PUE (Power Usage Effectiveness) is used as a metric to define the efficiency of the power and cooling of a data center facility.
The Green Grid defines the Power Usage Effectiveness metric for datacenter infrastructure power as PUE = (Total Facility Power ) / ( IT Equipment Power ):
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While widely cited by the vendor community, there are significant shortcomings of this metric of which practitioners should be aware. The denominator (power used for systems) contains two components that overstate the efficiency:
- The machine usage include the power used by fans in IT equipment, which should be included only in the numerator
- The denominator include equipment that not doing useful work; e.g., servers and storage powered on, but not running any application.
Revising the definition would find that the typical PUE is around 3.0
Action Item: The GreenGrid definition should evolve to address these limitations.
