Data centres: the dossier that makes a PUCD application admissible
7 min read
Anyone who has bought the site, obtained the grid connection offer and taken the environmental impact study to final draft has one number in mind: ten months. That is the maximum duration of the single procedure that authorises a data centre in Italy. Those ten months do not start on the day the application leaves by certified email, and a spreadsheet filled in outside the prescribed scheme is enough to stop them starting.
Ten months that begin with a check
Article 8, paragraph 4, of decree-law 21 of 20 February 2026, converted with amendments by law 49 of 10 April 2026, sets a duration «non superiore a dieci mesi, decorrente dalla data di verifica della completezza della documentazione di cui al comma 3» — no longer than ten months, running from the date the documentation under paragraph 3 is verified as complete. We described the charges, the permit boundary and the points at which the clock restarts when the first operational guidance came out.
On 27 July 2026 the Directorate-General for environmental assessments published the missing part: the application template, Annex 1, the public notice and the technical specifications for documentation in electronic format, version 1 of 24 July 2026. Fifteen pages that say nothing about environmental impacts: they talk about folders, file names, signatures and bytes. And they decide whether the application is admissible.
The sentence to read first
On the list of documents, the specifications state that «la mancata adesione del proponente al suddetto schema di predisposizione dell’elenco degli elaborati, impedendo all’Autorità Competente la corretta pubblicazione del progetto sul proprio sito web, di fatto costituisce motivo di non procedibilità della relativa istanza» — failure to follow that scheme prevents the Competent Authority from publishing the project on its website and in practice makes the application inadmissible.
The scheme is an XLS or CSV with one row per file: identifier, title, author, description, type (D for drawings and maps, R for text documents), scale, access rights, language, date, file name, size, path, extension. The rules are purely formal: no changes to column names or count, no empty rows or columns, no merged cells, no comments, no hyperlinks. The file stays outside the folders. The ministry distributes the empty format and GELAB, which generates it partly pre-filled.
Two constraints then propagate across the whole dossier. The identifier and the file name must match and stay within forty characters; the path allows no spaces and none of the special characters the specifications list, among them &, %, #, @, the apostrophe and accented vowels. At every later submission file names must differ from those already sent: anyone versioning with a revision suffix finds out late that forty characters are few.
Folders whose names are already written
The tree is not the proposer’s to choose. PUCD_0 holds the administrative documentation: application, public notice, calculation of the charges, payment receipts, sworn declaration of the value of the works, economic framework. Then come the AIA folders — document list, Forms A to E, non-technical summary, supplements — and sixteen EIA folders, PUCD_VIA_1 to PUCD_VIA_16, one per block: design documents, environmental impact study, non-technical summary, monitoring, appropriate assessment, landscape, health impact, excavated soil and rock, counter-arguments, supplements. Finally DATI_GIS and one PUCD_TITOLI_N folder for each further consent, with N in sequence.
This is where the cross-constraint bites. The Annex 1 template — the list of authorisations, agreements, licences, opinions, concurrences, clearances and consents — has a column headed «Cartella», folder: for each consent the proposer states where its supporting documents are stored. The list of consents and the folder tree match row by row, and every consent added along the way — a fire-safety clearance, a discharge permit, a heritage opinion — adds a folder, shifts the sequence and forces a rewrite of the document list.
DATI_GIS holds the part that network designers underestimate most often: shapefiles in WGS84 (EPSG 4326) or ETRF2000 at 1:10,000, with the data centre boundary, the connected works — the specifications name the duct or cable route to the transmission grid — the site works and a single polygon for the overall footprint. The duct is not a dashed line on a drawing: it is an information layer with its attribute table filled in and a metadata file of the same name with the MET suffix.
A signature on every file, thirty megabytes per document
Every document transmitted, except the document list and the GIS data, must be digitally signed in PAdES with a PDF extension by everyone responsible for its technical content. Files must not be compressed or exceed 30 MB; heavier drawings split into parts linked by a progressive number in title and file name. The cover carries full title, proposer, date, and the professional body and registration number of the engineers; inside, an index with hyperlinks and page numbers.
Transmission remains transitional: certified email with a single ZIP up to 50 MB total; above that, hand delivery on a hard disk or pen drive write-protected against modification, with a «leggimi» — readme — file outside the folders. For a data centre, where the impact study and its drawings alone comfortably exceed half a gigabyte, the second route is the rule.
The dossier exists in two versions
This is the point that most concerns anyone working on the infrastructure. There are folders reserved for documentation the proposer, on grounds of industrial or commercial secrecy, asks not to be made public: PUCD_VIA_13 for the EIA, PUCD_AIA_INT_RIS for the integrated environmental permit, PUCD_TITOLI_RIS_N for the other consents, plus their supplement variants. Two versions of the same document are submitted: one for public consultation, showing what has been omitted, one complete for the competent authority. Personal data goes in the same folders.
It means the same drawing exists twice, the two versions stay aligned at every revision, and one file in the wrong folder publishes the full layout of routes and entry paths on a public portal. In a data centre that layout is the list of points at which the network can be cut.
What we do not know
- The «Procedure in corso» report on the environmental assessment portal has no entry for the single data centre procedure: how many PUCD applications have been filed since 27 July is not publicly available.
- The public notice template allows thirty days for observations, consistent with halving the ordinary sixty-day term of article 24, paragraph 3, of legislative decree 152/2006. For projects under article 8, paragraph 2-bis, of the same decree, where the ordinary term is already thirty days, the published documents do not say whether the halving still applies.
- For hand delivery the specifications give Via Cristoforo Colombo 70, while the application template gives number 44: worth confirming before the courier leaves.
- The specifications are version 1 with no updates, and the online procedure is announced but not described: the certified email route is the only one documented.
The point
A PUCD dossier is a corpus of hundreds of documents with cross-references, deadlines and a confidential part required by the rules: it is not material to upload to a cloud service for convenience. On the part that falls to us we work on two fronts. The network documents we produce — entry-path layouts, duct routes, patching schedules, test reports — leave in the form the procedure demands: names within forty characters, PDFs signed in PAdES, covers with professional body and registration number, matching row in the document list, shapefiles with attributes filled in; the same clause goes into the specification for the other suppliers, and is checked on acceptance. Then, once the permit is issued, those files must not become a dead archive: traces, measurements, as-built records and alarms become a single map of the network, where every section stays tied to the document that authorised it, and on that map an AI makes the diagnosis while a crew closes the fault. Because the dossier contains, by construction, material from the confidential folders, that AI runs inside the client’s perimeter — on-premise or dedicated cloud with data centres in Italy — together with CSIDIA, the other company in the group. Our own crews, no subcontracting. It is the work we follow from survey to certification.
Do you have to assemble a PUCD dossier, or check that network documents already produced hold up to the format? Talk to an engineer: it helps to work out what must be redone and what only needs renaming.