn from a net zero home.
Get ready for "zero energy ready"
Lo says that making a home net zero tends to increase building costs by 20 to 25 per cent.
A big chunk of those extra costs are due to renewable energy features such as PV (photovoltaic panels that produce electricity from sunlight) and solar thermal, which use sun to pre-warm domestic water.
However, Lo says the cost impact of photovoltaics — generally the highest cost component — is going to change soon.
"In the past few years, the price of PV dropped down really, really, fast," says Lo. "We're talking about five to 10 years that PV will become affordable in the market. So if we build a home now, we have to prepare for that; we have to get ready."
The way to do that, Lo says, is to build "zero energy ready" homes. Although the exact definition of zero energy ready is still being developed (one organization working on it is the Net Zero Home Energy Coalition), the general idea is to build a home with highly efficient features, designed to support renewable technologies.
In a few years, when those technologies have reached an affordable market price, the home is ready for installation, and to switch to producing its own energy. Lo is currently working on such a home in Vancouver.
"I think that's the trend," says Lo. "That's the belief in our industry. The leaders are those who want to push the energy tools as far as possible, but still suit market affordability. We're building houses that are ready for the future."
Efficiency ideas for today
"Achieving net zero requires two things," says Lo. "Generating energy is the second most important — but first is saving energy."
There are plenty of energy-saving ideas from Harmony House that make sense to use right away, regardless of whether you're aiming for a net zero home in the future.
Design for natural lighting
Buyers love homes flooded with light. Smart design can mean they get this natural effect while also reducing their costs for lighting electricity, winter heating, and summer cooling.
"The layout of Harmony House is great for both natural lighting and natural ventilation," says Lo.
To let in light without losing energy, Lo recommends triple-glazed windows.
"People always think triple-glazed windows are more expensive, but the cost is getting closer to double-glazed now," he says. "And they can improve the energy efficiency of your window area by almost 50%.
"Consider that windows are the biggest heat loss in the house — about 30% of the heat loss. So if you can cut that nearly in half, even with the extra cost for windows, it may be a good investment."
Insulation and air tightness
These are the building blocks of energy efficiency, preventing energy loss to the outdoors. At Harmony House, insulated concrete forms were used , but Lo says an equally effective and less expensive system is a double wall: two layers of 2x4 wall.
Increasingly, municipalities are willing to allow thicker walls without losing the allowed indoor usable area.
As for airtightness, Lo says research has shown it's the most cost effective way to improve the energy efficiency of the house.
"You don't need to use a lot of extra material, although of course you do use more attention," he says. "Plus you can reduce the size and cost of your mechanical systems when you have less air leakage."
Heat recovery ventilator (HRV)
An HRV ensures that heat is retained when warm stale air is vented from the home. These are required to make sure well-sealed homes perform appropriately and ensure good interior air quality.
Don't forget the electric car
A charging station for an electric car was installed in Harmony House, because the "homeowner loved it so much," says Lo.
Right now, such charge stations might be considered a futuristic, and unnecessary, extra. But Lo says that's changing.
"I foresee the electric car will become much, much more popular," he says. "At this point, the charging station should be almost a standard feature."
Some municipalities are seeing the need on the horizon, and now require new builds to include prewiring for a charger in the garage.
Interested in net zero building? Or trying out some of the building practices mentioned above? BC Hydro's Power Smart New Home Program offers information and incentives to help builders improve their energy efficiency.