A paradigm shift is underway in regard to how new buildings and developments are designed and constructed. Unfortunately, many projects pursuing Built Green, LEED and other forms of green certification fall short of what is truly needed at this time. Currently, buildings contribute the largest single source of greenhouse gas emissions to our environment (emitting 30% of these pollutants directly, and another 18% indirectly, through procurement and transportation of materials, according to the U.S. Green Building Council). Buildings also represent a top priority health concern in regard to indoor air quality. The U.S. EPA states indoor air is over 2 to 5 times more polluted than the air outside; sick buildings are now all too common!
We can no longer deny the importance of building and retrofitting in a more holistic way, i.e. one that looks at all the connections among the systems in a building as well as those between it and the world at large. Energy efficiency is important, but the ingredients used in making building materials also need to be evaluated–in terms of health attributes, embodied energy, and potential for supporting the local economy. Earthen buildings are being considered more and more seriously; however, many of them are not suitable for Alberta’s climate. Hemp–or more specifically hemp-lime–has been shown to be superior to any earth building mix in terms of insulation R-values. Of course, building with hemp is not new! The Romans used it, as did the Japanese, and the material has been making a comeback for some time throughout Europe. The hemp-lime system caught on about 25 years ago in France and has since spread to others areas of Europe, including Ireland and England. It’s been said that if just 1% of the farmland in the U.K. was dedicated to growing hemp, it would be enough to build 180,000 houses a year!! Just recently (within the last 5 years), interest in hemp-lime has been growing in North America. But North American hemp can only be grown in Canada, as the U.S. does not differentiate between hemp and cannabis.
As a bio-fibre, hemp has been called a bio-composite superstar–it’s a fast-growing and versatile crop. While most straw yields about three tonnes of fibre per hectare, hemp weighs in at 10 to 15 tonnes. In addition, the plant sequesters carbon, producing carbon-negative products and helping to combat global climate change. In addition to having great synergy with lime and other natural mineral aggregates, hemp has unrelenting strength–making it the perfect material for a wide variety of natural, non-toxic building products. The hydrated lime binder that is combined with the hemp actually reverts back to limestone by carbonation, allowing the material to sequester even more carbon out of the air!
Hemp buildings are resistant to fire and mould and can be incorporated into passive design strategies, cutting down energy bills as much as 70% or more. Living in a “hemp house” can be viewed, in a sense, like living in a tree. The walls act like a permeable skin, releasing negative ions (as opposed to positive ones); thus residents have fewer problems with static electricity and electromagnetic fields (EMFs). Moreover, the hemp home supports the local economy and is pleasant to be in!
Building with hemp is the future!