"air infiltration is a huge loser of heat"..
Yeah, but on the plus side, you get plenty of fresh air!!
You just reminded me of the switch plate by the front door. I never noticed it much
until the other night when it was down to about -5deg F.
I could have cooled beer on that thing!!
I plan to change the front door soon, so when the old door & frame comes out,
I'll see about adding some insulation (foam maybe) to that switch box and maybe all around the new door frame.
Now, I just need to find an R-20 door!!