
Hempcrete – eco-friendly material in Australian homes - clouddrover
https://www.abc.net.au/news/rural/2019-12-08/carbon-neutral-hempcrete-homes-building-in-popularity/11769446
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twic
> Hempcrete, made from mixing woody hemp fibre (from inside the hemp stalk),
> with lime and water, is then pushed into timber frames by hand to build an
> insulating wall.

So it's a reinforced lime mortar, rather than a concrete alternative. You can
use it to fill space, but not to bear load. More practical and quantitative
detail here:

[https://greenbuildingcanada.ca/2017/advantages-building-
hemp...](https://greenbuildingcanada.ca/2017/advantages-building-hempcrete/)

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NeedMoreTea
Curtain walling is used just about everywhere else, no reason it can't succeed
in housing too. There was a Guardian piece about a hempcrete house just
yesterday, with the hempcrete held in frames made from the hemp stalks and
resin made from agricultural waste. Started out as a barn, so there was a
steel structural frame to be filled in.

The prospect of carbon negative building has to be a huge plus.

[https://www.theguardian.com/artanddesign/2019/dec/07/flat-
ho...](https://www.theguardian.com/artanddesign/2019/dec/07/flat-house-
margent-farm-cambridgeshire-hemp-practice-architecture-carbon-energy)

~~~
ogrisel
Lime production is carbon intensive (heat + chemical C02 release from the
limestone) and the hempcrete curing will take 50 years to fix back the second
part. So it can be carbon negative (by fixing the carbon of the hemp itself)
but only on the long term (50 years after production) and assuming that the
heat used for lime production was from non-fossil source in the first place
(which is not the case today: the cement industry typically produces heat by
burning natural gas).

The heat could be produced from burning green hydrogen (hydrogen produced by
water electrolysis using renewable power) but as of today is still too
expensive compared to using fossil fuels.

~~~
ogrisel
A simpler alternative to get carbon negative buildings is to use Cross-
Laminated-Timber (CLT) to build both the frame and the walls themselves.

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kyriakos
how is this carbon negative? since lime is used for the mixture, doesn't it
mean the carbon was removed earlier during production and released? so
essentially any carbon absorbed was the carbon released during production.

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testvox
Hemp is a plant which consumes CO2 from the atmosphere. Using it as part of a
structure keeps it sequestered within that structure.

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larnmar
That’s the same as every other fibrous cement product, though. Is this
different apart from using hemp for the purposes of marketing to a certain
crowd?

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petre
It has other advantages compared to fibrous cement, like being a very good
moisutre buffer, having a time shift of 10…12 hours, CO2 absorption as it
cures etc. It can use natural hydraulic lime or pozzolanic binders.

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traverseda
>It will negate any carbon emissions we've had to make — for the concrete for
instance; it'll be a carbon-negative house.

I wonder how that compares to geopolymer cement?

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cs702
Neat... although I can't help but wonder what would happen if the structure
catches fire. I mean, would the entire neighborhood end up smoking it
secondhand?

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cannaceo
There's very little to no CBD/THC on the stalk itself. Also, hempcrete isn't
flammable.

~~~
cs702
Thanks. I meant for my comment to be humorous... and evidently, it wasn't.

