ASHRAE Journal Supplement - AMCA InMotion - November 2022 - 32

the results show a reduction of 296 dangerous-heat-strain
hours, with signifi cant improvements in exceptionally
hot and humid environments (e.g., zones 1A and 2A) and
effi cient mitigation leading to much smaller increases in
the zones identifi ed in Table 4 as the most concerning.
Peak Cooling Load and HVAC Energy
Use in Existing Commercial Spaces
Unlike warehouses, the vast majority of smaller commercial
spaces, such as offi ces, fi tness facilities, restaurants,
and stores, are conditioned. While the loading profi les
of these spaces are inherently different than those of a
warehouse (much smaller, with more internal and latent
loads), the spaces are not immune to signifi cant performance
impacts from changing weather conditions, as it is
possible their mechanical systems will be unable to keep
up with envelope and ventilation loads they simply were
not designed for and will require more energy to maintain
desired performance, even in partial-load situations.
To examine the question of whether cooling effects
provided by air-circulating fans can improve the resilience
of existing mechanical systems while maintaining occupant
thermal comfort amid changing climatic conditions,
the medium-offi ce DOE reference model was analyzed
across the same 15 climate zones for a scenario with no
fans and a standard cooling setpoint (72°F/22.2°C) and for
a scenario with fans and an elevated setpoint (80°F/26.7°C).
Occupant comfort was identical across the two scenarios for
both current and future
weather conditions. Two
results-peak cooling
load in tons of cooling
requi red and annual
HVAC cooling energy use
in kilowatt-hours of electricity-were
recorded for
each simulation.
Figures 2 and 3 show
50
40
30
20
10
that, without mitigation,
peak cooling load and
HVAC energy consumption
increased in all but
one climate zone (1A). On
average, peak cooling load
32
-10
-20
-30
-40
-50
1A 2A 2B 3A 3B 3C 4A 4B 4C 5A 5B 6A 6B 7 8
Representative-City Climate Zone
increased by 9.7 percent and HVAC energy consumption
increased by more than 23,000 kWh (42.6 percent) relative
to current climatic conditions. When air-circulating fans
were added and the setpoint was increased, performance
under future weather conditions was much more similar
to that under current weather conditions, with multiple
climate zones seeing decreases in peak load and energy
consumption and others seeing signifi cantly smaller gains
than in scenarios without fans and an elevated setpoint.
On average, with fans, cooling capacity increased by only
0.1 percent, while energy use relative to current conditions
increased by only about 1,700 kWh (9.6 percent).
Conclusion
Returning to the two questions that formed the basis of
the research presented in this article:
Can cooling effects provided by air-circulating fans
mitigate climate-change-induced increases in occupant
heat strain in heated-and-ventilated-only warehouses?
Yes. With a properly designed fan solution delivering
airfl ow to occupants in a heated-and-ventilatedonly
warehouse, the effects of indoor conditions that
could lead to greater occupant heat strain under future
climatic conditions can be signifi cantly reduced. In
some cases, the addition of fans even improves future
conditions relative to current ones.
Peak Cooling Load
HVAC Electricity Consumption
50,000
40,000
30,000
20,000
10,000
-10,000
-20,000
-30,000
-40,000
-50,000
FIGURE 2. Comparison of HVAC-system performance with no fans, future conditions.
2022 AMCA inmot ion
www.amca.org
Peak-Cooling-Load Increase, %
Kilowatt-hours
http://www.amca.org
ASHRAE Journal Supplement - AMCA InMotion - November 2022

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