How Do I Make My Fireplace Cost-Effective?

Our fireplace is located in the basement in our finished game room area. We use it during the winter because we spend most of our free time down there and according to my husband, heat rises so the heat from the fireplace is eventually finding its way upstairs and keeping our thermostat from kicking the furnace on as much, thus saving us a little money. It makes sense to me (and I always believe what my husband tells me) so I would say that using your fireplace would be cost effective. Even if your fireplace is located let's say on the first floor in a living room, the heat from it should still affect your thermostat. Admittedly, we get our fire wood for free whenever we can so we are not paying anything in cost of firewood to use our fireplace. Plus, cost effective or not, fireplaces offer so much more than heat by way of comfort feelings, romantic feelings, etc. that I think it would be a shame to be lucky enough to have a fireplace and not use it!