I have 4 rooms all upstairs. Below 3 are all indoors like living room,
etc. They're cool. One is above outdoor driveway. It's noticeably
warmer. I can't think of any explanation. One day I used a thermometer
to measure floor temperature. It was between 1 and 2 degrees higher
than the floors of the other 3 rooms. I think that explains it. But I
don't think there's anything I can do.

Probably because this room is warmer, the previous owner noticed it
and they didn't want to use this room either. The carpet is much
thicker and less used than the rest of the upstairs. If it's because
the underside is outdoors this room is warmer, what about those many
rooms above a garage? Are they warmer too? What do you do to remedy
it? Thanks.

BTW, I remember in winter, this room is a little colder but I'll
double check that in a few months.