EU data centre energy and sustainability reporting

Article 12 of the recast Energy Efficiency Directive requires annual energy-performance reporting for data centres with at least 500 kW of installed information technology power demand. Commission Delegated Regulation (EU) 2024/1364 defines the information, indicators and measurement methods for the European database on data centres.

The return is an annual site record. It joins equipment inventory, facility boundaries, energy, water, cooling, renewable energy, information technology capacity and data traffic. A live monitoring system can supply some of those inputs, but it does not make the report compliant by itself.

Apply the 500 kW threshold to installed IT equipment

Installed IT power demand, PD IT, is the sum of the nominal power demand of the networks, servers and storage equipment installed in the data centre computer-room floor area. The Commission's July 2026 guidance calls this the equipment's nominal or sticker power. It is different from:

• the highest kW recorded at the utility incomer;
• the UPS output observed on a busy day;
• the contracted utility capacity;
• the design capacity of empty racks or future phases;
• the sum of several data centres at different sites.

The threshold is at least 500 kW, so a data centre at exactly 500 kW is in scope. It applies even when the equipment rarely draws its nominal demand. If installed IT power demand cannot be determined, Annex II allows the rated IT power demand to be used instead. That is the maximum IT load the power-distribution and environmental-control infrastructure can support at the required availability. The return must state which measure it uses.

Assess each physical site. Data centres at different addresses or physical perimeters are separate, even where one operator owns them. Within one site, several computer rooms or structures may be reported together. The Commission's guidance gives an example of two 300 kW rooms at one site: together they form a 600 kW data centre that reports. Two 600 kW rooms at that site can be reported separately or together.

Article 12 excludes data centres used for, or providing services exclusively with the final aim of, defence and civil protection. It does not create a general exemption for a mixed-use building, an enterprise server room or a colocation site.

Annual reports cover the preceding calendar year

Delegated Regulation 2024/1364 sets the continuing deadline at 15 May every year. Each return covers the calendar year immediately before the reporting year. A site that operated for only part of that year reports its operating period and states the dates covered.

Reporting goes through a national reporting scheme where the Member State has established one. Otherwise, the operator communicates directly to the European database. The Directive refers to owners and operators, while the Delegated Regulation places the database communication on the reporting data centre operator. Record who owns the building, who operates the data centre, who owns each source record and who submits the return. Check the national arrangement rather than assuming that a landlord, tenant or service provider has done it.

The first reporting deadline was moved to 15 September 2024. The temporary rules that allowed selected indicators to be omitted for technical reasons in the first period, and selected colocation indicators to be estimated during the first two periods, were transition provisions. They are not a standing permission to leave current annual fields blank.

What the annual return covers

Annex I identifies the data centre and its operation. Annex II supplies the measured and calculated inputs.

The database calculates four sustainability indicators from the submitted values:

• PUE = total data centre energy / IT equipment energy;
• WUE = total water input / IT equipment energy in MWh;
• ERF = reused waste heat / total data centre energy;
• REF = total renewable energy / total data centre energy.

The Commission publishes aggregated results at Member State and Union level. Individual data-centre information and indicators are kept confidential by the Commission and the Member State under Article 5 of the Delegated Regulation.

Fix the energy boundary before collecting totals

Total data centre energy, E DC, includes electricity, fuels and other energy sources used for cooling. Measure it at the input of the data centre system, before the supply transfer switchgear. Put measurement points on the primary supply, secondary supply and every additional source.

Backup generation is both inside the total and separately visible as E DC-BG. Include maintenance runs and load-bank or routine tests as well as operation during a supply failure. The Commission guidance says to count energy from backup generators of all types in kWh. A fuel delivery total is not automatically generator output energy. Record whether the source is a generator electrical-energy meter, a fuel input converted through an accepted method, or another measurement permitted by the reporting method.

Cogeneration and absorption chilling need an explicit boundary:

• when the equipment is inside the data centre system, measure fuel at its input;
• when cogeneration is external, measure electricity and heat at its outputs;
• when an absorption chiller is external, measure at the cooling output.

IT-equipment energy, E IT, is the combined annual energy at every UPS connected to IT equipment, using the category 1 PUE method in EN 50600-4-2 or an equivalent method. Where there is no UPS, Annex II allows measurement at the PDU, through the category 2 method, or at another point that the operator specifies.

Use one annual cut-off for every total. A facility figure from midnight on 1 January to midnight on 1 January cannot be divided by an IT figure built from billing months or local time intervals without documenting and correcting the mismatch.

Treat cooling, water and heat as measured boundaries

Cooling affects several fields rather than one cooling-energy total. Its electricity, fuel, heat or cooling input belongs in E DC. The return also carries the intake-air setpoint, refrigerant types, cooling degree days, water inputs, waste-heat temperature and reused heat.

Total water input, W IN, covers all water crossing the data centre boundary for data centre functions, including environmental control, power, security and IT. Total potable water input, W IN-POT, is a separate subset. The Commission guidance excludes sanitary water for toilets, showers, kitchens and other activities unrelated to data centre operation.

Use EN 50600-4-9 WUE category 2 for total water input, or category 1 where category 2 is not possible, or an equivalent standard. State the category used. Potable water uses category 1 or an equivalent method. Where a data centre sits in a building whose main use is different, report only the water used, or estimated as used, by the computer rooms and equipment needed to operate them.

Waste heat counts as reused only when it crosses the data centre boundary and substitutes for energy outside that boundary. Measure it at the hand-off to the receiving party. Heat recirculated internally for data centre cooling is subtracted. Average waste-heat temperature is measured where the heated cooling fluid reaches the heat exchanger at the computer-room boundary.

The JRC's Data Centre Code of Conduct is useful for improving cooling and energy performance, and Article 12 asks Member States to encourage its current best practices at sites of at least 1 MW installed IT demand. Participation in the voluntary Code and implementation of a good practice are separate from the annual reporting obligation.

Keep a ten-year measurement register

Annex II requires operators to keep a record of the measurement points and devices used for at least ten years. The Regulation does not prescribe the layout of that record. A defensible working register can contain:

Preserve the version used for each return. Editing the current diagram is not enough, because the ten-year record must still show which point and device produced an earlier figure.

Put limits around estimates and repaired data

An estimate needs a stated regulatory basis and a reproducible method. The Commission guidance recognises estimates where a cooling or electrical system serves both the data centre and unrelated space and specific metering is absent. It gives similar guidance for shared cooling water. In those cases, record the shared meter, allocation driver, period, calculation and uncertainty. Replace the estimate with direct measurement when practical, but do not rewrite an earlier return without following the reporting scheme's correction process.

Use status alongside every interval: measured, estimated, substituted, missing or invalid. Keep raw cumulative registers as well as interval values. They help detect these common failures:

• a meter replacement resets the register during the year;
• a current-transformer ratio or pulse multiplier changes without a dated record;
• backup generation appears at an internal meter but is missing from the facility total;
• a UPS bypass changes the IT measurement boundary;
• a shared chiller or cooling tower is allocated twice or not at all;
• potable and non-potable water sources are combined without retaining the split;
• daylight-saving or time-zone handling creates a gap or duplicate hour;
• a missing month is silently filled with a normal month, hiding the estimate.

Reconcile each annual result in both directions. Compare interval sums with opening and closing registers, and compare the sum of supplies with the downstream IT and facility loads. Explain the difference through known losses, unmetered loads, shared services and time alignment. Do not force a balance by scaling every submeter to the utility bill.

Close the reporting year as a controlled dataset

A practical annual close has six steps:

1. Confirm the physical site, rooms, structures and installed IT inventory used for the 500 kW test.
2. Freeze the meter and device register for the year, including changes, bypasses and periods out of service.
3. Export raw annual registers and interval data, with quality status and time-zone information.
4. Calculate each Annex II input with the named standard, category, boundary and approved estimate method.
5. Reconcile energy and water totals, then have the operator review exceptions and source evidence.
6. Submit through the national route or European database and retain the submitted values, calculations and acknowledgement with the source record.

PUE and WUE are annual ratios built from matched inputs. A real-time dashboard value can help find an operating fault, but it is not the annual value unless it uses the same boundary, method and complete reporting period.

Where EpiSensor fits

EpiSensor can measure electricity at selected facility, UPS, cooling and distribution supplies, and can collect documented pulses or registers from existing water and energy meters. Edge can retain interval readings on site and export them for the operator's annual calculation and evidence pack.

This supports boundary checks, annual reconciliation, missing-data review and investigation of cooling or backup events. It does not determine whether a site is legally in scope, replace the prescribed EN 50600 or equivalent method, validate a national allocation, submit to the European database or certify compliance.

Start with the data centre power monitoring guide to map the facility and IT energy points. Use the energy monitoring project worksheet to assign each source, calculation and annual review before choosing devices.