Pubdate: Fri, 04 Jul 2014
Source: Day, The (New London,CT)
Copyright: 2014 The Day Publishing Co.
Contact:  http://www.theday.com/
Details: http://www.mapinc.org/media/293
Author: Dirk Langeveld
Page: 5

"HEMPCRETE" TOUTED AS HEALTHY, ENVIRONMENTALLY FRIENDLY BUILDING MATERIAL

It's certainly not the most common building material, but advocates of
"hempcrete" are saying it makes plenty of sense for environmentally
conscious homeowners.

This substance, also known by the registered name of Hemcrete, is a
bio-composite material. American Lime Technology, a joint venture of
the Chicago-based U.S. Heritage Group Inc. and UK-based Lime
Technology Ltd., says the material is made by combining the woody core
of the industrial hemp plant, or "shiv," with a lime-based binder. The
shiv has a high silica content, allowing it to bind well with the lime.

The resulting material is lightweight, only about one-seventh or
one-eighth of the weight of concrete. Hempcrete isn't strong enough to
use as a structural element; rather, it has to be added to a
load-bearing wooden frame or other structural support. American Lime
Technology says it is often put together in mortar mixers and added by
hand to building cavities. The hempcrete is then given a render coat
and finish, making the home exterior look something like stucco.

Hempcrete Natural Building Ltd., which is based in Canada, says the
material is an effective insulator against noise and provides a
breathable shell around a structure. According to the Green Building
Press, hempcrete is a good insulator and provides thermal inertia,
allowing the building to store heat and slowly give it off to help
mainting regular temperatures in the structure. Lime Technology Ltd.
was recently recognized with the 2014 Ashden Sustainable Building
Award for its work with the material.

"This is a huge leap forward on the journey towards zero-carbon
buildings," the Ashden judges said in a statement. "By making it
cost-effective and commercially viable to use these products, the
possibilities for expanding the use of this superior sustainable
building material across the commercial and domestic building sectors
are boundless."

Hempcrete Australia says the use of hempcrete is more environmentally
friendly than traditional materials because it avoids the use of
non-renewable materials and toxic chemicals. The company says the lime
prevents the biological decay of the shiv, and that hempcrete allows
for sequestration of carbon through both the growing of industrial
hemp as well as the carbonation of lime. The material can also be
recycled or will naturally break down if a building is demolished.

The company says industrial hemp is a different strain of the plant
Cannabis sativa. Though this plant has been used as a psychoactive
drug, Hempcrete Australia says industrial hemp cannot be used in this
way. American Lime Technology says farmers in the UK, Canada, and
Europe grow industrial hempvarieties that have very low concentrations
of the psychoactive ingredient tetrahydrocannabinol, or THC.

Owen Geiger, writing for the Natural Building Blog, says the fact that
industrial hemp is illegal in several areas is one of the drawbacks of
hempcrete. Its carbon footprint, though beneficial in building
projects, is offset by emissions produced in transporting it from abroad.

However, the rules on industrial hemp have been relaxed in some areas
of the United States. According to the National Conference of State
Legislatures, the 2014 Farm Bill passed by Congress allows state
departments of agriculture and institutes of higher learning to grow
it. Fifteen states have laws providing for industrial hemp production
as described by the Farm Bill, excluding it from drug possession laws
and requiring growers to be licensed by the state.
- ---
MAP posted-by: Matt