Metrics for energy efficiency assessment in data centers and server rooms

The energy consumption of centralized IT-equipment and data centers has been a fast growing topic over the past few years. It is widely recognized that a number of effective measures exist that in many cases would allow energy savings of 20-60% or even higher. Following the motto 'You can't manage what you don't measure.' Energy efficiency metrics are typically used for benchmarking the energy consumption of single products or systems, hence covering equipment or facility-level. The major - not yet sufficiently resolved - challenge is the definition of the 'useful work' provided by a data center. Recently developed concepts to further address service related energy consumption will be discussed in the paper. Central criteria and options for further development will be addressed.