We recently had an energy audit conducted on the house. The result: our home has heat loss equivalent to a 24 inch diameter hole in the wall. It wasn't really fair that the storm windows are currently off, and we do in fact have holes in the walls, of various sizes. But still, our heating and insulation could be more efficient.
The new storm windows will help, but we really want to get away from so much oil use.
Eventually we may use the gas line to heat a boiler, but until then, we took advantage of a sale Finest Hearth and installed a gas fireplace insert. Now we can heat the downstairs to a cozy temperature without using any oil.
Bonus - it looks a lot better than the old non-functioning fireplace. Bonus #2 - it works in a power outage!
We're still trying to figure out what to do with the bricks and the tiles below, which are only temporarily placed there.