The efficiency of hemp in buildings. Economical and sustainable.
By Jim Gunshinan

Updated February 19, 2021

Hempcrete is used as a building material with a very low energy impact. It is water efficient in its manufacture and has a smaller carbon footprint impact than other housing construction materials. Concrete consumes a lot of energy in its manufacture and hemp could be an alternative material for integrated housing construction. Hemp can be used in the manufacture of housing to provide occupants with warm living areas in winter and allow them to stay cool in summer.

All building materials have strengths and weaknesses. In the case of hemp it is a very good insulator as we have already mentioned, on the other hand it is not the best material to support loads. However, it is very effective at insulating against moisture and reducing the possibility of mold growth and thus preventing poor indoor air quality. Another of hemp’s strengths is that it absorbs carbon from the environment and is easy to harvest and is a simple crop to manage.

The use of concrete has been used at least since the days of the Roman Empire. Today, concrete is composed of sand, binders, limestone, shells, chalk, slate and clay. These components are heated to high temperatures and once the rock is formed it is ground.

Hempcrete consists of hemp together with lime binder and water, and does not require heat to form the material. The material can be used in building blocks, bricks or even Lego-like shapes to fit together. It weighs much less than cement blocks and therefore requires less energy during the construction process.

We can also use hemp to protect the exterior walls of the house, applying it as a form of stucco to protect it from humidity. Being a vapor permeable material, it can absorb water and let it evaporate when the sun hits it. This prevents it from rotting and also prevents mold and mildew growth.

Hempcrete works well with relative humidities above 90% and can store vapor in the material without degrading. It should be noted that the lime binder used in the Hempcrete mix has antimicrobial and antifungal properties.

Wood and steel have superior load-bearing qualities to hemp, but we can state that, as a filler between traditional framing, hemp has the properties of strengthening the walls against buckling.

Hempcrete is a material with better insulating properties than traditional concrete. The resistance of materials to heat flow through them is represented by an R. Therefore, the higher this value is, the more resistance it offers in losing heat in cold weather and the harder it is to gain heat in summer. The value of Hempcrete is estimated to be between 2.4 and 4.8 per inch while concrete has a value of 0.1 to 0.2 per inch.

Hempcrete material is not compressed, thus avoiding a reduction in its effective R-value. It is also very easy to cut, making it easy to fill the spaces for insulation.

Environmental benefits of hempcrete homes

The constituent energy in a building is composed of the energy used in various activities. For example, in the extraction and construction of the material, transportation, assembly and destruction of the material. Concrete generally comes from burning oil or coal, and according to the U.S. Energy Information Agency, the concrete industry is the most energy-intensive industry. Concrete manufacturing accounted for 0.5 to 0.6 tons of carbon dioxide per ton of concrete in 2018 internationally.

On the other hand, hemp removes carbon from the air and thus reduces the impact on its production. It is proven that hemp is very useful in soil regeneration by absorbing heavy metals. It is also worth noting that hemp can be grown at high planting densities. The density of the crop can be so high that the adventitious weeds of the crops have practically no option to grow, thus avoiding the use of pesticides.

Unlike other building materials or furniture, Hempcrete does not contain volatile organic compounds harmful to health. If we manage to grow hemp locally, transportation and labor costs for construction are significantly reduced.

Hemp, like any other crop, has weaknesses. It is not really drought resistant and uses about the same water as other fibrous crops. However, as long as we continue to use materials from renewable sources and move away from fossil fuels, it will always be a marked improvement towards a more sustainable future. Increasing in this case, the efficiency of houses in terms of energy consumption.

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