Fan Energy Index (FEI): A New Measure of Fan Efficiency

What is FEI?

Fan Energy Index or FEI is a fan efficiency metric developed by AMCA International and its members as a response to the U.S. Department of Energy’s requirement to capture a fan’s true efficiency more accurately. Different from previous efficiency calculations, FEI accounts for all parts of the fan system including the motor, drive, transmission (gears or belts), and aerodynamic losses, as well as eliminating variation based on fan size. It does this by comparing a fan against a “baseline” fan of the same size that has a minimum allowable efficiency.


The general definition of FEI is this:


Since these efficiencies are both calculated at the same airflow and pressure, this ratio can also be written as follows:


If a fan has a FEI = 1.0, that means it has the same efficiency as the baseline fan. FEI above 1.0 signifies that the fan being tested used less electricity than the baseline fan to get the same output. The higher the FEI, the more efficient the fan. The baseline fan electrical input is calculated at the same airflow and pressure as the fan being tested, so FEI is calculated over the entire operating range of the fan, resulting in a compliant range “bubble”.


Why it matters:

New government regulations are going into effect requiring all commercial and industrial fans to be tested using a common procedure that the Department of Energy has specified, based on AMCA standards. Soon, all fans in the scope of the new rules will need to be tested per the procedure and the FEI will need to be calculated.

This will give regulators a clearer picture of fan efficiency, help manufacturers design high quality products, and empower users to choose the best fan for their application.