ASHRAE Journal - March 2021 - 61

TECHNICAL FEATURE

Climate Zone

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50

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This article demonstrated discrepSmall Ofﬁce
ancies between plug load assumptions
in NECB and measured electricity
use in existing buildings based on previous studies. By
quantifying the effect of plug load assumptions on building simulation results for different building types, code
versions and climate zones, the following observations
were made: 1) the effect of plug load assumptions generally increased in milder climate zones and decreased in
colder climate zones, irrespective of the building type; 2)
the effect of plug load assumptions on total energy use
generally increased in larger buildings; and 3) the effect
of plug load assumptions generally increased as code
requirements become more stringent.
The current approach of using a single plug load schedule based only on building type disregards the evident
diversity between buildings of the same type, which was
demonstrated in previous studies. To address this limitation, stochastic or at least scenario-based approaches for
simulating plug loads should be explored (e.g., two to
three scenarios as shown in this article), and conclusions
should only be drawn based on their aggregate results for
both code compliance or design development.
Otherwise, different plug load assumptions may
be used at the space-level to capture spatial diversity. Finally, measurements of plug load use must be
expanded with the current growth in advanced metering infrastructure. Such data can be processed to
identify and update design EPD and scheduled plug-in
equipment use due to occupant interactions, especially
with the expected changes in commercial and residential building occupancy patterns (and consequently
plug load use), which is expected to persist beyond the
COVID-19 pandemic.

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FIGURE 5 Variations in energy use intensity relative to the baseline across three
different versions of the NECB, considering low, high and medium plug loads' use
scenarios in five climate zones.

NECB

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60

2011
2015
2017

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Variation (%)

Conclusion

FIGURE 4 Variations in energy use intensity relative to the baseline across five Canadian climate zones, considering low, high and medium plug load use scenarios and three different versions of the NECB.

Variation (%)

load assumptions can lead to inaccurate energy use estimates, which
may result in suboptimal choices of
design parameters for new buildings.
Furthermore, such assumptions can
negatively inﬂuence sizing of HVAC
systems, particularly for cooling size
calculations, which assume all plug
loads are used; thus, more representative plug load assumptions for different
building types are needed.

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Acknowledgments
This research was supported by the National Research
Council of Canada (NRC) under contract number
936198. The authors would like to acknowledge the contributions of Mr. Mirata Hosseini to this work.

References
1. NRC. 2017. " National Energy Code of Canada for Buildings
2017. " National Research Council Canada.
2. ANSI/ASHRAE/IES Standard 90.1-2019, Energy Standard for
Buildings Except Low-Rise Residential Buildings.
3. O'Brien, W, et al. 2020. " An international review of occupantrelated aspects of building energy codes and standards. "
Build. Environ 179(July 15):106906. https://doi.org/10.1016/j.
buildenv.2020.106906
4. Abushakra, A, A. Sreshthaputra, J.S. Haberl, P.E. David, et al.
2000. " Compilation of Diversity Factors and Schedules for Energy
(Continued on page 65)
MARCH 2021

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ASHRAE Journal - March 2021

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