ASHRAE Journal Supplement - AMCA InMotion - November 2021 - 13

BY THE AMCA INTERNATIONAL NORTH AMERICA
REGION AIR MOVEMENT ADVOCACY COMMITTEE
Editor's note: This article is adapted from the AMCA
International white paper " Introducing Ceiling Fan Energy
Index (CFEI) and Changes to the U.S. Regulation for LargeDiameter
Ceiling Fans. " For the full white paper and related
resources, go to the AMCA International large-diameterceiling-fan
microsite at www.amca.org/ldcf.
Part 1: The Problematic cfm/W Metric
The DOE defi nes LDCF as a ceiling fan with a blade span
greater than 7 ft (2.1 m). Blade span is fan diameter plus
the extent to which fan diameter is enlarged by " wing
tips " extending from the blades (Figure 1).
A different test procedure is used for ceiling fans with
diameters less than or equal to 7 ft (2.1 m).
ANSI/AMCA Standard 230, Laboratory Methods of
O
n May 27, 2021, the U.S. Department of Energy
(DOE) published in the Federal Register a fi nal
rule codifying the change of the regulatory metric for
large-diameter ceiling fans (LDCF) from cubic feet per
minute per Watt (cfm/W) to ceiling fan energy index (CFEI).
The change is a result of the Ceiling Fan Improvement
Act, part of the Energy Act of 2020 provision in
the omnibus bill signed into law on Dec. 27, 2020. The
Ceiling Fan Improvement Act resolves constraints of the
cfm/W metric on high-performing LDCF while making
passage of low-performing LDCF from a simple reduction
in speed more diffi cult.
This article describes cfm/W and explains why a
change in metric was needed.
Testing Air Circulating Fans
for Rating and Certification,
descr ibes how to per form
laboratory measurements for
LDCF and calculate cfm/W for
a given speed, specifying that,
for variable-flow LDCF, tests
be conducted at fi ve speeds: 20
percent, 40 percent, 60 percent,
80 percent, and 100 percent. An
average cfm/W is not calculated
as part of the ANSI/AMCA Standard 230 procedure.
ANSI/AMCA Standard 230 describes how to uniformly
measure or calculate and report:
■
Thrust (pound-force or newton)
■ Airfl ow rate (cfm or cubic meters per second [m3/s])
■ Power (W)
■ Effi cacy (cfm/W or m3/s/W at one speed)
■
Effi ciency (air power/electrical input power)
The initial DOE test procedure requires the same fi ve
speeds, but additionally requires that power consumption
be measured while a fan is idle. In calculations of
cfm/W, the fi ve operating speeds are equally weighted
by time (2.4 hr, for a total of 12 operating hours per day)
and averaged. Standby-power time is estimated to be
12 hr per day.
Ceiling-fan effi ciency (cfm/W) =
Σi (CFMi × OHi)
Wsb × OHsb + Σi (Wi × OHi)
where:
CFMi = airfl ow at speed
OHi = operating hours at speed
Wi = power consumption at speed
OHsb = operating hours in standby mode
Wsb = power consumption in standby mode
FIGURE 1. " Wing tips " need to be included in
measurements of blade span. Photographs courtesy of 4Front
Engineered Solutions
www.amca.org
cfm/W vs. CFEI. Table 1 compares cfm/W and CFEI.
2021 AMCA inmot ion
13
http://www.amca.org/ldcf http://www.amca.org
ASHRAE Journal Supplement - AMCA InMotion - November 2021

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