July 23, 2014

How to Pick an Energy Efficient Appliance

If you are confused by the different claims of energy efficiency by appliance manufacturers, JamesDulley of the Detroit Free Press has some helpful advice.

Depending upon the type of product and the fuel it uses, efficiency ratings can mean different things. Also, some manufacturers and/or salespeople play fast and loose with the accuracy of efficiency claims.

A basic definition of efficiency for any energy-consuming product is the amount of usable energy (heat, light, sound, etc.) output divided by the energy input. The energy input is usually an electric plug in the wall or a gas or propane line coming into your house. Electricity input is usually measured as wattage and gas or propane input as Btuh (Btu per hour).

Most plug-in electric heating devices and heaters, from the cheapest to the heavily advertised ones for $400, are nearly 100% efficient. All of the electricity consumed ends up as heat inside your house. The actual differences in operating costs depend upon how you use one and if the design is the proper one for your needs.

Always read efficiency claims thoroughly when comparing products. For example, some lower-quality gas space heaters may claim a very high 90% combustion efficiency. Combustion efficiency refers to how efficient the gas burns, not how efficiently the heat is transferred into your house. Its actual heating efficiency may be only 70%.

For electrical appliances, such as window air conditioners, you can calculate the efficiency by dividing the Btuh cooling output by the electric wattage shown on the nameplate.

For other major appliances, such as washers and refrigerators, rely on the yellow energy label. Your usage habits often have more impact on the overall efficiency than the appliance design itself.

For central heating and cooling equipment, the manufacturer’s efficiency ratings should be accurate.

They are AFUE (annual fuel utilization efficiency for furnaces), SEER (seasonal energy efficiency ratio for air conditioners) and HSPF (heating seasonal performance factor for heat pumps).