Does the spread of direct liquid cooling make PUE less relevant?

The power usage effectiveness (PUE) metric is predominant thanks to its universal applicability and its simplicity: energy used by the entire data center, divided by energy used by the IT equipment. However, its simplicity could limit its future relevance, as techniques such as direct liquid cooling (DLC) profoundly change the profile of data center energy consumption.

PUE has long been used beyond its original intention, including as a single defining efficiency metric and as a comparative benchmark between different data centers, ever since it was developed by The Green Grid in 2007. Annualized PUE has become the global de facto standard for data center energy efficiency, in part because it can hide many sins: PUE doesn’t account for important trade-offs in, for example, resiliency, water consumption and, perhaps most crucially, the efficiency of IT.