The Power of FEI

Fan Energy Index

The Fan Energy Index (FEI) is a powerful engineering tool that allows you to pick the best fan system for your application.
It's a comprehensive energy metric for identifying fan systems that operate more efficiently, quietly, and reliably.
To get the most out of FEI, design to the latest versions of ASHRAE 90.1 and IECC. Include and hold duty point FEI on your fan schedule.
Use to learn how FEI is calculated and its advantages in fan selection.

TAG	QTY	TYPE	MAKE & MODEL	CFM	"W.C.	BHP	SONES	ELECTRICAL DATA		FEI	WEIGHT (LBS)	NOTES
TAG	QTY	TYPE	MAKE & MODEL	CFM	"W.C.	BHP	SONES	V/C/P	HP	FEI	WEIGHT (LBS)	NOTES
EF 1	1	D.D. UPBLAST CENTRIFUGAL	��Ƶ CUE-240HP-VG	4,300	1.50	1.69	17.3	460/60/3	3	1.53	236	1, 2, 3
EF 2	1	INLINE CENTRIFUGAL	��Ƶ SQ-15-M2-VG	3,600	1.25	1.44	15.5	460/60/3	2	1.47	119	1, 3
EF 3	2	D.D. CENTRIFUGAL	��Ƶ G-140-VG	2,000	1.25	0.81	15.2	460/60/3	1	1.38	69	1, 2, 3
EF 4	1	D.D. CENTRIFUGAL	��Ƶ G-130-VG	1,700	1.00	0.48	13.9	208/60/1	1/2	-	53	1, 2

NOTES:

MOTORS SHALL BE HIGH EFFICIENCY EC TYPE
PROVIDE WITH 12" HIGH ROOF CURB
FANS SHALL MEET OR EXCEED SCHEDULED FEI VALUE AND BE LICENSED TO BEAR THE AMCA CRP SEAL FOR FEI

• The Fan Energy Index (FEI) is a powerful engineering tool that allows you to pick the best fan system for your application.

• It’s a comprehensive energy metric for identifying fan systems that operate more efficiently, quietly, and reliably.

• To get the most out of FEI, design to the latest versions of ASHRAE 90.1 and IECC. Include and hold duty point FEI on your fan schedule.

• Use , Greenheck’s engineer application suite, to find efficient fan systems by FEI ratings.

• Browse our page and to learn how FEI is calculated and its advantages in fan selection.

Comprehensive Energy Metric

FEI is a comprehensive energy metric that goes beyond brake horsepower to include the impact of all components in the fan system including the aerodynamics, motors, VFD, drives, and bearings. Brake horsepower only considers the bearing and aerodynamic losses and ignores the rest of the fan system.

How is FEI Calculated?

FEI is simply the ratio of the Reference Electrical Input Power of a conceptual fan to the Actual Electrical Input Power of a fan system at the same duty point. The Reference Electrical Input Power is derived from actual historical fan sales data submitted by AMCA manufacturers and is intended to represent the typical power used at a specific duty point. The Actual Electrical Input Power is the power required to operate the actual fan system you are considering at the same duty point. An FEI >1.00 indicates your fan system uses less energy than the reference fan while a FEI<1.00 indicates it uses more energy than the reference fan.

If you want to dive deeper into the calculations behind FEI, read our .

Or let a manufacturer’s fan selection software, like Greenheck’s eCAPS®, do the work for you. Click to access eCAPS and start selecting fans using FEI.

Select the Best Fan System

In addition to helping you compare and optimize the energy consumption of your fan system, FEI may also help you identify fan systems with better sound performance and more flexible operating ranges.

Quieter Operation

Fans with lower FEI values tend to be operating at higher speeds or may be using less efficient rotors, both of which can create more sound power. By optimizing FEI, you are selecting a fan system with a more efficient rotor or a larger fan that is operating at slower speeds, both of which improve sound performance.

Flexible Operating Range

Selecting a fan with higher FEI means that you are relatively more central in the fan curve, which allows you more adjustment in the field if the installed duct system is different from your design intent.

FEI Fan Curve 1.20 FEI Fan Curve 1.30

Energy Efficiency

FEI is first and foremost an energy metric which allows you to compare the energy use of similar fan systems. For example, a fan system with an FEI value of 2.00 will use approximately 25% less energy than a comparable fan system with an FEI value of 1.50.

Codes and Compliance

Minimum FEI requirements are now included in the current ASHRAE 90.1 standard and International Energy Conservation Code (IECC). It is now up to states or local municipalities to incorporate these into their building codes. Since 2021, several states have incorporated the current 90.1 standard into their code, thereby setting minimum FEI values. Some states lack a state-level code but are seeing adoption at the municipal level. Navigating the complex landscape makes understanding how to comply with FEI codes and regulations difficult.

To stay ahead of these ever-changing codes, design to the latest versions of ASHRAE 90.1 and IECC and include and hold duty point FEI on your fan schedule.

Fan Efficiency Regulatory Journey

This timeline shows the journey FEI has taken from being published as a fan energy metric in AMCA 208 to being part of energy regulations in 15 states.