RagingWire is a colocation facility1 that provides enterprise-class, high-power density data center space
to allow companies to meet mission-critical IT needs. Colocation facilities tend to face greater efficiency
challenges due to the higher power density required to support the newest server, storage, and network
technologies, when compared with purpose-built, single-enterprise data centers.
Despite these challenges, RagingWire's first Sacramento data center (CA1 - a 100,000 square foot, 20 MW IT
load capacity data center) has always been considered energy efficient. CA1's power usage effectiveness2
(PUE) was an impressive 1.653 in 2008 when the national average was 1.91.4 However, RagingWire recognized
that the potential existed for further improvements. For example, in 2008, CA1's data center computer room air
handler (CRAH) fans, mechanical cooling pumps, and chilled water pumps all had constant-speed instead of
variable-speed motors. Also, chilled water supply temperatures remained at the approximate system design
level of 45 degrees Fahrenheit (F).
In 2009 and 2010, RagingWire completed a series of energy-efficiency retrofits at the CA1 facility that lead to
annual savings of $900,000. By 2011, after completion of the retrofit project, the PUE decreased from 1.65 to
1.48,5 with efficiency improving by over 10%. Due to the success ofthese efficiency upgrades, RagingWire's
CA1 facility became one of the first colocation facilities to earn the ENERGY STAR Buildings designation.6
The Team
In 2008, RagingWire launched its efficiency effort at the CA1 facility. In order to create an effective strategy and
a collaborative team, they brought together the following facilities and IT personnel:
¦	Director, Critical Facilities Engineering
¦	Mechanical Engineer, Critical Facilities Engineering
¦	Vice President, Data Center Operations
¦	Director, Client Services Delivery Group
¦	Other key Critical Facilities Department staff
In addition, RagingWire involved its equipment and service vendors in the efficiency efforts. Through this
collaboration, all necessary parties were able to be involved with the decision-making process, which was
essential to the project's success.
The Retrofit
Efficiency measures selected by the team included:
¦	Wireless data center floor environmental monitoring system: Wireless temperature sensors were placed at
the top, middle, and bottom of cold aisle server and equipment racks, and at the top and middle of hot aisle
racks. Wireless pressure sensors were placed under the raised floor to monitor static cooling air pressure.
All of these wireless sensors were monitored using a centralized monitoring and alarm platform. Installing
' Retail co-location providers rent space to multiple tenants that are only responsible for managing their IT equipment.
2	Power usage effectiveness (PUE) is the ratio of the amount of power entering a data center to the power used to run the information technology (IT) infrastructure within
it. As the data center's overall efficiency improves as PUE decreases toward I.
3	With an uninterruptible power supply (UPS) output of 7.2 MW and total facility power usage of 11.9 MW.
4	Based on ENERGY STAR data collected as part of the development of the ENERGY STAR Buildings designation.
5	With an uninterruptible power supply (UPS) output of 7.2 MW and total facility power usage of 10.7 MW.
6	Please visit httD'J/www.eneravstar.aov/datacentereneravefficiencv for more information on the ENERGY STAR Buildings program.

this system provided a more accurate and detailed thermal
map of the data floor, including a thermal picture of hot and
cold aisles, from the perforated tile floor to the output of
the rack's top server. Such monitoring ensured that, as the
chilled water supply temperature was carefully increased,
temperature and humidity would be maintained in accordance
with the ASHRAE TC 9.9 standard.
Hot aisle containment: RagingWire maintains a strict hot aisle/
cold aisle rack configuration within all of its customer cages.
During the retrofit program, RagingWire coordinated with its
CA1 customers to further isolate and contain the hot aisle
side of the IT network and equipment racks. Plastic curtains
were placed at the end of each hot aisle, and, in some cases
where equipment configurations required it, blanking panels
were installed inside racks, further isolating cold and hot
aisles. Extended return air ducts were installed on CRAH unit
air intakes to prevent cold air from short-cycling back into the
CRAH intake. The resulting increase in return air temperatures
increased CRAH unit efficiency.
Chiller plant quick restart programming: RagingWire
implemented a chiller plant quick restart program, which
returns the chilled water supply temperature to the established
setpoint within two minutes following a utility power
interruption. Programming changes start the chiller plant at
a faster-than-normal rate, enabling the plant to return to a
steady-state, lower-energy consumption status more quickly
than would be possible without the improved programming.
Variable frequency drive (VFD) motors:VFDs were installed
on all mechanical cooling pumps, chilled water pumps, and
data floor CRAH units. Consequently, fan speeds decreased
Figure 1. Total Chilled Water Plant Consumption (kW)
an average of 42%.
With motor power use
proportional to the cube
of fan speed, VFDs
provided substantial
Chilled water
temperature adjustment:
After completing hot
aisle containment,
chilled water
temperatures were
carefully increased from
the initial plant design
temperature to about
60 degrees F. Figure 1
shows the effects of
increasing the chilled
water supply from 50
to 60 degrees F, which
resulted in significant
changes in power
demand from the chiller
As shown in Table 1, these measures saved $900,000 annually,
with the majority of savings attributed to VFD installations on
pumps and fans. The measures produced an overall payback of
0.75. (Cost of equipment and labor included utility rebates
of $150,000.)7
VFDs Increase Redundancy
and Lengthen Equipment
In the original CRAH control
system, if one machine went
offline, another unit would
start. With the installation
of VFDs, if one unit failed,
another in the vicinity can
simply operate at higher
speeds (rather than starting
another unit). Across the
facility, CRAH unit fans now
operate at 42% lower speeds,
resulting in greater equipment
lifetime, as fans are subjected
to less stress from lower
static pressures.

May 21: 60 F
Chiller Supply [66 F
Maximum Outdoor Air
Temperature (MOAT)]
May 20: 55 F Chiller
Supply (75 F MOAT)
May 19: 50 F Chiller
Supply (66 F MOAT)
^ ^ ^ ^ ^ ^ ^

Time of Day
7 The custom incentives program paid up to 30% of project costs or SI50,000, whichever was less, on motor upgrades and related systems, including controls.

Table 1. Payback for Raging Wire Retrofit Measures
Measure Name
Cost of Equipment
Annual kWh
Annual $
Payback (cost/
and Labor
Maximize Chiller Plant Efficiency (including raising
chill water supply temperature, hot aisle isolation, and
control programming improvements)
158 CRAH Fan VFDs
Chiller Pump VFDs
Wireless Environmental Monitoring System

RagingWire's collaborative team encountered the
following challenges:
One-hundred and fifty-eight CRAH fans with VFD motors
required retrofitting, reprogramming, balancing, and testing,
without interrupting customer cooling. As the facility's
electrical/mechanical infrastructure is both maintainable
and fault tolerant, changing equipment configurations
to ensure cooling while retrofitting units could be
accomplished without client impacts, but the project's
large scale required extensive coordination with clients to
accomplish VFD installs.
Implementing hot aisle containment proved challenging
due to differences in every customer's rack and server
configurations, thus requiring slightly different containment
strategies. Some customer aisle configurations only
required plastic curtains at the either end of the hot aisle,
while others required blanking panels in certain rack areas.
Nevertheless, the configurations shared a common goal: air
entering the top of every rack at less than the 80.6 degrees F
ASHRAE TC 9.9 standard. The previously described wireless
environmental monitoring solution aided the process by
ensuring RagingWire's cooling infrastructure adequately
met customer demand.
As an ASHRAE class A1 data center with tightly controlled
environmental parameters (dew point, temperature, relative
humidity, and air quality), the group worked hard to achieve
IT department concurrence on data floor environmental
changes to increase energy efficiency. Multiple coordination
and informational meetings were held to ensure the
IT department and Client Services delivery personnel
understood proposed data floor environment changes, and
could communicate these to customers, as required.
RagingWire personnel cited detail-oriented project
managementas key to ensuring cooling availability and IT
department buy-in. Ultimately, two initiatives—wireless
environmental monitoring and site-wide hot aisle containment—
assured the IT department that data floor environmental
changes were well within accepted standards, and posed no
risks to customer equipment. Given these upgrades, efficiency
opportunities such as raising chiller water supply temperatures
and VFD motor installations became possible.
All energy-efficiency measures implemented at RagingWire's
CA1 data center are planned for implementation at
RagingWire's second Sacramento, CA, data center. Further,
RagingWire's Ashburn, Virginia, data center facility will include
the same types of energy-efficiency improvements, along with
utilizing reclaimed water, and installing airside and waterside
economizers in the chiller plant.
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.
July 31,2012