Recently I have viewed some interesting sites about using rice hulls for insulation. They are a throw-away and as insulation, perform as well as fiberglas insulation at as little as 1/5 the cost, depending on transportation costs.
http://www.axwoodfarm.com/PAHS/RiceHulls.html
I plan to try these as wall insulation in the low 3' walls of the GH I hope to build this summer, and from there... who knows?
Rice Hulls
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