Hempcrete Houses Studied for Construction Research
With help from Homeland Hempcrete, Grassroots Development is constructing two residential properties in Fargo, North Dakota. One structure incorporates traditional framing and insulation, while the other has utilized hempcrete.
By having a controlled comparison, researchers intend to study how hemp can be used as a construction material.
“We're just trying to get that concrete nonbiased research to contribute to the industry so we can troubleshoot and figure out how to do better,” said Grassroots Development Sustainability Consultant Sydney Glup. “We want it to be so that anybody who wants a healthier dwelling can afford it.”
Hempcrete for Homes
According to Grassroots Development President Justin Berg, the homes are identical in blueprint, each measuring 13 by 23 feet, with 12-foot-high ceilings. Constructed on a lot just outside of downtown Fargo, one of the homes was constructed with a traditional wood frame, fiberglass insulation and covered in a white wrap material.
The other home, also incorporating a wood frame, instead used what reports are calling “hurd” to fill the walls. According to Minnesota Public Radio (MPR News), hurd consists of the core of a hemp plant, chipped into small wood-like pieces that are then mixed with a lime binder and water.
“And you blend the mixture to a consistency, a nice sort of chicken salad—is our joke—consistency,” noted Glup. “And we hand packed, physically hand packed, this entire house.”
Grassroots Development received help from Homeland Hempcrete on the process of making hurd, schlepping buckets of the material and packing the walls between two by six wood studs for support. The material required a cure of six weeks before the forms could be removed from the structure. Following this step, crews then applied a finishing plaster to the interior and exterior.
In comparison to the traditional structure, the hemp building cost roughly 25% more, mostly attributed to the cost and availability of raw materials. However, researchers believe that over the long term, hemp construction will actually save money.
Reports went on to note that the hurd material is a healthier alternative to insulation by reducing mold, serving as a thermal mass, and is also flame resistant.
To collect data on the structures, sensors were tucked into the walls of both homes to monitor moisture and air temperature. Researchers also plan to monitor energy consumption as well.
“This from my knowledge, is the only study of its kind,” said Riley Gordon, principal engineer with the Minnesota-based Agricultural Utilization Research Institute, a non-profit organization partially funded by the state, which helps develop new markets for Minnesota crops. “We're just looking to bring to leverage the opportunity of having these two buildings built side by side. They're identical, it's perfect for a controlled study.”
Gordon is reportedly working alongside a Minneapolis-based Center for Energy and Environment to analyze the data.
When the study is completed, there is talk that the structures will be turned into short-term rentals.
Other Hemp Research
Back in 2020, research at Montana State University, funded by the Montana Farmers Union, took a look at if the area’s industrial hemp plant’s waste could be combined with a lime-based binder for the latest iteration of “hempcrete.”
Drew McNally, a junior majoring in civil engineering, along with assistant professor Kirsten Matteson and associate professor of civil engineering Michael Berry, in the Department of Civil Engineering in MSU's Norm Asbjornson College of Engineering, used massive hydraulic pistons to measure the crushing strength of soup can-sized cylinders of hempcrete made with different proportions of cement and lime.
The team also set out to measure the insulating properties of the different mixes, which, the team said at the time, wasn’t studied yet for hempcrete.
More recently, in June, Texas A&M University College of Engineering received a $3.74 million grant from the U.S. Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) Harnessing Emissions into Structures Taking Inputs from the Atmosphere (HESTIA) program.
The funding will be utilized by the university to research 3D-printed hempcrete, a new green material that has the potential to lower the environmental impact of traditional construction and make housing more affordable.
For this project, Petros Sideris, assistant professor in the Zachry Department of Civil and Environmental Engineering, will lead the research as principal investigator with the goal of developing residential and potential commercial construction designs.
Working as a team alongside Sideris, other researchers for the project include assistant professor Maria Koliou, department head and professor Zachary Grasley, professor Anand Puppala, associate professor Manish Dixit and professor Wei Yan from the Texas A&M College of Architecture.