I just got a link to the 2009 International Energy Conservation Code, a pdf of the book that'd cost ya somewheres from $26 to over $100; people in the construction trades have to study this stuff. I just downloaded it today and I've been busy so I haven't had a chance to read it deeply but there's a section about alternative materials that bears more study.
http://www.iccsafe.org/store/pages/doeregistration.aspx Enjoy, Chris
