Water usage effectiveness

${\displaystyle \mathrm {WUE} ={{\mbox{Water quantity}} \over {\mbox{IT Equipment Energy}}}}$

The unit is ${\displaystyle L/kWh}$,^[3] or, equivalently, ${\displaystyle m^{3}/MWh}$.^[4]

The standard ISO/IEC 30134-9:2022^[5] gives more context for accurate measure, as well as specific WUE categories and various WUE derivatives.

The WUE is a positive number. It can be 0 L/kWh (with air cooling) or up to 2.5 L/kWh (with evaporative cooling).^[4]

Facebook published a WUE of 0.22 L/kWh for their datacenter of Prineville, Oregon for the second quarter of 2012.^[2]

For the year 2025 Equinix reports a global WUE of 0.91 L/kWh for all their datacenters, and a WUE of 1.41 L/kWh for sites using evaporative cooling.^[6]

WUE is less widespread than the Power usage effectiveness (PUE), but is becoming more publicized by data center operators due to ESG considerations and/or due to water scarcity.^[4]

According to Equinix,^[4] PUE and WUE are partially opposites: with evaporative cooling the WUE increases and the PUE decreases, and with air cooling the WUE decreases (or is zero) but the PUE increases. The cooling technology of a given datacenter may be dependent on the region (and other considerations), and may be a mix of different technologies, possibly activated differently depending on the season.

• Power usage effectiveness (PUE)
• Data center infrastructure efficiency
• Performance per watt
• Green power usage effectiveness
• Green computing
• IT energy management