Water usage effectiveness
Water Usage Effectiveness (WUE) is a sustainability metric created by The Green Grid in 2011 to attempt to measure the amount of water used by datacenters to cool their IT assets. To calculate simple WUE, a data center manager divides the annual site water usage in liters by the IT equipment energy usage in kilowatt hours (Kwh).
Source: Wikipedia — Water usage effectiveness (CC BY-SA 4.0)