Energy efficiency metric for a data centre, the ratio of total energy consumed to energy used by IT equipment.
PUE is the reference metric for the energy efficiency of a data centre. It relates the total energy consumed by the facility to the energy actually used by IT equipment. A PUE of 1.0 would represent an ideal centre where all energy goes to computing, with no cooling, power or lighting losses. Traditional centres show PUE around 1.5 to 2.0, while optimised hyperscale facilities descend toward 1.1. The metric is used to compare operators, set regulatory targets and assess a site's footprint. For insurance, a low PUE signals intensive cooling, often liquid or immersion, whose failure can cause critical overheating and a major business interruption. PUE captures neither water consumption nor carbon intensity, hence the complementary metrics WUE and CUE.
A hyperscaler announcing a fleet-average PUE of 1.1 signals highly optimised cooling, but also greater dependence on systems whose failure has heavy consequences.
PUE, efficacité d'utilisation énergétique, power usage effectiveness