ASHRAE Journal Supplement - AMCA inmotion - Fall 2017 - 3

FEI

4 in. wg
RPM

BHP

5 in. wg
FEI

RPM

in buildings at a reasonable cost and minimal burden to industry
and customers.
INTRODUCTION

Over the past six years, the DOE fan initiative has helped
AMCA develop and nurture relationships with advocacy
organizations, regulators and other associations. The result
is that AMCA and its members developed FEI with many
perspectives in mind. When finalized by the DOE, FEI will
replace existing fan efficiency metrics in U.S. model energy
codes and standards, and it is already being considered for
utility incentive programs.1
FEI is a wire-to-air metric consistent with the regulatory
approaches being taken for other motor driven loads, such as
pumps and air compressors. It also has a "sizing and selection"
clause baked into the metric, in a manner acceptable to the
DOE.2 With these basic conditions in place, FEI stands to
revolutionize how fans are sized, selected and specified by
practitioners. In fact, the rationale behind the development of
FEI is consistent with the European Commission regulation's
"extended product" approach for regulating motor driven
equipment. FEI takes this further by adding application-based
parameters to the energy savings opportunity, which may
introduce new regulatory approaches to other equipment as
well.
With much of the low-hanging fruit having been picked
from the product-efficiency-savings tree over decades of
regulation, FEI grafts a new and exciting variety of energy
savings to the tree.
This breakthrough has occurred because fans differ from
other appliances; their operating efficiency varies significantly
based on how they are applied and where they are selected
within their operating envelope. Fan application and selection is therefore far more influential than peak fan efficiency
in determining the actual energy consumed by a fan. Unlike,
for example, an incandescent light bulb, a fan that is least
efficient in some applications may be the most efficient in
others.
Instead of specifying a minimum peak efficiency level for
each of the various fan types, FEI establishes a baseline efficiency and resulting baseline power that varies with both
airflow and pressure, universally applied to all fan categories.
This establishes a range of compliant operations rather than
a single-point pass/fail efficiency threshold. Instead of eliminating inefficient models, the FEI metric seeks to eliminate
inefficient selections.1 FEI also has the operating point characteristics built into the calculation, so compliance officials
W W W. A M C A . O R G

BHP

6 in. wg
FEI

RPM

FEI

BHP

for any program, code or regulation need only check the FEI
rating on the label.1
In the absence of a DOE test procedure, the FEI metric is
currently being formalized in an AMCA rating standard and
the ISO standard for fan efficiency. The harmonized AMCA
and ISO FEI rating standards will prescribe how an FEI
rating is calculated from data taken during the two organizations' performance-rating tests.
FEI, THE METRIC OF FUTURE REGULATIONS

The Appliance Standards and Rulemaking Federal Advisory
Committee (ASRAC) created a term sheet that describes FEI
as a metric calculated as the ratio of the actual fan efficiency
to a baseline fan efficiency (Equation 1), both at a given airflow
and pressure point. Since these efficiencies are each calculated
at the same airflow and pressure, FEI is also defined as the
ratio of the baseline electrical power to the actual electrical
power of a fan (Equation 2).

Equation 1: FEI =

Fan Efficiency
Baseline Fan Efficiency

Equation 2: FEI =

Baseline Fan Electrical Input Power
Electrical Input Power

Equation 2 is equivalent to Equation 1, but because the goal
of mandatory and voluntary programs is to reduce wasted
energy, Equation 2 is preferred. Its specific mention of reducing electrical power consumption has more relevancy to
regulatory goals than increasing energy efficiency. Equation
2 also is easier to apply and has the added benefit of working
along the entire fan curve.
Equation 2 suggests that there is an intermediary calculation leading to FEI, and there is: the measurement or calculation
of FEP. FEP is obtained either by directly measuring fan
electrical input power during rating tests or by measuring
fan shaft power and incorporating default values for motors
and drives.3 The default values are defined in AMCA Standard
207,4 which is currently being approved for publication. Fan
rating tests can be conducted using AMCA Standard 210,5
which the ASRAC fan working group adopted as the basis
of the DOE test standard.3
Once the FEP rating of a fan is known, it is compared against

A M C A I N T E R NAT I O NA L

inmotion

Fa l l 2 0 1 7

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Table of Contents for the Digital Edition of ASHRAE Journal Supplement - AMCA inmotion - Fall 2017