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article: Hemp Homes could be the future

Hemp is a versatile material used for paper, health food supplements, fabric and a growing list of other uses. Add to the list a new use - environmental freindly building materials.

A wide variety of construction materials can be made from Hemp fiber, such as composite fiber board which is both lighter and stronger than comparable wood products, 2x4's, lightweight concrete substitutes that have both insulative and soundproofing qualities. Isochanvre, a French company has built over 250 hemp homes. They have combined Hemp fiber with lime to create a thermal and acoustical barrier which is stronger and 7x lighter than concrete!

A Suffolk-based study into using the material to build environmentally-friendly homes has found hemp to be the ideal choice and, although more expensive than conventional brick and block, experts are sure the costs will fall.

The social housing organization in Suffolk, England has completed a test project that studied the environmental impact, energy use and other factors of hemp housing in comparison to more traditional construction methods.

The project involved the construction of eighteen dwellings, 16 of which were built using
conventional construction methods and materials but two of which were of a form of
construction referred to as Hemp.

During the project BRE studied the two systems for:
• Relative structural, thermal, acoustic, permeability and durability qualities;
• Reduction in waste generated on site;
• Environmental impact;
• Construction costs.

The main findings were:
Structure & durability: The qualities of hemp homes were found to be at least equal to
those of traditional construction.
Thermal comparisons: Heating fuel consumed by the hemp homes is no greater than
that used in the traditionally constructed houses.
Acoustics test: Hemp homes did not perform as well as the traditional houses but they
did meet the sound resistance requirement.
Permeability: Both forms of construction appear to give complete protection against
water penetration. However, the hemp homes generate less condensation.
Waste minimisation: There appears to be little difference in the amount of waste
produced by each method. Although the waste is of a different nature in each case both
are likely to have an environmental impact.
Construction costs: It is estimated that the true cost of hemp construction was £526 per
square metre compared to £478 for traditional construction.

The project was studied by the Building Research Establishment (BRE) in regards to the sustainability, economic and environmental differences between the two construction methods. The first tenants moved into a two-bedroom hemp home in December, 2001. For three months, their lives were closely monitored by sophisticated instruments measuring qualities such as insulation, energy efficiency, sound proofing, structural stability, resistance to water and condensation factors. The second hemp home remained empty until the spring of 2002 so that its properties as an unoccupied house could also be monitored. The same occupation pattern applied to the brick/block houses.

The BRE report’s principal conclusions are that while the hemp homes have far less impact on the environment – they use less energy to build, create less waste and take less fuel to heat – they cost about 10 percent more to build than brick and block houses. It is expected that this cost will go down with production efficiencies and economies of scale.

The full report is available at: http://projects.bre.co.uk/hemphomes/HempHousesatHaverhillfinal.pdf

Suffolk Housing Society has published a summary of the findings that is available in hard copy or from its web site www.suffolkhousing.org.

Other Developments:

Australia: Alivefoods with the help of the HFIA are building luxury hemp mud brick and timber homes soon in Australia. Contact alivefoods at build@alivefoods.com for further information.

Canada: A Canadian company has developed an "Enviro shake" which looks like a handsplit cedar shake but is made from hemp and 100% recycled materials and has a 35 year warranty!

United States: Since 1997, the Lakota Sioux at Pine Ridge Reservation in South Dakota have passed multiple pro-hemp resolutions and declarations.This year, the tribe sowed about two acres by an already growing field of wild hemp. Since Native reservations are considered as independent nations for many purposes, the DEA has made no official reaction.

The Lakota tribe is also receiving $5 million from US feds, to replace two dozen homes recently destroyed by tornados. They intend to use part of that money for hemp-based buildings.

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