In our new quest for greener more sustainable building materials in this age of rising energy costs, the answer may be an all natural solution – hempcrete.
Hempcrete is a natural solution because it is from a sustainable plant that grows anywhere and matures very quickly (about 14 weeks) in order to be used.
Hempcrete was discovered in a bridge abutment in France, which was originally built in the 6th century. Since its rediscovery, hempcrete has been growing in popularity as a building material in Europe, because it really is a natural solution. Given that the abutment has lasted more than 14 centuries, there is reasonable hope that this could be a very long term solution.
Hempcrete, in comparision to other free-form construction materials, has a much higher R Value – the measurement of thermal resistance – than concrete. Although this is still being tested, concrete has a typical R Value of about 0.08 per inch of thickness, compared to Hempcrete which is roughly 2.08 per inch of thickness. There is no other construction material which is as high R Value with such a low production value.
Hempcrete also has the additionally useful properties of being breathable, fire-proof, pest resistant, and is a carbon negative material. It is carbon negative because of not only the carbon from the hemp plant itself, but with the lime it is mixed with, which wants to return to being a rock, pulls carbon from the air as the structure slowly petrifies. This means that the hempcrete will actually increase in strength and density as time passes. Coupled with the fact that it naturally breaths and regulates moister, there is no mold, dry rot, or other moisture related problems one typically finds in other construction. This would mean less energy going into a house built of hempcrete in the form of air conditioners or heaters, since the thermal resistance keeps a more consistent temperature inside the structure. Perhaps hempcrete will be.
The only issue is that hemp is still an illegal product to grow in the US and has been for over 60 years. The prime component of hempcrete is the inner shunt of the plant stem from cannabis sativa. This means a need to import the fiber from the UK, which puts a slightly higher price tag on the material than it would be once Canada or the US begins growing production. Homes are starting to be built in the US from this material, but it is not as wide spread as the proponents of the material hope it will become.
Construction with this amazing and natural material is still a basic frame and timber bearing type, but it is not difficult to imagine that an entire house could be made of interlocking hempcrete bricks. Only the future will tell where we can go with hempcrete as a natural solution to our building and energy needs. A sustainable, renewable, breathable, low cost, and natural building material sounds almost to good to be true. Yet, we have known for millennia that hemp is an amazing plant that can meet many of our needs, from pulp for paper, to clothing fibers, and now to building materials. Perhaps the renewed interest in the green and sustainable will finally push laws in the US to change, but only time will tell. Hempcrete, a natural solution for so many of our needs and now we can add building homes to the list. What an amazing plant!
By Iam Bloom