Looking for Green/Sustainable Insulation/Materials

Hi there,

I'm looking for sustainable materials for insulation.

My father is building a small bunky in Ontario, and needs to have a high R value, in a small space.

I know Strawbales would be my choice, but it isn't prudent in his location, or this instance.

Are there any other choices/suggestions anyone can make?

So far I have looked into Structural Insulative Panels.

Any other suggestions?

I'd like options for high R value, as well as durability, and cost comparisons.

Any help greatly appreciated.

Links to builders/producers in or near Ontario appreciated as well.