Lisa Sundberg and Peter Holmdahl want to change the construction industry in North America by using one of the oldest cultivated plants in human history: hemp. Sundberg is an activist from Trinidad, California, with a background in industry development. She met Holmdahl, a Swede with a background in business development and sustainability, through a shared commitment to expanding the use of hempcrete (also known as hemp lime).
This building material made from industrial hemp byproduct is gaining attention for its sustainable properties. Since industrial hemp absorbs carbon dioxide as it grows, its cultivation is carbon-negative. Additionally, hempcrete’s natural insulation cuts heating and cooling needs, while its porous structure prevents mould and boosts air quality. With lime’s fire-resistant properties, hempcrete is also emerging as a possible solution for fire-prone regions.
Since founding the Indigenous Habitat Institute in 2021, Sundberg and Holmdahl have partnered with municipalities, industry organizations and post-secondary institutions to transfer knowledge about hempcrete construction from Europe to communities in Turtle Island (North America).
Sundberg: I’ve always been a bit of a freelance person. When things are changing, I like to be in the middle of that. When you live in California’s Humboldt County, a place internationally known for its cannabis culture, you feel a certain responsibility to stand up in an industry that has been here for 70 years. Out of the thousands of different businesses in the cannabis industry, I wanted to do something impactful. Industrial hemp caught my attention. In 2015, I learned about hempcrete.
Holmdahl: I've been working with the material for 10 years. Hemp lime dates back to the mid-’80s when it was found in France. France never outlawed industrial hemp so they were trying alternatives to use the hemp waste product: the inner part of the hemp plant, the hemp hurd or hemp shiv. Hemp lime was an experiment that went very right. The inner part of the hemp plant is mixed with a specialized mixture of lime.
Sundberg: When I first worked with hempcrete, it felt like being in a batch of macaroon mix — a bit like wood chips mixed with flour. It’s simple — just three ingredients, mixed with water. My granddaughter was out there mixing it in a wheelbarrow. We even made a little dollhouse. It’s a tactile, hands-on experience. We want to bring that to communities. But the challenges were immediate.

Holmdahl: For the past 25 years, France has been experimenting and using hemp lime on a larger scale. They’ve got it down to a science. North America, we’re still catching up here.
Sundberg: At the time, it was illegal to grow hemp in America, so we had to import material from out of the country. How do you grow with a great idea when you can’t even access the materials? I realized this wasn’t just about a single business — it was an industry play.
The building materials that people use in construction, a lot of it, it's just garbage. I live right next to the ocean. I've got black mould going on. Then we're getting hit by heat waves and wildfires. I really feel hempcrete would be the answer for that.
One of the largest contributors to CO2 emissions is construction. But hempcrete can have an impact on the CO2 emissions.
Holmdahl: The hemp will grow in four months and absorb more CO2 during that time span than your average trees will absorb during the whole year. So you're sequestering a lot of carbon.
Then what you're getting is like a really well-insulated stone house, because the lime basically petrifies back into limestone. But by mixing in these hemp hurds, you get a much better insulation value. You get a home that is, in layman's terms, breathable. It can absorb and release moisture. So you're avoiding humidity or mould problems. That has a lifespan of at least 100 years. Most modern insulation materials, even natural ones like wood fibre, have a lifespan of 50 years.
On top of that, hempcrete has a four-hour fire rating. So it doesn't burn. Australia is the second-largest market outside of France because they use it for their bushfire regions.
We’re doing a third-party-certified fire test in Vancouver, Washington, so that we can showcase how we can rebuild Los Angeles in a way that’s sustainable and resistant to fire.

Sundberg: We started the Indigenous Habitat Institute in July 2021. We’re jumping off the deep end but we believe in hempcrete. We're going through the standards process, setting standards for regular industry. But we're anchored in working with Indigenous communities.
The first grant that we got, it's called the people of the plank house. In Northern California, the people in our community lived in redwood plank houses that keep you warm in the winter, cool in the summer. Redwood tree wood is the most fire retardant of all woods. And they burned it, they make charcoal components, so the insects won't eat it when it's partially in the ground.
We want to build a plank house using hempcrete walls and redwood planks on the outside. Where you feel like you're walking into a plank house but it'll be made with hempcrete.
Holmdahl: We have a couple of interesting projects. The drawings have been done for the first couple of houses that will be developed with the Indigenous band in Quebec. We have funding to do training. We're getting support for this band to be a pioneer in hempcrete building on the East Coast. Our first shipment of hemp and lime has arrived at the band. It sadly made more economic sense to ship one container of French hemp and lime together. But moving forward our goal is to engage with the Canadian hemp community and use local resources.
We're in talks for a multi-storey build in Humboldt County, California. It's a mixed-use building, so commercial in the bottom and affordable apartments up top. That's going to be a lot of hurdles to go through, but we have to go through those in any case. Our colleagues in Paris, they build up to nine storeys. We're looking at four to five. But it's exciting because it’s higher than anything that's been built in North America.

Sundberg: We've got our first accessory dwelling unit, or ADU, going up in Eureka. It meets California codes. That will be one of the first in Humboldt County built under professional rules. The frame is already done. The panels will be made on one of the reservations inside of a modular facility they had made for housing. It's getting revitalized. And a handful of other homes will be built. We want to learn how to build them at scale and speed so that it can become a system.
One of our initiatives is knowledge transfer from France to Turtle Island (North America). The College of the Redwoods is receiving the curriculum. So we have an accredited workforce training program. This is how you get traction. Not by building one house. It's a new material, it's a new way to build, but it's going to really change how we build and how fast we build.
Holmdahl: What I’m really excited about is the idea of building hyperlocal. We can grow the hemp, produce the lime and source the wood all within a 200-to-300-mile radius. That way, we’re not just building sustainably, but also supporting local economies. And by prefabricating, we can build faster and work year-round, even in colder climates like Canada.
There are challenges, though. The cost of hemp hurd is still high, and we need more local lime production. But by localizing production and lowering costs, we can make hempcrete a real alternative to conventional materials. It’s not going to be easy, but I see a sustainable future in this.
Sundberg: I'm seeing this as an opportunity to help communities develop a housing model that's going to help them from the fires and the heat and the mould and in longevity. I want to be able to pass my house off to my family and they don't have to buy one again and again.
I call it “the Green Buffalo.” The Pine Ridge Sioux people talked about the prophecy of the Green Buffalo. To their people, the buffalo was their food, their shelter. It was their clothing. They made tools out of it. The buffalo represented many things. The prophecy was that there was going to be a Green Buffalo that's coming. And I've heard them say that the Green Buffalo is hemp.
Since Sundberg spoke with The Tyee, the Lower Sioux Indian Community and Patagonia released a documentary film titled ‘The Green Buffalo’ exploring their developments in hempcrete. Watch it below:
This article runs in a new section of The Tyee called ‘What Works: The Business of a Healthy Bioregion,’ where you’ll find profiles of people creating the low-carbon, regenerative economy we need from Alaska to central California. Find out more about this project and its funders, Magic Canoe and the Salmon Nation Trust.
Read more: Housing, Environment
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