Not your mama's prefab: The rise of prefab passive house systems
Prefabrication is not new for the construction industry. Drawn to their cost-effectiveness, convenience, and streamlined design, consumers have been able to choose prefab homes since the early 20th century.
Though it has not had the same uptake in North America than in parts of Europe (84% of detached homes in Sweden are prefabricated), prefab is on the rise.
Coast to coast, a growing list of Canadian companies are manufacturing high-performance wall panels for passive house buildings.
Rob Blakeney is an engineer with Local Impact Design and a consultant with BuildSMART, the first North American company to construct passive house prefabricated wall panel systems.
“I think it’s a natural progression of where the industry is going,” says Blakeney. “In North America, we’re experiencing a skilled labour shortage and very high-priced labour, so it’s natural that we move towards prefabrication.”
In general, prefabrication saves money. Not only can off-site modular construction save between 10 to 25 percent in building costs compared to conventional on-site construction, you can also minimize the transport of workers and equipment and shorten project schedules significantly.
This has been true for Abby Xerri, President of Ontario-based Quantum Passivhaus, who explains that the cost- and time-efficiency of prefab is one of its main advantages.
“We have quick assembly and construction times and have exceptional measures of installation. We’re building in our shop in 7 to 8 days and we install anywhere from a day to a day and a half--that’s a complete structure with the floor systems.”
This type of efficiency means passive house buildings are more accessible than ever.
“We’re seeing more of a cost parity on multi-family units and mid-rises. Here you get to see the real benefits because usually you have repeated form and a longer schedule...with a multi-family unit, the [time] savings can be in the order of months,” says Blakeney.
In addition, while building a traditional passive house on site might require specialized knowledge from the builder, prefab panels don’t require the same know-how. This can remove barriers and allow for passive house buildings to be constructed in more remote areas where this type of skilled labour is lacking.
Kyle Moen of BC Passive House explains that this has been central to their work.
“We've done lots of stuff in northern BC, Vancouver island, and the Gulf islands and we can skip out a contractor to do the framing and build almost overnight,” says Moen. “It really allows us to achieve higher performance standards and avoid mistakes made on site. If something is framed wrong on site, it takes a lot of time to correct.”
Having the panels built by skilled practitioners in shop means that the quality of the build is tightly controlled for passive house standards.
“..a major advantage that prefabrication has is the control over detail that is achieved in a shop setting,” says Jan Pratschke of B.C.-based Collective Carpentry. This is especially important with PH walls as they tend to be a lot more complex and need to live up to very high air sealing and insulation standards. Prefab also excels at scheduling simplicity, and controlling damage caused by weather during the construction phase.”
Many companies are also opting for carbon-storing materials like timber and cellulose in the fabrication of their panels.
For Rick Zytaruk of the Muskoka-based Tooketree Passive Homes, the environmental and climate impact of prefab homes is imperative.
“We need to ensure that everything we build today is our best effort to mitigate and adapt to the climate crisis. Simultaneously, we have a great need for safe healthy homes. By prefabricating passive house enclosures that store carbon and use safe materials we are building climate safe buildings faster and assure higher quality with less waste,” says Zytaruk.
So what’s next for prefab passive house building? Some companies are expanding the types of builds beyond the usual single-family home.
“We think of prefab as a method, not just a structure,” says Xerri of Quantum Passivhaus. “We’ve been encouraging other types of construction to incorporate prefab in a passive house system… we’re looking at large-scale projects that can actually consider building to a standard that allows us to use renewable products, not just concrete and steel systems… but post and beam and log timber frame.”
On the West Coast, Kyle Moen is singing a similar tune. “We're not limited to one type of building. We've done high-end residential, many in Whistler, and our first 24-unit apartment building, which will be low-cost housing. Post-and-beam taller structures, high-rise wood construction, will be the next frontier...”
An (incomplete) list of Canadian companies that are selling prefabricated PH panels:
BC Passive House - Pemberton, BC. Products: High-performance building panels. Geographic area served: BC and Yukon
Collective Carpentry - Invermere, BC. Products: Pre-designed and custom designed super-insulated panelized building envelope components including floor, wall & roof panels, timber, glulam and steel design and fabrication. Geographic area served: Northern BC, Alberta, US (recently in Taos, New Mexico)
Agora Construction - Luseland, SK : (306) 834-7480 Products: Everything from full-build turn key buildings to prefab envelope packages. Geographic area served: Alberta, Saskatchewan
Tooketree Passive Homes - Muskoka, ON. Products: Passive House wall, floor and roof panels that store carbon and are made with safe materials. Geographic area served: Ontario
Pinwheel Structures - St. Catherines, ON. Products: Panelized passive house walls that are wood framed with cellulose or mineral wool insulation.Geographic area served: Greater Toronto Area
Quantum Passivhaus - Minden, ON. Products: Structural insulated building panels suitable for passive house structures. Geographic area served: Ontario
Simple Life Homes - Ontario. Products: Prefabricated building components for high performance and carbon storing buildings. Geographic area served: Ontario
Maisons Éléments - Magog, QC. Products: Passive house performance walls. Geographic area served: Quebec, Ontario, United States
Photos from Simple Life Homes
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