Page 162 -

7: The Need for Standard IT Energy-Use Metrics 127

In addition to developing best practices, metrics, guidelines, and stan-
dards to help improve data center efficiency, The Green Grid also proposes
defining metrics at the rack level as rack-level cooling solutions become more
prominent. The group will also offer guidance for measuring both power
consumption and “useful work” at both the facility and rack levels, and will
continue to provide technical updates as these metrics and measurement
techniques evolve. In the meantime, The Green Grid recommends the use of
either PUE or its reciprocal, DCiE.

So—What’s the Future for Green IT Energy-Use Metrics?

As we discussed, there are currently several green IT energy-use metrics,
including SPEC, EPA, EPEAT, LEED, and The Green Grid systems. In the
United States, green IT and green data center metrics will converge on those
developed by the EPA. However, the EPA effort is very much a collaborative
effort, and all current measurement systems will play a part. To complicate
the problem, some measurement systems and certifications, such as the
LEED certificates for green buildings, are outside of the scope of the EPA ptg
standards being developed for green IT. In the future, we may have both EPA
and SPEC energy-efficiency ratings for servers. That dual-available metric
could be beneficial. The EPA ratings will probably be more general (like esti-
mated miles per gallon for an automobile). The SPEC ratings (with con-
trolled tests run by the IT manufacturers) will probably be much more
specific, and users will determine more precisely how energy efficient a server
will be for their specific server needs (including use of virtual server technol-
ogy). Ratings for server efficiency—and much more for data center energy
efficiency—will always be complicated and dependent on the IT technology
needs of each individual customer. Because of this complexity and the contin-
uing evolution of IT technology and user needs, the ratings need to evolve.
Having several rating with some overlap can provide the competitive aspect
to continually improve green IT metrics and rating systems. We will all
benefit.