Inspired by a Netherlands green building technique called EnergieSprong, the project used digital capture technology to model the 1970s 1,180-square-foot home to get the exact dimensions needed for the panels to fit, including pre-installed doors and windows. Peter Amerongen, one of Retrofit Canada's co-founders and a partner at Butterwick Projects, used the 3D model to design airtight, pre-built panels. The panels were manufactured offsite and then installed on the outside of the house, forming a snug thermal cover.
In a matter of months, this 50-year-old house transformed into a state-of-the-art, energy-efficient building with a brand-new look.
The Hoffman retrofit followed a similar construction process as that used on the Sundance Housing Co-op retrofit, the first panelized retrofit project in Canada, and two other single-family-home panelized retrofits, all managed by Butterwick Projects, a green builder in Edmonton, Alberta.
Here's how it went:
One of the benefits of a panelized retrofit is that most of the work is on the outside of the home, meaning residents can remain during construction. In this case, the reconstruction was more disruptive for the family because of the removal of a massive brick chimney and fireplace. On the bright side, removing the chimney provided an easy solution for getting HRV ducting into the attic so it could feed the kitchen and bathroom - and the Hoffmans are enjoying a literally brighter, open living space.
Doing a full, net-zero retrofit can be a complicated undertaking. The project management is not easy, but Sean says that homeowners can mitigate this with careful planning and by giving the project the attention it deserves.
“You need to be aware that if you put more time and attention into the project, it’s going to go more smoothly and faster,” Sean said. “If you don’t, then it'll take a bit longer, and you might have unexpected problems.”
Another challenge is that using brand-new technology and techniques to make an old home net-zero comes with a price tag. A retrofit similar to the Hoffman’s currently ranges from $100 to $200 thousand, depending on the building and what it needs to get to net-zero. But the Hoffmans are philosophical about it. They want to see the technique explored so it can be rolled out for millions of homes in short order, bringing down costs substantively.
Melanie says that for her, this was a natural next step of taking climate action at an individual level.
“My commitment to climate action is such an important value for me that it makes the final costs of this project absolutely worth it,” she said. “Your house is probably your most valuable asset and one of your largest sources of personal carbon emissions, next to travel. So why not invest where you can make a real difference?"
“Your house is probably your most valuable asset and one of your largest sources of personal carbon emissions, next to travel. So why not invest where you can make a real difference?" - Melanie Hoffman, Homeowner
Before the retrofit, the Hoffmans had made some energy-efficiency improvements to their house. Some of these piecemeal upgrades had to be redone because they weren’t part of a comprehensive retrofit plan. For example, some insulation was added to the attic without first sealing the substantial air leaks. Unfortunately, crews had to suck all that insulation out of the attic so they could seal it up with a continuous 2” layer of spray foam. Besides the wasted energy, a leaky attic risks damaging the home through moisture build-up in winter.
Like other panelized retrofits Butter Projects has done, this project provided further proof that panelization works: the panels fit perfectly.
Melanie and Sean were very impressed by the holistic approach that the design team used on the project from start to finish. This team approach supported nimble problem-solving that used a big-picture lens to make real-time decisions.
The retrofit also slashed the home’s energy consumption from 128 to 16 GJ a year. The house is now 70 to 80 per cent more efficient and gets nearly all its power from rooftop solar arrays. Check out the Before and After table below for more details.
In Melanie’s words, “ the finished product is beautiful.” But besides having a brand new-looking house, there’s a long list of improvements.
The house has a new basement-to-attic, super-insulated and airtight envelope, state-of-the-art HVAC equipment like a heat pump and air exchange and new high-performing windows and doors.
The Hoffmans enjoy nice, even temperatures throughout the house. The new exterior, sided with LP SmartSide, will last for decades. Their place looks like it was built yesterday but still has its original character. The building can now protect its occupants from climate-change-related extreme weather like air pollution from wildfires or prolonged heat waves and cold snaps. The house is also way quieter thanks to the added insulation, and the indoor air quality is fresher and healthier. In the winter, the family gathers around the high-efficiency wood stove they installed during the retrofit.
When the panels were built and delivered, Butterwick crews worked with a crane operator to install them. All the panels were installed in less than a day and fit beautifully within the design tolerances. The new high-performance windows were factory-installed in the panels. Doing this in a controlled environment results in bullet-proof installation that enhances long-term durability.
Funded in part for innovation by Smart Sustainable Resilient Infrastructure Association
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