The efficiency of any furnace is measured in Annual Fuel Utilization Efficiency (AFUE). The AFUE shows how much of the fuel you pay for is actually turned into usable heat. When you have a system designed that is built to be efficient, you get the savings and the performance needed.  Trane 95 and 90 gas furnaces deliver at least 90% efficiency, far exceeding the government minimum standard of 80 AFUE for new furnaces. If you have a furnace that is at least 10 years old, its probably time to upgrade, and you could save up to 40 cents of every dollar you pay for fuel.  Delcor likes saving you money.