A retrofit to make Jim Sandercock's Edmonton home 'net zero' energy-efficient using a process its developers say is unique in North America.RetroFit Canada
In what could be a glimpse at a greener future for existing homes in Canada, a 1,950-square-foot single-family house built in Edmonton just after the Second World War has been retrofitted to be “net zero” energy-efficient using a process its developers say is unique in North America.
Depending on who you ask, net zero means different things, but if you ask Melanie Ross, research manager of Green Building Technologies at the Southern Alberta Institute of Technology, she’ll give you a definition now being adopted by many green developers: any system that outputs an amount of energy equal to or greater than the amount it demands in from external infrastructure.
“Being a net-zero building means you can employ a whole lot of different strategies based on a whole lot of conditions, and the key goal is to assess all of your components as a system that has to work together to create the best outcome,” said Ms. Ross, who manages SAIT’s GBT Lab and Demonstration Centre – a project meant to showcase the latest in residential and commercial design solutions.
When thinking about any net zero project, Ms. Ross said the No. 1 thing to consider is the building envelope, which includes a building’s walls, foundation, ceiling, windows and doorways.
“The goal is to reduce the demand on electricity, so you’re using less to start with by ensuring you don’t need as much energy to heat or cool the building. That all starts with the envelope.”
For Butterwick Projects Ltd., the developers behind the Edmonton project, the unique design of its envelope is where their bragging rights lie. Using 3-D renders of the existing structure, the planners were able to design prebuilt panels that could be affixed to the house’s exterior with the help of a crane, the goal being to create an airtight seal that would prevent heat and humidity leakage both into and out of the home.
If proven to work at scale, the approach could be a game-changer for the greenification of hundreds of thousands of Canadian homes and buildings designed around nearly century-old architecture.
“Since the 1970s oil crisis, the world has been focused on piecemeal, incremental changes to meet targets,” said Peter Amerongen, a partner of Butterwick Projects Ltd., and a director at Retrofit Canada, an open-source organization dedicated to increasing the feasibility and accessibility of “deep retrofit” design in Canada.
“You can redo the insulation in your house and save a little on consumption, sure, but if you don’t fix the foundation and get those walls airtight, you’re never really going to have an impact.”
At face value, the idea of getting a building’s walls and foundation to be completely airtight sounds like a fantasy, but technology actually exists today that can solve the issue. In the case of the Edmonton home, Butterwick has used a specific type of membrane that weather-seals the home’s innards, creating a durable but flexible layer between the outdoors, the framing and the insulation.
Temperature and humidity retention is just the beginning of a net-zero home project, however. Many homeowners, for example, especially in areas where electricity is expensive or generated from non-renewable sources, will also want to look at measures such as installing a heat pump – a system that extracts heat from the outside air and converts it to usable indoor heat with the help of electricity – and perhaps even a heat pump water heater to replace their old hot water tank. There are also HRVs, or heat recovery ventilators, which help replace stale indoor air with ventilated outdoor air, and of course solar panels, to help bring down the demand for external energy sources.
For the home in Edmonton, owned by Jim Sandercock, who also happens to be head of the Alternative Energy Program at the Northern Alberta Institute of Technology, all these measures alone weren’t enough. Because of the age and construction style of the house, Mr. Sandercock and Butterwick also had to completely replace and remodel the roof to prevent temperature and humidity loss through the ceiling.
In some instances, Mr. Sandercock said that prebuilt, truss-style roofs could be used on new or existing net-zero projects, which would significantly reduce costs. This was not possible in his own situation, which is one of the reasons both Mr. Sandercock and Mr. Amerongen say that costs for deep retrofits remain high.
“I know a lot of people who might be willing to do something, but they’ll see the cost and it’s out of their range,” Mr. Sandercock said.
Another issue is the availability of trained labourers and project managers who know the ins and outs of sustainable building construction, which Mr. Amerongen said presents both a challenge and an opportunity for the skilled trades work force and the push for net-zero projects.
“Training and capacity building is a huge issue we’re struggling with,” he said. “We need to find folks who understand heat pumps and airtightness and all those issues. There’s jobs till kingdom come here if we get serious about this.”
Over time, costs for deep retrofits are expected to go down, especially as Canada moves toward its 2050 goal of net-zero carbon emissions. But budget constraints mean that for many homeowners, piecemeal-style retrofits remain the norm.
“If you have an unlimited budget, you can do all sorts of things and get to net zero no problem,” Ms. Ross said. “But if you don’t have an unlimited budget, which is the case for most, then you have to make some key decisions.”
What might those decisions look like? They could involve considering how much of a building’s immediate surrounding environment and geography could be used to its advantage. That includes the degree to which a building is warmed by sunlight, how different seasons may affect the level of energy use, and considering modifications to the behaviour of and energy consumption by a building’s occupants.
There are the tiny changes, too: replacing lights with more energy-efficient alternatives or swapping between electric appliances and tools with mechanical ones. It might also involve compromise, such as forgoing a completely renewable system for one that is a hybrid system, perhaps with heating coming from natural gas and electricity coming from solar.
While Ms. Ross said she advocates for retrofitting over demolition – as demolition itself presents its own problems when it comes to air pollutants, environmental damage and energy demand – she acknowledges that there are many buildings that will simply never be able to meet net zero in their current form. Ultimately, however, she believes that a combined and gradual effort will lead to a future in which Canadian building infrastructure is largely, if not entirely, sustainable.
“We’ll keep building and we’ll keep building and testing and sharing what we find,” Ms. Ross said.
“I always say that we’re in it for the long game. In my career, we may not come up with a perfect solution, but I hope to be retired by 2050.”
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