The new frontier of sustainability in industries such a fuel and clothing, hemp is also leading the way to more sustainable building. From the cutting down of oxygenating trees to the chemical reactions of compounds used to make modern building materials, the construction industry is a substantial contributor to pollution worldwide. Replacing certain staples of building in the modern world with hemp-based materials will both decrease the output of CO2 and increase the level of CO2 absorption necessary to clean up our air.
Hemp As A Building Material
Beginning in Ancient Rome in the days of Julius Caesar, hemp as a building material is not a new concept (5). A bridge built in France in the 6th century was discovered to have been made with hemp abutments, and there are buildings with hempcrete walls all over Europe and the UK that have been standing for over 700 years. This sturdy, cost-effective, and carbon-neutral siding material can take the place of plywood, insulation, and drywall. It also stands the test of time better than nearly any other component, organic or not. (2)
Hempcrete, the primary building material derived from the hemp plant, is made from hemp hurds–the inner fibers of the hemp stalk–ground up with lime and mixed with water. The hemp begins to petrify as it interacts with the lime. This process does not lend itself to a quick-setting material that enables fast access, but it does mean that hempcrete only gets stronger over time as the lime continues to calcify. (3)
Hemp can be harvested in perpetuity, meaning the maturation of the plant does not have to be reached before it can be harvested, nor will it affect the quality of the resulting materials made from the plant. A standard hemp crop takes about four months to grow, and in some parts of the US this lends itself to the crop being harvested twice a year. This fact alone makes hemp much more sustainable than any other building material resource, i.e. trees, cement, and steel.
Hemp Vs Concrete: A Sustainability Comparison
When concrete is manufactured, the resulting carbon emissions from the chemical reaction that occur are unavoidable and are not affected by energy saving techniques. In comparison, hempcrete slashes the carbon footprint during manufacturing and actively extracts carbon from its environment (1).The use of lime in building materials emits 80% less CO2 than that of cement and when combined with hemp, it absorbs carbon even once it is made into a building material.
In 2010, Push Design out of North Carolina built the first hemp house in the US in the town of Asheville, NC . Sourcing their hemp from the UK, the builders of Push Design realized that hemp was the most sustainable effective building material apart from the cost of importing it from Europe or China. With the passing of the 2018 Farm Bill, this became a non-issue in a lot of states that lifted bans on industrial hemp production.
Benefits Of Hemp As A Building Material
Aside from the environmental benefits of building with hemp-based products, it is a sensible option with performance to back up its reputation. It is highly fire-resistant due to the limestone and continued calcification. Hempcrete also regulates temperature, humidity, and is mold and pest resistant. Also, because of its insulating capabilities, greenhouse gas emissions of buildings that use hempcrete are cut by 64 percent. (3)
Factors To Consider
In building with hempcrete specifically, there are a few drawbacks that limit its use in infrastructure. Hempcrete takes a long time to set, so it is not used for load-bearing walls (3). This means it is not being used in the foundation of homes or to support any type of structural integrity. One solution builders have found for this issue is hempcrete bricks. Hempcrete bricks cure faster, so they work better when trying to fill a wall cavity quickly. (1)
There are other uses for hemp in building and home maintenance besides hempcrete. Hemp oil can be used to treat wood. It is natural and adapts to the character of the wood while protecting it from weather and physical damage. Hemp can also be made into a bioplastic alternative for a variety of uses. It can also be made into a particle board used for finishing walls. (4)
The benefits of using hemp as a sustainable building material are inarguable, and with the lifting of restrictions on growing, the accessibility is only going to fan the flame of industrial hemp production and usage.