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 pyramids.
27-23 B.C.— Vitruvius provides specifications for lime mortar mixes in his treatise De Architectura .
1756— James Smeaton develops the first hydraulic lime product.
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 system.
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 plant
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 lime.
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 Council)
Tradical® Hemcrete actually sequesters carbon emissions from the atmosphere, locking up approximately 110 kg of CO 2 per cubic meter.
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 heat.
Hemcrete is airtight, minimizing loss of heat through draft.
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 Advantages—Buildings and Health
Since 1987, the EPA’s 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 environment.
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 Machynlleth, Wales
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 respective states.
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
2006—North Dakota passes legislation allowing for the issuance of industrial hemp farming licenses.
February 13, 2007—H.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 so.
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 sequestration.
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 agriculture.
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.