Data center energy label: the EU's A to G rating explained

When you shop for a fridge or look around a flat, the energy label is often the first thing you check. One letter, one color, and within two seconds you know whether the bills are going to hurt.

Data centers have never had anything like it. Each operator publishes its own PUE, calculated its own way, over whichever period suits it best, sometimes based on design targets rather than actual operations. Comparing two colocation offers on energy efficiency meant comparing figures that didn't quite measure the same thing.

On September 21, 2026, the European Commission adopted the delegated regulation that creates a common Union rating scheme for data centers, with a public electronic label. Two A to G scales, a QR code, the energy mix, and several indicators that are bound to come up in tenders. Here is what the text contains, what it leaves out, and how you can use it.

⚡ The short answer

Delegated Regulation C(2026) 3472 introduces a sustainability label for data centers in the EU. It assigns one A to G class for energy efficiency (PUE, class A if PUE ≤ 1.15) and another for water efficiency (WUE, class A if WUE ≤ 0.1). The label is generated automatically by the European database, using data that operators already report under the Energy Efficiency Directive. The first labels are due by August 15, 2027 at the latest, then every year. They will be public and available to any customer.

1. Where does this label come from?

It didn't come out of nowhere. It's the third step of a staircase Brussels has been building since 2023.

The first step is Article 12 of Directive (EU) 2023/1791 on energy efficiency, usually called the EED (Energy Efficiency Directive). It requires data centers with at least 500 kW of installed IT power to publish information about their energy performance.

The second step is Delegated Regulation (EU) 2024/1364, adopted in March 2024. It set up the European data center database and defined the indicators to report each year: total consumption, IT consumption, water, reused waste heat, share of renewable energy and so on. The database has been live since September 2024, and two reporting campaigns have already taken place.

The third step is the September 21 text. It turns that raw data into a readable label, and uses the opportunity to fix several measurement rules that were causing problems.

Why now? Because the curve isn't flattening. According to the Commission, EU data centers used 68 TWh of electricity in 2024, a figure expected to reach 114 TWh by 2030, or 3.2% of European electricity demand. AI is named as one of the main drivers of that growth.

Did you know? According to the regulation's explanatory memorandum, bringing a data center from a PUE of 1.6 (the European average estimated by the Commission) down to 1.2 (best available technology) cuts its electricity use by 25%. And reusing, on average, half of the waste heat from European data centers would cover the heating needs of almost 4 million households.

2. Who does it apply to?

The scope follows the existing reporting rules, with two notable openings.

Data centers of 500 kW IT and above already report their data to the European database, either directly or through a national platform. They will therefore receive a label automatically every year. Nothing extra is required of them, a point the Commission stresses: no new burden for operators.

Data centers below 500 kW can now take part on a voluntary basis. For a regional operator or an edge site, that's a real opportunity: an official label, comparable to those of large campuses, instead of a self-declared PUE in a sales brochure.

Data centers not yet in service can also register, by reporting the indicators they are targeting after two full years of operation. They then switch to actual values from their first year of operation. Until the site is up and running, its commissioning date will appear with the mention "DESIGN".

There is only one explicit exception: data centers used exclusively for a Member State's defense or civil protection are exempt from reporting.

Key point: Operators get two new, simple obligations. First, make the label available to anyone who asks for it, on their own website or by pointing to the European database. Second, don't produce look-alike labels that imitate the official one. In other words, home-made badges styled like an energy label will have to go.

3. Two A to G scales: PUE and WUE

The label doesn't give an overall score. It shows two separate classes, one for energy and one for water.

PUE, or energy efficiency

PUE (Power Usage Effectiveness) is the ratio between the site's total energy consumption and the consumption of the IT equipment alone. A PUE of 1.5 means that for every 1 kWh used by the servers, another 0.5 kWh goes to cooling, UPS, lighting and electrical losses.

Class	PUE
A	≤ 1.15
B	> 1.15 and ≤ 1.25
C	> 1.25 and ≤ 1.35
D	> 1.35 and ≤ 1.5
E	> 1.5 and ≤ 1.7
F	> 1.7 and ≤ 1.9
G	> 1.9

The bar is set high. According to the first technical report prepared for the Commission in 2025 (AIT, Borderstep, EY), the average PUE of the data centers that reported is 1.36 across the EU, with national averages ranging from 1.15 to 1.66. A data center sitting right at the European average would therefore be rated D.

For reference, Google reports an average PUE of 1.09 across its fleet in 2025, which would put it comfortably in class A. But that's hyperscale with very high utilization, a situation few colocation sites ever reach.

WUE, or water efficiency

WUE (Water Usage Effectiveness) measures the amount of water consumed per unit of IT energy, in practice liters per IT kWh (or m³ per MWh, which gives the same value).

Class	WUE (L/IT kWh)
A	≤ 0.1
B	> 0.1 and ≤ 0.2
C	> 0.2 and ≤ 0.4
D	> 0.4 and ≤ 0.6
E	> 0.6 and ≤ 0.8
F	> 0.8 and ≤ 1.0
G	> 1.0

One significant change along the way: WUE is no longer calculated on drinking water, but on all freshwater entering the data center's boundary, whatever its source (mains, borehole, river). A site pumping from an aquifer can no longer show a flattering WUE on the grounds that it doesn't use mains water. On the other hand, water circulating in a closed-loop cooling system isn't counted on every pass.

Key question: Can a site have a low PUE and a low WUE at the same time? Yes, but it's often a trade-off. Adiabatic cooling (water evaporation) lowers PUE but pushes WUE up. Conversely, a site cooled entirely by dry chillers uses little water but more electricity. Looking at only one of the two letters means seeing only half the picture.

4. What else the label shows besides the two letters

Beyond PUE and WUE, the label has eighteen fields. Some are purely descriptive (name, operator, location, data center type, size category, commissioning date, reporting period). Others deserve a closer look.

The energy mix, nuclear included

A pie chart breaks down where the energy comes from, across seven categories: renewables generated on site, renewables bought through a PPA (Power Purchase Agreement, a long-term electricity supply contract), renewables covered by guarantees of origin, then the same three categories for nuclear, and finally energy from an unspecified source.

Including nuclear among "low-carbon" sources was far from a given and was debated while the text was being drafted. For operators based in France, it's an important nuance.

There is a catch, though: electricity drawn from the grid with no guarantee of origin or PPA attached will show up as "unspecified source". A French data center running on a very low-carbon grid, but not buying any contractual instrument, could therefore show a large "unspecified" slice. Reading the pie chart takes a bit of context.

This data also feeds a new reported indicator, the LEEF (Low-Emission Energy Factor), which is the ratio of total low-carbon energy to the site's total consumption.

Contribution to new capacity

This is probably the most interesting field if you care about greenwashing. The label shows two separate percentages:

the share of energy from PPAs signed with installations commissioned (or substantially refurbished) less than 10 years ago;
the share covered by stricter guarantees of origin: same production period as consumption (at the finest time granularity available in the country), same bidding zone or same Member State, and installations less than 10 years old.

Put simply, an operator buying cheap guarantees of origin at year-end, backed by an old Scandinavian dam, can still display a "100% renewable" mix. But the "contribution to new capacity" line will show that the purchase doesn't fund any new generation.

Climate, grid and heat

Three more pieces of information complete the picture:

the cooling degree days (CDD) for the location, calculated automatically using the Eurostat method. They show how hard the local climate makes cooling, which helps put the PUE in context;
whether the site provides flexibility services to the power grid (peak shaving, frequency response, etc.);
the "waste heat reuse ready" status: is the site equipped (heat exchangers, dedicated hydraulic loops, heat metering) to deliver its waste heat to an external user, even if no district heating network is connected yet?

Did you know? Every label will come with a common explanatory document written by the Commission. It covers, among other things, how PUE relates to climate and to a site's size or age, the trade-offs between PUE and WUE, and why WUE matters more in water-stressed areas. The aim is to avoid a recent Nordic site being compared at face value with a twenty-year-old Mediterranean one.

5. What changes in how things are measured

This is the least visible part of the text, but not the least important. To make the label credible, the Commission tightened several calculation rules from the 2024 regulation. These are changes the operator will have to implement in its metering.

IT consumption is measured as close to the racks as possible. The reference method becomes category 3 of the EN 50600-4-2 standard, meaning metering at the rack PDU or rack outlet level. Failing that, category 2 (metering at the PDUs feeding the IT equipment) is accepted. The further upstream you measure, the more non-IT losses end up counted as "IT", which artificially improves the PUE.

Generators count. Total consumption is measured at the site's point of entry, upstream of the transfer switch, backup supplies included. Energy produced by generators, including during maintenance tests, must be reported separately.

Mixed-use buildings are covered. If the data center occupies part of an office building, only the energy used by the IT rooms and the equipment they need to operate is counted.

Heat reuse isn't penalized. Energy used by a heat pump that raises the temperature of waste heat before sending it to a network is deducted from total consumption. An operator investing in heat recovery won't see its PUE worsen as a result.

A new "certification" field. Operators will be able to state whether their measurement and reporting procedures are validated by an accredited third party (as part of ISO 50001, for example) or simply self-certified.

6. Colocation: what your provider might ask of you

If you're a colocation customer, this part concerns you directly.

The text acknowledges that a colocation operator doesn't always control the metering of every customer rack. In that case, it must estimate and state the percentage of white space floor area covered by the data it reports. A label calculated on 40% of the data halls doesn't carry the same weight as one calculated on 100%.

To fill those gaps, the regulation explicitly allows colocation operators to set up an internal data collection mechanism with their customers, anonymously where appropriate.

💡 Good practice: Expect colocation contracts to start including clauses on sharing consumption data, or even on installing smart PDUs. It's worth raising the question at your next renewal: who provides the metering, who has access to it, and in what form is the data passed on?

7. Key dates

The Commission has adopted the text, but it isn't in force yet. Since it's a delegated act, the European Parliament and the Council have two months to raise an objection. They can reject it, but they can't amend it.

Date	What happens
September 21, 2026	Commission adopts the delegated regulation
Fall 2026	Two-month scrutiny period for Parliament and Council
December 14, 2026	Public consultation on future minimum performance standards closes
20 days after publication in the OJEU	Regulation enters into force
Spring 2027	Annual reporting of 2026 data to the European database
August 15, 2027	First labels generated automatically, then every year on the same date
Q2 2027	Legislative proposal on minimum performance standards expected
December 31, 2028	First review of the scheme, then every three years

Each label is valid from August 15 of the year it's issued until the following August 15. If a Member State hasn't confirmed in time that its national reporting campaign is complete, the previous label stays valid for longer, until December 31 at the latest.

Key point: The label sets no thresholds: a data center rated G is still perfectly legal. But what comes next is already on the table. On the same day, the Commission launched a consultation on minimum performance standards. The accompanying technical report mentions, for example, an operational PUE below 1.5 for existing sites by 2030, and a design PUE below 1.3 for new builds. Nothing is decided yet, but sites currently rated E, F or G know which way the wind is blowing.

8. How to read a label without getting it wrong

A label is handy. It's also a shortcut, and shortcuts have blind spots. Before ruling out an operator because of one letter, keep in mind a few limitations that the text itself acknowledges.

The label's blind spots

• Climate matters a lot. Cooling a data hall in Marseille takes more energy than in Lille. That's why cooling degree days appear on the label: compare sites in similar climate zones.
• Utilization skews PUE. A new data center at 20% occupancy almost always has a mediocre PUE, because its cooling and power infrastructure is running for a still-small IT load. A poor rating in year one says little about performance at full load. For a recent site, ask about the trajectory.
• The data is still self-reported. For now, no independent audit is required. The review planned for the end of 2028 will look at introducing full or partial certification or auditing. Until then, a "third-party certified" mention will make a difference.
• The label says nothing about your own servers' efficiency. PUE measures the building's infrastructure, not the useful work done by IT. An excellent PUE can house ageing, underused servers. This is actually one of the areas explicitly listed for future reviews.
• There's no overall score. A site rated A for energy can be E for water. The Commission will later look into an aggregate indicator, but for now it's up to you to weigh them according to your priorities.

9. What you can do right now

There's no need to wait until August 2027 to factor these criteria into your hosting decisions. The data already exists, since sites above 500 kW have been reporting it since 2024.

1 Ask for the latest reported values. PUE, WUE and share of low-carbon energy submitted to the European database for 2025. An operator who hesitates to share them is already telling you something.

2 Question the measurement method. Is IT metering category 2 or 3? What percentage of the data halls is covered? Are generators included? These questions tell you whether the advertised PUE will hold up once it goes through the European methodology.

3 Tell GOs and PPAs apart. If decarbonization matters in your CSR policy, ask for the share of PPAs and recent guarantees of origin. An unqualified "100% renewable" claim won't be enough anymore.

4 Add the label to your specifications. For tenders that run beyond 2027, you can already require the official label as soon as it's published, or even set a minimum class. The Commission also indicates that the rating will serve as a reference in other EU legislation, including the upcoming Cloud and AI Development Act, and that it was taken into account in the revision of the Taxonomy delegated acts.

5 Think about your contract term. If you're signing for five years with a site rated F today, ask the operator for its improvement plan. With minimum standards possible by 2030, an inefficient site may have to carry out works while you're under contract.

Frequently asked questions

Is the data center energy label mandatory?

For data centers with at least 500 kW of installed IT power, effectively yes: they already report their data to the European database, and the label is generated automatically. Operators must provide it to anyone who asks. For sites below 500 kW and projects not yet in service, participation is voluntary.

When will the first labels be published?

By August 15, 2027 at the latest, provided the European Parliament and the Council do not object to the delegated regulation during the two-month scrutiny period.

What PUE do you need to get an A rating?

A PUE of 1.15 or less. Class G means a PUE above 1.9. For WUE, class A requires 0.1 liters of freshwater or less per kWh consumed by IT.

Will individual data center data be made public?

Only the information shown on the label, in the form in which it appears there, becomes public. The other reported indicators remain confidential as trade secrets.

Does the label replace building energy performance certificates?

No. According to the Commission, buildings housing data centers remain subject to the energy performance certificates required by the Energy Performance of Buildings Directive. The two schemes sit side by side without overlapping.

Conclusion: transparency switches sides

For years, PUE has been more of a sales pitch than a comparable indicator. With this label, it becomes public data, calculated using a common method and displayed next to the competition's. For operators, that's new pressure. For CIOs and infrastructure managers, it's above all a negotiating tool that has finally arrived.

The label doesn't replace a full assessment of a site: its location, occupancy trajectory, certifications, redundancy level and connectivity matter just as much when choosing colocation. But it will help you ask the right questions earlier, and spot the gaps between what's promised and what's delivered more quickly.

This is exactly what we set out to make easier at Datalok: bringing structured information about data centers and their operators together in one place, so you can compare colocation offers on objective criteria.

If you're preparing a hosting project and want to factor these new sustainability criteria into your selection, explore the Datalok Marketplace or get in touch with our team for support along the way.

Data center energy label: what the EU's A to G rating will change