Assess a proposed data centre by asking for its projected annual electricity and water volumes, the boundaries and assumptions behind those forecasts, its cooling design, and evidence about local grid and water conditions. Use PUE and WUE to compare efficiency—not as substitutes for the absolute demand or a site-specific impact assessment.
Start with annual electricity and water demand
Ask the developer to state projected annual total-facility electricity use and IT-equipment energy use, together with the forecast period and operating assumptions. The figures should clarify which loads are included and how the facility is expected to operate. A ratio can describe efficiency without showing the scale of the proposed facility’s resource demand.
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Request projected annual water input as an absolute volume as well. Ask which sources and uses are counted, and whether the forecast reflects expected operating conditions. Under the EU framework, water input covers volumes entering the data-centre boundary and used in relation to its functions.
Check what PUE and WUE mean
| Metric | What it measures under the EU framework | How to use it |
|---|---|---|
| PUE | Total data-centre energy divided by IT-equipment energy. | A lower value indicates less supporting energy per unit of IT energy, but it does not reveal absolute electricity demand. |
| WUE | Water input divided by IT energy. | Interpret it alongside absolute water volume, water source, cooling method, and local water conditions. |
| ERF | Energy reused divided by total facility energy. | Describes energy reuse; it does not establish whether a particular grid or water source can support the proposal. |
| REF | Renewable energy divided by total facility energy. | Describes renewable energy use; it does not establish local grid capacity or water availability. |
The EU definitions are set out in Commission Delegated Regulation (EU) 2024/1364. For every metric, ask for its reporting period and the boundary used to calculate it. Otherwise, apparently comparable values may describe different loads, uses, or periods.
Examine the cooling design and site conditions
Ask the developer to explain the proposed cooling technology and connect that explanation to forecast water use. The European Commission says water consumption depends primarily on cooling technology. Climate also affects WUE: cooler regions generally need less water cooling, while warmer regions may depend more on it. A cooling label alone is not enough; the proposal should show how the design and local conditions inform its water projection.
Ask what water source the facility expects to use and whether the forecast accounts for the conditions at the proposed location. Then seek site-specific evidence about water availability and the grid. EU reporting metrics and sector-wide figures provide context, but they do not determine whether a particular location can supply the required resources.
Compare proposals on a like-for-like basis
When evaluating more than one proposal, compare the same categories and ask whether each uses comparable operating assumptions. Separate measured or modeled projections from aspirational targets.
- Projected annual electricity demand and annual water input.
- IT-energy and total-facility boundaries, including which loads and water uses are counted.
- PUE and WUE definitions, values, and reporting periods.
- Cooling approach and the climate assumptions used in forecasts.
- Water source and evidence about local water conditions.
- How renewable energy and reused heat are treated, including REF and ERF where reported.
- Whether each figure is measured, modeled, or aspirational.
Use EU figures as context, not as a site forecast
The European Commission’s 2026 report estimates that data centres consumed 68 TWh of electricity in the EU in 2024 and projects 114 TWh by 2030, equal to 3.2% of EU electricity demand. The report also gives an average reported EU WUE of 0.58 for 2024, with Member State values ranging from 0.07 to 1.28. These EU-wide figures describe sector context, not the expected consumption or impact of a proposed site.
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The report says electricity typically accounts for over 90% of a data centre’s direct energy use. It also states: “The expanding data centre sector poses a challenge for energy availability, availability of electricity grids, carbon emissions and environmental resources such as water.” Both statements appear in the Commission’s 2026 report on the energy efficiency of data centres in the EU.
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The Commission describes an EU database that collects and publishes energy-performance and water-footprint information for data centres subject to reporting. Its energy performance of data centres page provides information about this reporting framework. Public aggregated information can help establish context; it cannot replace defensible site-specific projections or local review.
The cited reporting rules and figures are EU-specific. They do not decide whether a particular site has adequate grid capacity or water availability, and they do not identify the approvals required in every jurisdiction. Identify the site and consult the competent planning, water, grid, and environmental authorities about locally applicable requirements.
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