Once the exterior of the home is sealed as well as possible, it is valuable to do the same to the inside as well. Below are some basic guidelines on areas you can secure to keep heat and air conditioning from escaping.
Baseboards and Floors
Gaps are often left between baseboards and hard floors, such as tile, hardwood, or laminate flooring. These gaps can be successfully and neatly filled with latex caulk, thus preventing air from entering the home at foot level.
Gaskets Can Block Drafts
Wind can sneak in through tiny gaps and cracks that you don't even know are there. Often, the first time you're aware of such a problem is when you flick a switch or plug an electronic device into a receptacle mounted on an exterior wall. Not only does the switch or receptacle feel cold, but it's sometimes possible to actually feel a cold draft blowing into the room.
You can block many of these types of drafts from inside the house by purchasing and installing inexpensive switch and receptacle gaskets from a hardware store or home center. The gaskets, made of nonelectrically conductive fiber matt material, fit snugly around the switch or receptacle after the cover plate is removed. With the gasket in place the standard cover plate goes back on, creating an airtight seal against the wall. For the cost of just a few cents each, gaskets are a worthwhile investment in energy saving and comfort.
Caution: To avoid electrical shock, you should remove cover plates from switches and receptacles only after power has been shut off at the main service panel to the circuits where work is being done. Other than that, each gasket installation will require about two minutes of your time.
A Canister of Trouble
Recessed ceiling canister lights pose special problems for a homeowner bent on making a home more energy-efficient. The older types are extremely leaky and are difficult to make airtight. Because of regulations concerning fire safety, the best you can do is to build an airtight box of flame-resistant material -- sheet metal, for instance, or drywall -- at least three inches larger than the light's housing to cover the portion of the fixture that is in the attic. This box can then be sealed to the drywall. It cannot be covered with insulation, however, as heat buildup inside the fixture could cause problems with the wiring inside.
Heat generated by the bulbs inside recessed canister lights is usually lost to the attic and doesn't contribute to heating the house. This excess heat flowing unchecked into the attic space can cause problems with ice dams on the roof during the winter.
Another solution to older, leaky canister lights is to replace the fixtures entirely with new airtight units. "ICAT" (insulation contact, airtight) canister lights are the most energy-efficient recessed canister lights on the market.
As the name suggests, they are airtight and can also be covered with insulation. To further improve their performance, airtight ceiling canister lights can also be sealed to drywall or plaster with caulk. When you calculate the cost of allowing heat to escape through a leaking ceiling canister light, the cost it takes to replace it with a more energy-efficient model is easy to justify.
Attics and the Stack Effect
The floor of an attic is an important battlefield on the energy conservation front because of a phenomenon known as the "stack effect."
Warm air rises. That much is nearly universally known; it is the reason hot air rises up a fireplace flue or "chimney stack." What isn't so commonly recognized is that rising warm air creates pressure at the top of whatever is containing it. In a household situation the top-floor ceiling acts as a containment barrier to rising warm air. As such, any small hole or gap in that area is subject to pressurized warm air trying to escape.
Warm air loss due to the stack effect has another consequence. As air exits through the top-floor ceiling or other holes, it creates a slight negative pressure inside the house. The air leaving has to be replaced, and that air comes from outside the house: cold, dry air. The incoming air has to be heated, and that's when your furnace or boiler comes on.
Up the Flue
Builders occasionally run into difficulty framing and sealing an opening around a fireplace. There needs to be clearance between the wood and the masonry or metal, so the framing can't fit tightly against those materials. That means the finish wall material -- usually drywall or plaster -- is supposed to bridge the gap for fire safety and also provide an airtight closure. Comprehensive sealing in this area, however, can sometimes be neglected. In some cases that means there are gaps around fireplaces that allow air to leave the house easily.
Take time to look inside and around fireplaces with a good flashlight to see whether there are any holes and gaps that need to be sealed with spray foam, fireproof caulk, or other filler material. Not only will this reduce the amount of air leaving the house via these pathways, but it can also protect areas from sparks or embers leaping out of a fire.
Weatherstripping around doors can help keep drafts out of your house, which can keep your heating and cooling bills under control. In the next section, we'll discuss how to better secure your doors.