If there were a large hole in your living room ceiling leading directly to the outside of the house, you'd probably notice it and seal it to prevent air from shooting up there. In many homes there is such a hole, but it's hidden inside the fireplace. That hole is the fireplace flue pipe.
Wood-burning fireplaces usually have a damper installed in the upper part of the firebox. The damper is designed to be shut when the fireplace is not in use and can be easily opened when it is. It's common to forget to close the damper after a fire goes out, however, and that leaves a big hole through which heated or cooled air can escape the house.
Even when a fireplace damper is closed, the sealing is often not very effective. Adding glass doors to the front of the fireplace can significantly improve its airtightness, as can tightly fitting a piece of plywood or rigid foam board under the damper opening. Sealing a fireplace flue in this manner can also reduce or eliminate soot odors that are prone to travel into the house during windy or stormy days. Of course, the blocking material must be removed before a fire is started.
One caution, though: Fireplaces with installed gas logs are required to have the damper open at all times. That's either because a pilot light is constantly burning under the logs or because the homeowner might forget to open the damper when he or she turns on the fire. Because gas-log fires produce copious amounts of carbon monoxide, they have to vent outside in a fail-safe manner. That's why there is, or should be, a keep-open device attached to the damper in gas-log fireplaces. Unfortunately, that open damper means house air is running up the flue or cold air might be traveling down.
Another cautionary note: A wood-burning fire must be completely out and the ashes cold before the damper can be shut or other sealing is put into place. The hazard is carbon-monoxide poisoning. A smoldering fire, even though it might not be visible through a layer of ashes, still produces combustion gases. Those gases contain carbon monoxide. Therefore, while it's great to save energy by closing off the damper inside a fireplace, be sure to do so in a safe manner. Do not close a fireplace damper until the fire is completely out.
Shut Off the Pilot
Gas-log fireplaces are equipped with either a standing pilot light (one that is lit all the time) or with electronic ignition. The electronic-ignition models are much more energy efficient because they burn only when they are turned on.
Standing pilots, on the other hand, burn constantly, wasting a lot of gas when they aren't needed. It is not unusual to find one blazing away in a fireplace during the heat of summer when the probability of someone starting a fire is very remote. If you have a gas-log fireplace with a standing pilot light, consider learning how to shut it off -- at least during the summer months. You can start it again in the fall when the weather turns cold and you're more likely to want a fire. Instructions on how to shut off and relight gas-log pilot lights are printed inside the front panel of most installations or are available from the installer or manufacturer.
Space heaters don't have to be electric. Gas and wood fireplaces and stoves can also be used in this way. "Ventless" gas fireplaces and kerosene space heaters should be used with caution, as both produce combustion byproducts that are released into the air. These heaters are not designed to be a home's primary heat source. Read and follow all directions concerning setup and use of ventless fuel-burning space heaters.
In the next section, learn about several different ways you can save energy around the house by such means as using halogen lightbulbs and lowering the thermostat on your refrigerator and freezer.