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EU Data Centre Label: What Class A PUE 1.15 Really Takes

To get class A on the EU’s new data centre label, a site needs a power usage effectiveness (PUE) of 1.15 or less. The average reported across the EU is 1.36. Closing that gap means cutting the energy spent outside the IT equipment by more than half, and for most sites the realistic place to start is cooling.

What is the EU data centre rating scheme?

On 21 September 2026, the European Commission adopted a delegated regulation that creates a common EU rating scheme for data centres. It applies to sites with an installed IT power demand of 500 kW or more, which already report energy and water data under the Energy Efficiency Directive.

Each site gets two grades from A to G: one for energy (PUE) and one for water (WUE). Class A requires a PUE of 1.15 or less, and class G applies above 1.9. For water, class A requires a WUE of 0.1 litres per kWh or less. The first labels are due by 15 August 2027, generated automatically from the data operators already submit.

The regulation is still in its scrutiny period with the European Parliament and the Council. In parallel, the Commission is consulting on binding minimum performance standards for data centres. That consultation closes on 14 December 2026.

How far is the average data centre from class A?

The Commission’s report from the first round of reporting puts the EU average PUE at 1.36, based on 681 data centres that reported a reliable value. On the label’s scale, where class C runs to 1.35 and class D to 1.5, that average would land in class D. The global average of 1.52 reported by Uptime Institute for 2026 would be class E.

A PUE of 1.36 means that for every kWh used by IT, another 0.36 kWh goes to everything else: cooling, power conversion losses, lighting. At 1.15, that overhead has to drop to 0.15 kWh. That is a reduction of almost 60 % in the energy used outside the IT equipment.

Why is cooling the main lever for PUE?

Power conversion losses can be reduced, but rarely by much without replacing the electrical infrastructure. Cooling is different, because its energy use depends heavily on one design choice: the temperature of the water it runs on.

Traditional room cooling often needs water at 6 to 7 °C. Making water that cold requires compressors for much of the year. Rear-door cooling typically runs on 12 to 21 °C, and chip cooling on 32 °C or more. Warmer water means more hours where outdoor air does the job through a dry cooler, and fewer hours with chillers running.

Does the label also rate water use?

Yes, and this is where many sites face a trade-off. Evaporative cooling, in cooling towers or adiabatic coolers, saves electricity and helps PUE. But it consumes water, which pulls the WUE grade down. The US national laboratory LBNL notes the same trade-off: evaporative systems are generally more energy efficient, while systems without evaporation use more energy.

The way to score well on both is again temperature. A dry cooler can bring water to about 4 °C above the outdoor temperature without evaporating anything. The warmer the cooling loop, the more of the year it can run that way.

Why can PUE get worse when utilisation is low?

Many data centres run well below their design load. Pumps, fans and power equipment have losses that do not fall in step with the IT load, so the overhead per kWh of IT rises. This is why operations matter as much as equipment: how the cooling is controlled at part load decides whether the design PUE is reached in practice.

Does class A say anything about resilience?

No. An annual PUE describes how efficiently a site ran over a year. It does not show how much load the site can carry through a hot day, a pump failure or a power event. Two class A sites can have very different safety margins. Redundancy, response time and how the cooling behaves when a component fails need to be assessed separately.

What have we measured in operation?

At Next Generation Cooling (NGC), we have measured a pPUE as low as 1.004 for our rear-door solution under real operating conditions, and 1.035 for the full cooling solution. pPUE covers cooling only, so it is not the same as a site PUE, but it shows how small the cooling overhead can become. At supply temperatures of 22 to 30 °C and return temperatures up to 56 °C, our solutions use up to 90 % less energy for cooling than room cooling. In Denmark, our designs use free cooling 92 to 96 % of the year, with no water evaporated to reject the heat. Redundancy is built in at door level, N+1 or N+2. Read more about energy efficiency and RDHx Active Flow.

FAQ

When will the first EU data centre labels appear?

The first labels are due by 15 August 2027, based on data operators already report.

Does class A mean the data centre uses green energy?

No. PUE measures how much energy is used per kWh of IT, not where the energy comes from. The label grades PUE and WUE only.

Which data centres are covered?

Data centres in the EU with an installed IT power demand of 500 kW or more.

Sources

This article builds on a LinkedIn post by Ole Kristensen and the questions raised in the comments.

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