"Rich" writes:

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.

There are too many variables to answer this unfortunately. Cost of
running the space heater, cost of fuel, size of the rest of the house,
efficiency of the furnace, how lossy your home is in terms of heat,
etc. The larger, the lossier, the rest of teh house and the less
efficient your furnace, the more money your current tactic will save
you.

My gut says you're probably saving money leaving the rest of the space
drop down in temp during the day and using the electric heater in the
only occupied space. Your furnace will have a fairly long continuous
run when you bring it back up to temp at the end of the day, but you
should still end up ahead by not having to heat the rest of the joint
to a balmy room temp for all those hours each day.

--
Todd H.
http://www.toddh.net/