At least for most General Aviation aorcraft, the primary purpose of fuselage
insulation is for sound deadening, not for heat loss.
The insulation is typically closed cell foam, with some level of fire
protectant.
I suspect that what you will find of insulating value in most small aircraft
will be (from inside out):
1. A liner - cloth or vinyl, often padded (maybe 1/4 inch thick)
2. Then maybe one inch of air space
3. Then 1/2 inch insulation
4. Then exterior aluminum (or fabric)

MUCH less insulating capability than a modern building.

I think you will find a much higher level of insulation in larger aircraft,
but again, not likely approaching a building
"Robert M. Gary" wrote in message
oups.com...
I would be surprised if its nearly as good as what is in building
walls. The insulation on aircraft is much thiner (at least much thiner
than the madated insulation for new buildings here in California). The
insulation I've seen is between 1/2" and 1" thick compared to 5" or so
that you see in modern buildings.

-Robert