ASHRAE Journal - October 2013 - 86

Column EmErging tEchnologiEs

taking advantage of this increased flexibility. The
industry has historically been conservative regarding
temperature and humidity setpoints, and especially
regarding economizer technology. This may be because
most IT departments do not pay their own electricity
bill, and thus have weak financial incentive to optimize
energy usage.10 A better incentive structure could cause
a necessary shift in thinking: energy usage should be factored into decision making across the entire life cycle of
data center design, implementation and operation, from
equipment selection forward.

Table 4 Uptime Institute survey responses: “Which power-saving strategies have

you deployed, or plan to deploy in the next 12 months?” Company size is selfdesignated by respondents.10
large Companies

small Companies

Cold-aisle/hoT-aisle ConTainmenT

78%

62%

raising inleT air TemperaTures

75%

42%

deTailed power moniToring, benChmarking

55%

43%

power managemenT feaTures on servers

44%

43%

vfds on Chillers, Crah, or pumps

62%

21%

modular daTa CenTer design

33%

24%

air-side eConomizaTion

36%

19%

waTer-side eConomizaTion

31%

10%

liquid Cooling

19%

11%

direCT CurrenT power

Energy Savings
The energy savings achieved with any of the approaches
described here are highly dependent on the facility,
IT equipment, and climate, but they can be very large.
For example, reducing PUE from 2.0 to 1.5 corresponds
to a 50% reduction in cooling and fan energy. A recent
research paper compared three efficiency strategies for a
12,000 ft2, 3 MW data center with a chilled water CRAH,
sited in three different climates. By optimally increasing
air and water temperatures (Table 2, Page 85), significant
energy savings can be achieved (Table 3, Page 85). In addition to this system optimization, the use of a water-side
economizer further improved energy savings for all three
climates. The use of an air-side economizer improved
energy savings in the coolest climate. Based on the data
center modeled, monetary savings of at least $425,000
per year could be realized. Maintenance savings of at least
$40,000 per year could also be realized.11 It is worth noting that the optimized temperature and humidity values
are still well within the ASHRAE allowable ranges, even
for Class A1 equipment.

Market Potential
The data center market is large and growing. A 2011
report by Microsoft estimates the annual market size for
data center construction to be about $15 billion for the U.S.
and $50 billion globally, growing to $80 billion globally by
2020.12 The Uptime Institute 2012 Data Center Industry
Survey, which polled data center owners and operators,
mostly from the financial, technology services, manufacturing, and government sectors, found that 37% of the 1,100
respondents planned to build a new data center to meet
increased capacity demand over the next 36 months.10
The same survey also reported that 57% of the respondents considered data center energy consumption “very
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important” to their company overall.10 The data on
technology adoption, however, tell a somewhat different
story: Table 4 shows adoption trends across some of the
power-saving methods discussed earlier.10 Efficient data
center cooling may be on many organizations’ radar, but
the market is clearly far from saturated for several wellestablished energy-saving technologies, in particular
economizers and VFDs.

References
1. Koomey, J.G. 2011. “Growth in Data Center Electricity Use 2005 to
2010.” http://tinyurl.com/lz5ce82.
2. The Green Grid. 2012. “PUE: A Comprehensive Examination of the
Metric.” http://tinyurl.com/lm6eol4.
3. DOE EERE. March 2011. “Best Practices Guide for Energy-Efficient
Data Center Design.” http://tinyurl.com/mtp3ghx.
4. Moss, D.L. 2010. “A Comparison of Room-, Row-, and Rack-Based
Data Center Cooling Products.” Dell. http://tinyurl.com/nqy2zph.
5. DOE NREL. 2012. “High Performance Computing Data Center Fact
Sheet.” http://tinyurl.com/k6db9mv.
6. Witkin, J. 2012. “Cooling a computer server with mineral oil.” The
New York Times. http://tinyurl.com/cgulupv.
7. Hughes, P. , W. Tschudi. 2011. “Energy efficient and lower capital
cost – an alternative data center cooling strategy.” ASHRAE Transactions
117(2).
8. McFarlane, R. 2011. “Using free cooling in the data center.” http://
tinyurl.com/m4okxvb.
9. ASHRAE. 2012. Thermal Guidelines for Data Processing Environments,
3rd Ed.
10. Stansberry, M. J. Kudritzki. 2012. Uptime Institute 2012 Data
Center Industry Survey. http://tinyurl.com/m62cbgb.
11. Spangler, R., G. Jeffers. 2010. “Total cost of ownership comparison
of air economizers to other energy saving techniques in data center
applications.” ASHRAE Transactions 116(2).
12. Belady, C. 2011. “Projecting annual new datacenter construction
market size.” Microsoft. http://tinyurl.com/kb4o6ye.

ASHRAE Journal - October 2013

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