Wednesday, September 23, 2015

What’s Missing From Passive Houses: Hemp

By Jeremy Daw
Source: theleafonline.com

Kentucky Now Taking Hemp Applications, Source: http://upload.wikimedia.org/wikipedia/commons/0/0d/Hempfieldkentucky1898.jpg
Hemp was once a proud part of America’s history. Will climate change force its return?

Politico has a good article on how “passive” home construction can have a hugely positive impact in the fight against global climate change. It’s an urgent read, and highly recommended.
The only reason I don’t call it “excellent” is a single glaring omission: nowhere does the article mention one of the most promising of the eco-friendly construction materials: hemp.
Given that residential and commercial buildings represent one of the top sources of greenhouse gas emissions in the US, the need for passive houses is urgent. Unlike most homes built today, these buildings use super-efficient walls, ceilings and floors to keep homes naturally cool in the summer and warm in the winter, drastically reducing the need to expend energy to keep them comfortable. The secret sauce, as Politico correctly points out, is the insulation — eleven inches of high-density cellulose fiber.
But the article fails to mention hemp, which through both its bast fibers and its cellulose-rich hurds (the woody core, often considered a waste product) represents one of the best sources of cellulose known to material science. Even more intriguing is the plant’s versatility; its various parts can be used for the hempcrete foundation, the insulation in the home walls, and the roof. That’s not quite the whole building, but it’s pretty darn close.
Best of all, the “cradle to grave” impact of hemp materials is an environmentalist’s dream. Whereas most construction sites today are a source of pollution in many ways, in most temperate environments the hemp needed for construction projects can be grown locally (or even on-site) and then composted back to the earth when the building is taken apart. And the crop will probably even improve the quality of the soil it’s grown in, as a side benefit.
So, bravo to Politico. Now go do your research.


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