PUE: The golden metric is looking rusty

When the PUE (power usage effectiveness) metric was first discussed at a meeting of The Green Grid in Santa Clara, back in 2007, a microphone stand was placed in each aisle of the auditorium. The importance of the initiative was understood even then: experts, including the founders of Uptime Institute, formed lines to give their considered input. And if there was one point that came across, it was that the industry should not treat PUE as a comparative metric, a gold standard that every designer, operator and planning authority must chase down, for comparison, presentation and applause.

Thirteen years on, that is almost exactly what has happened. PUE, thanks to its simplicity and universal applicability, has become the critical benchmark for scoring data centers for efficiency and “greenness” (environmental responsibility). But it is often used uncritically.