Can hemp become a viable and widespread form of insulation in housing and other construction? There has already been a fair amount of media coverage devoted to the use of hemp as a construction material. For several years now international researchers and some companies have considered the benefits of so-called “hempcrete;” essentially, blocks made by combining the hurd – or the inner core of hemp stalks – with water, lime, chalk, and other materials.
The potential use of hemp as an insulating material got a boost recently, after the U.S. Department of Energy (DOE) announced it was awarding a fellowship, via its partnership with the Oakridge National Laboratory (ORNL), to Hempitecture, an Idaho-based company that specializes in sustainable building materials. According to the ORNL website, Hempitecture was one of six start-ups that received a cost-of-living stipend, along with money for research and development, to help advance what the laboratory described as “game-changing technologies from the laboratory to the marketplace.”
The product produced by Hempitecture that caught the DOE’s attention is the company’s HempWool fiber insulation. HempWool uses decorticated bast fiber from the plant’s inner bark. With an insulation, or R-Value, of R-3.7 per inch, according to the Hempitecture website, a HempWool batt, or blanket of material, “outperforms our toxic competitors and is made from 92% industrial hemp fiber.”
In comparison, according to the Home Depot website, standard fiberglass batts can have R-values ranging from R-2.9 to R-3.8 for every inch of thickness, with high-density insulation batts having R-values as high as R-4.3 per inch.
“Hempcrete and HempWool have something in common; they’re both plant-based and therefore have low-embodied carbon and low-embodied energy, because we’re using a rapidly renewable material for our building material,” Mattie Mead, Hempitecture’s CEO and co-founder, told Hemp Benchmarks.
Hemp insulation is a relative newcomer to the U.S. construction sector; it has reportedly been produced in North America for only about three years. Hempitecture, meanwhile, began business in 2013 as a special contract construction firm that started with hempcrete, but found itself pivoting towards hemp insulation.
“It started off with niche, early adopters, who were really focused on creating a healthy home for themselves and their families,” Mead remembered, “but it’s since expanded to architects and developers that see the value in a healthy home, and want to really advertise that and use that … as a selling point.” With its hemp insulation, Mead said, “we now have a product that’s really a product substitution. Hempcrete is a system of building, whereas HempWool is a one-to-one replacement for conventional insulation products; whether they be rock wool, fiberglass, spray foam, things like that.”
Mead’s company works with hemp decorticators and processors, who in turn contract the raw hemp material from cultivators. “We buy the raw materials from these processors and convert it in a process that produces insulation,” he said. The company currently works with businesses outside of Idaho and has developed a primary partnership with an organization in Montana. It also imports hemp fiber.
As to just how much hemp is needed to create hemp insulation, Mead said that figure can vary depending on the hemp cultivar used, as well as the yield per acre. On average, he said, “we use a little less than a pound of fiber in a square foot of R-13 HempWool; a mere fraction of an acre.” In previous reporting on the hemp fiber industry, market participants told Hemp Benchmarks that, ideally, fiber hemp should yield four to five tons per acre, once genetics and cultivation practices are optimized for the U.S.’s various growing regions.
As a product, hemp insulation still faces some challenges, particularly regarding its fire retardancy. According to Mead, HempWool currently has a Class C fire retardant rating, because it is an untreated, natural product. In order to boost hemp insulation to the highest rating – Class A – he said, “we’re engaged in a study with the University of Idaho on selecting and applying fire retardants to HempWool to improve that fire retardancy, so that it also meets our health and environmental goals.”
There is also the issue of cost. Due to its novelty and the current need to import hemp fiber into the U.S., HempWool is more expensive than other traditional insulation products. That could change, however, if and when more parts of the construction industry start adopting hemp insulation as a mainstream product. Mead noted that his company is currently constructing a new facility in Idaho, with that purpose in mind.
“The infrastructure that will make HempWool … produced on a mass scale is being developed by both our supply chain partners and ourselves, as we build out a manufacturing facility,” Mead added. “What it will take for mass adoption, and for more wide scale implementation of the use of [hemp insulation], is a recognition in building codes, as well as potentially incentives that are going to encourage the use of low-embodied carbon building materials. And this is really where the DOE partnership enters.”
From a sustainability perspective, Mead said hemp insulation and its manufacturing is more environmentally-friendly than current technologies, due in part to hemp’s unique ability to capture carbon. “Early indications show that there is more biogenic carbon uptake than there is output,” he added. “Simply put, that means that it stores more carbon dioxide than is released in the manufacturing process. And there are no other wide scale manufacturing materials that can claim that.”
Mead said the fast-growing modular housing sector has an interest in hemp insulation. According to a recent report by the firm Market Research Future, the modular construction sector is expected to reach a global market size of $118.3 billion, with a compound annual growth rate (CAGR) of 6.50% from 2020 to 2027. The report also noted that the construction industry “has lagged behind other industries in terms of efficiency over the last decade,” as it attempts to find more efficient and less time-consuming construction techniques.
“I think that interest is representative of the understanding that the future of housing needs to revolutionize and needs to incorporate more low-carbon materials,” Mead said. “I would say the mainstream housing market, the business-as-usual construction types, are less willing to adopt [hemp insulation], or it’s just not on their radar yet. Housing construction is a very traditional industry and somewhat resistant to change.”
That being said, he expects consumer demand for energy-efficient and environmentally-friendly products, along with government initiatives, to help fuel more demand for hemp insulation. In January, the Biden Administration announced a series of initiatives meant to combat climate change, including the identification of ways that the U.S. “can … drive innovation and deployment of clean energy technologies.”
“That’s where incentivization comes in,” Mead said, “when folks like the Department of Energy will be able to incentivize the use of low-embodied carbon building materials, in essence giving you a credit or a write-off for using these products versus conventional products. But it does require more U.S. manufacturing and a developed supply chain.”