Wood and Hempcrete: Building Materials for a Green Century

September 21, 2020

Bloomberg Green:

Nestled among spruce forests in an Alpine valley in southern Austria, a workshop was the first some two decades ago, to begin manufacturing a green new material that’s now super-sizing wooden buildings and speeding the adoption of a solution to mitigate climate change. 

“We can build very quickly and cleanly with it and that’s the key,” said Marco Huter, a 57-year-old executive surrounded by giant slabs of cross-laminated timber, called CLT, at his KLH Massivholz GmbH factory.

Huter had to double capacity in the midst of coronavirus lockdowns to satisfy booming global demand for the mass timber he produces. Developers are adopting the material to reduce their carbon footprints while also cutting the cost and time needed to construct high rises, he said.

CLT uses a high-tech manufacturing process that turns ordinary wooden planks, often made from the nearby Spruce trees, into structures that can bear thousands of tons of weight. Architects from Australia to Scandinavia and the U.S.have been buying from Huter as they leapfrog each other in a race to construct the world’s tallest wooden skyscraper. Vienna made an entire new city quarter out of CLT. Designers in Japan have planned a 350-meter (1,148-foot) tower.

Huter pointed to a project at 55 Southbank Boulevard in Melbourne, Australia which used his timber to add 10 stories onto a six-floor building, more than doubling its height and living space in less than a year. Because wood weighs just 30% of concrete, CLT is being used to expand scarce space in cities by building higher. Construction time is quicker than pouring concrete on site, resulting in lower labor and equipment costs.

Once again, the hippies were right.


Around the world, builders are putting modern twists into ancient construction methods that employ the hearty hemp weed. Roman engineers used the plant’s sinewy fibers in the mortar they mixed to hold up bridges. More recently, former White House adviser Steve Bannon weighed in on using so-called hempcrete to build walls. Early results indicate it’s possible to tap demand for cleaner alternatives to cement.

“We have way more demand than we can supply,” said Radford from his plant in Airdrie, which is undergoing expansion and soon expects to churn out enough Lego-like hemp bricks each year to build 2,000 homes.

Greener alternatives to cement add to the pressure on companies including LafargeHolcim Ltd. and Votorantim Cimentos SA as the global economy pivots toward dramatically lower emissions.

Cement makers are responsible for about 7% of global carbon dioxide emitted into the atmosphere every year, with copious volumes entering via limestone kilns needed to produce the material. Manufacturers say they’ve struggled to find markets for greener alternatives, giving easy entree to entrepreneurs like Radford who cater to customers concerned about their impact on the Earth.

“They love it once they understand it,” said Radford of the builders who’ve adopted the modular, inter-locking bricks he invented for their projects. “Our old practices we have to change.”

While architects and developers have traditionally concentrated on the energy used by their buildings once they’re are standing, it’s actually the materials required in their construction that represent the brunt of a structure’s lifetime carbon footprint. Replacing high-carbon-intensity materials like cement with greener alternatives like hemp can dramatically reduce or even offset greenhouse gas pollution.

Hemp fields absorb carbon when they’re growing. After harvest, the crop continues to absorb greenhouse gases as it’s mixed with lime or clay. Hempcrete structures also have better ventilation, fire resistance and temperature regulation, according to their proponents.

Numbers across the industry vary depending on the process, but JustBioFiber says that its hemp captures 130 kilograms (287 pounds) of carbon dioxide for each cubic meter it builds. Those structures made with their bricks will sequester more greenhouse gases than they emit in production. By contrast each ton of cement produced emits half a ton of carbon dioxide, according to the European Cement Association.

First developed in France more than 30 years ago, hempcrete was initially used for renovating old houses since it mixed well with stone and lime. That has progressed to new build homes, offices and municipal buildings some as tall as seven floors, according to Quentin Pichon, founder of CAN-Ingenieurs Architectes who specialize in hempcrete buildings.

Hemp growth in France has grown by fifth in the last decade as a result of an increase in its construction use but also because seeds from the plant that can be used to make cannabidol, he said. Hemp sales in Canada could hit $1 billion within five years from $140 million last year, according to the Northern Alberta Institute of Technology.

8 Responses to “Wood and Hempcrete: Building Materials for a Green Century”

  1. jmmirsky Says:

    Are there examples of CLT structures and the corresponding manufacturing infrastructure being built up in the U.S.? (I’m aware of projects and infrastructure in British Columbia, Canada.)

  2. redskylite Says:


    “Wooden Tower Set to Reduce Carbon Dioxide Footprint from Future Wind Turbines

    Vattenfall and Modvion have entered into collaboration on using wooden towers for onshore wind turbines, a venture expected to reduce carbon dioxide emissions in manufacturing by at least 25%. Vattenfall will be assessing Modvion’s wooden tower for potential use in future wind farms.
    Wooden Tower Set to Reduce Carbon Dioxide Footprint from Future Wind Turbines
    Courtesy of Modvion
    “During their life cycles, Vattenfall’s wind turbines already have very low levels of climate-impacting emissions. We want to drive those levels down even further. We see that wooden towers can be part of our solution for decreasing our carbon dioxide footprint, which can complement the work we are already doing with fossil-free steel as an example”


    • jmmirsky Says:

      Thanks for the insights! I’d not seen anything about the building in MN; I’ll look into it. I had seen the announcement about wood wind towers but hadn’t made the connection to the likelihood that factories for the latter could also potentially produce CLT building elements; hopefully the owners realize this diversification possibility!

    • Keith McClary Says:

      I wonder what they do with wooden (plus glue) towers at the end of their life cycle?

  3. Sc Says:

    I don’t know about hempcrete structures in the US, but here is another interesting carbon-eating alternative to cement-based concrete, ran on PBS back in 2015. The bricks may not work for tall buildings but seem quite useful for paving
    As far as I know this small scale initiative is still operational today


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