I’d like to share it here so that anyone can use it to help reduce their own heating or cooling costs. It's an excellent fix for seldom-used doorways or windows, in particular, but could be used in any number of places in the house where cold air is seeping in.
Or heat, for that matter.
It's dirt cheap and easy to do, too. And could be combined with some creativity to make a long-term solution.
A winner, as far as I'm concerned.