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7: The Need for Standard IT Energy-Use Metrics 125

As part of the effort to promote dramatic efficiency improvements in the
data center, The Green Grid can provide clearer distinctions between facility
and IT equipment and recommend power consumption measuring tech-
niques throughout the data center, as well as for the equipment.

Data Center Productivity (DCP)

For the long term, The Green Grid is working on metrics to define data
center productivity. This is the natural evolution from PUE and DCiE, and
such a metric could be in a form that looks as follows:

Data Center Productivity = Useful Work / Total Facility Power

Although data center productivity is much more difficult to determine,
members of The Green Grid feel that this is a key strategic focus for the
industry. In effect, this calculation defines the data center as a black box:
Power goes into the box, heat comes out, data goes into and out of the black
box, and a net amount of useful work is done by the black box. This process
in some ways parallels the work being done with the EPA and Standard
ptg
Performance Evaluation Corporation (SPEC) at the server level, in which
the SPEC working group might produce a standard on the performance of a
system, and the EPA provides a process by which to measure power con-
sumed by the server.
The Green Grid hopes to eventually increase the scope of its work to all IT
equipment and will require broad participation from the IT community to
help guide and define this pursuit of accurate metrics.

Further PUE Developments
The Green Grid will also consider the development of metrics that pro-
vide more granularity for the PUE and DCiE metrics by breaking it down
into the following components:

PUE= 1/ DCiE = Cooling Load Factor (CLF) + Power Load Factor
(PLF) + 1.0
where all factors are ratios that are divided by the IT Load and

■ 1.0 represents the normalized IT Load. Effectively, this is the IT Load
Factor (ILF) but is always 1.0.