Making Sense of Energy Ratings

Furnaces are rated by the Annual Fuel Utilization Efficiency (AFUE) ratio, which is the percent of heat produced for every dollar of fuel consumed.

AFUE works a lot like the miles-per-gallon rating on your car - the higher the rating, the lower your fuel costs. All furnaces manufactured today must have an AFUE ratio of at least 78%. If your furnace is 10 - 15 years old, it very well may fall below the current furnace minimum and waste energy.

Furnace ratings are usually displayed on the yellow-and-black EnergyGuide label on heating equipment.

Source: U.S. Federal Trade Commission, 2000