While studies from across the world have demonstrated hempcrete’s potential as a sustainable building material, data on U.S-produced hempcrete is sparse. But research into its benefits is beginning to take place in projects across the country.
In March, Vancouver, Wash.-based Earth Merchant was one of just 25 recipients of the Small Business Innovation Research grant from the Environmental Protection Agency (EPA) to research its hempcrete bricks.
Gina Engel, founder of Earth Merchant, says the nearly $100,000 grant is funding research partnerships with both Oregon State University (OSU) and the University of Tennessee (UT) to study hempcrete’s environmental impacts from cultivation to construction.
“We don’t want to ship across the country. We want to reduce shipping as much as possible. Want to reduce carbon emissions as much as possible,” Engel says.
Hempcrete is a simple mixture of hemp hurd, water and lime (a mineral frequently used for other construction applications).
It primarily comes in two different forms: spray insulation or a material that can be tamped in place. (Engel, however, has developed a pre-dried brick because it’s a material contractors would be more likely to use—hempcrete takes weeks to dry, according to the Northeast Sustainable Energy Association, which could cause schedule hangups that many contractors can’t afford.)
Current hempcrete products on the market are not load-bearing, so they need to be combined with timber, concrete or other more stable materials.
While research on U.S.-produced hempcrete is in its beginning stages, research from other countries offers clues as to what domestic researchers may soon discover.
As outlined in the book Essential Hempcrete Construction: The Complete Step-by-Step Guide, written by Chris Magwood, Canadian and European studies have shown hempcrete maintains its integrity in humid conditions. The lime in the mixture has antimicrobial and antifungal properties. And though hempcrete is not load-bearing, it does provide additional support for studs and other structural components in a building.
But perhaps its most promising advantage comes from its carbon-sequestering properties that have been proven through multiple studies: Researchers at the University of Toronto, for example, found one metric ton (2,204 pounds) of dried hemp sequesters 716.6 pounds of CO2.
Still, even with these studies, Magwood cautions more research is needed.
“Any discussion of hempcrete is complicated by the fact that all three elements in the biocomposite can have a range of types and characteristics, and can be added to the mix in varying ratios,” Magwood writes.
Carbon Sequestration During Cultivation
Engel is aiming to fill in some research gaps through her work at Earth Merchant.
Her goal is to control every aspect of the supply chain to produce the hempcrete bricks, from growing to manufacturing them. Ultimately, she’s aiming to establish facilities across the country that can produce the bricks hyper-locally.
“We’re going to do everything we can to stay as carbon-neutral or -negative as possible,” Engel says.
Her family runs a 500-acre farm in Tennessee, where she is coordinating with the University of Tennessee on studying the carbon sequestering properties of the hemp they grow there.
Engel is working with the ChinMa variety, a fibrous hemp cultivar from China, which she sourced from two different suppliers.
She has taken soil samples to measure carbon levels throughout the season.
“We are testing the soil and the material of the plant itself to see how much carbon is sequestered during the growth phase,” Engel says.
At the end of the season, the researchers will take their own soil samples to calculate how much carbon the hemp removed from the atmosphere in total.
Measuring Manufacturing Effects
Meanwhile, Engel (who lives on the southern border of Washington) is working with OSU on the manufacturing side to conduct a series of other tests gauging the bricks’ performance.
“One of my goals with what I want to do at OSU is continue funding research on hemp and building materials, and OSU is one of the top schools in the nation to test building materials,” Engel says. “It just seemed natural to do the work here.”
OSU has been conducting a wide variety of tests in partnership with Engel. Aside from working to develop the bricks themselves—a process that has included manufacturing hundreds of bricks to find the perfect ingredient formulation ratio and size—OSU has run tests on the bricks’ performance. These tests include determining how they hold up to extreme temperatures, their general durability and their insulation properties. Another purported benefit of hempcrete? It provides better temperature control than other types of home insulation.“Once we get our testing done, if our research performs the way we expect, it’s possible a home built with hempcrete may not even need a heating or cooling unit,” Engel says.
Engel’s team has also developed an app that will be able to measure how much carbon sequestration each block provides.
If Engel receives Phase II of the EPA’s grant (which is another $400,000), she plans to conduct further testing of the bricks’ durability in various climates.
“We also have a climate-controlled machine where we can build a wall with blocks, put it in the machine, and it will simulate [a year’s worth of] weather” in a condensed amount of time spanning anywhere from six weeks to six months, Engel says.
Other Research Ongoing
In a separate project, Coexist Build, a Pennsylvania-based architecture firm, recently partnered with Alvernia University in Reading to study the life cycle of hemp-derived building materials over the course of two years.
The research, funded by a $4,500 grant from the Pennsylvania Department of Agriculture, will track the carbon footprint of a hemp-based building project by measuring data from farming to construction of a 140-square-foot building.
“The purpose of the grant is to conduct a full life cycle assessment of all the materials that are being used for the structure,” Drew Oberholtzer, co-founder and partner of Coexist, told Hemp Grower in August. “That includes the hemp log that we manufacture in Pennsylvania, hemp insulation that’s manufactured in Quebec, and then the timber frame—everything from going into the forest, cutting down the tree—that entire process—so that we know how much carbon each material embodies.”
As for Engel, she is trying to advance her research and product development not only through EPA grants, but also by submitting her project to XPRIZE Carbon Removal, a project development competition funded by Elon Musk and the Musk Foundation. The winner of the four-year competition will receive $50 million, while $30 million will be distributed to three runners up.
“We’ve got to find a way to reduce [carbon emissions],” Engel says. “I think hempcrete is a tool, and hemp itself is a tool.”