Three years ago, FEG was something you'd see on a data sheet if you looked hard enough. Now it's in ASHRAE 90.1, it's in IECC, and plan reviewers are checking for it. If your fan submittal doesn't show a valid FEG rating, you're getting a comment back-or worse, a rejected permit.
What FEG Actually Measures
FEG stands for Fan Efficiency Grade, defined under AMCA Standard 205. It rates how efficiently the complete fan assembly converts mechanical input power into air power. Not the motor by itself-the whole thing, including impeller, housing, inlet, and discharge.
Grades run from FEG 67 to FEG 98 in 7-point increments. Higher number, higher peak total efficiency. A FEG 71 fan delivers more airflow per watt than a FEG 67. The math isn't complicated, but the implications are.
Why This Matters Now
Energy codes have caught up. Many jurisdictions now mandate minimum FEG 71 for general ventilation fans, and FEG 75 for certain fan types and applications. Specify a unit that doesn't meet the threshold and you'll find out at submittal review-not when you're ordering equipment.
The operational side is just as important. In a commercial building where fans run 8,000 hours a year or more, a 5-point FEG difference translates to thousands of dolars over the system's service life. It's not a line item anyone gets excited about on bid day, but it shows up on the utility bill every month.
Don't Confuse FEG with Motor Efficiency
This is where a lot of people get tripped up. A high-efficiency EC motor does not automatically mean a high-FEG fan. You can bolt a premium motor onto a poorly designed impeller and still end up with mediocre overall performance. The impeller and housing are doing the real work on airflow efficiency. Always ask for the FEG of the complete assembled fan, not just the motor nameplate data.
MIDI Industrial and Code Compliance
MIDI Industrial centrifugal and EC fan systems are selected with FEG compliance built in. We provide efficiency data sheets that document FEG ratings for each model, so contractors and engineers can verify compliance before submittal rather than after rejection. When you specify MIDI Industrial, the paperwork is as solid as the hardware.