ENERGYSTAR
TARGET "EXPECTS MORE AND PAYS
LESS" FOR ITS DATA CENTERS
"At Target, we always are
looking for ways to improve
our operations. With this
project, the goal was to
improve reliability through
advanced management. The
byproduct of improving our
cooling management was
improved energy efficiency.
Once we saw the associated
energy efficiencies, we
conducted an assessment
of the entire data center,
with the highest priority
requirement of the project
being maintaining our
level of power and cooling
reliability."
- Paul Peoples, senior
group manager of
Infrastructure, Target
TARGET'S COMMITMENT TO ENERGY EFFICIENCY
Target's data centers are a critical part of the company's business and
infrastructure. As with many mission-critical data centers, improving
their energy efficiency is not always the highest priority. Ted Hight,
Target's lead engineering consultant, said Target's early efficiency
efforts included "basic blocking and tackling, which involved creating
hot and cold aisles, blanking plates in racks, and blocking holes in tiles
under the racks."
As a part of its commitment to sustaina bility. Target set a goal of
increasing its percentage of ENERGY STAR-certified buildings from nine
percent in 2009 to 75 percent in 2016.' To help meet its environmental
goals and improve data center operations, Target's Technology Center
Engineering Team conducted a series of cost-effective energy-
efficiency upgrades on two 45,000-square-foot2 data centers in
Minnesota: Target's Brooklyn Park facility, which was built in 2001, and
its Elk River facility, which was built in 2007.
Scott Hovet, data center engineer, described the shift in attitude: "Our
team developed a passion for managing our cooling technologies
as mission-critical delivery, not settling for simple cooling of our IT
infrastructure. Therefore, energy efficiency became a byproduct of
precise technology management, which led us to perform an efficiency
audit on the entire data center." As a result of the efficiency upgrades.
Target was the first company to have two data centers earn the
ENERGY STAR building certification.
DATA CENTER EFFICIENCY MEASURES
The Brooklyn Park and Elk River data centers house 3.4 MW of IT load, which powers more than 6,900
computing devices and can support up to 9.7 total MW of IT load. Cooling for the data centers is provided
by 12 650- to 675-ton chillers that feed 102 computer room air handlers (CRAHs), ranging in size from 20 to 30
tons. Target's efficiency audit determined which retrofits provided the best return on investment. With the
assistance of its trade allies, a mechanical engineering firm, and incentives fromXcel Energy, Target took the
following actions:
¦ Installed variable frequency drives (VFDs) on CRAHs, air handling units (AHUs), and exhaust fans.
¦	VFDs allow fans to run at lower speeds by controlling the frequency of the electrical power supplied
to the fan motor. Fan power consumption is proportional to the cube of fan speed, so a decrease in
fan speed can lead to extraordinary reductions in fan energy use.
¦	Before VFD installation, exhaust fans and AHUs were redundant and rotated on a weekly basis. After
VFD installation, both technologies were run at reduced fans speeds, leading to significantly lower
energy use. Fan speed was reduced by as much as 78 percent in some instances, resulting in a 99
percent reduction in power use. CRAH and AHU motor sizes ranged from 7.5,10, and 15 horsepower
(HP). Exhaustfans (used in battery rooms, chiller rooms, etc.) were 1.5 HP.
' Learn more about Target's sustainability commitment:htto://hereforaood.taraet.com/learn-more/aoals-and-Droaress
2 The data center has 45,000 square feet of white space. Other areas of the buildings are devoted to electrical/mechanical plant, storage and office space.

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Reduced temperatures on generator heaters.
Standby generators are typically specified with jacket
and oil warmers that use electricity to maintain the
system in standby mode at all times. The manufacturer
indicated thatthe temperature of the generator heaters
could be lowered because each was located within
conditioned space.
Target reduced temperatures from 140 to 110 degrees
Fahrenheit, resulting in a 4 kW decrease in the power
consumption at each of these 16 heaters.
Installed timers and efficient lighting.
Timers were installed to turn lights on at 6:00 a.m. and
off at 4:30 p.m.
Inefficient lighting was replaced with efficient lighting
throughout the building (e.g., conversion of T-12s to T-8s,
high-beam metal halides to high-output T-8s).
Turned off unloaded transformers.
Two unloaded, 300 kilo volt-ampere (kVA) power
distribution units (PDUs) were taken offline at the Elk
River data facility, where the computing load was not
yet completely built out.
For a variety of reasons, several evaluated measures were
not implemented:
Energy-efficiency improvement options for water side
economizers were found to have a high simple payback of
8.5 years and would have required costly retrofitting of chiller
equipment.
Temperature and humidity adjustments were deemed
unnecessary because supply temperatures to equipment had
already been adjusted to 74-75 degrees Fahrenheit in previous
upgrades. Also, humidity sensors had already been switched
from relative humidity (which varies with temperature) to dew
point (which does not) to minimize unnecessary humidification.
RESULTS
As shown in Table 1, Target's data center retrofits led to more
than 5.8 million kWh annually and, on average, paid back in
1.4years, including utility rebates.3The installation of VFDs
accounted for 79 percent of the savings realized by the efficiency
upgrades. The annual carbon emission reduction achieved
through these efforts is the equivalent of taking 800 cars off the
road. It is important to note that powering down the unloaded
transformers and reducing the temperature of generator jacket
heaters incurred virtually no cost for installed equipment
and labor.
Table 1: Payback for Measures Installed
Measure Description
Measure
Quantity

Payback
(Years)
Installed VFDs on AHUs,
CRAHs and exhaust fans;
rebalanced instead of
rotated
117
4,578,469
1.7
Reduced temperatures on
generator heaters
16
630,720
0.0
Installed timers and
efficient lighting
N/A
349,813
0.8
Powered down unloaded
transformer
2
261,875
0.0
Total Annual Savings/Average Payback
5,820,877
1.4
These measures led to 25 percent overall power savings on the
mechanical loads. The ENERGY STAR rating system scored the
Brooklyn Park data center with a 91 in 2012. This means the data
center was more efficient than 91 percent of the data centers in
the United States. The Elk River data center received the same
upgrades but was not completely built out at the time of the
scoring. It received a 77 in 2012.
LESSONS LEARNED
Top-down commitment is needed. A key to this effort's
success was that Target's leadership was open to new
ideas and concepts. Senior executives understood that
data center energy-efficiency improvements aligned with
Target's sustainability and energy-saving goals and, therefore,
encouraged integration of these initiatives and options
throughout Target's business model (e.g. Target's goal of
having 75 percent of its buildings ENERGY STAR qualified
by 2016).
Data center efficiency does not necessitate large
expenditures on new equipment. Target was able to realize
significantsavings by retiring two unloaded transformers and
lowering the jacket heater temperature settings on generators.
These two efforts did not require any up-front costs.
With a redundant system, VFD savings can be huge. Target
was able to take advantage of the savings potential of VFDs
due to its redundant systems. In the past, single-speed,
redundant exhaust fans and AHUs were rotated on a weekly
basis. By using the two redundant, variable-speed fans
simultaneously—at significantly lower speeds—to accomplish
the same job, enormous savings were realized.
Also, since this analysis was completed, Target has installed chimneys on the cooling units, and all new CRAHs installed will be controlled by supply-side air monitoring.
ENERGY STAR®, a program sponsored by the U.S. EPA and DOE, helps us all save money and
protect our environment through energy efficient products and practices. Learn more.
Vis it www. en e rgysta r. g o v.
ENERGYSTAR
August 22,2012

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