Rating numbers indicate the efficiency of heating and air conditioning equipment and are directly related to the amount of energy a specific model uses. The higher the rating, the more efficient the product, and the lower your energy bills can be. The federal government establishes rating guidelines and sets minimum efficiency levels. For cooling equipment, the rating is SEER (Seasonal Energy Efficiency Ratio), for heat pumps, the rating is HSPF (Heating Seasonal Performance Factor) and for gas furnaces the rating is AFUE (Annual Fuel Utilization Efficiency).