Hemp at the heart of Western Australia's first eco-village
The project manager of Western Australia's first eco-village, partly built with hemp, believes the finished product will add weight to the growing push for it to be widely used in the construction industry.
Tendering contracts are out for the construction of 12 dwellings, due to be built in the WA south coast town of Denmark, about four and half hours from Perth.
Project manager Paul Llewellyn said a key feature would be the combination of hemp hurd, the innards of the plant's stem, and lime, which is used to render the traditional timber frames.
"The two combine to form a lightweight masonry product, which is very thermally efficient, breathes and has lots of acoustic properties," Mr Llewellyn said.
"It provides a wall — which is much more thermally efficient than a double brick wall and is equal in effect to the thermal efficiency of a very wall insulated timber wall — but this wall breathes, which regulates the humidity in the house."
Mr Llewellyn said though similar houses had been built in other parts of Australia, the Denmark project was the first of its kind for WA.
"The houses themselves will be small, but the common space around the community will be large," he said.
"Our primary drive has been to create houses that are comfy, easy to live in and cost little to run because they are energy efficient."
From kitty litter to the job site
Mr Llewellyn also said hemp hurd had a high silica content, which repelled white ants, and when combined with lime the product was extremely fire proof.
"You could put a blow torch on it and it simply will not burn," Mr Llewellyn said.
"In that way, it could be viewed as a breakthrough in building construction in our fire-prone areas."
Commercially referred to as hempcrete the product is commonly used throughout Europe and was the result of hemp manufactures looking to find a use for the "mountains" of hemp hurd leftovers.
"It actually makes a fantastic kitty litter, but there is only so much use for kitty litter," Mr Llewellyn said.
"So it was eventually combined with lime to make this amazing technology."
Preconceived ideas slowly being put to bed
A thesis of the utilisation of hemp in the construction industry conducted by University of Western Australia student, Gareth Robert Shun'an Jones, concluded lime-hemp concrete (LHC) met sustainability and environmental concerns while also "exceeding in many areas of building performance".
The author surmised LHC "provides a superior overall performance in terms of sustainability and comfort levels than comparative 'green' building materials, including autoclaved aerated concrete, rammed earth and straw bales".
However, the thesis concluded LHC was not being widely used due to research and information still disseminating throughout the scientific and public community.
"Combined with the [incorrect association] of hemp with marijuana, has resulted in public perception generally being distrusting of a building material, which is mainly formed from cannabis," the thesis stated.
Mr Llewellyn agreed the tide was beginning to turn for proponents of hemp.
"There are about 200 varieties of hemp and they are about as different as a chihuahua and a great dane," he said.
"The industrial hemp, for example, has very few traces of the psychoactive component, but it has all the products you can make.
"Here we have a building technology that will solve a lot of environmental issues."