flowerbug
Sustainability Master
Find a deep cave to live in? lots of natural thermal mass to keep the temperature regulated. Might have to fight of a bear or two as winter approaches though.
not any of those around here other than man-made mine shafts (which are probably flooded). it's very flat and often wet enough that any underground dwelling would be likely to be a mess, but above grade you'd have a better chance of it working better as long as you understand you'd have to be building the hill you'd put the house in.
as something else to think about though for insulation and thermal mass are the houses that have green roofs. with a good enough membrane and the structural strength to hold it up it works very well and can be very useful for moderating temperature and also rainfalls.