As a developer and builder of high-efficiency homes, Karin Eger-Blenk says she is always on the lookout for ways to reduce her company’s carbon footprint.
That’s why the Wilden Group CEO recently decided to incorporate hemp insulation into one of the homes in the company’s 1,500-acre master-planned community in Kelowna.
“I asked our construction team if we could have an alternative insulation material that would be carbon-negative, and this is how we actually discovered hemp insulation,” she said. “We were just basically exploring what’s out there, and hemp seems to be the most sustainable material.”
Wilden’s “hemp house” is now among the first net-zero-ready homes with hemp insulation in B.C., Eger-Blenk said. It’s an example of the widening industrial application for hemp—a strain of cannabis plants with only trace amounts of the intoxicating compound THC.
While the hemp insulation cost Wilden about $3 more per square foot than the usual fibreglass—totalling $10,000 extra for the whole house—she said the carbon savings are worth it.
“It is definitely the sustainability aspect,” Eger-Blenk said. “It’s the lower carbon footprint. It’s the material that is actually carbon-negative, because when it grows, it takes carbon out of the air.”
Hemp contributes to sustainable construction through embodied carbon reduction and thermal performance, but other benefits can include healthier indoor air, moisture control, mould resistance, durability and enhanced soundproofing.
The use of hemp in the building trades is becoming more common, in part because production capacity within the industry is increasing, making more product available for use as insulative material in housing.
“Hemp has been recognized as a source of low-carbon building products that is finding a home in environmentally conscious construction,” said Ted Haney, president and CEO of Canadian Hemp Trade Alliance.
“The hemp industry is expanding its capacity to produce insulative fibers which will serve the building trades going forward.”
There are two different forms of hemp insulation, he said. Hemp “batts” are long, strong fibres from the outside of the stalk, and can be used for insulation in place of traditional fibreglass or rockwool.
Meanwhile, hemp “hurd” is the woody core of the plant, and can be used to create “hempcrete”—a combination of hurd and lime, a rock material used for binding purposes.
Brandon Cochran, founder and CEO of HempWorks Canada, said hempcrete is considered the more premium option.
“It’s a complete envelope system which replaces most conventional materials,” he said. “In our hempcrete there’s no batting, there’s no vapour membranes, there’s no drywall used, there’s no exterior sheeting.”
He touted hemp’s lack of toxic chemicals or components, and its fire-resistance.
Cochran, who supplied hemp insulation to Wilden’s “hemp house,” said barriers to adoption include six-figure certification costs and distant suppliers in Quebec and Europe. He said the product’s price will come down with wider adoption in B.C.
Once a buyer moves into the Kelowna house, they will be able to take it from net-zero-ready to net-zero by installing solar panels on the roof. The reason Wilden didn’t complete this last step is because homeowners, unlike developers, are eligible for a federal government incentive program that offers an interest-free loan of up to $40,000 for solar panels.
In the province, BC Hydro also incentivizes solar panels. However, Wilden is not in the BC Hydro region, and FortisBC doesn’t currently offer a comparable incentive.
Eger-Blenk said that with a 10-year track record of advancing home-building practices, her company is bullish on hemp.
“We’re always exploring better practices,” she said.