MathWhiz wrote:
We have converted a three season porch into a four season by adding a
gas stove and some new windows. Below is an unfinished basement - the
joists and subfloor are exposed. Do I gain any efficiency by
installing insulation between the joists?

Yes ... but if you ever plan to heat that basement below, it would make
sense to insulate the basement walls now, rather than insulate the
floor, and then the walls later. If not, insulate the floor ... if the
floor feels cold as in, even wall to wall carpet with underpad would
probably provide all the insulation you need. To continue, I had a
similar situation with a hadwood floor ... I insulated the basement
walls.