Building With Hemp

Ultimate green living

By Emily Riopelle

 

Have you ever seen a hemp house? Have you ever wondered just how strong and durable hemp could be? Most of us have no first-hand experience with hemp houses, because the American hemp industry is in its infancy. But in France, hemp has been used as a building material for about 30 years, mostly as insulation. More recently, companies such as Tradical in the U.K. and Hemp Technologies in the United States have begun to build entire houses with a material called hempcrete. These companies discovered that by mixing hemp with lime and water, they were able to create a compound comparable to concrete, with additional benefits. As a building material, hemp is an incredibly untapped resource to this day. Only a few lucky companies are privy to the benefits of building with hemp. Hemp and lime together create an astounding material that is more energy efficient, environmentally friendly, and healthier for both consumer and builder.

 

Carbon friendly

Building houses with hemp can greatly reduce the environmental impact of our construction industry. Hemp-lime actually sequesters carbon dioxide (CO2) from the environment, rather than contributing more carbon into the atmosphere. Hemp Architecture confirms: “Using hemp within the structure of a building can be better than zero carbon, sometimes referred to as carbon negative.” Over 200 pounds of CO2 can be locked away in 35 cubic feet of hempcrete, which is about the size of a refrigerator. Whereas traditional homes contribute greenhouse gases into the atmosphere during construction whilst using energy, hemp houses actually hold those gases in for the life of the house. But the benefits do not end there. According to a 2007 EPA report, building-related construction and demolition waste totals 160 million tons a year. Building with hemp-lime cuts down on construction waste considerably because it is an all-natural, recyclable material.

 

The environmental benefits of the material could be amplified with both legalization and further research. Currently, hemp-lime is used as filler requiring timber frames for structural support. Since hemp grows much faster than trees and has a smaller environmental footprint, a method of using hemp stalks for structural support would be ideal. A company mentioned in Sativa Magazine’s June issue, Hemp Architecture, is working on just that. Furthermore, since industrial hemp is illegal to grow in the United States under federal law, domestic companies such as Hemp Technologies must import their hemp, increasing the financial costs as well as drastically increasing the carbon footprint of hemp products.  

 

Energy efficient

Although traditional homes are built using toxic materials said to aid in insulation, they still require significant amounts of energy to heat and cool. In Europe, hemp insulation has been shown to be more efficient. Hemp Architecture explains that: “Simplification of the construction process with fewer materials and layers is also a benefit. It is usually where different layers or materials meet that the failure occurs and it is also more cost effective to have one material performing many functions rather than many materials, each performing a single role.” Since hemp-lime achieves all of the functions of the traditional house in one single layer, it can create a more airtight cocoon.

 

Hempcrete Australia, a company that markets their own version of hemp-lime points out that hempcrete homes use less energy during construction because large machinery isn’t necessary to mix and vibrate the mixture, this also makes it easier to recycle.

 

If you’re looking for numbers, according to Hemp Technologies, a typical home will require 60 percent more energy to heat and cool than one constructed with hempcrete, allowing a substantial and welcome reduction in energy bills.

 

Healthy

If that’s not enough incentive to purchase some hempcrete and start building, start thinking about the materials that were used to build your traditional house. A report published in 2008 by the Healthy Building Network showed that numerous chemicals may be lurking within the structure of your home, including: polyvinyl chloride (PVC), a common type of plastic, which has been shown to emit dioxins that are associated with many health issues and cancer; volatile organic compounds like formaldehyde, which are often used in insulation and have been associated with many health issues; semi-volatile organic compounds, which are often used in building materials to inhibit ignition or flame, can spread and may cause cancer, and the list goes on. The study also states that: “The U.S. EPA has registered more than 80,000 chemicals for use and identified 16,000 of them as chemicals of concern; they have only subjected 250 to mandatory hazard testing and only restricted five chemicals or chemical classes.”

 

On the other hand, hemp meets the four criteria that the study lists as a guide for safer building materials: grown without the use of GMOs; compostable into healthy and safe nutrients; certified as sustainable, and grown without the use of pesticides containing carcinogens, mutagens, reproductive toxicants or endocrine disruptors. Hemp will not give you cancer. Hempcrete is also a breathable material, meaning it will absorb and pass water vapor but not liquid. This makes hemp houses mold-resistant and low-allergen environments. Hemp-lime also acts as natural and safe insulation and is non-combustible.

 

Worth the extra cost

With all of these amazing benefits, you’d think the cost of a hemp house would be astronomical, but it’s not. In 2011 the National Association of Home Builders conducted a survey and found that the average square footage of a single family home is 2,311 sq ft., total construction costs added up to $184,125 which works out to about $81 per square foot for the average American home. Hemp Technologies is the only company currently building hemp homes in the United States and they list several styles of hemp homes starting at $140 per sq. ft. And as an emerging market, costs are only going to go down.

 

Though this is a heftier initial price, if you plan to build a hemp home and stay there forever, the difference will be made up in just a few years with all the money you’ll save on energy bills. And your hemp house will last forever. American Lime Technology sells the Tradical Hempcrete and explains that the pH and vapor permeability of the lime binder make the perfect environment to preserve the hemp shiv, creating a structure they say will last centuries.

 

Sidebar:

 

Not only is the hemp ‘green house’ an amazing and innovative environmental feat, a hemp greenhouse can be one as well. Suppose you wanted to build an awesome and earth-friendly greenhouse with hemp materials to grow the other, medicinal and psychoactive, form of Cannabis?  Not a problem, here’s a quick sketch of how to do so:

 

Make your lower walls out of hempcrete with galvanized steel posts at intervals to support the frame and glazing. If the greenhouse is oriented along the north-south axis, the entire north wall need not be glazed at all and can be made of hempcrete to better insulate the greenhouse. This will create a heatsink that will store heat from the sun during the day and release it at night. The breathable nature of hempcrete will help mitigate moisture-related problems in the greenhouse.

 

If needed, a shade cloth could be made from hemp fibers to reduce the heat buildup from the sun. Since Cannabis devours full sunlight like a starving artist eats ramen, an opaque hemp fabric might be utilized as a light deprivation cloth to allow for extra crops. To learn more about light deprivation growing read the article “Fooling Mother Nature” in the June, 2013 issue of Sativa Magazine. On the topic of opaque, local authorities might require a wall around the greenhouse to keep prying eyes from seeing what you are growing — and perhaps reduce jealousy in the eye of the beholder. That wall could be made from hempcrete, or hemp or OSB (oriented strand board), and painted or stained with a hemp-oil based product to seal it from the elements and make it attractive.

 

The plants can be grown in fabric pots made from hemp fibers. Similar fabric pots allow excellent air exchange and air-pruning characteristics that promote a very healthy root system. As an added bonus, if the pots degrade they are compostable.

 

If the power goes out, a diesel-powered backup generator can run on hemp oil biodiesel. The entire greenhouse could be heated with a biofuel burning boiler system that uses hemp as one of the combustible fuel sources. How cool is it that hemp can be used in so many ways for a greenhouse?