Minimum performance standards for data centres: will the design on your desk clear them?

You set the design PUE of the data centre you are refurbishing by looking at current practice: what comparable facilities declare today. It is the wrong reference, and since yesterday a public number says so. Of the European data centres that reported to the Union database, about half sit above the reference values — and it is those values, not the market average, that underpin the minimum standard the Commission now proposes for new and refurbished facilities.

The first European census stopped at 36%

Report COM(2026) 500 final of 21 September 2026, on the energy efficiency of data centres in the EU, is a document declared by the Commission, not an act deposited in the Official Journal. It reads the first reporting period, May-September 2024, opened by Article 12(1) of Directive (EU) 2023/1791 — threshold: installed IT power of at least 500 kW; consolidated text 02023L1791 of 05.08.2026, markers ►B and ►M1 for Directive (EU) 2024/1788, no ►C, Article 12 untouched — and by Delegated Regulation (EU) 2024/1364, which set up the European database: deadlines 15 September 2024, 15 May 2025, then annual.

The sample: 770 data centres reported, «pari al 36 % circa del totale stimato dei centri dati soggetti all’obbligo di comunicazione nell’UE» — about 36% of the estimated total. And it is uneven: «Sei Stati membri hanno segnalato zero centri dati e cinque Stati membri ne hanno comunicati meno di tre» — six at zero, five below three. Eleven of twenty-seven: in much of the Union the obligation has not reached operators. Of what arrived, the report treats 70.1% as reliable.

The calendar counts too. Article 12(5) set a deadline: «Entro il 15 maggio 2025 la Commissione verifica i dati disponibili sull’efficienza energetica nei centri dati» — by 15 May 2025 the Commission reviews the data. The review came sixteen months late.

Half of them sit above the line

Section 3.3 is the passage for anyone designing: «circa la metà dei centri dati che hanno effettuato la comunicazione in Europa supera il valore di riferimento di 1,5 raccomandato per la PUE e/o il valore di riferimento di 0,4 raccomandato per la WUE» — about half exceed the recommended 1.5 PUE and/or 0.4 WUE.

Averages alone reassure: a weighted PUE of 1.36 in 2024 across 681 reliable facilities, a WUE of 0.58 across 458. But national averages run from 1.15 to 1.66 on PUE and from 0.07 to 1.28 on WUE. One line repays a second reading if you are sizing a new hall: «I centri dati più piccoli (500-1 000 kW) indicano una PUE media di 1,64, notevolmente superiore alla media» — 500-1 000 kW facilities average 1.64, well above the mean. The power band that triggers the obligation is the one performing worst.

What the database knows, and what it does not

The energy reuse factor (ERF): in the first period «solo 67 centri dati hanno segnalato un parziale riutilizzo del calore di scarto» — only 67 reported any waste heat reuse — and in the EU «si riutilizza circa l’1,8 %» — about 1.8% is reused — of the heat generated. Footnote 39 warns the figure may not fully represent the European picture. It is the indicator measured at the boundary of the facility: it demands plant that exists, and plant is what is missing.

The renewable energy factor (REF): an EU weighted average of 0.86, with over 70% of reported sites «copre già annualmente il 100 % del proprio consumo di energia elettrica con energia rinnovabile» — 100% renewable electricity, annually matched. The mirror image of ERF, until the next line: much of it comes from guarantees of origin or power purchase agreements «che non sono necessariamente collegati alla produzione locale o a nuovi contributi di produzione di energia rinnovabile» — not necessarily local or additional generation. One indicator measures plant, the other a contract.

You are already writing the label

Section 3.2 changes the value of a return already filed: «gli indicatori riportati sull’etichetta sono stati selezionati tra quelli già comunicati dai gestori dei centri dati alla banca dati europea» — taken from what operators already report — and «Le soglie sono state fissate sulla base dell’analisi dei dati del primo periodo di comunicazione» — thresholds set from first-period data. The calculation is automatic: platform automation «genererà etichette di classificazione alla fine di ciascun periodo» — will generate rating labels each period — and the label will be public in electronic form.

Nobody will ask for more data. The class comes from what you typed into the form, when it looked like a return to close by May. An indicator omitted for technical reasons, a category declared carelessly, a meter fitted where convenient rather than where prescribed: documentary discrepancies then, a public grade now.

The same section adds that «è stato adottato un secondo regolamento delegato relativo all’istituzione del sistema comune di classificazione dell’Unione» — a second delegated regulation on the Union rating scheme has been adopted; footnote 16 gives it as Delegated Regulation (EU) 2026/7000. It does not appear published in the Official Journal on this search: CELEX 32026R7000 is absent from Cellar, and on 18 September 2026 the 2026 numbering had reached 2026/2143. Delegated acts sit two months under Parliament and Council scrutiny: adopted is not published.

Minimum standards, and who they will apply to

Paragraph 5 calls for legislative proposals, the report says, «anche attraverso la definizione di norme minime di prestazione» — including by setting minimum performance standards; the Directive itself writes «tra cui norme minime di prestazione» — including minimum performance standards. The report proposes them for «tutti i centri dati nuovi o ammodernati in Europa» — all new or refurbished data centres in Europe — with possible thresholds on PUE, WUE and REF, or a combination, and a separate timetable for existing sites. First declared step: call for evidence, public consultation, impact assessment. No threshold is written yet.

The order of magnitude is reported by third parties, not measured: the Commission cites International Energy Agency estimates under which minimum standards would save «circa 65 TWh di energia l’anno a livello mondiale, di cui quasi 20 TWh in Europa» — about 65 TWh a year worldwide, 20 TWh in Europe.

What we do not know

The content of the label. The second delegated regulation does not appear published: indicators, thresholds and classes cannot be verified.
The Italian figure. Figure 1 breaks the count down by Member State, but in the rendering we consulted it is an image.
The sample behind REF. Footnote 40 writes «584 centri dati hanno comunicato valori WUE ritenuti affidabili» — 584 reported reliable WUE values — same wording as footnote 35, which for WUE gives 458; both language versions agree, so not a translation slip.
The consolidated delegated regulation. Version 02024R1364-20240517 is registered, hence unamended, but Cellar returns no text: we read the Official Journal version of 17.5.2024.
Standards behind a paywall. Footnote 34 states units «in linea con la norma EN 506400-4» — in line with standard EN 506400-4 — a designation with no catalogue match; of EN 50600-4 and ISO/IEC 30134 we cite number, title and status only.

The point

Between today’s return and tomorrow’s label there is no intermediate step: the same data, re-read by an algorithm. The game is played earlier, on the plant schematic. In the compliance specifications we deliver, the target PUE and WUE become a clause with its measurement category and its tapping point, verified at acceptance, not at the next reporting deadline. On the other axis, the twelve months of readings behind the indicators stop being a sheet filled in from memory each May: meters, temperatures, water flows, reused energy and as-built records converge into one map of the site, where an AI flags a stopped meter or the PUE drift that by December puts you above the line, and one of our teams acts before that value reaches the database. Where an AI is needed on that data, it runs inside the client’s perimeter, on-premise or in a dedicated cloud with data centres in Italy, together with CSIDIA, the group’s other company.

Are you sizing a new data centre, or a refurbishment above 500 kW, and want to know whether the design clears a minimum standard not yet written? Talk to an engineer: the site visit costs nothing, and the target value is decided on the plant schematic.