A Sustainable and Healthy Environment: Promoting Hemp and Lime
Construction A presentation to
U.S. Heritage Group
U.S. Heritage Group, Inc. is dedicated to the production and
use of lime-based masonry materials.
Brief History of Lime Construction
4,000 B.C. Lime is used as a plaster for the Egyptian
27-23 B.C. Vitruvius provides specifications for lime mortar
mixes in his treatise De Architectura .
1756 James Smeaton develops the first hydraulic lime
1824 Joseph Aspdin develops Portland Cement.
Building with Lime
One of the greatest selling points of lime-based products in
the building industry is their low impact on the environment during
production, construction and throughout their life in a building
Environmental Impact of Lime-Based Mortar versus Cement-Based
Mortar Building Research Establishment, Ltd. (BRE)
U.S. Heritage Group has the exciting opportunity to partner
with Lime Technology Limited, the market leader in the development
of lime based products in the U.K.
Introduction of material hempcrete--Tradical Hemcrete--to the
U.S. as a green building product.
What is Hempcrete?
The combination of lime and hemp as a building product is
commonly called hempcrete.
Hempcrete consists of lime, part of the fibrous stalk of the
industrial hemp plant, and water.
Hempcrete can be tamped into a framework, sprayed on as a wall
system, and used as an insulator.
Quicklime converted to dry hydrate. The fibrous stalk of the
industrial hemp plant.
The History of Hempcrete
INSERT INFO ON HISTORY OF HEMPCRETE, ISOCHANVRE
What is Industrial Hemp?
Used for textiles, plastic composites, paper, building
materials, food and personal care products.
Contains less than 1% THC (delta-9 tetrahydrocannabinol).
Photos from the Hemp Sys project in Italy.
Processing Hemp for Hempcrete The stem tissues outside the
vascular cambium are referred to as the bast (flexible inner phloem
fibers of the bark) and contain the fibers useful for textiles. The
tissues inside the vascular cambium (inner woody core) contain the
pith and the xylem vessels and are referred to as the hurd.
Transverse section through the stem of an industrial hemp
Processing the Hemp for Hempcrete The hurd, also known as a
shiv, is separated from the softer fibers that surround it. The
hurd is then chopped, graded, and all dust is removed. At this
point the hemp hurd is ready for use with lime.
Tradical HF (chopped, graded and de-dusted hemp hurds) is mixed
with Tradical HB to create Hemcrete.
Tradical HB is a lime binder that consists of hydrated air lime
and cementitious, hydraulic and inorganic materials.
The air lime, or pure calcium carbonate, is heated in a kiln to
approximately 900 Celsius (1,652 Fahrenheit). The heating process
chemically changes the calcium carbonate to calcium oxide, also
known as quicklime. Water is then added to produce hydrated
Advantages of Hemp and Lime Construction
Currently, construction and use of buildings accounts for 39%
of carbon emissions in the United States. (U.S. Green Building
Tradical Hemcrete actually sequesters carbon emissions from the
atmosphere, locking up approximately 110 kg of CO 2 per cubic
The hemp in Hemcrete absorbs CO 2 and converts it to glucose,
cellulose, hemi-cellulose and lignin. The carbon is contained in
the plant while oxygen is released back into the atmosphere.
Hemcrete has good thermal mass, or the ability to store
Hemcrete is airtight, minimizing loss of heat through
Hemcrete has low thermal effusivity. This property can reduce
heating costs and by extension, reduce carbon emissions.
Hemcrete is a highly breathable material with high water vapor
permeability, capilarity and hygroscopicity.
The combination of these thermal properties creates buildings that
are cool in the summer, warm in the winter, and that maintain
comfortable air quality due to the breathability of Hemcrete.
More AdvantagesBuildings and Health
Since 1987, the EPAs Science Advisory Board has ranked indoor
air pollution as one of the top 5 risks to public health. (
Environmental Health Perspectives ).
Environmental Protection Agency
Sick Building Syndrome
Sick Building Syndrome or SBS Health problems related to poor
air circulation and a variety of pollutants and allergens.
Headaches, nausea, fatigue are common symptoms of this rampant
health problem. Constant activity in indoor spaces designed without
concern for human health and comfort is serious problem in our
homes and workplaces.
Hempcrete contains none of the VOCs (volatile organic
compounds) typically linked to SBS.
Lime naturally inhibits the growth of mold, a common allergen
and aggravator of SBS.
The breathability of hempcrete in combination with
well-designed ventilation creates a healthy indoor
Symptoms and Illnesses Associated with Poor Indoor Air Quality
Encyclopedia of Occupational Health and Safety, 4 th ed.
Lime and Hemp Construction in the United Kingdom Townhouses,
Haverhill Suffolk, England. Centre for Alternative Technology
Drawing upon the rich history of lime and hemp construction,
architects and environmentalists in the U.K. have successfully
introduced hempcrete as a viable green material for use in a wide
variety of projects.
Industrial Hemp in the United States
Though the production industrial hemp is not legal in the
United States, the DEA does differentiate between industrial hemp
and marijuana as a commercial product and allows the possession and
sale of its oils, fibers and seeds.
Twenty-eight states have introduced industrial hemp growth
legislation. So far, fifteen of those states have passed
legislation which ranges from granting licenses to farmers to grow
industrial hemp following a thorough background check (North
Dakota) to the formation of study committees to assess the impact
of the agricultural production of industrial hemp on their
Wisconsin currently is considering legislation that would
create a committee to study the development of industrial hemp as
an agricultural crop.
History of Hempcrete in the United States
2006North Dakota passes legislation allowing for the issuance
of industrial hemp farming licenses.
February 13, 2007H.R. 1009, Industrial Hemp Farming Act of
2007, introduced to Congress.
Community leader Joe American Horse of the Oglala Sioux Pine Ridge
Reservation, South Dakota Beginning in 1998, the Oglala Sioux of
the impoverished Pine Ridge Reservation in South Dakota have grew
industrial hemp for use in the production of hempcrete. The
hempcrete was used to build homes on the reservation, thereby
minimizing the severe housing shortage suffered by the tribe and
providing employment for members of the community. Hemp production
took place under tribal sovereignty laws. Recently, the DEA, and
eventually the U.S. Court of Appeals, denied their ability to do
A Partnership for Health and Sustainability
The benefits associated with Hempcrete align closely with the
stated priorities of the Brico Fund.
Hempcrete has negative carbon emissions due to carbon
Hempcrete is made primarily of renewable resources.
Acceptance of hempcrete as a building material will encourage
the legalization of industrial hemp growth. Industrial hemp has
tremendous potential as a cash and rotation crop for American
farmers and could serve as a model for sustainable
A JUST AND EQUITABLE SOCIETY
Promoting building systems free of harmful VOCs and carbon and
radon emitting materials is a first step in raising our standards
of our indoor environments.