Water Usage Effectiveness (WUE) is a sub-aspect of Power Usage Effectiveness (PUE) for determining the energy efficiency of data centers
. The WUE value, which is about the water consumption for water cooling of the racks in data centers, is calculated from the ratio of the annual water consumption in liters (l) to the energy consumption in kilowatt hours
(kWh) of the IT equipment. TheWUE value is expressed in liters per kilowatt hour (l/kWh).