º£½ÇÉçÇø¹ÙÍø

Not typically fans of living beside construction for months while a house is torn down and rebuilt, the neighboursÌýin this caseÌýwere not only curious, they were excited.

The crane showed up on Monday morning and, by Wednesday afternoon, a three-storey house had been erected.

“That was fast,” said one woman, who paused briefly to check out the new build while walking her dog.

Prefabricated construction, where large panels are built in a factory, trucked to the site and snapped into place like an oversized Lego set, has long been touted as a solution to the housing crisis because the speed and repeatability of the process keeps costs down.

This prefabricated house, which went up in the Pocket neighbourhood off the Danforth in Toronto’s east end last month, shows how the building technique can also combat climate change by making zero-emissions homes that are ultra-energy efficient, resilient to extreme weather and even healthier for inhabitants because of their all-natural building materials.

Though at this phase, with the crane performing its oversized aerial ballet, the primary selling point has been the lack of noise, dust and disruption for neighbours.

“This is so much less disturbing to the neighbourhood than traditional building,” said Paul Dowsett, one of the architects who worked on the house. “People areÌýnot fighting with construction trucks for months and months.”

“There’s been very little banging of hammers to get it up. All the banging of hammers that will happen after this will be inside that very well insulated box — the neighbours won’t even hear it.”

HomeownersÌýErin Kern andÌýTerra Page weren’t planning on tearing down their house. They lived in their century home for 15 years and had two kids before they discovered tree roots had entered their pipes. What started out as a little project then grew and grew as they walked through their house with Dowsett, adding to their wish list.

At a certain point, the architect turned to them and said: “What would you think about just tearing down your house and starting over?”

Many in the sustainable building field discourage teardowns because it throws out all the “embedded” carbon in the existing house (emitted when producing the building materials) and adds more carbon — embedded and emitted during construction — to build a new one.

In some instances, however, there’s a case to be made for a new build, especially if it’s designed to minimize both the embedded emissions and all but eliminate the emissions that will come from running the appliances and HVAC for decades to come.

Kern and Page have always been ecologically minded, and were initially skeptical of building anew because of the environmental impact. But Dowsett explained that they could keep their foundation, which would mean not having to pour new concrete (typically the biggest source of embedded carbon in a house) and then put a prefabricated house on top. This way the house would not only have very low embedded carbon, it would also have near-zero carbon emissions to operate because it would be entirely electrified — with no natural gas connection.

And the basic structure, including siding, insulation, doors, windows and roofing could be put up in three days.

“It seemed really cool actually,” said Page. “We want to be here for many years. And we want to leave a better footprint (than we started with). Since we were going to have to do this reno anyway, we thought this would be the way to go.”

Jeremy Clarke at Simple Life Homes, who took five weeks to fabricate the house panels in his warehouse in Brighton, said unlike a typical new build, which can have as much as 120 tonnes of embedded carbon concentrated in the concrete foundation and styrofoam and spray foam insulation, this house’s basic structure (before finishings) has negative embedded carbon.

That’s because it’s mostly made from natural materials like fibreboard and cellulose insulation, which come from trees that absorbed carbon out of the atmosphere while growing. So instead of emitting carbon to produce the building materials, this home sequesters carbon, resulting in a negative-16-tonne carbon footprint, Clarke explained.

Add solar panels on the roof, a heat pump instead of a furnace and an induction stove, and this house not only requires less energy to operate than a typical home, but because it’s entirely electrified, the energy it uses produces few emissions.

It’s a solution that is extremely promising for ensuring the coming building spree to address Canada’s housing crisis isn’t a disaster for the climate.

The federal government’s National Housing Strategy envisions the construction of nearly four million homes in the next five years. A new report by Clean Energy Canada estimates that if these homes are built using traditional construction techniques, they’ll add the equivalent of in embedded carbon alone.

“That’s before you even turn on your heat for the first time,” said JanaÌýElbrech, a policy adviser with the environmental think tank based at Vancouver’s Simon Fraser University.

With low-carbon building techniques being demonstrated on housing projects around the country, the solutions are ready-to-hand, but that hasn’t been enough to bring about change in the building sector, she said.

“There is always a little bit of hesitation. Yes, we need affordable housing and we need it quick. So people ask: ‘Do we have the time and the money to go green?’ And what this report shows — and I think that home that you’re looking at also shows — is that you can do fast and clean and affordable.”

Clarke, the panel fabricator, says his company’s philosophy has always been to build houses that are energy-efficient, durable and non-toxic. Prefabrication just speeds things up and keeps costs down.

“I hesitate to use the word ‘affordable’ because building housing is just very expensive these days. But it does help. It’s pushing the needle in the right direction,” he said.

The prefabricated components in this build were no more expensive than conventional building, saidÌýDaniel Hall, the lead project architect on the house, but the savings come during the rapid assembly.

“There are significant savings in time on-site, which translates into lower overhead costs to maintain the job site, site supervision costs, insurance, etc. There are certainly far fewer delays due to weather and waiting on various building inspections, which are replaced by the CSAÌýcertification process in the factory,” he said.

Clarke said he was able to deliver the prefabricated components for $150 per square foot. While there are then crane and finishing costs, he said this compares favourably to at least $450 per square foot for a fully-finished custom-built home.

“We still have overhead and costs similar to those in a site-built scenario. The significant advantage is that we’re delivering an exceptionally energy-efficient, durable (and dry, mold-free), and healthy (free of toxic materials) home package in under a week,” he said.Ìý

Clarke said the majority of his prefab projects have replaced teardowns, but he has a townhouse project in Huntsville that will show how the same principles can be applied to entire subdivisions of new housing, presenting an interesting strategy for addressing the nation-wide housing crisis.

For the time being, however, less than five per cent of housing in Canada is prefabricated, badly trailing the world leader, Sweden, where 90 per cent of new housing is made in a factory.

“Imagine building a car like we build houses, bringing each part to a customer’s driveway and welding it together,” said Clarke. “We need to build houses on assembly lines like cars, phones and everything else.”