Zero carbon homes
Hempcrete is a “better-than-zero-carbon material”. More atmospheric carbon is locked away in the material for the lifetime of the building than was used in its production and use.
Why is that important?
The construction industry is responsible for around 60% of the UK’s total carbon emissions, both through energy used in the construction phase and by the occupants of the building (“energy in use”). In an effort to counter the effects of climate change, the last few years has seen a ‘commitment’ by the UK government, the construction industry and its regulatory framework, for all new homes to be “zero-carbon” by 2016.
Unfortunately this ambitious target will not be met, largely because efforts to date have focused on building systems (such as small scale solar installations) and reducing energy in use through the upgrading of the fabric in new buildings to include a very high standard of insulation. Sadly neither approach takes any notice of the “embodied carbon” in the materials used.
Embodied carbon is a measure of the total carbon emissions associated with a material, product or service, taking into account its extraction from raw materials, manufacturing process, transport, application, and the energy used in recycling or replacement of the material at end of life.
Currently there is a lack of emphasis on these “hidden” carbon emissions within the regulatory structure in the UK, and as a result the materials we are using – especially those used to construct and insulate our homes – are often very high in embodied carbon, making the target of constructing zero-carbon homes seem further away than ever. However effectively we insulate our buildings, and whatever low carbon systems we install, we are still failing to offset the huge embodied carbon associated with constructing the building in the first place, and eventually disposing of non-recyclable materials at the end of its life.
Because the hemp plant absorbs a very high level of atmospheric CO2 as it grows, and because the production and application of hempcrete is quite a low-tech process, the end result is a material which, even accounting for the production of the lime (a relatively high embodied carbon material), transport, and the energy use during construction, still locks away a net 110 – 160 kg of CO2 per m3 of hempcrete for the lifetime of the building. What is more, hempcrete walls have a much better thermal performance than conventional or lightweight insulation constructions, meaning that the energy used by the occupants of the building is dramatically reduced compared to conventional construction.
When you build with hempcrete a “side-effect” of your build is active carbon capture and storage, making hempcrete the obvious choice for creating true (better than) Zero Carbon Homes!
To find out more about this aspect of hempcrete construction, see our FAQ guide