What does the AFUE rating in gas furnaces measure?

The Annual Fuel Utilization Efficiency (AFUE) rating is a critical measure in assessing how efficiently a gas furnace converts fuel into usable heat. Specifically, AFUE represents the percentage of energy in the fuel that is converted to heat over the course of a year. For example, a furnace with an AFUE rating of 90% means that 90% of the fuel consumed is effectively turned into heat for your home, while the remaining 10% is lost through venting and other inefficiencies.

Understanding AFUE is essential for homeowners and HVAC professionals because it directly relates to energy costs and the overall efficiency of heating systems. Higher AFUE ratings indicate more efficient systems that will typically result in lower energy bills and a reduced environmental impact due to less fuel consumption.