Though it lacks the structural stability its name might suggest, hempcrete does provide natural insulation and is virtually fireproof. In 2015, according to The New York Times, hemp-based building materials could usher in a new era of 'green' building in the US. While hemp has had a long history as a fibre used in ropes, sails and paper products - US Presidents Washington and Jefferson both grew it - a small number of US entrepreneurs have turned to hempcrete.
b) Reducing energy consumption due to excellent insulation and airtightness. There is little heating or cooling loss from a hempcrete building which means constant energy output to cool or warm the building is not required. Hempcrete has low effusivity and high thermal inertia, it does not take as long to heat and once heated will slowly release heat when the temperature drops, at night, so a heater is rarely needed.
Growing industrial hemp under license is already legal in Queensland, New South Wales, Victoria, Tasmania and Western Australia. However, the industry is very restricted because of archaic law/s not allowing hemp for human consumption (only two countries ban it, Australia and New Zealand) based on missguided concerns by law enforcement that hemp consumption could somehow affect roadside saliva drug testing or would 'send the wrong message' about Cannabis consumption.
Hemp is Cannabis sativa, a member of the Cannabaceae family. Cannabis is the plant genus, sativa (Latin for 'cultivated') is the species. A high-resin crop, Cannabis is generally planted about 1.2-1.5m (four to five feet) apart and mostly used for its medicinal/therapeutic leaves and buds. Hemp, however, is a low-resin crop, generally planted about 10 cm (four inches) apart, mostly used for its versatile stalk and seed. Different types of Cannabis are classified as strains and different kinds of hemp are classified as varieties and cultivars.
Tasmanian hempcrete house under construction
Queensland has allowed industrial production under license since 2002, with issuance controlled under the Drugs Misuse Act 1986. If you intend to grow or research industrial hemp, you must have a license. All activities carried out under a license are subject to monitoring at the licensee’s expense by inspectors who, among other things, sample plants before harvest to test for THC content.
|Ruth Trigg, IHA SA and Greens|
MP Tammy Franks
Hemp itself is a beneficial crop requiring no fertiliser, weed killer, pesticide or fungicide. It grows so thickly that weeds cannot grow. Farmers grow it in rotation with other crops such as barley or rye. The crop following hemp requires no weed killer because hemp drives the weeds out.
It is encouraging to see a trend in some developed countries of accepting the use of energy and resources to fuel a wasteful and profligate construction industry is way beyond the ability of the planet to continue to support. Mass materials like cement and concrete cause significant pollution, use a lot of energy and non-renewable resources. Many of the materials such as insulation and finishes contain toxic chemicals like brominated fire retardants which can seriously damage our health as well as the ecosystem. It has long been recognised that buildings and their use contribute significantly to CO2 emissions however it seems there are two main approaches to creating a lower impact on the environment. There are those focussed on getting mainstream construction to be more energy efficient, even though they still rely on high-embodied energy products such as cement, bricks, concrete and steel. This focus is based on retaining the same style of construction using the same materials with more insulation (petrochemical-based) and solar technology to reduce the impact. It would seem the intent is to appease the environmental conscience without pain. In the UK, the construction and use of buildings accounts for over 50% of the carbon dioxide produced. Studies have shown that up to 200kg of CO2 is emitted in the production of each square metre of walling for houses alone, equating to 40 tonnes for the walls of a typical house using double brick. The other approach has been to look at low impact alternatives that also are healthier and less polluting in both manufacture and construction technique.
|Hemp Cottage, County Down, Northern Ireland|
Resources included; Hempcrete Could Be Putting the Green in Green Building, What is Hempcrete, National Hemp Association, Hempcrete, Politics of Pot, Hempcrete Sustainability, Hempcrete Best Concrete, Hemp Now Seen As Growth Industry, DPI NSW Summer Crops/Fibres, Qld Industry Agriculture Niche Hemp, Industrial Hemp Queensland, Industrial Hemp Western Australia, DPIW Tasmania, New Laws Aim to Streamline Tasmanias Industrial Hemp Industry, Hemp Victoria, DPI Victoria, Australian Hemp