ASHRAE Journal - April 2023 - 38

TECHNICAL FEATURE
level, the weighted ECI is highest for the Apartment
building group.
Energy Cost Index Breakdown By End Use
Figure 2 (page 36) shows the national weighted site
energy and energy cost of U.S. commercial buildings
built to Standard 90.1-2019 broken down by end use.
For both metrics, the largest contribution comes from
the Equip end use, which is currently unregulated by
Standard 90.1. For loads directly regulated by Standard
90.1, Cool and Light end uses constitute the highest
share of the total simulated national building energy
cost. For site energy, Heat, Cool and SHW are the largest
end uses on a national scale.
Energy Cost Index Breakdown by Building Group
The simulated results aggregated by building group
identify contributions
by building group to the
national weighted ECI
in $/ft2·yr. For Standard
90.1-2019, Apartment is the
largest contributor.
A
0.3
0.29
1.5
0.32
0.31
Review of Standards Progression
In this section, we review
the weighted ECI of six
consecutive editions of
Standard 90.1 to identify
trends in the Standard 90.1
progression. Figure 3 shows
the energy cost breakdown
by building activity group
(Figure 3a) and end use
(Figure 3b) for 90.1-2004,
90.1-2007, 90.1-2010,
90.1-2013, 90.1-2016 and
90.1-2019. The comparison
shows steady savings
achieved between consecutive
code cycles, with the
largest savings magnitude
in the 2010 code cycle. Each
bar represents the composite
weighted national
ECI for a code edition; color
blocks in each bar represent
38
1.0
0.5
0.0
B
0.4
1.5
0.34
1.0
0.5
0.0
0.36
0.27
0.1
0.2
0.1
0.09
90.1-2004
ASHRAE JOURNAL ashrae.o rg A P R I L 2 0 2 3
0.4
0.31
0.36
0.23
0.1
0.16
0.1
0.09
90.1-2007
0.4
0.39
0.39
0.23
0.2
0.28
0.17
0.1
0.12
0.09
0.05
90.1-2010
0.25
0.14
0.1
0.08
0.09
0.05
90.1-2013
0.19
0.19
0.13
0.1
0.09
0.09
0.03
90.1-2016
0.18
0.16
0.13
0.1
0.08
0.08
0.03
90.1-2019
0.39
Light.Int
Fan.Aux
SHW
Heat
Misc
Light.Ext
Equip
Cool
0.32
0.31
0.2
0.14
0.14
0.12
90.1-2004
0.3
0.28
0.2
0.13
0.13
0.11
90.1-2007
0.28
0.25
0.25
0.23
0.22
0.16
0.1
0.11
0.08
90.1-2010
0.24
0.2
0.19
0.15
0.1
0.1
0.08
90.1-2013
0.24
0.23
0.18
0.16
0.14
0.1
0.1
0.06
90.1-2016
0.24
0.22
0.17
0.15
0.13
0.09
0.09
0.06
90.1-2019
Apartment
Medical
Retail
Education
Offi ce
Food Service
Hotel
Warehouse
the contribution of a building group (Figure 3a ) and end
use (Figure 3b) toward the composite national ECI. Note
that the Warehouse building group has the second largest
construction volume, but the smallest weighted ECI .
The comparison in Figure 3a indicates that with
each edition of the code ECI reductions are achieved
across all building groups. Figure 3b shows that Interior
Lighting and Space Cooling end uses have achieved the
most energy cost reductions since 2004. Future codes
and standards that infl uence energy consumption in
Apartment and Medical buildings and measures that
impact equipment and space cooling end uses can have
the most signifi cant potential for overall national energy
use reduction. Also noteworthy: more aggressive measures
are required in future codes to achieve signifi cant
savings reductions and bring the current site energy use
(46.3 kBtu/ft2·yr [526 MJ/m2·yr]) close to net-zero goals.
FIGURE 3 U.S. weighted energy cost index: a) by building activity group and standard edition; b) by end use type and standard
edition.
Energy Cost Index, $/ft2·yr
Energy Cost Index, $/ft2·yr
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