The U.S EPA sets minimum efficiency standards for appliances such as heating and cooling equipment.

  • Many older furnaces still operating and functioning well have efficiencies between 70% and 75%.
  • Furnaces installed after 1992 must have efficiency ratings above 78%.
  • Modern, high-efficiency furnaces have ratings in the mid-90%.

Heating systems with leaky, uninsulated ducts or that are improperly sized can reduce even a high-efficiency furnace to an efficiency of under 65%.