Recover heat, re-charge power

Recently I attended the Data Center Dynamics (DCD) Smart Energy conference in Stockholm. During a panel discussion on energy, data centers and innovation, David Hall (Senior Director of Technology Innovation for Equinix) made two observations, almost in passing, about metrics and monitoring. Both were intriguing and, to my ears, suggested that operators’ thinking about sustainability and data center energy use is starting to evolve.

The first metric was power usage effectiveness (PUE) — the universally applied but widely criticized standard way to measure data center energy efficiency. In essence he asked, What does it matter if your data center PUE is (a very inefficient) 4 or 5, if you are capturing and re-using the heat (i.e., the byproduct of wasted energy)? After all, as many at the conference pointed out, waste energy can be used for district, building or campus heating; for greenhouses; for heating swimming pools; or, as both Facebook (in Northern Sweden) and the National Renewable Energy Laboratory (in Colorado) do, for melting snow.