Certification to ISO50001 can yield benefits but would be fatally compromised if a misleading energy performance indicator is used to track progress.

Power Utilisation Effectiveness, PUE, is the data-centre industry’s common way of reporting energy performance, but it does not work. It is distorted by weather conditions and (worse still) gives perverse results if users improve the energy efficiency of the IT equipment housed in a centre through (for example) virtualisation.

This presentation given at Data Centres North in May 2018 explains the problem and shows how a corrected PUE should be computed.