1. Introducing the Fan Energy Index Metric for Energy Efficient Fan Systems

2. Learning Objectives
Learn why Fan Efficiency Grade needs to be replaced by Fan Energy Index
Learn how to obtain FEI-rated fan data from manufacturers and AMCA
Learn about FEI ratings in energy codes and standards
Learn how to use FEI in VAV systems

3. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

4. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

5. FEG Is Becoming Obsolete
Fan only; does not consider motors and drives
Cannot be used for low-power fans in energy codes and standards
Requires sizing/selection window at design phase that is difficult to enforce by code officials
Miscommunicates efficiency of small fans, which can have efficiencies almost 50% less than the FEG rating
U.S. Department of Energy (DOE) and industry stakeholders opted for Fan Energy Index in negotiated advisory toward a DOE regulation

6. Fan Efficiency Varies with Size for a Duty Point… FEG Does Not
Fan Size
in.
(mm)
Fan Speed
rpm
Fan Power
bhp
[kW]
Actual Total Efficiency
(%)
FEG
18 (460)
3,238
11.8 [8.8]
40.1 85
20 (510)
2,561
9.6 [7.2]
49.5
22 (560)
1,983
8.0 [6.0]
59.0
24 (610)
1,579
6.8 [5.0]
69.1
27 (685)
1,289
6.2 [4.6]
75.8
30 (770)
1,033
5.7 [4.3]
82.5
36 (920)
778
6.0 [4.5]
78.7
Here is an example that shows for a fan rated at FEG 85, the peak efficiency occurs at 770 mm diameter. However, engineers can select an FEG 85 fan that has half of the peak total efficiency at 460 mm. For this reason and others, the Fan Energy Index was developed.

7. FEI is Replacing FEG in U.S. Codes and Standards
Wire-to-Air metric – considers motors and drives
Can be used for low-power fans in energy codes and standards
Does NOT need sizing/selection window
Consistent with efficiency of fans of all sizes; differentiates fans tested with static pressure or total pressure
DOE and industry stakeholders opted for Fan Energy Index

8. Fan Energy Index Establishes Compliant Ranges or Bubbles
FEI emphasizes proper fan sizing and selection
Selection bubbles are regions of a fan curve that are compliant with a code, standard, regulation, or design requirement
USA model energy standards and pending regulations use FEI > 1.00
Designers must size and select fans so that the selected duty point (airflow, pressure, air density) falls within the bubble associated with the required or desired FEI rating
Manufacturers software will only show compliant selections for given operating conditions
The Fan Energy Index is a an application-dependent metric; meaning that it encourages right-sizing fans so they operate more frequently at optimal efficiencies.

9. Compliant Range (FEI > 1.00) for Constant Speed Fan
Unlike FEG ratings, FEI ratings help make better fan sizing and selection decisions. In this graph of duty points for a constant-speed fan, for a regulation with FEI = 1, the compliant range of pressure/airflow combinations (i.e. duty points) is shown in color. This is why FEI is called an application-dependent metric. What’s compliant depends on where the fan is applied.

10. Compliant Bubbles (FEI > 1.00) for Centrifugal with Speed Control
Here is the same concept applied to variable-speed fans. In this case, instead of a compliant range on curve, there is a compliant bubble. The more efficient the fan, the more duty points it will be compliant, so the larger the FEI bubble. This chart shows a more efficient fan on the left compared to a less efficient fan on the right. AMCA expects that over time, fans with small FEI bubbles will be removed from the market due to lack of purchases as more-efficient fans, with larger complaint bubbles, have higher sales because they satisfy more operating conditions.
FEI 1.20
FEI 1.00
FEI 1.00
EFFICIENT FAN
INEFFICIENT FAN

11. Comparing FEI against FEG
Fan Size
in.
(mm)
Fan Speed
rpm
Fan Power
bhp
[kW]
Actual Total Efficiency %
Baseline Power
FEG
FEI
18 (460)
3,238
11.8 [8.8]
40.1
7.96 85
0.67
20 (510)
2,561
9.6 [7.2]
49.5
0.83
22 (560)
1,983
8.0 [6.0]
59.0
0.99
24 (610)
1,579
6.8 [5.0]
69.1
1.16
27 (685)
1,289
6.2 [4.6]
75.8
1.28
30 (770)
1,033
5.7 [4.3]
82.5
1.39
36 (920)
778
6.0 [4.5]
78.7
1.32
FEI has many useful characteristics when sizing/selecting fans. FEI = 1 signifies compliance with a regulation. FEI < 1 is non-compliance. FEI > 1 is over compliance. Notice here how the FEI changes with impeller size, and is highest at 770 mm, where the fan has the highest total efficiency. Note that FEG does not change.

12. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

13. Benefits of FEI Clarity Flexibility Simplicity Greater energy savings
FEI covers fans, motors, and drives for “fan system” efficiency rating, and FEI rating changes with fan size at the duty point
Flexibility
Fan selections allow variety of fan types, motors, and drives to meeting efficiency requirement, budget, acoustics, and form factor
Simplicity
No “sizing/selection window” as needed for FEG – the FEI rating includes duty-point considerations
Greater energy savings
All the benefits above mean greater energy savings and lower lifecycle cost

14. FEI Emphasizes Proper Fan Sizing and Selection for Intended Operating Point

15. Company “A” 2012 Fan Selections
45,000 total fans
160,000 total shaft kW
0.75
7.5 75
Fan Shaft Power (kW)

16. Noncompliant Fan Selections: FEI > 1.00
160,000 shaft kW
33% non-compliant
0.75
7.5 75
Fan Shaft Power (kW)

17. Revised Fan Selections
160,000 shaft kW
10,300 kW saved (6%)
98% used same model
0.75
7.5 75
Fan Shaft Power (kW)

18. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

19. Manufacturers do these ratings tests and calculations
Rating Test Standard AMCA 210
Part-load calculation for motors, VFDs, belts via AMCA 207
FEI calculated using AMCA 208

20. FEI is a Simple Ratio…
𝐹𝐸𝐼= 𝑅𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝐹𝑎𝑛∗ 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝐼𝑛𝑝𝑢𝑡 𝑃𝑜𝑤𝑒𝑟 𝐴𝑐𝑡𝑢𝑎𝑙 𝐹𝑎𝑛 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝐼𝑛𝑝𝑢𝑡 𝑃𝑜𝑤𝑒𝑟 𝐹𝐸𝐼= 𝐹𝐸𝑃𝑟𝑒𝑓 𝐹𝐸𝑃𝑎𝑐𝑡𝑢𝑎𝑙
FEI is a calculation that uses data taken during rating tests. It is the ration of the fan efficiency at a known duty point and a reference fan. The FEI equation and other FEI parameters, such as the reference fan, are defined in ANSI/AMCA Standard 208, Calculating Fan Energy Index.
∗ Reference fan is the same for all FEI calculations every. It’s defined in AMCA 208.

21. What It Looks Like Within Software
AMCA 208 #5.3.3 uses Annex H of AMCA p
Reference Electrical Power
FEPi,ref= 𝐻 𝑖,𝑟𝑒𝑓 η 𝑡𝑟𝑎𝑛𝑠,𝑟𝑒𝑓 × η 𝑚𝑡𝑟,𝑟𝑒𝑓 × η 𝑐𝑡𝑟𝑙,𝑟𝑒𝑓
Actual Shaft Power &
Fan Laws Hi
Bare-shaft fan test Airflow, Pressure, Shaft Power
(Qi, Pi, Hi)
Reference Shaft Power
Hi,ref=f(Qi, Pi)
Calculation for regulated motors FEPi,act= 𝐻 𝑖,𝑎𝑐𝑡 η 𝑡𝑟𝑎𝑛𝑠,𝑟𝑒𝑓 × η 𝑚𝑡𝑟,𝑟𝑒𝑓 × η 𝑐𝑡𝑟𝑙,𝑟𝑒𝑓
Tested Drive Components FEPi,act= 𝐻 𝑖,𝑎𝑐𝑡 η 𝑡𝑟𝑎𝑛𝑠,𝑎𝑐𝑡 × η 𝑚𝑡𝑟,𝑎𝑐𝑡
Electrical Power
As run Wi
Legend
AMCA 210 or ISO 5801 test
AMCA 207 calculation
AMCA 211 rating
AMCA 208 calculation
Fan duty point Airflow, pressure
(Qi, Pi)
Default losses for other drive components FEPi,act= 𝐻 𝑖,𝑎𝑐𝑡 η 𝑡𝑟𝑎𝑛𝑠,𝑟𝑒𝑓 × η 𝑚𝑡𝑟,𝑟𝑒𝑓 × η 𝑐𝑡𝑟𝑙,𝑟𝑒𝑓
Fan+Motor
Wire-to-air test Airflow, Pressure, Electrical Power
(Qi, Pi, Wi) or
Several tested speeds
Fan+Motor+Drive
Airflow, Pressure, Electrical Power
Interpolated between tested speeds Wi
+Motor+Drive Airflow, Pressure, Electrical Power 1 2 3 4 5 6 7
AMCA 208 # broadened scope of AMCA 207 defaults through AMCA 208 #5.3.2.
AMCA 208 #5.3.2 matches the original scope of AMCA 207.
AMCA 208 #5.3.1 uses AMCA
FEP i,ref FEP i,act =𝐹𝐸𝐼
FEPi,act= 𝑊 𝑖
AMCA 208 #5.3.1 uses Annex I of AMCA p
Actual Electrical Power
FEPi,act

22. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

23. How FEI Used by Engineers
FEI-based fan selections based on engineer’s selected duty point
Airflow at most important design point
Static or total pressure (depending on fan type) at same design point
Air density of the installation location (altitude an important factor)
Using air density in duty point is a very recent decision by AMCA

24. Compliant Range (FEI > 1.00) for Constant Speed Fan
Unlike FEG ratings, FEI ratings help make better fan sizing and selection decisions. In this graph of duty points for a constant-speed fan, for a regulation with FEI = 1, the compliant range of pressure/airflow combinations (i.e. duty points) is shown in color. This is why FEI is called an application-dependent metric. What’s compliant depends on where the fan is applied.

25. Compliant Bubbles (FEI > 1.00) for Centrifugal with Speed Control
Here is the same concept applied to variable-speed fans. In this case, instead of a compliant range on curve, there is a compliant bubble. The more efficient the fan, the more duty points it will be compliant, so the larger the FEI bubble. This chart shows a more efficient fan on the left compared to a less efficient fan on the right. AMCA expects that over time, fans with small FEI bubbles will be removed from the market due to lack of purchases as more-efficient fans, with larger complaint bubbles, have higher sales because they satisfy more operating conditions.
FEI 1.20
FEI 1.00
FEI 1.00
EFFICIENT FAN
INEFFICIENT FAN

26. Example FEI requirement is FEI > 1.00 at design point of operation
Design Point of Operation = Duty Point = Selection Criteria
Air flow rate: 18,000 cfm (8.50 m3/s)
Air pressure: 5.4 in. w.g. (1345 pascal)
Air density: standard (sea level)
For constant flow, design point is static (100% flow)
For VAV:
50% flow: 4.25 m3/s
70% flow: 5.95 m3/s
100% flow: 8.5 m3/s (peak flow)
Pressures at these flow rates need fan curves

27. Example For constant speed, manufacturers software output at 100% flow
For VAV, manufacturers software output at three design points:
100% Flow
70% Flow
50% Flow
Designer runs software for each design point and makes table.

28. Impeller diameter in (mm) Fan Impeller Type (all double width)
100% Flow
18 (464)
Airfoil
0.90
20 (508)
1.05
22 (565)
1.13
24 (622)
1.23
27 (686)
1.21
Backward inclined
0.82
0.93
1.16
1.17
Example Constant Flow

29. Impeller diameter in (mm) Fan Impeller Type (all double width)
100% Flow
18 (464)
Airfoil
0.90
20 (508)
1.05
22 (565)
1.13
24 (622)
1.23
27 (686)
1.21
Backward inclined
0.82
0.93
1.16
1.17
Example Constant Flow

30. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

31. Impeller diameter in (mm) Fan Impeller Type (all double width)
Example VAV
Impeller diameter in (mm)
Fan Impeller Type (all double width)
50% Flow
70% Flow
100% Flow
18 (464)
Airfoil
1.05
0.89
0.90
20 (508)
1.17
1.06
22 (565)
1.21
1.15
1.13
24 (622)
1.24
1.25
1.23
27 (686)
1.20
16 (406)
Backward inclined
0.83
OVERSPEED
1.00
0.82
1.11
0.94
0.93
1.18
1.22
1.16
1.19
For VAV, 3 design points:
100% Flow
70% Flow
50% Flow

32. Example: 464-mm Airfoil Fan from Table
FEI for flow rates of 50%, 70%, 100%
50% flow = 1.00
70% flow = 0.80
100% flow = 0.90
Engineer could examine FEI bubble charges for every line in table

33. Impeller diameter in (mm) Fan Impeller Type (all double width)
50% Flow
70% Flow
100% Flow
18 (464)
Airfoil
1.05
0.89
0.90
20 (508)
1.17
1.06
22 (565)
1.21
1.15
1.13
24 (622)
1.24
1.25
1.23
27 (686)
1.20
16 (406)
Backward inclined
0.83
OVERSPEED
1.00
0.82
1.11
0.94
0.93
1.18
1.22
1.16
1.19
Which Selection Best?

34. Guidance for VAV Systems
Because slowing a fan’s rotational speed generally increases the FEI rating:
Best duty point for VAV is hottest day of year, which is equivalent to 100% airflow requirement
Select fan to have an acceptable FEI rating at the 100% (peak) flow rate
This will ensure fan is in compliance when it serves a load below the peak flow
If the fan meets the FEI criteria at the peak condition, it likely will meet the FEI criteria at a reduced-flow condition due to slower rotational fan speed
Ensure fan will avoid surge and overspeed at all operating points

35. For Constant Speed and VAV: What are the best selections?
Avoid yellow (non-compliant or overspeed)
Remaining fans are compliant with FEI > 1.00 requirement and structurally safe
Other design criteria need to be considered:
Form factor
Weight
Budget
Energy cost
Acoustics

36. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

37. AMCA Certified Ratings Program: FEI
AMCA certifying fans and manufacturer software for FEI
FEG certifications will remain in effect for foreseeable future
Manufacturers software easier for manufacturers
Motors and drives increase testing burden
Bare-shaft fans rated for FEI using default motor, no drive
Check for FEI certifications at
Expect surge in summer / fall 2019
Industry awaiting finished codes and standards

38. Outline Why changing from FEG to FEI in United States
Benefits of FEI over FEG
How FEI is Calculated by Manufacturers
How FEI is used by design engineers
Example of FEI for VAV systems
AMCA Certification of FEI
Status and timeline of FEI
Questions?

39. Timeline of FEI Codes, Standards, and Regulations
U.S. Department of Energy: Postponed indefinitely
California: Completion 2019; Enforcement:
Singapore: Awaiting California to complete before starting
ASHRAE : Awaiting final action from ASHRAE – June 2019
ASHRAE : Proposal started

40. Regulatory Direction FEI Requirements Covered Exempt
0.95 for VAV, 1.00 for others
Covered
Standalone fans (including PRVs) ≥1.0 HP or ≥0.89 kW
Embedded fans and fan arrays >5 HP or >4.1 kW
Exempt
Fans embedded in equipment that is regulated or 3rd party-certified for air performance or energy performance
Reversible tunnel ventilation fans
Fans for high temperatures, explosive atmospheres, high temperatures, or emergency conditions
Ceiling fans

41. Resources AMCA International: www.amca.org/
AMCA certifying FEI ratings; visit
AMCA 208 standard (free for 2019):
AMCA microsite for FEI training, technical papers, PowerPoints, and regulatory status:

42. Thank you!
Questions?