ICC Commercial Mechanical Practice Exam

The Annual Fuel Utilization Efficiency (AFUE) rating is the correct indication of the efficiency of a gas furnace. AFUE measures how efficiently a furnace converts the energy in its fuel to heat over the course of a typical year. It is expressed as a percentage and reflects the amount of fuel energy that is actually used to heat a home compared to the amount of fuel energy consumed. For example, an AFUE rating of 90% means that 90% of the energy in the fuel is converted to heat, while 10% is lost in the combustion process or through exhaust.

In contrast, the other ratings provided are used for different types of heating and cooling systems. The Seasonal Energy Efficiency Ratio (SEER) is specific to air conditioning systems and measures the cooling output during a typical cooling season divided by the energy consumed. The Coefficient of Performance (COP) is often used for heat pumps and indicates the ratio of heating or cooling provided to the energy consumed, typically in a specific operational state rather than over a full year like AFUE. Lastly, the Energy Efficiency Ratio (EER) measures the efficiency of cooling systems at a specific outdoor temperature, typically evaluated under peak conditions, again diverging from the annual assessment that AFUE provides.