Hemp concrete or hempcrete is a building material of biological origin that helps achieve a zero balance, but: How can a product developed millennia ago help address current environmental challenges?
It doesn’t seem like much, but hemp concrete is the eco-friendly building material that has enthused green homeowners and architects for its potential as a sustainable alternative to bricks and concrete, which are expensive for the environment.
It is manufactured with a carefully calibrated mixture of hemp shavings -the dried inner core of the hemp plant- mixed with lime and water. But although hemp concrete seems like a very modern building material, its history dates back to more than 1,500 years ago.
Origins in India during the 6th century
Hemp plaster from the 6th century still covers the walls of Ellora Caves, Indiaa UNESCO World Heritage Site, and hemp mortar has been discovered in ancient Merovingian bridge abutments in France, which is very appropriate, since France was at the forefront of the 1980s campaign to modernize concrete of hemp and introduce it to a new generation.
At that time, wet hemp concrete was molded in situlike today, but the difficulty of getting the right mixture made it a difficult product for laymen to use. Too much of any of the three ingredients could cause the material to become runny and weak, while too little could cause it to crumble.
He drying time also posed problems. Under good conditions, hemp concrete can take four to six weeks to dry. But a cold, wet winter could slow the process down to at least six months, restricting its widespread use in northern Europe.
Impeccable environmental credentials
Despite the difficulties, the undeniable green credentials of hemp concrete have made the question of when it will make its way into the construction sector, and not if it will or not.
Liam Donohoe, COO of UK Hempcrete – a Derbyshire-based company that designs and supplies materials for hemp concrete construction projects – explains to ‘Euronews Culture’ that Sustainability plays an important role in all areas of product development.
“Hemp, unlike conventional crops, does not need many fertilizers or pesticides to protect it while it grows. Hemp fibrous type of hemp that is usually used in construction is a high floor that grows fastso it can be grown and planted quite close, naturally suppressing weeds,” he explains.
“I’m not saying that it doesn’t take energy to produce hemp concrete. But if we compare it to artificial insulation and wall filling, It has an unlimited shelf life and the main ingredient is a renewable crop whose production costs much less energy and carbon.
Research and development changed everything
Experiments conducted in France and at the Belgian University of Leuven in the early 2000s allowed researchers to begin to overcome obstacles that prevented hemp concrete from realizing its full potential as a construction product.
The eureka moment was the development of hemp concrete block or “green brick”, which eliminated the need for specialized knowledge and guesswork when using the material.
This fibrous, lightweight block opened up a new world of possibilities for the material without diminishing its ecological credentials. Does not contain volatile organic compounds (COV) y retains its acoustic properties indefinitelyof moisture absorption and thermal conductivityunlike synthetic insulation, which decompresses over time and loses effectiveness.
Now it is a consistent, light and reliable product which can be easily transported to construction sites and used by builders without the need for extensive training.
Hempcrete vs. Concrete: Wrong Comparison
Despite its versatility, experts are quick to dismiss comparisons between hempcrete and concrete. Concrete is a reinforced structural building material that can support its own weightwhile the hempcrete It is used around a wood, steel or concrete framework. It’s like isolation that doesn’t cost an arm and a leg.
“When hemp concrete is made into blocks, it is strong enough to stand on its own, so it can be used to build buildings of several plants. There are several examples in Holland, South Africa and France, so it’s not that you can’t build tall or strong structures with it, but you have to use it around a framework,” explains Donohoe.
ADVERTISING“Researchers are working on developing a structural application for hemp concretebut that currently usually means adjusting the recipe. The sweet spot is finding something that is very consistent, that arrives on site like any other construction product, without compromising too much on the carbon contributions to the recipe by using ingredients that are produced in a less sustainable way.”
The time has come for hemp concrete
He hemp concrete is proving to adapt well to the radically different way in which many lives are lived in the post-COVID world and the desire to do more to ensure the survival of the planet.
“In the recent past, people would go to their heated offices, do their workday, and come home to turn on the heat for an hour or two at night,” Donohoe explains. “Now we no longer live like that. More and more of us want a healthy and stable environment at home, because it is where many live and work.”
“Synthetic insulation, such as polyurethane and fiberglass, forms a barrier between heat and cold, but heats up and cools down very quickly.. On the other hand, natural materials, such as earth or hemp concrete, heat up a little more slowly at first, but They retain heat much longera process called ‘decay retardation’. “This process adapts to today’s world, where people are at home much more and the heating is turned on more frequently during the colder months,” he adds.
ADVERTISINGEurope sets the pace for the use of hemp concrete
The main players in the world of hemp concrete come from Europe. In the Netherlands, France, Belgium, Germany e Italiahemp concrete is commonly used for rehabilitate old buildings and form the core of new constructions.
One of the largest producers is the Belgian companyIsohemp. The company, based in Fernelmont, has operated in five countries since 2011.
Produces more than one million hemp concrete blocks a year and affirms that the projects he has worked on They have saved 18,000 tons of C02 to the environmentwhich is equivalent to the emissions produced by a patrol car circumnavigating the planet 32,000 times.
Although the United Kingdom is a few steps behind, the gap is rapidly closing. UK Hempcrete knows of between 300 and 400 homes in the UK that have been built with hempcrete and sees a bright future for the product.
ADVERTISING“The future of hemp concrete will be in prefabrication with modular construction methods. We already have half-timbered houses that are largely assembled in factories, taken to the construction site and built there. “There is no reason why hemp concrete houses cannot be prefabricated in a similar way,” says Donohue.
In Britain, there are companies that build conventional single-family houses with hemp concrete that look the same as single-family houses anywhere else in the country, but with much superior ecological performance.
“We focus on the rehabilitation of pre-1940 housing. We work with social housing cooperatives around the country that have old, cold and leaky houses. The biggest opportunity is to develop that market along with new construction.”
But the full potential of hemp and hemp concrete may not yet be exploited. BMW currently uses a weight-saving hemp polymer in the door panels of its i3 electric carwhile in the seismic zones of southern Italy hemp concrete is used as a flexible construction material that can withstand earth movements, instead of rigid and brittle concrete.
ADVERTISINGThe future of hemp concrete as an ecological construction material seems assured. But while researchers work on increasingly innovative ways to use it, we may have only seen a tantalizing glimpse of the difference it can make.
