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Sustainability - Building an Industrial Hemp Economy

By Pat Rasmussen

In our last state Legislative Session, the House unanimously passed House Bill 1888 to legalize the cultivation of hemp and create a hemp industry in Washington. Multiple debilitating amendments were then placed on the bill, and the Senate ran out of time to hear the butchered version before the session ended.

In January, 2015, the Legislature will again consider making industrial hemp cultivation legal, and multiple new bills are expected. It is critical to make our voices heard concerning how important industrial hemp is to our State's economy and environmental and agricultural goals by contacting our representatives now and often throughout the Session. For more information, go to the Hemp Industries Association, at www.thehia.org.

Hemp History

Why aren't farmers in Washington growing industrial hemp today? Hemp has over 26,000 known beneficial uses. Powerful lobbies made and have kept it illegal on a federal level to eliminate the need to compete with it over their synthetic, inferior, tree-based and/or petrochemical-based materials. In 1937, the Marijuana Tax Act criminalized hemp cultivation, yet George Washington and Thomas Jefferson grew it and used it for all manner of necessities (taking on great personal risk themselves to smuggle prized hemp seed varieties from China through Turkey). In 1619 farmers were mandated to grow hemp, and in 1763-67 it was actually illegal not to grow hemp in Jamestown, Virginia due to shortages - the new colonies depended on it. During World War II, we needed hemp for the war effort after the Japanese had cut off our industrial hemp fiber supplies from the Philippines. The United States Department of Agriculture encouraged farmers to grow hemp during that war and produced the film "Hemp for Victory" to show farmers how to grow it (https://www.youtube.com/watch?v=a1oFcgLfgV0). Most recently, the historical "Legitimacy of Industrial Hemp Research" Amendment (§7606) to the Farm Bill was passed by Congress and signed into law by President Obama in February of this year, which allows for industrial hemp test pilots and research in conjunction with institutions of higher learning in states where hemp is legal.

Building with Hemp

Hempcrete is a lightweight, non-toxic, bio-composite building material made from the inner woody core of industrial hemp stalks (known as "hurd" or "shiv"), a lime-based binder, and water. It is mold-resistant, pest-resistant, rot-resistant, and fire-resistant, with no off-gassing. It is non-toxic, has high vapor permeability, is breathable and inherently air-tight. Hemp and lime have been used for building for thousands of years. Homes in Europe made of hempcrete have lasted 500 years. Modern day hempcrete was revived in France in the mid-1980's by sustainable builder and historical restorationist Monsieur Charles Rassetti.

Thirty-one other developed nations are growing and using hemp for building materials, food, fiber, and fuel. Right now the United States has to import hemp hurd for hempcrete from the Netherlands and England, and only from experienced, reliable suppliers because of the aggregate specifications required for hempcrete. It's readily available for builders from the trusted source Hemp Technologies Global (http://www.hemp-technologies.com/).

Hempcrete is a "carbon-negative" material when there is a local supply of hemp and regional supply of lime (hempcrete is otherwise "carbon-neutral"). This is for two reasons: (1) industrial hemp absorbs more carbon from the atmosphere as it grows than the carbon emitted into the atmosphere during the limestone burning process necessary to produce the lime binder; and (2) the lime in the hempcrete continues to absorb and lock carbon from the atmosphere for several years as it attempts to once again become whole until it is fossilized or petrified. This is known as carbon sequestration. Hemp is a tall, fast-growing plant, taking only 90-120 days to grow. The strong woody core of the stem is comprised of 77% cellulose, and this "hurd" is processed into consistent and specifically-sized pieces to be used for hempcrete aggregate - - a truly natural, renewable, sustainable material. Hempcrete walls, floors, ceilings and roofs have extraordinary thermal properties which preclude the need for heating and/or cooling systems in many environments. And when your hempcrete structure's life has come to an end in several hundred years, it can be crushed up and added into the mix of a new hempcrete structure!

The very basic recipe for a hempcrete wall mix is four parts hemp hurds, one part lime binder and one part water; but that recipe is altered for the roof, the floor, the interior and exterior plasters, the humidity of the day, the absorption rate of the hurd being used, and the region and purpose of the structure. Lime is a very sponge-like, porous structure that can take on and expel water, and can even be used as an exterior waterproof layer (as well as beautiful, non-toxic, interior plaster).

A brief botany lesson regarding the Cannabis sativa L. plant species is in order. "Cannabis" is the plant genus, "sativa" is Latin for "sown" or "cultivated" (and is included in many scientific plant species names), and the "L." we often see associated with Cannabis sativa merely stands for the surname initial of Carl Linnaeus, the Swiss botanist who invented taxonomy. Together, the term "Cannabis sativa" comprises the plant species. Within this plant species, we have the oilseed and fiber type known as "industrial hemp," which is a low-resin, non-psychoactive crop generally planted about four inches apart for its versatile stalk and seed (with its different kinds classified as "varieties" or "cultivars"); and we have the drug type known as "marijuana," which is a high-resin, psychoactive crop generally planted about four feet apart for its medicine or narcotic rich leaves and buds with different kinds classified as "strains."

Need to See It to Believe It?

Build a hempcrete tiny house for the Olympia Village Building Convergence August 15-23, 2015! Watch the Facebook page - Olympia Village Building Convergence. For more information contact Pat Rasmussen, edibleforestgardens@gmail.com or Joy Beckerman, joy@hempace.com


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Updated 2015/01/07 21:14:22