PUE - Understanding PUE Measurement

The PUE metric is an easy to understand ratio about data centre energy efficiency. If a facility has a PUE of 2 it means that the power used to run the IT equipment is fifty percent (50%) of the power consumed by the entire data centre. For another example, let’s take the relatively common PUE of 2.2, this means that forty-five percent (45%) of energy consumed delivers IT services and fifty-five percent (55%) powers the supporting infrastructure.

Therefore the lower the PUE, the more efficiently the data centre uses the energy it consumes.

With this in mind, the lowest PUE value a data centre can achieve is 1. This is where the amount of power used by the IT equipment equals the amount of power consumed by the data centre. In reality, this is an almost impossible value to achieve as it implies that there are no power requirements for the non-IT equipment and support environment.

A PUE of less than 1 has no true meaning as it suggests that the power being consumed by the data centre is less than that being consumed by the IT equipment it hosts. Any claims of a PUE below 1 should be treated with extreme scepticism.