Why Zero Carbon Buildings Will Be High on Hemp
When a person hears the word “crops,” their mind likely goes straight to food. But in an agricultural society that cultivates a diverse group of crops, “crops” means a lot more than just food. There’s lumber, notably, but also biofuels, clothing, and oils, among other things. And in terms of alternative uses of crops, one plant looms above the rest: hemp. This controversial crop requires few pesticides or herbicides, grows in high density, gobbles up carbon dioxide, and works well in rotation with other crops to maintain soil nutrition. Moreover, hemp has a new use that’s quickly coming to prominence. We can build with it.
Lime Technology has been pioneering hemp building materials for years, but new innovations have made hemp more attractive for contractors. The old product, branded as Hemcrete, was a biocomposite of hemp and lime and was molded on-site as something of a cement substitute. Though Hemcrete performed exceptionally well in terms of insulation, thermal inertia, fire resistance, and humidity control, it had significant drawbacks when it came to implementation. Recognizing this, Lime Technology has produced Hemclad and Hembuild, which make installation not only easier but also more reliable. Hemclad and Hembuild are prefabricated pieces manufactured to easily fit together like a puzzle after being shipped to the building site. The two separate brands are for cladding and for load bearing walls respectively, and ensure ecologically sound construction can be viable and reliable year-round. Taking the work away from the actual construction site also gives hemp biocomposites the potential to be used in remote areas, where builders may not have the time, tools, or expertise to employ ecologically sound materials. And though slightly more expensive than traditional alternatives, they’re made economically attractive by heating, venting, and air-conditioning savings that result from unique properties of the biocomposite. In fact, their performance as insulators leads to carbon savings 17% higher than comparable materials. In other words, they’re simultaneously being green and saving green.
So far, the new hemp materials have seen their biggest field test in Mark & Spencer’s Cheshire Oaks location, a architectural project that has gone out of it’s way to be sustainable via renewable energy sources, fresh air cooling, and passive lighting. Though this example is by far the most visible, Hembuild and Hemclad have been implemented in a multitude of other sites for cumulative carbon savings of over 2300 tons. This achievement has been recognized with a 2014 Ashden Award, citing them as a way to bring “zero-carbon buildings one step closer.” Hemp building can serve as an example for all ecological architecture, showing that tacking on technology to existing structures isn’t the best way to be sustainable. Sometimes it’s necessary to go back to the drawing board and change what the structure really is, what it’s made of.
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