QUOTE=AC_Hacker michael, I came across an interesting article, discussing, "
How Much Insulation Is Enough?"
Good link...thanks. I can easily increase the attic insulation to 50, and I shall. The walls pose a larger problem, but I'm working on the idea of staggered studs and increased fill with fiberglass. I'm also reluctant to go to triple glazing, so I may be stuck with windows with a 3.3 R value. I'm surprised the author doesn't comment on underfloor insulation except re: slabs. Here's a link that speaks to underfloor insulation for framed floors:
BPA - Energy Efficiency | How to Insulate a Floor
In reference to a comment by MikeSolar about maintaining a 3/4" space between reflective insulation surfaces, it seems to me to be too great a space in a wall because convection can circulate up and down in a tall space like that with one heated and one cool surface, but under a floor, convection may prove to be less of an issue as the horizontal space might offer less opportunity for large air movement in a vertical direction, and I believe convection does rely on gravity in most cases.
I wish I had put a quilted reflective foil on top of the subfloor between the wood and concrete, but I was more concerned about trapping water and future degradation of the plywood, so I've opted to place it under the plywood. That should add a little to the R value of insulation. mm