Gore Residence, insulated with AirKrete
When it comes right down to it, most insulation is simply some form of entrapped air, whether in foam or in fiberglass or in cellulose. The greenest one is going to have the fewest chemicals that can outgas, the lowest impact during manufacture, good stability so that it doesn't settle and good fire resistance. I was really surprised to find that it might also be made from cement.
Cement is not one of TreeHugger's favourite materials, given that a ton of CO2 is emitted for every ton of cement produced. But materials made with it have some great attributes, including longevity and fire resistance. If you mix it with air and foam it up with special equipment, you get AirKrete, a foam-in-place insulation that looks like shaving cream and has an R value of 3.9 per inch, which is pretty good.
I had never heard of it but Al Gore had- He insulated his house with it.
it is foamed in place like a lot of other insulations, but does not increase in volume, so if you are using it in a renovation it will not pop the plaster or drywall off the wall as it expands in place. It has been in the United States since 1984 and just become available in Canada.
For all of my complaints about cement, this seems to be an appropriate use- its mostly air, a fireproof, VOC free, rodent proof insulation. Al knows how to pick'em.
Watch Steve Thomas talking about AirKrete on Planet Green's Renovation Nation
More at AirKrete Canada,
There is an Airkrete product in the UK, but it appears to be a different thing, a structural element rather than an insulation.
Other green insulations in TreeHugger:
TreeHugger Picks: Green Insulation
UltraTouch Recycled Denim Insulation
Mushroom Spores: The Newest Green Insulation Material
Warmcel Recycled Paper Insulation
Green Insulations: More Choices
Oh, and comments about the size of Al Gore's house, its energy consumption (pre-renovation) and comparisons to George Bush's Crawford Ranch (pre his purchase of a monster home) will by unceremoniously dumped. Been there, done that.