Im in Eastern Canada, New Brunswick.
Will be building a super-adobe complex dome in spring/summer/fall 2013.
Insulation has been something of a stickler for me.
Looking more to ensure moisture on exterior (rain/snow/ice) does not penetrate structure.
Insulation will be a (
local soil mixture with approx 5% cement) mix with an additional 5-10% of scoria or similar local material.
Not trying to increase R-Vals to maximum.
Win the heating battle with sure proven small steps.
An approach that is truly hybrid and organic to your specific build.
Berming is going to be primary method of isolating structure from atmospheric conditions.