Wood-fibre insulation: an effective, renewable choice for residential buildings
By Silvia Cademartori
By Silvia Cademartori
The last nail driven into wood-fibre panel insulation in a home in British Columbia could mark a new standard in building construction for the Canadian homebuilding industry, while ushering in a new era of green, sustainable, and high-performance building insulation for residential and commercial structures.
The non-profit forestry R&D company FPInnovations, 475 High Performance Building Supply, and the Canadian Wood Council have partnered to build three high-profile residential projects located in Ontario, Saskatchewan, and B.C., to demonstrate the suitability of wood-fibre insulation panels for use in residential buildings. The panels are environmentally friendly and are expected to perform better than traditional rigid foam insulation.
The B.C. home, completed in the spring, is the last of the high-performance projects built to Passive House standards in the trial. Contractors used wood-fibre insulation panels imported from Europe, where they’re a mainstay in home construction, instead of rigid foam, to insulate exterior walls. The trio behind the initiative are certain the panels can be manufactured in Canada far less expensively than in Europe, with an R-factor rating equivalent to rigid foam panels.
“Dry-process wood-fibre insulation panels are the future of building insulation in Canada because we have the natural resources and industry to produce them economically,” says FPInnovations lead scientist, Bob Knudson. “We have excess fibre from sawmills for their production, and they offer superior performance and insulation, in addition to being environmentally safer than rigid foam insulation.”
FPInnovations designed tests to determine the fire safety, stability, durability, and insulation rating of the panels. Wood-fibre insulation demonstrates superior fire performance compared to polymer foam insulation types that are currently used in North America. The panels also show superior moisture management in wall and roof systems compared to polymer foam insulation. Additionally, the panels have greater thermal mass, reducing the temperature rise and fall in an interior space.
The panels are made using a dry-processing method of refining wood chips and shavings. The resulting fibre is dried, mixed with polyurethane adhesive and paraffin, formed into a continuous fibre mat, sized to desired thickness, and cured. The resulting panels are then milled to different sizes and edge configurations. The manufacturing process allows for a homogeneous board from 20 to 300 millimetres thick. The panels offer R-values in the 3.5 to 3.9-per-inch-range, while polymer foams have R-values in the 4.5 to 6-per-inch-range. Therefore, wood-fibre panels need to be a little thicker to reach the same R-values as polymer foams.
“We believe that wood-fibre insulation is a high-performance board that is not only breathable and highly insulating, it’s ecologically sound, renewable, recyclable, and lasts the lifetime of the building,” says municipal affairs and technical manager of Wood WORKS! B.C. and the Canadian Wood Council, Peter Moonen. “Wood-fibre insulation is not a structural panel plywood, OSB, or other structural sheathing. It’s a superb insulation panel that offers exceptional thermal and acoustic insulation in both partition and structural walls.”
The three residential building projects were selected in part for their locations in different Canadian climate regions. The Ontario building is a single-family residence near Collingwood in cold-humid climate zone 6A. The Saskatoon, Sask. project is a nine-unit co-housing development in very cold climate zone 7, while the B.C. house located in Gibsons is in mixed-marine climate zone 4C.
“These panels have the potential to lead a transformation of the North American construction industry towards making durable, high-performance Passive House and zero-energy buildings more common,” says western regional manager of 475 High Performance Building Supply, Lucas Johnson. “We built three unique projects, each with distinct features, to demonstrate the versatility of wood-fibre insulation panels.”
The Collingwood renovation project adds a two-storey contemporary addition to a 150-year-old pioneer cedar log house. Eighty-millimetre dry-process wood-fibre insulation panels are attached to the outside of two-by-eight load-bearing stud walls sheathed with half-inch plywood.
The Saskatoon co-housing project showcases low cost of living through low energy use. It has both 40-millimetre and 240-millimetre panels attached to the outside of two-by-six insulated load-bearing stud walls sheathed with 3/4-inch plywood.
The B.C. single-storey prefabricated house is built to meet LEED Platinum standards. Its exterior walls are insulated with 100-millimetre-thick wood-fibre panel insulation fastened to the outside of 3-ply 100-millimetre-thick CLT load-bearing walls. The green roof has 240-millimetre wood-fibre panel insulation. Performance monitoring instrumentation is installed onto the prefabricated wall and roof modules.
“Our low-cost construction methods required a thick rigid exterior insulation product and wood-fibre insulation is one of the few products we found with negative embodied carbon,” says Knudson. “The pressed-wood fibres trap carbon and sequester it for the life of the building.”
The instrumentation installed in each building consists of point moisture measurement, relative humidity and temperature sensors, data logger units, and a tactical intelligence gateway. Each home’s performance is being monitored by FPInnovations for at least one year and meaningful results are expected by July of 2019.
“We have the natural resources for the raw materials and the industry know-how to make these panels in Canada,” says Johnson. Currently, wood-insulation panels are an imported construction material. “They can truly transform the industry because they’re environmentally friendly to make, reduce onsite labour and waste, and they’re recyclable as well.”
Knudson envisions Quebec and Ontario manufacturing plants, which would be close to raw materials, sawmills, large Canadian cities such as Montreal and Toronto, and densely populated American cities such as New York, Boston, and Chicago. The western provinces offer excellent opportunities for manufacturing wood-fibre insulation for western North American markets.
The future of wood-fibre panel insulation faces many challenges. Wood is thought of as a combustible product, yet the panels exceed fire-safety standards. In Canada, they’re seen as a hard-to-believe-it’s-true new product, but they’ve been used for over 25 years across Europe and their popularity there is growing. Knudson is convinced education is the key to building a Canadian market. “We first had to build homes to show the industry that these panels are as good as rigid foam insulation,” he says. “When the data are analyzed, the results will demonstrate their effectiveness and reliability, and then I’m sure manufacturers will come forward.”