What is Water Usage Effectiveness (WUE)?
Water Usage Effectiveness (WUE) is the water a data centre consumes per kWh of energy used by its IT equipment, in litres per kWh.
Why it matters
WUE compares the water consumed by data centre systems, mostly for cooling, with the energy the IT equipment uses. A lower WUE means less water per unit of computing. Like PUE, it is a site-level efficiency figure that data centre operators and cloud providers publish.
WUE covers only water used on site. Generating the electricity a data centre draws also consumes water, and that share depends on the regional generation mix. A full water figure for cloud or AI needs both.
An example
How much water is used is only half the picture. Greenpixie records a water stress category for each cloud region, taken from Aqueduct 4.0 for the province or region containing its data centres. Two regions with similar WUE can then be compared on how scarce local water is, as well as on how much each uses.
How Greenpixie measures it
Greenpixie estimates water for each line of a cloud bill in two parts:
- cooling water is IT electricity multiplied by the cloud provider's published WUE
- site or region WUE values are used where providers publish them, a global average otherwise
- electricity generation water comes from regional water intensity factors that reflect the local grid mix
- a World Resources Institute global average fills gaps in regional generation data
The two parts are reported as separate columns, in litres. The approach was developed with Dr Shaolei Ren at the University of California, Riverside, and informed by Making AI Less Thirsty by Li et al.
Sources
- Greenpixie Cloud methodology: 3. Definitions
- Greenpixie Cloud methodology: 7. Assessment and Calculation
- Greenpixie Cloud methodology: 5. Inputs and Evidence Sources
- GPX Cloud methodology diagram
- Greenpixie Grid and Regions methodology: 7. Assessment and Calculation
- Greenpixie CUR enrichment reference: output format