We have not tried too much in the way of insulation, but by enclosing our 5th wheel trailer in a "high tunnel" we have stopped convective heat loss by more than 30%. We have been living in our trailer for the last 8 years in our harsh Canadian winters with up to 4 feet of snow and down to -40F. It is literally a green house, on sunny days it will get above freezing, that greatly reduces heating requirements.
The last two mild winters we got away with only one 500 Gallon propane fill. The -40+ years takes two fills. The
hot water heater and furnace are vented to the outside of the tent. We have a single 15 amp circuit for our electrical requirements, hoping to switch to
solar in 2016. Plastic used is a single 20' x 100' roll 6 mil uv stabilized builders plastic. We put it up before the first snow and take it off in the spring.
A new roll every year, the used plastic sheeting goes to green house and other uses. Cost was $80 CDN is now up to $130 CDN. Hop vines grow up the structure in the summer giving us shade.
My heroes are real people: These are the real Rock Stars: Sepp Holzer, Paul Wheaton, Geoff Lawton, Joel Salatin, Masanobu Fukuoka RIP, Larry korn, Toby Hemenway, Dr. Elaine Ingham, Gabe Brown, Vandana Shiva to name only a few.