ARLINGTON HEIGHTS, Ill. — In the just-published 2021 edition of the International Energy Conservation Code (IECC), fan energy index (FEI) replaces fan efficiency grade (FEG) as the metric for fan-efficiency provisions.

The ratio of the electrical input power of a reference fan to the electrical input power of an actual fan at a given duty point (airflow, pressure, and air density), FEI considers motors and drives, not just fans, which makes it consistent with new efficiency metrics for pumps and air compressors. The higher the FEI rating, the more efficient a fan will be for a given duty point. This allows engineers to perform return-on-investment analyses for different fan types, sizes, and motor/drive combinations when designing systems.

“AMCA is excited about the IECC now being published, as this will help accelerate the phaseout of the FEG metric in the United States until an anticipated federal fan-efficiency standard is in place,” said Michael Ivanovich, senior director, global affairs, Air Movement and Control Association (AMCA) International. “Harmonizing metrics is important to industry and to the commercial and industrial markets, as it reduces confusion and lowers the cost of code enforcement.”

The 2021 IECC requires that FEI ratings be third-party-certified. AMCA International, which formalized FEI in ANSI/AMCA Standard 208-18, “Calculation of the Fan Energy Index,” has been certifying FEI ratings since 2019. Currently, nearly 300 fan models are FEI-certified, mostly through AMCA certification of manufacturer sizing and selection software. AMCA-certified FEI ratings can be found at ANSI/AMCA Standard 208-18 is available for download free of charge from AMCA’s online store at

“AMCA is hoping states either adopt the 2021 IECC or, if adopting the 2018 edition, swap out the 2018 fan-efficiency section with the 2021 language to help phase out FEG,” Aaron Gunzner, advocacy manager, AMCA International, said. “AMCA has resources to help state energy offices consider such a change.”

For links to online training, white papers, and other FEI-related resources, visit AMCA International’s FEI microsite at

FEI previously replaced FEG in ANSI/ASHRAE/IES 90.1-2019, “Energy Standard for Buildings Except Low-Rise Residential Buildings.” Like that standard, the 2021 IECC increases the scope of the fan-efficiency provision by lowering the minimum size of covered fan systems from 5 HP to 1 HP and removing the exemption for powered roof ventilators. The 2021 IECC is available for purchase on the International Code Council website.