Infrastructure — Measurement

Every indicator the European Union asks for at five hundred kilowatts, produced at twenty.

Instrumentation is standard on every system, wired to the reporting schema before it leaves.
The threshold

Article 12 of the Energy Efficiency Directive obliges data centres at or above five hundred kilowatts of installed IT power to report annually[src]. Delegated Regulation (EU) 2024/1364 fixes the schema at twenty-four data points across energy, sustainability indicators, capacity and traffic[src]. The first return covered 2023 and was due in September 2024; returns are due each 15 May thereafter[src].

Two things follow. First, Member States may lower the threshold and may not raise it[src], so a facility below five hundred kilowatts at Union level can still be in scope nationally. Second, the reporting schema is a good schema. It is the product of a long argument about what is worth measuring in a data centre, and the fact that a smaller facility is exempt from filing it is not an argument for not producing it.

Our systems produce it regardless of size.

Indicators

The four reported indicators[src], each against the standard that defines it[src].

PUE
Power Usage Effectiveness

Total facility energy divided by IT equipment energy.

ISO/IEC 30134-2 · EN 50600-4-2
WUE
Water Usage Effectiveness

Site water consumption per unit of IT equipment energy.

ISO/IEC 30134-9
ERF
Energy Reuse Factor

Energy exported for reuse as a proportion of total facility energy.

ISO/IEC 30134-6 · EN 50600-4-6
REF
Renewable Energy Factor

Renewable energy as a proportion of total facility energy.

ISO/IEC 30134-3
The category is the claim

A Power Usage Effectiveness figure without its measurement category is not a measurement.

The standard defines categories that differ in where energy is measured and how often. Measure at the uninterruptible power supply output rather than at the rack, sample monthly rather than continuously, and the same facility reports a materially different number — a better one[src].

This is why the industry’s published figures are not comparable with each other, and why we print the category beside every value we produce. A number you cannot reproduce is a number you cannot use in a procurement.

How it is measured
Measurement stack
Platform telemetryRedfish DSP0266[src]Vendor-neutral HTTPS and JSON interface for power and thermal metrics
Processor energyOn-die energy countersPer-package and per-domain accumulation, sampled continuously
Facility energyPer-outlet PDU meteringDetermines the measurement category that can be claimed
EnvironmentalInlet and outlet temperature, humidity, loop supply and return
WaterMake-up and blowdown meteringWhere an evaporative stage is present
Heat exportSecondary-side thermal meteringEnergy Reuse Factor is instrumented whether or not an offtake is connected
Report schemaDelegated Regulation (EU) 2024/1364[src]Field-for-field, exportable on demand
Facility standardEN 50600 series[src]
Discipline

Directive (EU) 2024/825 restricts environmental claims that cannot be substantiated, and the FTC Green Guides do the same in the United States[src][src]. A comparative efficiency percentage without a stated workload, standard, measurement point and date is not substantiated in either market.

So we publish measurements, not comparisons. Every figure that leaves a system carries the workload it was taken under, the standard it was taken against, the point it was taken at and the date. Where a Union rating scheme is not yet in force, nothing claims a rating[draft].