ASHRAE Journal Supplement - AMCA InMotion - November 2021 - 10

Fan
Fanspeed
label
FS-0.6
FS-0.9
FS-1.2
FS-1.5
FS-1.8
FS-2.1
FS-2.4
FS-2.7
FS-3.0
speed
(%
max.
rpm)
20
30
40
50
60
70
80
90
100
Fan
speed
Air speed
exiting fan
Airfl ow exiting
fan
Average air
speed at side
surface1
16
23
31
39
47
55
62
70
78
0.9 (177)
1.2 (236)
1.5 (295)
1.8 (354)
2.1 (413)
2.4 (472)
2.7 (531)
3.0 (591)
18 (38,400)
27 (57,600)
36 (76,800)
45 (96,000)
54 (115,200)
63 (134,400)
72 (153,600)
82 (172,800)
91 (192,000)
0.2 (39)
0.3 (59)
0.4 (79)
0.5 (98)
0.6 (118)
0.7 (138)
0.8 (157)
0.9 (177)
1.0 (197)
Average
fan-zone2
air speed
0.4 (79)
0.6 (118)
0.8 (157)
1.0 (197)
1.2 (236)
1.4 (276)
1.7 (335)
1.9 (374)
2.1 (413)
Maximum air
speed in fan
zone
rpm m/s (fpm) m3/s (cfm) m/s (fpm) m/s (fpm) m/s (fpm)
0.6 (118)
1.0 (197)
1.3 (256)
1.7 (335)
2.2 (433)
2.5 (492)
2.9 (571)
3.4 (669)
3.8 (748)
4.4 (866)
1The side of the cylinder of the fan zone colored by yellow in Figure 5c.
2A cylinder around the fan center at a height of 1.7 m (5.6 ft).
TABLE 2. Fan air speed and airfl ow rate in the fan zone for a case of U-H-D-3.
Location of
most occupants
Close to the fan(s)
Far from the
fan(s)2
Summer
Operate the fan(s)
downward at high speed.
Operate the fan(s)
downward at high speed.
Winter
Operate the fan(s) at the highest speed that does not cause
discomfort in either forward or reverse direction, whichever was
used prior to the pandemic.1
Operate the fan(s) at the highest speed in either forward or
reverse direction, whichever was used prior to the pandemic.3
1 Simulations show slightly lower concentrations with reverse fl ow than with forward fl ow at a given low speed, but this is based on a much
smaller number of simulated scenarios (two as opposed to the 16 for a typical forward-direction scenario) and is a small effect given
simplifi cations and assumptions in the model. For simplicity, retaining the pre-pandemic direction is advised-unless reversing the fan
allows for substantially higher fan speeds while avoiding draft at the occupied level.
2 At locations more than three fan diameters from the center of a fan the majority of the day.
3 Although simulations show a slight increase in average whole-warehouse-breathing-level concentration with fans at low speed as opposed
to off, the distribution is far more uniform across the entire warehouse (i.e., no " hot spots " ). Based on feedback from the science team, this
homogeneity likely is a net advantage, as more mixing (i.e., dilution) is benefi cial for times when workers who may be far apart for much of
the workday meet and interact more closely. Lastly, the still-air results depend highly on model assumptions and simplifi cations (e.g., plume
effectiveness, lack of local mixing, the presence of racks, etc.), and this small difference could be an artifact of those.
TABLE 3. AMCA LDCF guidance. Note: The green/yellow/red color coding is an approximate indicator of how
clear the effect was in the simulations.
References
1) Raftery, P., et al. (2019, May 15). Ceiling fans: Predicting indoor air
speeds based on full scale laboratory measurements. Building and
Environment, 155, 210-223. Retrieved from https://bit.ly/Raftery_BE0519
2) Chen, W., et al. (2020, March 15). Ceiling-fan-integrated air
conditioning: Airfl ow and temperature characteristics of a sidewallsupply
jet interacting with a ceiling fan. Building and Environment, 171,
106660. Retrieved from https://bit.ly/Chen_BE0320
3) Gao, Y., et al. (2017, November 1). Ceiling fan air speeds around
desks and offi ce partitions. Building and Environment, 124, 412-440.
Retrieved from https://bit.ly/Gao_BE1117
4) Wang, H., Luo, M., Wang, G., & Li, X. (2020, December 1). Airfl ow
pattern induced by ceiling fan under different rotation speeds and
blowing directions. Indoor and Built Environment, 29, 1425-1440.
Retrieved from https://bit.ly/Wang_IBE1220
10
2021 AMCA inmot ion
5) Present, E., Raftery, P., Brager, G., & Graham, L.T. (2019, January).
Ceiling fans in commercial buildings: In situ airspeeds & practitioner
experience. Building and Environment, 147, 241-257. Retrieved from
https://bit.ly/Present_BE0119
6) Bassiouny, R., & Korah, N.S. (2011, August). Studying the features of
air fl ow induced by a room ceiling-fan. Energy and Buildings, 43, 19131918.
Retrieved from https://bit.ly/Bassiouny_EB0811
About the Authors
Michael Ivanovich is senior director, global affairs; Aaron
Gunzner is senior manager, advocacy; and Scott Arnold
is manager of industry content for AMCA International.
www.amca.org
https://www.bit.ly/Raftery_BE0519 https://www.bit.ly/Present_BE0119 https://www.bit.ly/Chen_BE0320 https://www.bit.ly/Bassiouny_EB0811 https://www.bit.ly/Gao_BE1117 https://www.bit.ly/Wang_IBE1220 http://www.amca.org
ASHRAE Journal Supplement - AMCA InMotion - November 2021

Table of Contents for the Digital Edition of ASHRAE Journal Supplement - AMCA InMotion - November 2021
