欧州のデータセンター報告は500kWから。様式は水についても尋ねている
改正エネルギー効率指令第12条は、IT機器の設置電力500kW以上のデータセンターに年次の報告義務を課す。報告内容を定める委任規則2024/1364は、エネルギーだけでなく水使用量や廃熱も対象とする。義務は二つ、行き先も二つ、期限は5月15日。
Most arguments about AI and energy in Europe are arguments about megawatts. How many a cluster will draw, which grid can carry it, who waits in the connection queue.
Europe already has a form that asks a wider question, and it has been in use since 2024.
The duty comes from Article 12 of the recast Energy Efficiency Directive, Directive (EU) 2023/1791. It catches a data centre with an installed IT power demand of 500 kW or more. Above that line, the operator reports every year. Delegated Regulation (EU) 2024/1364 sets what goes into the European database, drawing on its Annexes I and II.
The Swedish Energy Agency, which administers the scheme nationally, describes the content as information on the data centre’s energy use, its water use, its waste heat, and whether the facility contributes to grid services.
A megawatt figure tells you what a site takes off the grid. It tells you nothing about how much water the cooling plant evaporates in August, whether the heat leaving the building goes into a district network or into the sky, or whether the site can shed load when the system is tight. Those three are where the local argument about a data centre is actually conducted, and Europe has put them on a form.
500 kW is a low line
The threshold is set on installed IT power demand, not on the building’s total electrical capacity and not on floor area.
500 kW is small by the standards of the facilities that dominate the AI conversation. It is well below a single modern hall, let alone a campus. The scheme is therefore not a large-operator reporting regime with a long tail excluded. It reaches colocation suites, enterprise rooms and the kind of mid-sized facility that rarely appears in a market report.
A rating scheme that only measured the twenty largest sites in Europe would produce a number that moved with where those twenty happened to be built. A threshold at 500 kW produces a population.
Two duties, and they land in different places
The first duty is publication. Spain’s Ministry for the Ecological Transition, describing the same scheme from the other end of the continent, states that under Article 12 of Directive (EU) 2023/1791 the information in Annex VII of the directive is published annually, with a deadline of 15 May each year.
The second duty is the database. Under Delegated Regulation (EU) 2024/1364, operators register their data centres and report the information set out in Annexes I and II. The first deadline for that was 15 September 2024. Since then it has run on 15 May, the same date as the publication duty.
What comes back out of the database is not the same as what goes in. The Swedish Energy Agency is explicit: reported data will be available to the public in aggregated form, at member state and EU level, under Annex IV of Regulation 2024/1364. In Sweden the filed information also sits under statutory secrecy, by way of Chapter 30, Section 23 of the Public Access to Information and Secrecy Act (2009:400).
The European database will not be a site-by-site map of the continent’s compute. The aggregate is the output.
The site-level picture, where it exists, comes from the first duty, not the second. It comes from what operators publish themselves.
Anyone tracking the European AI build-out should read operator disclosures for site-level numbers and the register for trend lines.
The year being measured has already closed
Reporting runs a year behind, which is normal for energy data and easy to forget when reading a fresh filing.
Sweden’s current cycle makes the lag concrete. Notification to the Swedish Energy Agency is due by 27 April 2026. The report into the EU database is due by 15 May 2026. The data must cover the full year 2025.
A number published in May 2026 is therefore a 2025 number. If a site came online in March 2026, its first full year of operation will not appear anywhere in this scheme until 2027. For a building type whose European footprint is changing quickly, the register is structurally a rear-view mirror.
Annual energy data cannot be collected any faster than this. The caution is only against reading the first aggregates as a current picture.
National routes differ, and the detail matters
The directive sets the duty. Member states implement it, and the operational detail is national.
Sweden legislated through Act (2025:570) on the Disclosure of Information on the Energy Performance of Data Centres, in force on 1 July 2025. It added a national notification step ahead of the database filing, with its own earlier deadline. It also carved out an exemption: the obligation to notify and report does not apply to data centres used under the Protective Security Act (2018:585) for security-sensitive, defence or civil contingency purposes, or that serve such activities exclusively.
Information submitted to the authority in the notification step becomes a public document, so the agency advises including only the company name and company email address. The filing into the EU database is treated differently from the notification that precedes it, in the same scheme, in the same country.
Sweden’s two dates are sequential rather than parallel. The agency’s instruction is that after notification you apply for access rights to the EU database in order to report, so the April date is a gate on the May filing rather than a second task alongside it.
Spain’s ministry describes the same database duty from its own side, with operators registering each of their data centres individually and the Commission showing the aggregated data reported into it.
An operator with sites in several member states is dealing with one directive, one delegated regulation, and several national procedures underneath them. The 15 May date is common. Almost nothing else should be assumed to be.
A reporting duty caps nothing
It is worth being precise about the limits of the scheme, because it is easy to over-read.
It establishes a population and a dataset. Every EU data centre over 500 kW of installed IT power is counted and described on a common basis, annually, on water and waste heat as well as energy.
It does not, by itself, cap anything. There is no consumption limit in a reporting duty and no siting decision in a database. Those are national and local matters, and they are where the real constraints on European AI capacity are being set.
Once water use is a reported field rather than a contested estimate, a planning dispute about a site’s draw starts from a number instead of from a guess.
Japan measures the same thing with a different instrument
Japan has gone a different way on the same problem, and we covered it in Japan Added a Data Centre Table to Its Energy Report, and Set PUE at 1.4. Japan’s route runs through an existing energy reporting manual and attaches a benchmark figure to it. Europe’s route creates a dedicated register, sets a capacity threshold, and asks about water and heat alongside power.
The European AI conversation will get its numbers. They will arrive one year late, mostly in aggregate, and they will include the water.
Tech for Impact Summit 2027 is co-hosted by the United Nations University in Tokyo on 18 and 19 May 2027, an invitation-only gathering of leaders across business, policy and culture working on technology against the hardest problems. The energy and resources behind AI are on the agenda.