The Annual Fuel Utilization Efficiency or AFUE: This measures the average efficiency of furnace, boilers and also water heaters. It does not take into consideration the electricity consumption. It is only a theoretical measurement of the heating season.
Buyers must be aware of the fact that higher numbers as far as SEER, EER, HSPF and AFUE is concerned indicates a higher energy efficiency and these numbers are used in two energy rating programs. They are:
EnergyGuide Label: It is mandatory for HVAC manufacturers to display the EnergyGuide Label. This label is an indicator of the energy usage of the system. It also compares the energy usage of other equipment and also gives an approximate operating cost of the system. However, the exact cost depends on the local utility bills and the source of energy that is being used.
Energy Star Certification: Stars are used on products which are more energy efficient than products of the same genre, thus, making it easier for buyers to make the right choice.