Efficiency Ratings

Gas furnaces. Gas furnace efficiency, or AFUE (annual fuel utilization efficiency), indicates the percent of fuel burned that is converted into heat for the home. A higher AFUE rating indicates higher efficiency and lower gas bills. Modern gas furnaces are usually rated between 80% and 97% AFUE. In comparison, AFUE ratings for many old furnaces fall between 50% and 60%. Replacing an old 50% AFUE furnace with a new 80% AFUE furnace reduces fuel consumption by more than a third.

Heat pumps and air conditioners. The SEER rating is the primary efficiency rating for both heat pumps and air conditioners. A higher SEER rating indicates higher efficiency and lower power bills. The U.S. Department of Energy has been enforcing a minimum SEER rating of 13 on any new residential systems manufactured since January 2006. As a comparison, a 15-year-old air conditioning unit would probably have a SEER rating around 6. Upgrading a 15-year-old unit to a modern, 13-SEER-rating unit cuts cooling cost in half. In addition, most utility companies and federal tax credit programs impose minimum SEER rating requirements in order to be eligible for a rebate or tax credit.