WUE
WUE, or Water Usage Effectiveness, measures a data center's annual water consumption divided by its IT equipment energy use, expressed in liters per kilowatt hour. It is the companion metric to PUE and often moves in the opposite direction.
Water Usage Effectiveness measures annual site water consumption against IT equipment energy consumption, giving a figure in liters per kilowatt hour. It was developed as a companion metric to PUE by The Green Grid.
The tradeoff with energy
Evaporative and adiabatic cooling reduce electricity consumption by using water to reject heat, which improves PUE while increasing WUE. Air-cooled and closed-loop designs reverse that relationship. There is no single optimum, only a choice appropriate to the climate and the local resource picture.
Why it has become contentious
Data center water consumption has become a subject of local scrutiny in drought-affected regions, occasionally affecting permitting and community acceptance. Operators in those markets increasingly treat water strategy as a siting decision rather than an engineering detail.
Why it matters for marketing
Water has become a genuine reputational and permitting issue for data centers in a growing number of markets, and silence on it now reads as something to hide.
Operators with a real story, whether that is closed-loop cooling, reclaimed water use, or simply a low WUE figure in a water-sensitive region, should tell it plainly with numbers. This is also increasingly a community and local media topic, which means the content serves stakeholders well beyond the buying committee.
Common questions
How is WUE calculated?
WUE is calculated as annual water consumption divided by IT equipment energy, expressed in liters per kilowatt hour. A facility using air-cooled chillers or waterless cooling can approach zero, while evaporative cooling designs consume substantially more water in exchange for lower energy use.
Why report WUE alongside PUE?
Because water and energy efficiency frequently trade against each other. Evaporative cooling lowers PUE while raising WUE. In water-stressed regions that tradeoff has become a permitting and community relations issue, not just an operational one, which is why both metrics now get scrutinized together.