Sustainable building materials: how hemp is changing construction

This spring just past, Sydney was struck with a scorching heat wave with temperatures peaking at 40 degrees.

We are living on a warming planet and our dependency on energy for cooling will just increase in the coming decades, and with it, also our carbon emissions.

As you are already aware, Co2 emissions are not only created when we use the buildings (cooling and heating meanly), also called OC - Operational Carbon; but also when we build and construct the building, EC - Embodied Carbon.

Hempcrete has a negative EC, which is extremely rare for a building material

It’s because hemp is a living, carbon-breathing lifeform. Just like timber, the carbon is sequestered and stored in the fabric of your home.‍Hemp is a tremendously effective carbon-sequestering machine:

• It absorbs more carbon per kilo than timber during its growth phase.
• It’s six times more efficient than a timber plantation at sequestering carbon in its biomass.
• It breathes in carbon molecules to use as building blocks, growing up to four meters tall in three months. During that time, it can take from the atmosphere anywhere from 20.5 up to 25.5 tonnes of Co2 per hectare
• Finally, Hemp isn’t a water-intensive crop. For comparison, hemp requires a third of the water load as a cotton crop.

When discussing the carbon-negative nature of hemp in the context of hempcrete housing, I actually like to quote Graham Durrant. He is not only a great mentor to me in the Hempcrete world, but he also can really sum up in a couple of sentences just how good a job Hempcrete does in addressing the issue of carbon emissions in the construction industry.

Here are his words:

“One cubic metre of hempcrete will sequester approximately 110kg of carbon from the atmosphere. An average-sized house would be built using around 50 cubic metres of hempcrete for the walls, meaning that an average hempcrete house would lock up 5.5 tonnes of carbon for the lifetime of the building. This compares to a more standard new house of a similar size, in which the walls would be likely to emit 48 tonnes of carbon into the atmosphere (M. Berners-Lee 2010). This is a saving of 53.5 tonnes of carbon for every house built.”

Graham Durrant - “The Long Version - Hemp-Lime Spray.” Hemp, 8 June 2019

For the good of us and our planet, we need to act swiftly to the adoption of genuine carbon-negative materials in the design of our dwellings.

Thank you so much for your time. We spend a great deal of time writing about Hempcrete. That’s because our purpose at RespiraBuilt is to help as many people as possible to insulate our homes with a naturally grown, carbon-sequestering carbon-based lifeform that not only provides the best thermal comfort but also has a genuinely positive impact on the environment, and your bank account!

See you in the next blog post - Pillar #5: Hempcrete, is it affordable?

Talk soon,

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Will

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