ENERGY STAR®
PortfolioManager™
DataTrends
Energy Use in Office Buildings
Office Buildings
Using Portfolio Manager
57,247 Properties
9.5 Billion ft2

Average
ENERGY STAR Score
The U.S. Environmental Protection Agency's (EPA) ENERGY STAR Portfolio Manager is
changing the way organizations track and manage energy. Because of this widespread
market adoption, EPA has prepared the DataTrends series to examine benchmarking and
trends in energy and water consumption in Portfolio Manager. To learn more, visit
www.energystar.gov/DataT rends.
Benchmarking by State
Number of Office Buildings
What is a typical operating profile?
Energy use intensity (EUI) ranges from less than 100 to more
than 1,000 kBtu/ft2 across all office buildings, with those at the
95th percentile using almost 7 times the energy of those at the
5th percentile. The distribution has a negative skew, which
means the most energy intensive buildings are much further
away from the median than the most efficient. Buildings may use
more or less energy for many reasons, including variable
equipment efficiency and energy management practices, as well
as variations in climate and business activities.
Up to 200 buildings
201-400 buildings
401-800 buildings
801-1,600 buildings
More than 1,600 buildings

6,000 -I

5,000 -
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4,000 -
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3,000 -
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2,000 -
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1,000 -
Portfolio Manager Median = 207 kBtu/ft2
_
I
95th percentile = 472
5th percentile = 71
¦	
Source EUI (kBtu/ft2)
The median office building in Portfolio Manager is approximately
70,000 square feet and operates 60 hours per week. But the
typical building use patterns observed in Portfolio Manager vary
just as much as energy. As you can see, there are offices of all
shapes and sizes benchmarking in Portfolio Manager.
a
El
Range of Values



r
Building
Characteristic
5th
percentile
Median
95th
percentile
Square Feet
7,215
69,635
549,681
Operating Hours
40
60
120
Workers per
1000 ft2
0.7
2.4
5.6
Computers per
0.6
2.5
6.5
1000 ft2
Heating
Degree Days
965
4,221
6,799
Cooling
Degree Days
154
1,114
3,671
What is Source Energy? Source energy is the amount of raw fuel required to operate your building. In addition to what you use on
-site, source energy includes losses from generation, transmission, and distribution of energy. Source energy enables the most
complete and equitable energy assessment. Learn more at: www.enerqvstar.qov/SourceEnerqy.

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What characteristics affect
energy use?
How does EPA's ENERGY STAR score
vary with energy use?
Business activity and climate are often correlated with energy
consumption. For example, offices that are open longer hours,
have more workers per square foot, and/or experience more
cooling degree days (CDD) use more energy, on average, The
orange trend line in the graphs below is the steepest for hours,
meaning that hours has a stronger effect on energy than CDD or
Workers, While these trends hold true on average, two buildings
with the same hours could have very different energy, as shown
by the range in the blue dots. Similar trends can be seen for
other indicators of business activity, such as number of
computers.
if Hours
CO 800
P. 600
400
70 90 110 130
Weekly Operating Hours
Workers
170
1200
— 1000
(N
3
£ 800
%/•£.*** 'f.* •

Workers per 1000 ft2
Cooling Degree Days
1200
1000 •
m 600
1000	2000	3000
Cooling Degree Days
EPA's ENERGY STAR score normalizes for the effects of
operation. While buildings with lower EUI generally earn higher
scores on the 1-100 scale, an individual building's result
depends on its business activities. For any given EUI, a range of
scores is possible.
ENERGY STAR Score Range
0
Ui
cs
O
o
if)
a:
£
C/)
>-
o
For any value of EUI,
a range of ENERGY STAR
scores can be expected
Range represents
10th - 90th percentile
values for score
ill..
100 200 300 400 500 600 700 800 900 1000+
Source EUI (kBtu/ft2)
Let's look at two office buildings, Office A and Office B, They
have the same EUI of 225 kBtu per square foot, and are identical
except that Office B is open longer hours and has more workers
per square foot. Because Office B has more intensive activities,
it is expected to have a higher EUI than Office A, based on
ENERGY STAR scoring models. Since Office B is expected to
use more energy, but actually uses the same energy, it earns a
higher score,
Hours: 110
Workers: 325
Hours: 60
Workers: 250
Expected EUI
315
Expected EUI:
277

:s:
Note: Number and floor area of buildings benchmarked
includes cumulative data through 2011. Analysis of energy
use and business activity includes buildings benchmarked
between 2006 and 2012. The data is self reported and has
been filtered to exclude outliers, incomplete records, and test
facilities. Portfolio Manager is not a randomly selected sample
and is not the basis of the ENERGY STAR score. To learn
more, visit: www, energystar. gov/Data Trends
October 2012
v>EPA
United States
Environmental Protection
Agency

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