Edge data centre in a tender: ITU-T L.1306 does not fix the size
7 min read
The specification you are about to put out to tender carries the line “edge data centre”, and beneath it, as the technical reference, ITU-T L.1306. It looks as though the size of the thing has been pinned down. It has not: the only number in the whole Recommendation is preceded by the word generally, and the count derived from it is printed with the wrong unit of measurement. At acceptance you will have nothing to test against, and whoever is preparing the bid will have noticed that before you do.
A single number in twenty-two pages
Recommendation ITU-T L.1306, Specification of an edge data centre infrastructure, edition 02/2023, first edition, was approved on 22 February 2023 by Study Group 5, has been in the catalogue since 18 April 2023, is listed as In force and can be downloaded free of charge. Twenty-two pages, twelve figures, not one table.
The definition, clause 3.2.1, contains no measurements: “A data centre located near the final user in which it is necessary to finish relevant data processing in a short time and with low latency”. How near, how short: neither is stated, and neither is qualified anywhere later in the text. It is the same gap the companion Recommendation leaves on efficiency in micro data centres.
The size turns up further on, in clause 6, inside a bulleted list, and it turns up like this: “The scale of edge data centres in different scenarios can be different. Generally, the power of a single edge data centre does not exceed 250 kW”.
That adverb changes what kind of sentence this is. A value preceded by generally describes a population of installations; it does not delimit the object of a contract. A supplier delivering 320 kW is not in breach of L.1306, because L.1306 asked nothing of them. Nor is there a second sentence anywhere in the document that narrows the figure, attaches a tolerance to it, or says what follows if it is exceeded.
The cabinet count, printed in kilowatts
The very next sentence sets out to derive the number of cabinets from the power, and reads like this: “Given that the average power per servers cabinet is not less than 5 kW, the number of servers cabinet in an edge data centre does not exceed 50 kW”.
A count of cabinets expressed in kilowatts. The arithmetic behind it reconstructs itself without effort — 250 kW divided by 5 kW gives 50 — and the correct unit would be cabinets. It is a typographical error in a text that has been in force since February 2023: the catalogue lists no amendment and no corrigendum against the Recommendation.
This is not proofreading pedantry. Anyone who refers in a specification to clause 6 is also referring to that line, and under challenge the party reading it literally has the better case: the text fixes no number of cabinets at all. If you need a cabinet limit, you write it yourself, with its unit — and you write the power limit yourself as well, because the one in the text was never drafted as a limit.
Where they end up, and who is not there
Two characteristics in clause 6 carry direct contractual consequences. The first is the location: “Edge data centres are located near the physical body of users such as commercial buildings, factories, autonomous driving vehicle stations, etc.” Places where a data hall was never designed, and where the protections taken for granted elsewhere have to be asked for one at a time.
The second is staffing, and the Recommendation states it plainly: “Due to scattered arrangement, there is nobody on daily maintenance when the edge data centre is installed outdoors”. Read as a contractual fact rather than as a description, that sentence shifts the weight of the whole specification: whatever a duty engineer would otherwise catch on a walk-round has to be caught by instrumentation and by a response clause.
What can actually be copied
Clause 7 lists the composition — “a servers cabinet system, monitoring system, power feeding system, cooling system, cabling system and other components of the aisle” — and from there on, across clauses 8 to 11, the text is descriptive almost throughout. Almost: there is something that can be made binding, and there is little of it.
Three binary requirements, verifiable on sight or on the as-built drawings. Clause 9.1, where the data centre shares a building with other functional rooms: “there should have an independent cooling system”. Clause 9.3, with chilled water: “The key part of the cold water cooling system should have the same stand-by one”, and “it should be made sure that there is no water pipe routed from the indoor edge data centre”. Clause 10: “The lithium battery should comply with [ITU-T L.1221]”.
And two usable figures. Clause 9.3 gives the only thermal threshold in the document: above 6 kW of load per cabinet the heat exchanger of the in-row system takes over. Clause 8.2.2, on direct current supply up to 400 V, warns that the output voltage is not constant and that “each user can choose a different voltage such as 336 V or 240 V”. In a specification those two values are there to be chosen, not listed: cabinets wired for 240 V and equipment ordered for 336 V are a supply dispute, not a detail.
Figures that look like performance
Two efficiency figures remain, and it is worth knowing how they are written before quoting them. On the ECO mode of the modular UPS: “the total power efficiency can reach up to 99%”. On direct current supply: “the up to 400 VDC power products with different brands can reach up to 98%”. Can reach up to is not a guaranteed performance: the load point, the operating mode and the test standard are all missing. The words measurement, verification, acceptance and tolerance never appear in the document, and PUE is named seven times without once carrying a value. The count of the verbs confirms the shape of the text: across the normative body shall does not occur once — the only instance in the entire file sits in the cover note that explains what shall means — and the requirements are fifteen should.
The same holds for the system that, with nobody on site, is the watch itself. Clause 11 lists what to monitor — indoor temperature, relative humidity, air pressure difference, water leakage; on the electrical side “the switch state, current, voltage, power, power factor, harmonic distortion” — without a threshold, a sampling interval or a notification time, and it closes on a sentence that sits oddly in a specification: “It is apparent that safety can be totally guaranteed.” A monitoring system with no numbers in it cannot be tested, and it is precisely the part that stands in for the absent engineer at an unstaffed site. The alarm thresholds are still yours to write.
The point
A normative reference protects you only to the extent that somebody can be disproved by a measurement. In the compliance specifications we deliver, the word edge arrives with its numbers written by us — maximum site power and number of cabinets with its unit, thermal load per cabinet, the direct current voltage chosen between the two on offer, monitoring thresholds and notification times, stand-by provision for the critical parts — and every one of them is verified at acceptance, with the record and the documentation handed over together with the work. On the other axis, an unstaffed site produces data nobody looks at: temperature and humidity readings, flood alarms, UPS status, cabling as-builts. With us they converge into a single map of the site and the network, where an AI recognises the drift before the outage and a team of ours steps in, with no subcontracting. Where an AI is needed on that data, it runs inside the client perimeter, on-premises or in a dedicated cloud with data centres in Italy, together with CSIDIA, the other company in the group.
Are you writing the edge data centre line of a tender, or do you have to accept a supply that declares compliance with L.1306? Talk to one of our engineers: the site visit is free of charge, and a size is written so that it holds up under challenge.