Reviewed and Revised on 10/15/2013
The following terminology can help one understand the energy efficiency of common Home Heating Systems.
Annual Fuel Utilization Efficiency (AFUE)
The efficiency of a gas (natural or propane) or oil furnace or boiler is measured in terms of its Annual Fuel Utilization Efficiency (AFUE), which describes the heat produced from the energy used. This rating takes into consideration various losses that may be involved such as from pilot lights, heat out of the exhaust stack, …