Drafts around doors and windows can waste a tremendous amount of energy. The U.S. Department of Energy estimates that roughly 20 percent of the energy used to heat or cool the average home literally creeps out the doors or windows [source: Energy Star]. For an older house with poor seals under the doors or old, ill-fitting windows, the costs can be much higher. If you're on a budget and want to find a project that will make a big difference in your heating and cooling bills, controlling airflow is an excellent place to start.
Warm or cool air leaking into or out of your house is not the only airflow problem that can cost energy. Air creeping in from a cool room, such as your basement, or from a warm area to a cooler one, can cause additional problems. Interior doors, improperly sealed ductwork and even small gaps around switches and electrical outlets can lead to energy-consuming air leaks [source: Energy Star]. Be sure to check these areas as well.
Repairing these air leaks requires a variety of techniques and tools. Caulking can seal gaps that don't need to be opened. Something as simple as a draft-catcher placed under a door or along the base of a leaky window can help control airflow through these openings [source: Howard].