Here's an idea-
1. Do what you're doing for a month. Add up gas/electric/oil bills
2. Set t-stat at 68 for 1 month. Add up utility costs. Compare. Do
what's cheaper.

Rich wrote:
I set my thermostat to 60 degrees and then use a space heater to heat the
office as that is the room I'm in mostly, and that works fine but I'm
wondering how much money it really saves instead of just setting it to 68
and leaving it there? I live near Chicago if that helps.

Thanks, Rich