Hemp cements place as green brick in wall
THEY LOVE IT ONCE THEY UNDERSTAND THE MODULAR, INTERLOCKING BRICKS. OUR OLD PRACTICES WE HAVE TO CHANGE
The hemp fields sprouting in a part of Canada best known for its giant oil patch show how climate change is disrupting the construction industry.
Six years after setting up shop in the shadow of Calgary’s tar sands, Mac Radford says he cannot satisfy all the orders from builders for Earth-friendly materials that help them limit their carbon footprint. His company, Just BioFiber Structural Solutions, is the vanguard of businesses using hemp — the boring cousin of marijuana devoid of psychoactive content — to mitigate the greenhouse gases behind global warming.
Around the world, builders are putting modern twists into ancient construction methods that employ the hearty hemp weed. Roman engineers mixed the plant’s sinewy fibres in mortar that hold up bridges.
More recently, former White House adviser Steve Bannon weighed in on “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 and Votorantim Cimentos as the global economy pivots towards dramatically lower emissions.
Cement makers are responsible for about 7% of global carbon dioxide (CO²) emitted into the atmosphere every year, with copious volumes entering via limestone kilns needed to produce the material. Manufacturers say they have struggled to find markets for greener alternatives, giving easy entrance to entrepreneurs such as Radford, who cater to customers concerned about their effect on the Earth.
“They love it once they understand it,” said Radford of the builders who have adopted the modular, interlocking bricks he invented. “Our old practices we have to change.”
While architects and developers have traditionally concentrated on the energy used by their buildings once they are standing, it’s actually the materials required in their construction that represent the brunt of a structure’s lifetime carbon footprint. Replacing high-carbonintensity materials such as cement with greener alternatives such as hemp can dramatically reduce or even offset greenhouse gas pollution.
Hemp fields absorb carbon when they are growing. After harvest, the crop continues to
absorb greenhouse gases as it is 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 Just BioFiber says its hemp captures 130kg of CO² for each cubic metre it builds. 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 tonne of CO², 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 as tall as seven floors, according to Quentin Pichon, founder of CANIngenieurs Architectes who specialise in hempcrete buildings.
Hemp growth in France has grown by a fifth in the past decade as a result of an increase in its construction use but also because seeds from the plant can be used to make cannabidol, he said. Hemp sales in Canada could hit $1bn within five years from $140m in 2018, according to the Northern Alberta Institute of Technology.
That ability to quickly ramp up local cultivation virtually anywhere in the world is one of hemp’s appeals, according to Alex Sparrow, MD of UK Hempcrete.
“Demand is rising steadily but we need to accelerate this as, currently, the UK construction industry accounts for approximately 7% of GDP and 50% of total UK carbon emissions,” Sparrow said.
One of the principal challenges his UK company faces are legal hurdles imposed on the cultivation of hemp — British farmers are only allowed to grow hemp for building materials but cannot profit from the oil extracted from seeds.
Back near Calgary, the black denim-clad Radford is already turning a profit and is preparing to invest C$37m ($28m) more to expand hemp production to 3.5million bricks a year.
He credits his children with convincing him to go green after four decades in commercial development. “They think that finally it’s not about money, it’s about doing good for the planet.”