EU Data Centre Labels Grade Efficiency, Not Total Power

The European Commission adopted an A-to-G sustainability rating for data centres above 500 kW on 21 September 2026. First electronic labels are due on 15 August 2027. They grade power and water efficiency. They do not cap how many megawatts a hall may draw.

Parliament and the Council now have two months to object, and they cannot rewrite the text. The same day, Brussels opened a separate fight over binding floors for 2027.

Server Halls Above 500 kW Get an A-to-G Sticker

The delegated act sets a common rating scheme for data centres with installed IT power above 500 kW. Smaller sites and halls that have not yet opened may join if they file the same indicators, using design figures for the first two years of operation.

The European database will auto-build each label from numbers operators already send in. Energy Commissioner Dan Jørgensen said understanding that consumption is “the essential first step towards integrating them sustainably into our energy system.” Digital sovereignty, he added, “must go hand in hand with energy responsibility.”

Power usage effectiveness, PUE, is the share of site electricity that never reaches the servers because cooling, lights and other kit ate it. Water usage effectiveness, WUE, is water used per unit of IT energy. Both get a letter.

PUE AND WUE LETTER BANDS

The EU’s own 2024 average PUE of 1.36 sits in class D. The average WUE of 0.58 sits in class D as well. A cut in PUE from 1.6 to 1.2 would trim site electricity by 25%, the Commission’s memorandum says, and a cut in WUE from 1.0 to 0.5 would halve water use.

Those letters are ratios. A lightly loaded hall can look cleaner than a packed AI cluster because the grade tracks overhead per unit of IT energy, not the megawatts on the substation. Cheap power still decides where GPU halls go.

WHAT ELSE THE ELECTRONIC LABEL SHOWS

• Waste heat: Whether the site can send leftover heat into nearby networks or other users.
• Clean power: On-site generation and contracted low-carbon supply, not only the letter grades.
• Grid flexibility: Whether the hall can shift load when the system is tight.
• Languages and life: The file is public in every official EU language and runs from 15 August to the next 15 August.

The act says the rating will feed other EU law, including the Cloud and AI Development Act. That is how a sticker becomes a procurement filter rather than a kWh ceiling.

The First Filing Round Reached Only 36%

The letters sit on a database that is still thin. Under the 2024 reporting scheme for data centres, operators had to file by 15 September 2024, then by 15 May 2025, and every year after that.

The Commission’s 21 September 770 data centres reported in 2024, about 36% of the halls thought to sit above the 500 kW line. Six member states sent none. Five sent fewer than three, which the report itself calls a limited picture of those regions.

Water figures are thinner still. WUE in that first round ran from 0.07 to 1.28 across countries, a spread the Commission ties to kit choice and climate, not only to operator skill. Cooler regions need less water-heavy cooling. Warmer ones often do not have that option, which is why a single EU water scale will grade very different physics with the same letters.

Member states must tell the database by 15 August each year whether their territory has finished reporting. If a country is late, a hall’s label can run on until a new one is issued, or until 31 December at the latest. The grade is only as current as the slowest capital.

Brussels Still Plans 28 GW of Capacity by 2030

The package lands beside a build-out, not instead of one. The strategic roadmap for digitalisation and AI in the energy sector, COM(2026) 501, puts installed capacity at about 12 GW in 2025 and around 28 GW by 2030. That is more than a doubling. Separately, the Commission says it wants to triple capacity over the next five to seven years, a longer political target than the 2030 GW path.

THE LOAD THE LABELS WILL SIT ON

• 68 TWh: Electricity used by EU data centres in 2024, in the Commission report that cites the International Energy Agency.
• 114 TWh: Projected use by 2030, 3.2% of EU electricity demand that year.
• About 2.5%: The roadmap’s figure for the sector’s current share of EU electricity, a different year from the 3.2% outlook.
• 12 GW to 28 GW: Installed capacity from 2025 to 2030 in that same roadmap.

Teresa Ribera, executive vice-president for a clean, just and competitive transition, tied the sticker to that build.

Tripling our data centre capacity cannot mean tripling the pressure on our grids, our water and our energy bills. That starts with transparency, rating large data centres depending on their impact on our energy system. Efficient, flexible, powered by additional clean energy and reusing waste heat, this is how data centres become an asset for EU’s energy transition.

Teresa Ribera, Executive Vice-President, 21 September 2026

The rating does not decide whether a 28 GW fleet gets connected. Grid queues, water permits and local plans still do that. The new file gives those fights a public letter, which cities and network operators can quote even when they cannot see the hall’s full meter.

Four Million Homes and 67 Halls That Reuse Heat

The political prize in the press release is leftover heat. Reusing around half of all waste heat from European data centres, the Commission says, matches the total heating demand of 4 million households. The delegated act’s memorandum uses the same order of magnitude.

The database tells a smaller story. Only 67 data centres reported any waste heat reuse in the first filing round. The Commission lists the usual blocks: halls that were never built to export heat, the cost of pipes to a buyer, heat that arrives at the wrong time or temperature, and no buyer at all.

That gap is where the sticker has bite. A hall that scores well on PUE can still show a blank on reuse. District-heating operators and city planners gain a public flag for sites that dump heat next to a network that could take it. Operators gain a reason to wire export into the next permit, because the letter will sit in the same EU file that other laws are told to use.

Flexibility is the other grid claim. Halls that can shift load, the Commission says, can cut system costs and help soak up more renewable power. The label will show that contribution. It will not require a hall to offer it.

How a Confidentiality Clause Survived the New Label

The 2024 regulation that built the database also locked down site-level filings. Article 5 told the Commission and member states to keep individual information and key performance indicators confidential as commercial data. AlgorithmWatch and Corporate Europe Observatory showed in April 2026 that the clause matched wording sent in by Microsoft and the lobby group DigitalEurope.

Thirty-five MEPs later asked the Commission to drop that line, arguing it sat badly with environmental-information rules. The 21 September act says the public label respects trade secrets and follows the already-public slice of the 2024 annexes. Bram Vranken, a researcher at Corporate Europe Observatory, said the Microsoft confidentiality clause is kept in, though rewritten, “so that’s hugely problematic,” and that much of the information in the label will be impossible to check. A strong PUE letter, on that reading, can sit on a hall whose absolute gigawatt draw never appears.

Microsoft’s July 2026 filing with Germany’s federal government backed clean power, energy efficiency and water efficiency as indicators, while seeking changes to the proposed water-efficiency bands. The water letters in Annex I are now fixed unless Parliament or the Council objects to the whole act.

Industry’s other objection is geography. CCIA Europe, the Computer and Communications Industry Association’s Brussels office, says a flat PUE and WUE scale skips climate. A Nordic hall on air cooling is not the same machine as a southern hall on water-heavy chillers. In a 22 September statement the group said the rating scheme “risks pushing data centre investment outside the EU, undermining both competitiveness and the environmental goals.”

Press release 📄 EU's First-Ever #DataCentre Rating Scheme Overlooks Engineering And Geographic Realities 🌍

"The rating scheme risks pushing data centre #investment outside the EU, undermining both competitiveness and the #environmental goals."

👉 https://t.co/IkeNm6AHY7 pic.twitter.com/XLuSnYaFPp

— CCIA Europe (@CCIAeurope) September 22, 2026

Its April paper asked the Commission to put climate zones into the draft grades so a Finnish air-cooled site and a Greek water-cooled site are not scored as if they share the same weather.

WHERE THE FIGHT SPLITS

• The Commission: Publish comparable letters first, then use them in procurement and later standards.
• CCIA Europe: One EU scale that ignores climate will mis-rank halls and shove capital outside the bloc.
• Corporate Europe Observatory: A letter without a checkable site load lets a green grade hide a huge draw.

The practical split is simple. Operators want the grade to reflect local cooling physics. Watchdogs want the grade to sit next to litres and kilowatt-hours for that address. The adopted label does the first job with two letters and leaves the second inside the confidential file.

The 2027 Floor Goes to Public Consultation

Minimum performance standards are the part that can block a design. The Commission opened a 12-week consultation on minimum performance standards on 21 September 2026. It closes on 14 December 2026. A legislative proposal is planned for the second quarter of 2027. Jørgensen has already said those floors will add pressure on operators who will not raise their game on their own.

The Commission has not said which technologies would fail a floor, or whether old halls and new halls would face the same line. A supporting study started in early 2026 and runs 24 months. A first review of the rating scheme itself is due by the end of 2028, with a possible later aggregate score and audits of reported data.

THE PACKAGE CALENDAR

1. 14 March 2024: Commission adopts Delegated Regulation (EU) 2024/1364 and the European database.
2. 15 September 2024: First reporting deadline for halls at or above 500 kW.
3. 21 September 2026: Rating scheme adopted; consultation on minimum standards opens.
4. 14 December 2026: Consultation closes.
5. 15 August 2027: Database auto-issues the first electronic labels.
6. Second quarter of 2027: Commission plans the minimum-standards proposal.

A June 2026 declaration of intent still points to a tripartite deal with operators, grid firms, energy suppliers and public authorities in the second half of 2026. That track is about connecting new halls without breaking local systems, which is the job the letters cannot do alone.

Until 15 August 2027 the public still has a ratio, not a meter. After that date a city can point to a D on water while the hall’s absolute draw stays in the confidential file, and the 28 GW build will still need substations, permits and pipes either way.