What does AFUE stand for in the context of furnace efficiency?

AFUE stands for Annual Fuel Utilization Efficiency. This measure is crucial in assessing how efficiently a furnace converts the energy in fuel to heat over the course of a year. The AFUE percentage indicates the amount of fuel used that actually results in usable heat, allowing consumers to understand how much energy is wasted. For example, a furnace with an AFUE of 90% means that 90% of the fuel energy is converted into heat for the home, while the remaining 10% is lost in the process.

Understanding AFUE is vital for homeowners and energy professionals as it directly impacts heating costs and energy efficiency. This metric also helps in comparing different heating systems, guiding choices that can lead to cost savings and reduced environmental impact.

In the context provided, the other options do not represent the formal definition of AFUE and thus lack the accuracy required for understanding furnace efficiency in the industry.