ISO/IEC 30134 Data Centre KPIs
Everyone in the data-centre industry quotes PUE, far fewer know it is only one of nine standardised metrics, and almost no one knows the standard deliberately refuses to combine them into a single score.
ISO/IEC 30134 is not a metric — it is a suite, designed to be read together precisely because no single number tells the truth about a data centre.
ISO/IEC 30134 is the international series of data-centre key performance indicators developed by ISO/IEC JTC 1/SC 39. It defines nine parts — including PUE, REF, ITEEsv, ITEUsv, ERF, CER, CUE, and WUE — under a common framework, with no targets and no single aggregate score by design.
Executive Summary
ISO/IEC 30134 is the international standard series that defines how data-centre performance is measured. Under the general title “Information technology — Data centres — Key performance indicators,” it sets out a holistic suite of metrics — energy, renewables, IT utilisation, heat reuse, cooling, carbon, and water — each in its own numbered part, all built on a shared framework in Part 1. The series is the reason a PUE figure means the same thing in Frankfurt as in Singapore, and the reason regulators can demand comparable numbers across thousands of facilities.
Three design decisions define the series and are routinely misunderstood. First, it sets no limits or targets — the standard tells you how to measure, not what counts as good; thresholds come from regulators and national law. Second, it explicitly does not aggregate the KPIs into a single combined score, because compressing energy, water, carbon, and utilisation into one number destroys the information each is designed to carry. Third, it separates infrastructure metrics from IT-equipment metrics, because the operator controls one and the tenant controls the other. A sustainability team that treats the suite as a dashboard — several gauges read together — uses it correctly; one that fixates on a single metric uses it badly.
(1) It is a multi-part series, not a single standard — nine parts, each defining one KPI or the common framework. (2) Part 1 sets shared terminology, boundaries, and rules; Parts 2–9 define the individual KPIs. (3) It specifies no targets and no aggregate score by design. (4) The KPIs split into infrastructure metrics (PUE, REF, ERF, CER, CUE, WUE) and IT-equipment metrics (ITEEsv, ITEUsv). (5) The EU EED mandates reporting of four of them — PUE, WUE, ERF, REF — making the series a compliance backbone, not just an operational convention.
Provider directory
Now you need somewhere to keep it.
See who does this work. Every listing names the standards it works to, and paid placements are labelled. Including Terrascope and Preoptima.
Browse 3 carbon software providers →Do this work? A listing is US$390 a year. Get listed →
What the ISO/IEC 30134 Series Is
The ISO/IEC 30134 series is a family of international standards, each defining a single key performance indicator for data-centre resource use, sitting on a common foundation. It is developed jointly by ISO and IEC because data centres sit at the intersection of information technology (ISO’s domain) and electrotechnical systems (IEC’s domain). The series is technology-neutral and geographically neutral: the same KPI definition applies to a hyperscale campus, a colocation hall, and an enterprise server room, anywhere in the world.
A deliberate vocabulary choice runs through the whole series. It prefers “resource usage effectiveness” over “efficiency,” reserving “efficiency” for the narrow case where the input and output of a ratio share the same units. PUE, for example, divides energy by energy, so it is technically an efficiency — but the series uses “effectiveness” for continuity across metrics whose inputs and outputs differ, such as water per unit of energy. The distinction is pedantic until an auditor challenges it, at which point it matters.
Critically, the series is aimed at operational measurement and improvement, not facility design. The question “how is this running?” is ISO/IEC 30134’s domain; the question “how should this be built?” belongs to the data-centre design standards. For that design layer, see the ISO/IEC 22237 / EN 50600 data-centre design reference, and for the energy-management system that operationalises continual improvement against these KPIs, the ISO 50001 Energy Management reference.
The Nine Parts at a Glance
The series comprises a framework part and eight KPI parts. The table below is the canonical map. Edition years are a June 2026 snapshot — individual parts revise on independent five-year cycles, so always confirm the current edition against ISO for any formal citation.
| Part | KPI | Acronym | What it measures | Family | Edition (snapshot) |
|---|---|---|---|---|---|
| 30134-1 | Overview and general requirements | — | Common structure, terminology, boundaries, and rules for all KPIs | Framework | 1st ed. |
| 30134-2 | Power Usage Effectiveness | PUE | Total facility energy ÷ IT equipment energy | Infrastructure | 2nd ed., 2026 |
| 30134-3 | Renewable Energy Factor | REF | Share of facility energy from renewable sources | Infrastructure | 1st ed. |
| 30134-4 | IT Equipment Energy Efficiency for servers | ITEEsv | Energy-efficiency characteristic of servers (via benchmarks) | IT equipment | 2017, Amd 1:2025 |
| 30134-5 | IT Equipment Utilization for servers | ITEUsv | Utilisation of servers in the data centre | IT equipment | 2017 |
| 30134-6 | Energy Reuse Factor | ERF | Share of energy reused outside the data centre (e.g. waste heat) | Infrastructure | 2021 |
| 30134-7 | Cooling Efficiency Ratio | CER | Cooling output relative to cooling energy input | Infrastructure | 2023 |
| 30134-8 | Carbon Usage Effectiveness | CUE | CO₂e emissions per unit of IT equipment energy | Infrastructure | 2022 |
| 30134-9 | Water Usage Effectiveness | WUE | Water consumed per unit of IT equipment energy | Infrastructure | 2022 |
Of the nine parts, PUE has the deepest operational history and the most regulatory weight. It has its own full reference on GreenCalculus — see the Uptime Institute PUE (Power Usage Effectiveness) deep-dive for the formula, the PUE0–PUE3 measurement categories, the boundary edge cases, and the gaming vectors. This page covers PUE only as one member of the suite.
Part 1 — The Common Framework
ISO/IEC 30134-1 is the part nobody quotes and everybody depends on. It defines the shared scaffolding that makes the individual KPIs comparable: a common structure for how each KPI is specified, the definitions and terminology used across the series, the boundary conditions that fix what is and is not inside the measurement, and the common objectives and usage guidance. Every other part is “produced in accordance with” Part 1, which is why a KPI defined in Part 8 uses the same boundary logic as one defined in Part 2.
Two of Part 1’s rules shape how the entire suite must be read.
The series sets no limits or targets for any KPI — it standardises measurement, not acceptability. And it explicitly does not combine the individual KPIs into a single overall score. There is no “ISO/IEC 30134 rating.” Any vendor presenting one combined data-centre efficiency number “per ISO 30134” is going beyond the standard. The KPIs are designed to be monitored together, each preserving the dimension it measures.
The “no aggregation” rule is the most important and least understood feature of the series. It is a deliberate refusal to let a strong score on one axis hide a weak score on another. A facility can have an excellent PUE and a terrible CUE; combining them would mask exactly the trade-off a sustainability team needs to see. Part 1 forces the suite to stay disaggregated so that each KPI remains diagnostic.
The Two KPI Families
The eight KPIs split into two families along the line of accountability. Infrastructure metrics describe the facility — the building, power chain, cooling, water, and energy sourcing — which the operator controls. IT-equipment metrics describe the servers — their efficiency and utilisation — which the tenant or IT team controls. The split matters because it tells you who can move each number.
| Family | KPIs | Describes | Owner |
|---|---|---|---|
| Infrastructure | PUE, REF, ERF, CER, CUE, WUE | Facility energy overhead, renewable sourcing, heat reuse, cooling, carbon, and water | Facility operator |
| IT equipment | ITEEsv, ITEUsv | Server energy efficiency and server utilisation | Tenant / IT team |
The accountability split is why PUE alone is a weak management tool in a colocation context. The operator can drive PUE down by improving cooling and the power chain, but if tenants run idle, over-provisioned servers, the facility wastes most of its compute regardless of how good the infrastructure number looks. The IT-equipment family — ITEEsv and ITEUsv — exists to make that waste visible, and it sits outside the operator’s direct control.
The KPIs in Depth
Concise definitions of each KPI follow. PUE is treated in full on its own reference page; the others are defined here at the depth a practitioner needs to read a reported figure correctly.
PUE — Power Usage Effectiveness (Part 2)
Total facility energy divided by IT equipment energy. The headline infrastructure metric, with a theoretical floor of 1.0 and no upper bound. Standardised measurement categories (PUE0–PUE3) distinguish estimate from continuously measured figures. Full treatment, including the formula, the categories, and the limitations, is in the PUE deep-dive.
REF — Renewable Energy Factor (Part 3)
The share of the data centre’s energy that comes from renewable sources. REF is the bridge between an energy-overhead metric like PUE and the carbon picture: a low PUE on a high-REF facility is genuinely low-impact, while a low PUE on a zero-REF facility is efficient but not clean. REF interacts directly with renewable procurement — power purchase agreements and certificates — governed by the RE100 Technical Criteria and operationalised through energy attribute certificates.
ITEEsv — IT Equipment Energy Efficiency for servers (Part 4)
A characteristic of the servers themselves: how much useful work they deliver per unit of energy, assessed through server performance benchmarks. ITEEsv is a technical KPI rooted in the design and procurement of hardware rather than the running of the facility — it tells you whether the IT estate is efficient by construction.
ITEUsv — IT Equipment Utilization for servers (Part 5)
How heavily the installed servers are actually used. Low utilisation is the silent waste of the data-centre industry: a server drawing power at 10% load is mostly converting electricity into heat for no useful output. ITEUsv exposes this, and it is the metric that explains why a facility can post a good PUE while wasting most of its energy — PUE rewards a larger IT denominator regardless of whether that IT load does useful work.
ERF — Energy Reuse Factor (Part 6)
The share of energy that is reused outside the data centre, most commonly through waste-heat capture feeding a district heating network or a neighbouring building. ERF is the metric that lets a data centre claim credit for turning its largest by-product — heat — into a useful output rather than dumping it. It is a rising regulatory priority, with waste-heat reuse targets appearing in national law.
CER — Cooling Efficiency Ratio (Part 7)
Cooling output relative to the energy consumed to produce it. CER drills into the single largest component of non-IT overhead in most facilities — the cooling system — and isolates its performance from the rest of the power chain. It applies to electrically powered cooling; heat-driven cooling sits outside its scope.
CUE — Carbon Usage Effectiveness (Part 8)
The carbon-dioxide-equivalent emissions associated with the data centre’s energy, expressed per unit of IT equipment energy. CUE is the series’ carbon KPI and the natural connection point to greenhouse-gas accounting — but it is a facility efficiency ratio, not a Scope 2 inventory figure, a distinction developed in the carbon-bridge section below.
WUE — Water Usage Effectiveness (Part 9)
The water consumed per unit of IT equipment energy, capturing the often-overlooked water cost of cooling. WUE matters because the cooling strategies that minimise PUE — particularly evaporative cooling — can dramatically increase water use, creating a direct trade-off between energy efficiency and water consumption that a single energy metric hides entirely.
Evaporative and adiabatic cooling can push PUE toward 1.1 while consuming large volumes of water. A facility optimising PUE in isolation can quietly become a major water consumer in a water-stressed region. This is precisely why the series refuses to aggregate: PUE and WUE pull in opposite directions, and only reading both reveals the trade-off.
Governance: ISO/IEC JTC 1/SC 39 and the Green Grid Origin
The ISO/IEC 30134 series is developed by ISO/IEC JTC 1/SC 39 — the joint ISO/IEC subcommittee for “sustainability for and by information technology” — through its Working Group 1. JTC 1 is the joint technical committee that ISO and IEC operate together for information technology; SC 39 is its subcommittee dedicated to the energy and environmental performance of IT and data centres.
PUE, the metric that anchors the series, did not begin at ISO. It was created by The Green Grid, an industry consortium, in 2007. The Green Grid subsequently passed ownership, development, and standardisation of the metric to ISO/IEC JTC 1/SC 39, which is why “genuine” PUE today means PUE as defined by ISO/IEC 30134-2, not the original white-paper version. The Green Grid’s assets and ongoing practitioner stewardship now sit within Uptime Institute. This three-stage lineage — industry originator (The Green Grid), steward (Uptime Institute), and formal standards body (ISO/IEC JTC 1/SC 39) — is covered in full on the PUE reference page.
Each part of the series is reviewed on a roughly five-year cycle and revised or confirmed independently. This is why the series carries a mix of edition years — Part 2 reached its second edition in 2026 while other parts remain on their first edition with amendments. There is no synchronised “version of the whole series”; each KPI evolves on its own schedule, and a formal citation should always name the specific part and its current edition.
ISO/IEC 30134 vs EN 50600-4 — The European Mirror
European practitioners encounter these KPIs twice: once as ISO/IEC 30134 and once as EN 50600-4, the CENELEC standard series. The two are near-identical by design — EN 50600-4 adopts the ISO/IEC 30134 KPI definitions into the European standardisation framework, so a metric measured to one is measured to the other. The practical value of knowing the mapping is that EU regulatory and contractual documents frequently cite the EN number rather than the ISO number.
| KPI | ISO/IEC | EN 50600-4 (CENELEC) |
|---|---|---|
| PUE | 30134-2 | EN 50600-4-2 |
| REF | 30134-3 | EN 50600-4-3 |
| ITEEsv | 30134-4 | EN 50600-4-4 |
| ITEUsv | 30134-5 | EN 50600-4-5 |
| ERF | 30134-6 | EN 50600-4-6 |
| CER | 30134-7 | EN 50600-4-7 |
| CUE | 30134-8 | EN 50600-4-8 |
| WUE | 30134-9 | EN 50600-4-9 |
The broader EN 50600 series also covers data-centre design and facility standards that sit alongside the KPI parts — the design layer that ISO/IEC 30134 deliberately stays out of. That design-and-facility material is covered in the ISO/IEC 22237 / EN 50600 data-centre design reference.
How the KPIs Interlock
The suite is engineered so that each KPI catches what the others miss. Reading them together is not optional best practice — it is the intended use, and the “no aggregation” rule exists to enforce it. Three illustrative cases show why a single metric always lies by omission.
PUE hides carbon → CUE catches it
A facility with PUE 1.1 on a coal-heavy grid is efficient but high-carbon. PUE cannot see the grid factor; CUE and REF can. Energy overhead and carbon intensity are independent axes.
PUE hides idle servers → ITEUsv catches it
A facility can lower PUE by running more servers, even inefficiently, because overhead spreads across IT load. ITEUsv exposes whether that IT load does useful work. Infrastructure efficiency and IT productivity are independent axes.
PUE hides water → WUE catches it
Evaporative cooling cuts PUE while consuming water. A facility can optimise energy and quietly become a heavy water user. Energy efficiency and water consumption are independent axes.
The series has been published part by part over more than a decade as each KPI matured through the standards process. The approximate publication arc of the suite:
| Point | parts published |
|---|---|
| 2016 | 2.00 parts published |
| 2017 | 4.00 parts published |
| 2021 | 5.00 parts published |
| 2022 | 7.00 parts published |
| 2023 | 8.00 parts published |
| 2026 | 8.00 parts published |
The build-out matters for one practical reason: a KPI that was a committee draft three years ago may now be a published standard, so a measurement programme designed against an older snapshot of the series may be missing parts — most recently CER (Part 7) and the carbon and water metrics (Parts 8 and 9) — that are now available and, in the water case, regulatorily required.
CUE and the Carbon Bridge
CUE — Carbon Usage Effectiveness, Part 8 — is the series’ carbon metric, and the point where ISO/IEC 30134 meets greenhouse-gas accounting. CUE expresses the carbon-dioxide-equivalent emissions associated with the facility’s energy per unit of IT equipment energy. Conceptually, it links to PUE through the grid: the carbon per unit of IT energy reflects both how much total energy the facility draws (the PUE relationship) and how carbon-intensive that energy is (the emission factor).
CUE and a GHG Protocol Scope 2 number answer related but different questions. CUE is a normalised efficiency ratio for benchmarking a facility against itself and others. Scope 2 is an absolute inventory figure, reported in two parallel methods — location-based and market-based — under strict accounting rules. They use overlapping data but are not interchangeable: a CUE figure cannot be dropped into a corporate inventory in place of a properly calculated Scope 2 number.
For a corporate carbon inventory, the data-centre energy that these KPIs help establish flows into Scope 2 through the accounting rules set by the GHG Protocol Scope 2 Guidance. The total facility energy is multiplied by a grid emission factor for the location-based figure — drawn from sources such as EPA eGRID subregions, UK DEFRA national factors, or the consolidated grid emission factors 2026 dataset — and by contractual instruments for the market-based figure. The underlying concepts are covered in the Scope 2 emissions, electricity emission factor, and CO₂e glossary entries.
Take the energy these KPIs establish and produce a compliant location-based and market-based Scope 2 figure.
The KPIs in Regulation — EU EED, Germany, CSRD
ISO/IEC 30134 began as a voluntary measurement convention and is now embedded in mandatory reporting, principally in the European Union. The regulators did not adopt the whole suite — they selected the subset most relevant to energy and environmental performance.
EU Energy Efficiency Directive (2023/1791)
Under Article 12 of the recast Energy Efficiency Directive and its Commission Delegated Regulation (EU) 2024/1364, data centres with installed IT power demand of 500 kW or more must report annually to a European database. The mandated sustainability indicators are PUE, WUE, ERF, and REF — four members of the ISO/IEC 30134 suite — reported alongside floor area, installed power, energy consumption, temperature set points, waste-heat utilisation, and renewable energy use. The first report covered the 2023 calendar year, with subsequent reports due annually by 15 May. The choice of these four, rather than a single composite, mirrors the series’ own no-aggregation principle.
A persistent misconception is that the EED imposes a PUE limit across the EU. It does not — it mandates reporting of the four KPIs and leaves performance thresholds to national law. Binding PUE limits come from member states, principally Germany.
Germany — Energieeffizienzgesetz (EnEfG)
Germany’s Energy Efficiency Act sets the strictest data-centre performance requirements in the EU. New facilities commissioned from July 2026 must reach a PUE of 1.2 within two years; existing facilities follow a graduated schedule (≤1.5 by July 2027, ≤1.3 by July 2030). The Act also ramps ERF (waste-heat reuse) targets and renewable-energy requirements, and obliges larger facilities to operate an energy-management system certified to ISO 50001 or EMAS — directly tying the ISO/IEC 30134 KPIs to a management-system obligation.
CSRD and corporate disclosure
Data-centre operators in scope of the Corporate Sustainability Reporting Directive report energy and emissions under ESRS E1, where the energy totals these KPIs establish underpin the Scope 2 line. Where data-centre electricity falls under carbon pricing, that same energy total feeds instruments such as the EU Emissions Trading System. The KPIs are the measurement layer; the disclosure regimes are what consume their output.
Common Misinterpretations
It does not. The series defines individual KPIs and explicitly refuses to aggregate them. There is no combined “ISO 30134 rating”; any single composite number presented as one is an extrapolation beyond the standard.
PUE is one of nine parts. A complete picture needs renewable share (REF), carbon (CUE), water (WUE), heat reuse (ERF), cooling (CER), and IT utilisation (ITEUsv) alongside it.
It sets none. ISO/IEC 30134 standardises how to measure; what counts as acceptable comes from regulators and national law, not the standard itself.
CUE is a normalised facility efficiency ratio; Scope 2 is an absolute, dual-method corporate inventory figure. They draw on overlapping data but are not interchangeable for disclosure.
They are near-identical. EN 50600-4 adopts the ISO/IEC 30134 KPI definitions; a figure measured to one is measured to the other. The difference is which number an EU document happens to cite.
Common Measurement and Reporting Errors
- Reporting one KPI as a verdict. A single metric — almost always PUE — presented as the facility’s overall performance, with no companion KPIs. The suite is diagnostic only when read together.
- Mixing boundaries across KPIs. Computing PUE on one boundary and CUE or WUE on another breaks the comparability Part 1 is designed to guarantee. All suite KPIs share the Part 1 boundary logic.
- Citing a part without its edition. Series parts revise independently; “per ISO/IEC 30134-2” without an edition is ambiguous now that Part 2 has a 2026 second edition that differs from the 2016 first edition.
- Treating ITEEsv and ITEUsv as the operator’s metrics. They belong to the IT-equipment family and are controlled by the tenant or IT team, not the facility operator — misattributing them confuses accountability.
- Confusing CUE with a corporate carbon inventory. CUE is a facility KPI; the corporate Scope 2 figure follows GHG Protocol rules and dual reporting. Substituting one for the other is a category error.
- Ignoring the PUE–WUE trade-off. Optimising PUE through evaporative cooling without reporting WUE hides a real environmental cost in water-stressed regions.
- Assuming EN and ISO figures need separate measurement. They do not — measure once to the shared KPI definition and report under whichever citation the audience requires.
Worked Example
One facility, read across four KPIs, shows why the suite resists a single score. All figures are illustrative and hardcoded to demonstrate how the metrics relate — they are not live factors for any specific market.
| KPI | Inputs | Result | What it tells you |
|---|---|---|---|
| PUE | Total facility 11,600,000 kWh ÷ IT 8,000,000 kWh | 1.45 | Moderate overhead — good, not best-in-class |
| REF | Renewable energy 4,640,000 kWh ÷ total 11,600,000 kWh | 0.40 | 40% renewable — over half the energy is still fossil |
| CUE (illustrative) | Total energy × grid factor 0.207, on IT energy basis | ~0.30 kg CO₂e/kWhIT | The carbon the good PUE does not reveal |
| ITEUsv (illustrative) | Average server utilisation | ~25% | Most installed compute capacity sits idle |
The lesson of the table is in the gap between the metrics. PUE alone (1.45) reads as a reasonable facility. REF (0.40) reveals it is mostly fossil-powered. CUE surfaces the carbon the energy metric hides. ITEUsv (25%) shows that the IT estate — outside the operator’s control — is the largest waste of all. A single composite score would have blended these into a flattering average and buried every actionable signal. To turn the energy line into a compliant, dual-method Scope 2 figure, use the Scope 2 electricity calculator.
Implementation Checklist
For a data-centre operator standing up an ISO/IEC 30134 measurement programme that satisfies EU EED reporting and feeds corporate carbon disclosure, the practical workflow runs as follows.
- Adopt the Part 1 framework. Fix the measurement boundary and terminology once, per ISO/IEC 30134-1, and apply it consistently to every KPI.
- Select the KPI set. At minimum the four EU-EED-mandated KPIs (PUE, WUE, ERF, REF); add CUE, CER, ITEEsv, and ITEUsv for a complete operational and carbon picture.
- Confirm current editions. Check each chosen part against ISO for its current edition before citing — Part 2 is now on its 2026 second edition.
- Instrument to the right measurement quality. For PUE, target the continuous (PUE3) category for regulatory use; instrument water, energy-reuse, and renewable metering to match.
- Measure once, report under both citations. A figure measured to ISO/IEC 30134 satisfies the EN 50600-4 citation; do not duplicate measurement.
- Read the suite together. Never present one KPI as a verdict — pair PUE with REF, CUE, WUE, and ITEUsv so trade-offs stay visible.
- Bridge to the carbon inventory. Carry the facility energy total into Scope 2 under the GHG Protocol Scope 2 Guidance, with location-based and market-based figures reported in parallel.
- Report to the right destinations. The European database for the EED; ESRS E1 for CSRD-in-scope entities; national registers where applicable.
Establish the energy and carbon chain from these KPIs, then test overall target alignment.
Frequently Asked Questions
ISO/IEC 30134 is the international standard series titled “Information technology — Data centres — Key performance indicators,” developed by ISO/IEC JTC 1/SC 39. It defines a holistic suite of data-centre KPIs across multiple numbered parts — including PUE, REF, ITEEsv, ITEUsv, ERF, CER, CUE, and WUE — on a common framework set out in Part 1. The series standardises how each KPI is measured but sets no targets and produces no single aggregate score.
Nine. Part 1 is the overview and common framework. Part 2 is PUE (Power Usage Effectiveness); Part 3 REF (Renewable Energy Factor); Part 4 ITEEsv (IT Equipment Energy Efficiency for servers); Part 5 ITEUsv (IT Equipment Utilization for servers); Part 6 ERF (Energy Reuse Factor); Part 7 CER (Cooling Efficiency Ratio); Part 8 CUE (Carbon Usage Effectiveness); and Part 9 WUE (Water Usage Effectiveness).
No, by design. The series explicitly does not combine its KPIs into one overall score, because aggregating energy, carbon, water, and utilisation into a single number destroys the diagnostic value of each. There is no “ISO/IEC 30134 rating.” The KPIs are meant to be monitored together as a suite, each preserving the dimension it measures.
PUE (Part 2) measures energy overhead — total facility energy divided by IT equipment energy — and says nothing about carbon. CUE (Part 8) measures carbon-dioxide-equivalent emissions per unit of IT equipment energy. A facility can have an excellent PUE and a poor CUE if it runs efficiently on a high-carbon grid. CUE is a facility efficiency ratio, not a substitute for a GHG Protocol Scope 2 inventory figure.
They are near-identical. EN 50600-4 is the CENELEC (European) series that adopts the ISO/IEC 30134 KPI definitions, mapping part for part — for example, ISO/IEC 30134-2 (PUE) corresponds to EN 50600-4-2. A figure measured to one is measured to the other; the practical difference is only which citation an EU regulatory or contractual document uses.
Four. Under the EU Energy Efficiency Directive (2023/1791) Article 12 and Delegated Regulation (EU) 2024/1364, data centres with 500 kW or more of installed IT power must report PUE, WUE, ERF, and REF annually to a European database, due by 15 May each year. CUE, CER, ITEEsv, and ITEUsv are not EED-mandated, though operators may report them voluntarily.
ISO/IEC JTC 1/SC 39, the joint ISO/IEC subcommittee for sustainability for and by information technology, through its Working Group 1. PUE originated with The Green Grid in 2007; The Green Grid passed standardisation of the metric to ISO/IEC JTC 1/SC 39, and its practitioner stewardship now sits within Uptime Institute.
No. The series specifies how to measure each KPI but sets no limits or targets. Acceptable thresholds come from regulators and national law — for example, Germany’s Energy Efficiency Act, which mandates a PUE of 1.2 for new facilities commissioned from July 2026. The standard itself is target-neutral.
The energy totals these KPIs establish feed the corporate carbon inventory. Total facility energy multiplied by a grid emission factor gives location-based Scope 2; contractual instruments give market-based Scope 2, under the GHG Protocol Scope 2 Guidance. CUE (Part 8) is the series’ own carbon metric but is a normalised facility ratio, not a substitute for a dual-method Scope 2 inventory figure.
Sources and References
Every definitional and numerical statement on this page reconciles to the primary sources below. Edition years are a June 2026 snapshot; confirm the current edition of any part against ISO before formal citation.
Primary standards
- ISO/IEC 30134 series, Information technology — Data centres — Key performance indicators, Parts 1–9, developed by ISO/IEC JTC 1/SC 39 (WG1). Part 1 (Overview and general requirements); Part 2 PUE (2nd edition, 2026); Part 3 REF; Part 4 ITEEsv (2017, Amd 1:2025); Part 5 ITEUsv (2017); Part 6 ERF (2021); Part 7 CER (2023); Part 8 CUE (2022); Part 9 WUE (2022).
- EN 50600-4 series (CENELEC), data-centre KPI standards adopting the ISO/IEC 30134 KPI definitions (EN 50600-4-2 through EN 50600-4-9).
- The Green Grid, original PUE and DCiE white papers (2007), predating ISO standardisation.
Regulation
- Directive (EU) 2023/1791 (Energy Efficiency Directive recast), Article 12 and Annex VII.
- Commission Delegated Regulation (EU) 2024/1364 (data-centre reporting scheme; in force June 2024).
- Germany, Energieeffizienzgesetz (EnEfG) — data-centre PUE, ERF, renewable-energy, and ISO 50001/EMAS provisions.
Related GreenCalculus reference pages
- Uptime Institute PUE (Power Usage Effectiveness)
- ISO/IEC 22237 / EN 50600 data-centre design
- ISO 50001 Energy Management
- GHG Protocol Scope 2 Guidance
- EPA eGRID
- UK DEFRA Emission Factors
- RE100 Technical Criteria
- CSRD / ESRS E1
- EU Emissions Trading System
- Scope 2 emissions
- Electricity emission factor
- CO₂e (carbon dioxide equivalent)
- Energy Attribute Certificates
- Grid emission factors 2026
- Scope 2 electricity methodology
- Scope 2 Electricity Calculator
- SBTi Readiness Checklist
What changed in this revision
Published 20 June 2026. Initial publication. Documents the ISO/IEC 30134 series as a whole: the nine parts and their KPIs, the Part 1 common framework and its no-targets / no-aggregation rules, the infrastructure vs IT-equipment KPI families, concise per-KPI definitions (with Part 2 PUE cross-referenced to its dedicated deep-dive), the ISO/IEC JTC 1/SC 39 governance and Green Grid origin, the EN 50600-4 European-mirror equivalence, how the KPIs interlock, the CUE carbon bridge to GHG Protocol Scope 2, and the regulatory regime (EU EED 2023/1791, Delegated Regulation (EU) 2024/1364, Germany’s EnEfG, CSRD/ESRS E1).