The Centre for Alternative Technology in Wales is using hemp concrete as part of a new training/conference venue. It produces less carbon emissions than conventional concrete.It's also natural, breathable, fire resistant and highly insulative.
Hemp, like flax and lambswool, is carbon neutral and able to significantly reduce a building’s embodied energy. Lime is an ideal binding agent for hemp. It sets hard, but remains porous enough to allow water vapour to pass through the insulation. The mix is also supremely versatile: it can be compressed into blocks using a mixture of limestone quarry waste, hydrated lime and blast furnace slag, or it can be fabricated into batts for fitting between studwork. Hemp can also be mixed with lime on site and sprayed directly on to a building frame before final rendering.
4 comments:
All depends on where the hemp comes from, Scott. It is grown in the UK but in small amounts, so most hemp is imported from China.
I dispute whether any crop grown in the UK could be described as being 'carbon neutral' in any case, given the mechanisation involved, if not agrochemicals.
We don't grow cotton in this country either, but I think a shift to organic fairtrade cotton is a good start. I think anything that addresses the carbon impact of concrete is welcome. The production of Portland cement, a key ingredient of concrete, releases 8% of greenhouse gases worldwide.
Yeah, concrete is bad news. I guess the thing is that we need to find local solutions to our carbon problems instead of expecting poor people to do it for us.
I like the idea of cob buildings, using more traditional skills. I know that isn't an alternative to concrete, so I don't know why I said it really...
The Times had an interesting story on straw houses the other day ... total cost of £4000.
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