From the outside in: a new way to renovate

How do you turn a 1940s Edmonton semi-bungalow into an energy-efficient net-zero home? Could it be as easy as just throwing an extra-large sleeping bag over it?

Well, perhaps not literally, but the idea isn’t as far-fetched as it might sound.

Eleven years ago, Jim Sandercock and his family found that 1940s home in Highlands, an older neighbourhood in the northeastern part of the city. They liked the home, it had good bones, and just as important, it was within walking distance to the schools their children could attend. So they bought it.

Now, or at least in the immediate future once an innovative renovation is completed, this same home will not only be net zero ready, it will be the first single-family home in North America to get a panelized deep retrofit. In short, with the help of Edmonton-based Butterwick Projects Ltd., pre-built airtight, super insulated wall panels have been attached to the house’s exterior to wrap the home and make it up to 80 per cent more efficient.

“As far as we know, this project’s the first time anyone has tried the approach on a single-family home in North America and maybe even the world,” said Peter Amerongen, partner, Butterwick Projects Ltd.

“About a third of greenhouse gases come from the buildings we use right now,” added Amerongen. “Most of these will still be in use in 2050. To deal with the climate emergency, we need to make our homes net zero long before that. Panelized deep retrofits are a great solution.”

Knowledge Transfer

The Sandercocks started improving the energy efficiency of their home once they bought it. There were easy things, like switching out incandescent light bulbs to more efficient LED versions, but they also added solar and put additional insulation in the basement. However, they weren’t reaching the net zero target they wanted to hit. Also, sometimes they took one step forward and two steps backward.

“Incrementally, just changing one thing at a time we were kind of tripping over ourselves by thinking of doing things and sometimes in the wrong order, which would kind of undo some of the things we wanted to do,” said Sandercock. “It would be nice just to be co-ordinated and just move forward.”

Sandercock ended up reaching out to an engineer who had done a retrofit of his own house. That process looped him into Butterwick and Retrofit Canada, a resource to help people plan and do smart deep retrofits.

Sandercock, who had mused about putting a sleeping bag over the whole building based on information he came across — it turns out a Dutch company had figured out how to scan an existing house and build an exterior expansion, hence the sleeping bag analogy — now realized it could be done and done locally.

The work would see Logan Gilmour, a software developer from the gaming world, digitally capture the dimensions of this 1,950-square-foot home using a drone and his custom photogrammetry software. Amerongen then used Logan’s 3D models to design the panels. The process, inspired by a Netherlands technique called Energiesprong, has a three- to five-millimetre accuracy.

The project is one of three single-family home deep retrofits Butterwick is doing. These retrofits are funded in part by the Smart Sustainable Resilient Infrastructure Association.

Neither Amerongen nor Sandercock are surprised by Edmonton being the first to do this. They point to Edmonton being a Canadian leader in net zero homes.

“For many years, Edmonton has had the most net zero houses anywhere in Canada. I think we have a community of very smart builders here,” said Amerongen.

House Enjoyment

The Sandercocks could have built a new net zero home and even considered buying an electric car but they decided it just made more sense to invest in their home, and as Sandercock noted, they don’t really drive that much. As for building new, they wanted to avoid expanding their carbon footprint even further.

Before the reno, the small upper portion of this semi-bungalow where the kids’ bedrooms are was too hot in the
summer and their basement was too cold in the winter.

“When you own a whole house wouldn’t it be nice to be able to use your whole house in all seasons?” asked Sandercock.

That will now change. And if you take away the removal of the gas furnace and replacing it with an air source heat pump water heater and a heat recovery ventilator, it was minimally invasive inside the home — this flows with one last thought from Amerongen, who notes that while the panelized deep retrofit helps, it’s just one tool in the energy efficiency toolbox.

Taking advantage of the renovation, the Sandercocks are also changing the house’s exterior elevation by adding a front porch and modifying the roofline to give the home more of a Highlands look.