Most people don't think of their refrigerator as being a big contributor to the home's energy bill, but in fact it is the third largest energy consumer in most homes, right behind space conditioning and water heating. They are usually between 6 and 16 percent of a home's total energy cost. Like air conditioners, refrigerators and freezers use the vapor-compression cycle to remove heat from a sealed and insulated containment box and exhaust it into the surrounding air.

Today's refrigerators are more efficient than older models. Improvements have been made to the containers, like better door seals and more insulation, as well as to the systems that move heat, including more area of heat exchanger, and improved controls, motors and compressors. Refrigerators with 15 to 20 percent higher efficiencies are available and may be cost effective depending on the utility rates. Be sure to look for EnergyGuide labels to see how many kilowatt-hours (kWh) the refrigerator or freezer will use in one year, and compare models based on these figures. There is a wide range in the energy use between models of refrigerators, so it's worth looking into carefully. Paying a little more for a unit that costs less to operate may be one of the best investments you can make. Also look for the EnergyStar labeled units, which exceed federal efficiency standards by at least 20%.

Refrigerators with freezers on top are more efficient than those with freezers on the side. And chest-type freezers are 10 to 25 percent more efficient than upright cabinet models. This is partly because they are better insulated, and partly because they don't allow air to pour out when the door is opened. Also look for good strong door hinges that create a good door seal.