Information technology — Data centres key performance indicators — Part 8: Carbon usage effectiveness (CUE)

This document specifies carbon usage effectiveness (CUE) as a key performance indicator (KPI) for quantifying the CO2 emissions of a data centre during the use phase of the data centre life cycle. CUE is a simple method for reporting the CO2 intensity of the data centre operating. By reporting CO2 emissions, it is possible to present the data centre's contribution to climate change (enhanced greenhouse effect). This document: a) defines the CUE of a data centre; b) introduces CUE measurement categories; c) describes the relationship of this KPI to a data centre’s infrastructure, information technology equipment and information technology operations; d) defines the measurement, the calculation and the reporting of the parameter; and e) provides information on the correct interpretation of the CUE.

Technologies de l'information — Indicateurs de performance clés des centres de données — Partie 8: Performance carbone (CUE)

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Publication Date
23-Mar-2022
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INTERNATIONAL ISO/IEC
STANDARD 30134-8
First edition
2022-03
Information technology — Data
centres key performance indicators —
Part 8:
Carbon usage effectiveness (CUE)
Technologies de l'information — Indicateurs de performance clés des
centres de données —
Partie 8: Performance carbone (CUE)
Reference number
ISO/IEC 30134-8:2022(E)
© ISO/IEC 2022
---------------------- Page: 1 ----------------------
ISO/IEC 30134-8:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO/IEC 2022 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 30134-8:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms, definitions, abbreviated terms and symbols .................................................................................................... 1

3.1 Terms and definitions ...................................................................................................................................................................... 1

3.2 Abbreviated terms .............................................................................................................................................................................. 2

3.3 Symbols ......................................................................................................................................................................................................... 3

4 Applicable area of the data centre .................................................................................................................................................... 4

5 Determination of CUE .....................................................................................................................................................................................4

6 Measurement of CUE ........................................................................................................................................................................................ 5

6.1 General ........................................................................................................................................................................................................... 5

6.2 Calculation and measurement method of CO ............................................................................................................ 5

6.2.1 Calculation, measurement period and frequency ................................................................................. 5

6.2.2 Categories of CUE ............................................................................................................................................................... 5

7 Application of CUE .............................................................................................................................................................................................. 6

8 Reporting of CUE .................................................................................................................................................................................................. 6

8.1 Requirements .......................................................................................................................................................................................... 6

8.1.1 Standard construct for communicating CUE data ................................................................................ 6

8.1.2 Data for public reporting of CUE .......................................................................................................................... 7

8.2 Recommendations ............................................................................................................................................................................... 7

8.2.1 Trend tracking data ......................................................................................................................................................... 7

8.3 Examples of reporting CUE values ........................................................................................................................................ 8

8.4 CUE derivatives ...................................................................................................................................................................................... 8

8.4.1 Purpose of CUE derivatives ...................................................................................................................................... 8

8.4.2 Using CUE derivatives .................................................................................................................................................... 9

8.4.3 Interim CUE ............................................................................................................................................................................. 9

8.4.4 Partial CUE .............................................................................................................................................................................. 9

8.4.5 Design CUE............................................................................................................................................................................ 10

Annex A (informative) Examples of use ........................................................................................................................................................11

Annex B (informative) Energy conversion factors .............................................................................................................................13

Annex C (normative) Emission factor for carbon dioxide ..........................................................................................................14

Bibliography .............................................................................................................................................................................................................................17

iii
© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that are

members of ISO or IEC participate in the development of International Standards through technical

committees established by the respective organization to deal with particular fields of technical

activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international

organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the

work.

The procedures used to develop this document and those intended for its further maintenance

are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria

needed for the different types of document should be noted. This document was drafted in

accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or

www.iec.ch/members_experts/refdocs).

Attention is drawn to the possibility that some of the elements of this document may be the subject

of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent

rights. Details of any patent rights identified during the development of the document will be in the

Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC

list of patent declarations received (see https://patents.iec.ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see

www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.

This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,

Subcommittee SC 39, Sustainability, IT and data centres.

A list of all parts in the ISO/IEC 30134 series can be found on the ISO and IEC websites.

Any feedback or questions on this document should be directed to the user’s national standards

body. A complete listing of these bodies can be found at www.iso.org/members.html and

www.iec.ch/national-committees.
© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)
Introduction

The global economy is today reliant on information and communication technologies and the associated

generation, transmission, dissemination, computation and storage of digital data. All markets have

experienced exponential growth in that data, for social, educational and business sectors and while the

internet backbone carries the traffic, there are a wide variety of data centres at nodes and hubs within

both private enterprise and shared/collocation facilities.

The historical data generation growth rate exceeds the capacity growth rate of information and

communications technology hardware. In addition, with many governments having “digital agendas” to

provide both citizens and businesses with ever-faster broadband access, the very increase in network

speed and capacity will, by itself, generate ever more usage (Jevons Paradox). Data generation and

the consequential increase in data processing and storage are directly linked to increasing power

consumption.

With this background, data centre growth, and power consumption in particular, is an inevitable

consequence; this growth will demand increasing power consumption despite the most stringent

energy efficiency strategies. This makes the need for key performance indicators (KPIs) that cover

the effective use of resources (including but not limited to energy and water) and the reduction of CO

emissions essential.

Within the ISO/IEC 30134 series, the term “resource usage effectiveness” is generally used for KPIs in

preference to “resource usage efficiency”, which is restricted to situations where the input and output

parameters used to define the KPI have the same units.

Carbon usage effectiveness (CUE) is intended to enable data centre practitioners to quickly calculate

the sustainability of their data centres, compare the results and determine if any energy efficiency and/

or sustainability improvements need to be made. The impact of operational carbon usage is emerging

as being extremely important in the design, location and operation of current and future data centres.

In order to determine the overall resource efficiency of a data centre, a holistic suite of metrics

is required. This document is one of a series of International Standards for such KPIs and has been

produced in accordance with ISO/IEC 30134-1, which defines common requirements for a holistic suite

of KPIs for data centre resource efficiency. This document does not specify limits or targets for the KPI

and does not describe or imply, unless specifically stated, any form of aggregation of this KPI into a

combination with other KPIs for data centre resource efficiency. This document presents specific rules

on CUE’s use, along with its theoretical and mathematical development. This document concludes with

several examples of site concepts that could employ the CUE metric.
© ISO/IEC 2022 – All rights reserved
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INTERNATIONAL STANDARD ISO/IEC 30134-8:2022(E)
Information technology — Data centres key performance
indicators —
Part 8:
Carbon usage effectiveness (CUE)
1 Scope

This document specifies carbon usage effectiveness (CUE) as a key performance indicator (KPI) for

quantifying the CO emissions of a data centre during the use phase of the data centre life cycle.

CUE is a simple method for reporting the CO intensity of the data centre operating. By reporting

CO emissions, it is possible to present the data centre's contribution to climate change (enhanced

greenhouse effect).
This document:
a) defines the CUE of a data centre;
b) introduces CUE measurement categories;

c) describes the relationship of this KPI to a data centre’s infrastructure, information technology

equipment and information technology operations;

d) defines the measurement, the calculation and the reporting of the parameter; and

e) provides information on the correct interpretation of the CUE.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO/IEC 30134-1, Information technology — Data centres — Key performance indicators — Part 1:

Overview and general requirements

ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules

3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)
3.1.1
carbon usage effectiveness
CUE
ratio of the data centre annual CO emissions and IT equipment energy demand
3.1.2
total data centre energy consumption

total annual energy consumption for all energy types serving the data centre at its boundary

Note 1 to entry: The total data centre energy is measured in kWh; the energy is measured with energy metering

devices at the boundary of the data centre or at points of generation within the boundary.

Note 2 to entry: This includes energy derived from sources such as natural gas, hydrogen, bioethanol and district

utilities (e.g. chilled water, condenser water).
Note 3 to entry: Total annual energy includes supporting infrastructure.
[SOURCE: ISO/IEC 30134-2:2016, 3.1.7, modified.]
3.1.3
IT equipment energy consumption

energy consumed by equipment that is used to manage, process, store or route data within the compute

space

Note 1 to entry: The IT equipment energy consumption is measured in kWh; examples for IT equipment are

servers, storage equipment, and telecommunications equipment.
[SOURCE: ISO/IEC 30134-2:2016, 3.1.1, modified.]
3.1.4
global warming potential
radiative impact of a given greenhouse gas relative to that of carbon dioxide
3.1.5
greenhouse gases
GHG

gaseous constituent of the atmosphere that absorbs and emits radiation at specific wavelengths within

the spectrum of infrared radiation emitted by the earth's surface, the atmosphere and clouds

Note 1 to entry: Within the context of this document, seven GHGs are considered: carbon dioxide (CO ), methane

(CH ), nitrous oxide (N O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF ) and

4 2 6
nitrogen trifluoride (NF ).

Note 2 to entry: A list of greenhouse gases with their recognized global warming potentials is provided in

ISO 14067.
3.1.6
carbon dioxide equivalent

global warming potential of a greenhouse gas expressed in terms of the global warming potential of

one unit of carbon dioxide
3.1.7
emission factor for carbon dioxide

specific carbon dioxide emission stemming from the data centre’s energy use and facility operations

Note 1 to entry: The term “facility operations” covers CO emissions caused, for example, by refrigerants or diesel

generators.
3.2 Abbreviated terms

For the purposes of this document, the abbreviated terms in ISO/IEC 30134-1 and the following apply.

© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)
CO carbon dioxide
CO e carbon dioxide equivalent
CUE carbon usage effectiveness
DC data centre
DC CO Data-centre-related carbon dioxide emissions
dCUE design carbon usage effectiveness
EFC emission factor for carbon dioxide
ex external
GHG greenhouse gases
GWP global warming potential
iCUE interim carbon usage effectiveness
iPUE interim power usage effectiveness
int internal
pCUE partial carbon usage effectiveness
PUE power usage effectiveness
3.3 Symbols
For the purposes of this document, the following symbols apply.
C CO emissions of the data centre in kg
DC 2
C CO emissions of the data centre for testing emergency power supply engines
DC,ee 2
C data centre CO emissions for electricity from the grid
DC,ex,el 2
C data centre CO emissions for on-site generation (e.g. testing diesel engines)
DC,int,el 2
C data centre CO emissions for refrigerant (leakage)
DC,rf 2
C CO emissions of a subsystem in kg
S 2
c filling capacity of refrigerant
E total data centre energy consumption (annual) in kWh
E IT equipment energy consumption (annual) in kWh
E acquired electrical energy from outside the data centre boundaries
ex,el

E acquired electrical energy and all additional energy supply from outside the data centre

ex,el,ad
boundaries
E electrical energy produced inside the data centre boundaries
int,el

E electrical energy and all additional energy supply produced inside the data centre boundaries

int,el,ad
© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)
f EFC in kg CO e/kWh
e 2
f EFC of external energy demand in kg CO e/kWh
e,ex 2
f EFC of external electrical energy demand
e,ex,el
f EFC of internal energy demand in kg CO e/kWh
e,int 2
f EFC of internal electrical energy demand
e,int,el
f EFC of refrigerant
e,int,rf
P annual average data centre power in kW
r annual leakage rate
L,a
r monthly leakage rate
L,m
t runtime for diesel engines
t runtime for gas engines
η carbon usage effectiveness
U,C
η partial carbon usage effectiveness
U,C,p
η power usage effectiveness
U,P
η interim power usage effectiveness
U,P,i
4 Applicable area of the data centre
CUE as specified in this document:

— is associated with the data centre infrastructure and IT equipment within its boundaries only;

— describes the CUE relative to facilities with given environmental conditions, IT load characteristics,

availability requirements, maintenance and security requirements;

— measures the relationship between the total data centre CO emissions and the IT equipment energy

consumed.
CUE does not:

— account for the efficiency of other resources such as human resources, space or water;

— provide a data centre productivity metric;
— provide a standalone, comprehensive efficiency metric.
5 Determination of CUE

CUE provides a way to determine the carbon emissions associated with data centres. CUE has an ideal

value of 0,0, indicating that no carbon use is associated with the data centre’s operations. CUE has no

theoretical upper boundary.
CUE is defined using Formula (1):
η = (1)
U,C
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ISO/IEC 30134-8:2022(E)
NOTE 1 The values for C differ regarding to the CUE category (see 6.2.2).

NOTE 2 The accuracy of measuring IT energy for CUE is not necessarily the same as the accuracy of measuring

IT energy for PUE (e.g. CUE category 1 can be reported with an accuracy of measuring IT energy referring to PUE

category 2).

CUE may be applied in mixed-use buildings when measurement of the CO emisions caused by the data

centre and that for other functions is possible.
6 Measurement of CUE
6.1 General
All KPIs of the ISO/IEC 30134 series are defined within the same boundaries.
6.2 Calculation and measurement method of CO
6.2.1 Calculation, measurement period and frequency

The minimum calculation and measurement period requires twelve months of cumulative DC CO

values. Annualized data used to calculate CUE shall be documented. The annual DC CO values

collected or calculated shall cover the same time period. It is not necessary to define the frequency of

measurement and calculation or assessments for the annual CUE determination, as the annual DC CO

value is a continuous integration of DC CO emitted in that timeframe. The required EFC values shall be

determined in accordance with Annex C.

NOTE 1 The measurement or assessment frequency can be necessary for subsystem improvements (refer to

partial PUE), but is not required for CUE disclosures.

NOTE 2 Direct measurements for CO can sometimes be taken (e.g. for diesel engines). However, calculations

are also sometimes made by measurements of energy, refrigerant losses, etc. and their EFC.

6.2.2 Categories of CUE
6.2.2.1 Introduction

CUE categories 1 to 3 are defined, as shown in Table 1, to provide a defined route that refines the extent

of the carbon emission sources considered.
Table 1 — CUE categories
Source Category 1 (CUE ) Category 2 (CUE ) Category 3 (CUE )
1 2 3
basic intermediate advanced

Considered emission External and internal DC External and internal DC Reserved for future use.

source electricity. electricity, all additional
DC energy supply and all
additional DC emission
sources.
Considered GHG CO CO equivalents. Reserved for future use.
2 2
Annex A provides examples for the calculation of the CUE categories.
6.2.2.2 CUE category 1: CO emissions from electricity only

For category 1, the CO emissions of all internal and external power supplies are considered, taking into

account electricity only. In the event that different energy sources are used, Annex B provides examples

© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)

for energy conversion factors. For instance, internal power supply can come from diesel engines

whereas external power supply can come from acquired electricity from the grid.
The CUE of category 1 only covers CO as one of the GHGs.
For category 1, CUE can be calculated using Formula (2):
Ef× + Ef×
C () ()
ex,ele,ex,el int,el e,int,el
η == (2)
U,C,1
E E
IT IT
6.2.2.3 CUE category 2: CO emissions from all energy

The CUE of category 2 covers both CO and CO e for all external and internal power supplies, for all

2 2
additional energy supplies and for all additional CO e-related emission sources.

For example, CO e are considered for external electricity from the grid, additional data centre energy

from internal combined heat and power stations based on natural gas, refrigerant losses or static

transfer switches isolation gases.
For category 2 CUE can be calculated by Formula (3).
EE × ff + ×
C () ()
ex,el,ad e,ex int,el,ad e,int
η == (3)
U,C,2
E E
IT IIT
6.2.2.4 CUE category 3: reserved for future use
Category 3 is reserved for future use.
7 Application of CUE

CUE can be used by data centre managers to monitor and report CO emissions in relation to IT

energy consumption in the data centre. This KPI can be used independently but to achieve a more

holistic picture of the resource efficiency of the data centre, other KPIs of the ISO/IEC 30134 series

should be considered. Using CUE particularity PUE should be considered. Where CUE is reported, the

corresponding PUE value should also be reported.
8 Reporting of CUE
8.1 Requirements
8.1.1 Standard construct for communicating CUE data

For a reported CUE to be meaningful, the reporting organization shall provide the following information:

a) the DC under inspection,
b) the CUE value,
c) the CUE category,

d) the termination date of the period of measurement using the format of ISO 8601-1 (i.e. yyyy-mm-

dd).

The CUE category shall be provided as a subscript to the name of the metric, e.g. CUE for a category 2

value.
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ISO/IEC 30134-8:2022(E)
8.1.2 Data for public reporting of CUE
8.1.2.1 Required information
The following data shall be provided, when publicly reporting CUE data:

a) contact information (only the organization’s name or contact should be displayed in public

inquiries);

b) data centre location information (address, county or region; only state or local region information

are required to be displayed in public inquiries);
c) measurement results: CUE with appropriate nomenclature;
d) factors, values and year for calculating CO emissions.
8.1.2.2 Required supporting evidence

Information on the DC which shall be available upon request as a minimum includes:

a) organization’s name, contact information and regional environmental description;

b) measurement results: CUE with appropriate nomenclature;
c) E and DC CO ;
IT 2
d) measurement(s) start dates and assessment completion dates;
e) the accuracy level;

f) report on the size of the computer room, telecom room and control room spaces;

g) external environmental conditions consisting of minimum, maximum and average temperature,

humidity and altitude;
h) corresponding PUE value and category;
i) factors reference according to Annex C.

NOTE 1 The PUE category provides information on the accuracy of measuring IT energy consumption.

NOTE 2 The IEC 62052 series and IEC 62053 series provide a reference for measurement of electrical energy.

8.2 Recommendations
8.2.1 Trend tracking data
The following information can be useful in tracking the CUE trends within a DC:
a) DC size (facility m );
b) total DC design load for the facility (e.g. 10 MW);
c) name of the possible auditor and method used for auditing;
d) DC contact information;
e) DC environmental conditions;
f) DC location and region;
g) DC's mission;
© ISO/IEC 2022 – All rights reserved
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ISO/IEC 30134-8:2022(E)
h) DC archetype percentages (e.g. 20 % web hosting, 80 % email);
i) DC commissioned date;
j) numbers of servers, routers, and storage devices;
k) average and peak server CPU utilization;
l) percentage of servers using virtualization;
m) average age of IT equipment by type;

n) average age of facility equipment by type (cooling and power distribution equipment);

o) DC availability objectives (see ISO/IEC 30134-1:2015, Annex A);
p) cooling and air-handling details.

NOTE Other KPIs within the ISO/IEC 30134 series can assist in the recording of the above information.

8.3 Examples of reporting CUE values

Using the construct of 8.1.1, this subclause provides two examples of specific CUE designations and

their interpretation:
EXAMPLE 1
Sample CUE designations:
DC X: CUE (2018-12-31) = 0,90 kg CO per kWh
1 2
Interpretation:
In the year 2018 the CUE value of DC X was 0,90. It was a category 1 CUE.
EXAMPLE 2
Sample CUE designations:
DC Y: CUE (2018-06-30) = 1,1 kg CO e per kWh
2 2
Interpretation:

In the period 2017-07-01 – 2018-06-30 the CUE value of data centre Y was 1,1. It was a category 2 CUE.

8.4 CUE derivatives
8.4.1 Purpose of CUE derivatives
Often, CUE values are needed:
a) to indicate CUE for periods less than 12 months; and/or

b) to provide the CUE for separated, non-standalone data centres (i.e. mixed building); and/or

c) to predict a desired CUE value during the design stage of the data centre.

For this purpose, CUE derivatives are introduced in 8.4.3 to 8.4.5, which address these specific needs.

Each derivative shall be accompanied with specific information that describes the specific situation.

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ISO/IEC 30134-8:2022(E)
8.4.2 Using CUE derivatives

CUE reporting shall be consistent with PUE reporting. The boundary conditions of the PUE report shall

be the same for CUE reporting. For reporting CUE, if there is a derivative PUE, a derivative CUE with the

same boundary conditions shall be provided.

Combined use of the terms is permitted to describe specific situations and values. An example use of

these derivatives is:
designed, interim pCUE (20xx-08-01:20xx-08-31) = 3,1 [ref. jjj]
[jjj]: [boundaries of the data centre, shared cooling, space, physical
...

FINAL
INTERNATIONAL ISO/IEC
DRAFT
STANDARD FDIS
30134-8
ISO/IEC JTC 1/SC 39
Information technology — Data
Secretariat: ANSI
centres key performance indicators —
Voting begins on:
2021-12-02
Part 8:
Voting terminates on:
Carbon usage effectiveness (CUE)
2022-01-27
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/IEC FDIS 30134-8:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO/IEC 2021
---------------------- Page: 1 ----------------------
ISO/IEC FDIS 30134-8:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO/IEC 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC FDIS 30134-8:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms, definitions, abbreviated terms and symbols .................................................................................................... 1

3.1 Terms and definitions ...................................................................................................................................................................... 1

3.2 Abbreviated terms .............................................................................................................................................................................. 2

3.3 Symbols ......................................................................................................................................................................................................... 3

4 Applicable area of the data centre .................................................................................................................................................... 4

5 Determination of CUE .....................................................................................................................................................................................4

6 Measurement of CUE ........................................................................................................................................................................................ 5

6.1 General ........................................................................................................................................................................................................... 5

6.2 Calculation and measurement method of CO ............................................................................................................ 5

6.2.1 Calculation, measurement period and frequency ................................................................................. 5

6.2.2 Categories of CUE ............................................................................................................................................................... 5

7 Application of CUE .............................................................................................................................................................................................. 6

8 Reporting of CUE .................................................................................................................................................................................................. 6

8.1 Requirements .......................................................................................................................................................................................... 6

8.1.1 Standard construct for communicating CUE data ................................................................................ 6

8.1.2 Data for public reporting of CUE .......................................................................................................................... 7

8.2 Recommendations ............................................................................................................................................................................... 7

8.2.1 Trend tracking data ......................................................................................................................................................... 7

8.3 Examples of reporting CUE values ........................................................................................................................................ 8

8.4 CUE derivatives ...................................................................................................................................................................................... 8

8.4.1 Purpose of CUE derivatives ...................................................................................................................................... 8

8.4.2 Using CUE derivatives .................................................................................................................................................... 9

8.4.3 Interim CUE ............................................................................................................................................................................. 9

8.4.4 Partial CUE .............................................................................................................................................................................. 9

8.4.5 Design CUE............................................................................................................................................................................ 10

Annex A (informative) Examples of use ........................................................................................................................................................11

Annex B (informative) Energy conversion factors .............................................................................................................................13

Annex C (normative) Emission factor for carbon dioxide ..........................................................................................................14

Bibliography .............................................................................................................................................................................................................................17

iii
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ISO/IEC FDIS 30134-8:2021(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that are

members of ISO or IEC participate in the development of International Standards through technical

committees established by the respective organization to deal with particular fields of technical

activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international

organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the

work.

The procedures used to develop this document and those intended for its further maintenance

are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria

needed for the different types of document should be noted. This document was drafted in

accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or

www.iec.ch/members_experts/refdocs).

Attention is drawn to the possibility that some of the elements of this document may be the subject

of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent

rights. Details of any patent rights identified during the development of the document will be in the

Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC

list of patent declarations received (see https://patents.iec.ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see

www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.

This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,

Subcommittee SC 39, Sustainability, IT and data centres.

A list of all parts in the ISO/IEC 30134 series can be found on the ISO and IEC websites.

Any feedback or questions on this document should be directed to the user’s national standards

body. A complete listing of these bodies can be found at www.iso.org/members.html and

www.iec.ch/national-committees.
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ISO/IEC FDIS 30134-8:2021(E)
Introduction

The global economy is today reliant on information and communication technologies and the associated

generation, transmission, dissemination, computation and storage of digital data. All markets have

experienced exponential growth in that data, for social, educational and business sectors and, while the

internet backbone carries the traffic, there are a wide variety of data centres at nodes and hubs within

both private enterprise and shared/collocation facilities.

The historical data generation growth rate exceeds the capacity growth rate of information and

communications technology hardware. In addition, with many governments having “digital agendas” to

provide both citizens and businesses with ever-faster broadband access, the very increase in network

speed and capacity will, by itself, generate ever more usage (Jevons Paradox). Data generation and

the consequential increase in data processing and storage are directly linked to increasing power

consumption.

With this background, data centre growth, and power consumption in particular, is an inevitable

consequence; this growth will demand increasing power consumption despite the most stringent

energy efficiency strategies. This makes the need for key performance indicators (KPIs) that cover

the effective use of resources (including but not limited to energy and water) and the reduction of CO

emissions essential.

Within the ISO/IEC 30134 series, the term “resource usage effectiveness” is generally used for KPIs in

preference to “resource usage efficiency”, which is restricted to situations where the input and output

parameters used to define the KPI have the same units.

Carbon usage effectiveness (CUE) is intended to enable data centre practitioners to quickly calculate

the sustainability of their data centres, compare the results and determine if any energy efficiency and/

or sustainability improvements need to be made. The impact of operational carbon usage is emerging

as being extremely important in the design, location and operation of current and future data centres.

In order to determine the overall resource efficiency of a data centre, a holistic suite of metrics

is required. This document is one of a series of International Standards for such KPIs and has been

produced in accordance with ISO/IEC 30134-1, which defines common requirements for a holistic suite

of KPIs for data centre resource efficiency. This document does not specify limits or targets for the KPI

and does not describe or imply, unless specifically stated, any form of aggregation of this KPI into a

combination with other KPIs for data centre resource efficiency. This document presents specific rules

on CUE’s use, along with its theoretical and mathematical development. This document concludes with

several examples of site concepts that could employ the CUE metric.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/IEC FDIS 30134-8:2021(E)
Information technology — Data centres key performance
indicators —
Part 8:
Carbon usage effectiveness (CUE)
1 Scope

This document specifies carbon usage effectiveness (CUE) as a KPI for quantifying the CO emissions of

a data centre during the use phase of the data centre life cycle.

CUE is a simple method for reporting the CO intensity of the data centre operating. By reporting

CO emissions, it is possible to present the data centre's contribution to climate change (enhanced

greenhouse effect).
This document:
a) defines the CUE of a data centre,
b) introduces CUE measurement categories,

c) describes the relationship of this KPI to a data centre’s infrastructure, information technology

equipment and information technology operations,

d) defines the measurement, the calculation and the reporting of the parameter, and

e) provides information on the correct interpretation of the CUE.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO/IEC 30134-1, Information technology — Data centres — Key performance indicators — Part 1:

Overview and general requirements

ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules

3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
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ISO/IEC FDIS 30134-8:2021(E)
3.1.1
carbon usage effectiveness
CUE
ratio of the data centre annual CO emissions and IT equipment energy demand
3.1.2
total data centre energy consumption

total annual energy consumption for all energy types serving the data centre at its boundary

Note 1 to entry: The total data centre energy is measured in kWh; the energy is measured with energy metering

devices at the boundary of the data centre or at points of generation within the boundary.

Note 2 to entry: This includes energy derived from sources such as natural gas, hydrogen, bioethanol and district

utilities (e.g. chilled water, condenser water).
Note 3 to entry: Total annual energy includes supporting infrastructure.
[SOURCE: ISO/IEC 30134-2:2016, 3.1.7, modified.]
3.1.3
IT equipment energy consumption

energy consumed by equipment that is used to manage, process, store or route data within the compute

space

Note 1 to entry: The IT equipment energy consumption is measured in kWh; examples for IT equipment are

servers, storage equipment, and telecommunications equipment.
[SOURCE: ISO/IEC 30134-2:2016, 3.1.1, modified.]
3.1.4
global warming potential
radiative impact of a given greenhouse gas relative to that of carbon dioxide
3.1.5
greenhouse gases
GHG

gaseous constituent of the atmosphere that absorbs and emits radiation at specific wavelengths within

the spectrum of infrared radiation emitted by the earth's surface, the atmosphere and clouds

Note 1 to entry: Within the context of this document, seven GHGs are considered: carbon dioxide (CO ), methane

(CH ), nitrous oxide (N O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF ) and

4 2 6
nitrogen trifluoride (NF ).

Note 2 to entry: A list of greenhouse gases with their recognized global warming potentials is provided in

ISO 14067.
3.1.6
carbon dioxide equivalent

global warming potential of a greenhouse gas expressed in terms of the global warming potential of

one unit of carbon dioxide
3.1.7
emission factor for carbon dioxide

specific carbon dioxide emission stemming from the data centre’s energy use and facility operations

Note 1 to entry: The term “facility operations” covers CO emissions caused, for example, by refrigerants or diesel

generators.
3.2 Abbreviated terms

For the purposes of this document, the abbreviated terms in ISO/IEC 30134-1 and the following apply.

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ISO/IEC FDIS 30134-8:2021(E)
CO carbon dioxide
CO e carbon dioxide equivalent
CUE carbon usage effectiveness
DC data centre
DC CO Data-centre-related carbon dioxide emissions
dCUE design carbon usage effectiveness
EFC emission factor for carbon dioxide
ex external
GHG greenhouse gases
GWP global warming potential
iCUE interim carbon usage effectiveness
iPUE interim power usage effectiveness
int internal
pCUE partial carbon usage effectiveness
PUE power usage effectiveness
3.3 Symbols
For the purposes of this document, the following symbols apply.
C CO emissions of the data centre in kg
DC 2
C CO emissions of the data centre for testing emergency power supply engines
DC,ee 2
C data centre CO emissions for electricity from the grid
DC,ex,el 2
C data centre CO emissions for on-site generation (e.g. testing diesel engines)
DC,int,el 2
C data centre CO emissions for refrigerant (leakage)
DC,rf 2
C CO emissions of a subsystem in kg
S 2
c filling capacity of refrigerant
E total data centre energy consumption (annual) in kWh
E IT equipment energy consumption (annual) in kWh
E acquired electrical energy from outside the data centre boundaries
ex,el

E acquired electrical energy and all additional energy supply from outside the data centre

ex,el,ad
boundaries
E electrical energy produced inside the data centre boundaries
int,el

E electrical energy and all additional energy supply produced inside the data centre boundaries

int,el,ad
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ISO/IEC FDIS 30134-8:2021(E)
f EFC in kg CO e/kWh
e 2
f EFC of external energy demand in kg CO e/kWh
e,ex 2
f EFC of external electrical energy demand
e,ex,el
f EFC of internal energy demand in kg CO e/kWh
e,int 2
f EFC of internal electrical energy demand
e,int,el
f EFC of refrigerant
e,int,rf
P annual average data centre power in kW
r annual leakage rate
L,a
r monthly leakage rate
L,m
t runtime for diesel engines
t runtime for gas engines
η carbon usage effectiveness
U,C
η partial carbon usage effectiveness
U,C,p
η power usage effectiveness
U,P
η interim power usage effectiveness
U,P,i
4 Applicable area of the data centre
CUE as specified in this document:

— is associated with the data centre infrastructure and IT equipment within its boundaries only;

— describes the CUE relative to facilities with given environmental conditions, IT load characteristics,

availability requirements, maintenance and security requirements;

— measures the relationship between the total data centre CO emissions and the IT equipment energy

consumed.
CUE does not:

— account for the efficiency of other resources such as human resources, space or water;

— provide a data centre productivity metric;
— provide a standalone, comprehensive efficiency metric.
5 Determination of CUE

CUE provides a way to determine the carbon emissions associated with data centres. CUE has an ideal

value of 0,0, indicating that no carbon use is associated with the data centre’s operations. CUE has no

theoretical upper boundary.
CUE is defined using Formula (1):
η = (1)
U,C
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ISO/IEC FDIS 30134-8:2021(E)
NOTE 1 The values for C differ regarding to the CUE category (see 6.2.2).

NOTE 2 The accuracy of measuring IT energy for CUE is not necessarily the same as the accuracy of measuring

IT energy for PUE (e.g. CUE category 1 can be reported with an accuracy of measuring IT energy referring to PUE

category 2).

CUE may be applied in mixed-use buildings when measurement of the CO emisions caused by the data

centre and that for other functions is possible.
6 Measurement of CUE
6.1 General
All KPIs of the ISO/IEC 30134 series are defined within the same boundaries.
6.2 Calculation and measurement method of CO
6.2.1 Calculation, measurement period and frequency

The minimum calculation and measurement period requires twelve months of cumulative DC CO

values. Annualized data used to calculate CUE shall be documented. The annual DC CO values

collected or calculated shall cover the same time period. It is not necessary to define the frequency of

measurement and calculation or assessments for the annual CUE determination, as the annual DC CO

value is a continuous integration of DC CO emitted in that timeframe. The required EFC values shall be

determined in accordance with Annex C.

NOTE 1 The measurement or assessment frequency can be necessary for subsystem improvements (refer to

partial PUE), but is not required for CUE disclosures.

NOTE 2 Direct measurements for CO can sometimes be taken (e.g. for diesel engines). However, calculations

are also sometimes made by measurements of energy, refrigerant losses, etc. and their EFC.

6.2.2 Categories of CUE
6.2.2.1 Introduction

CUE categories 1 to 3 are defined, as shown in Table 1, to provide a defined route that refines the extent

of the carbon emission sources considered.
Table 1 — CUE categories
Source Category 1 (CUE ) Category 2 (CUE ) Category 3 (CUE )
1 2 3
basic intermediate advanced

Considered emission External and internal DC External and internal DC Reserved for future use.

source electricity. electricity, all additional
DC energy supply and all
additional DC emission
sources.
Considered GHG CO CO equivalents. Reserved for future use.
2 2
Annex A provides examples for the calculation of the CUE categories.
6.2.2.2 CUE category 1: CO emissions from electricity only

For category 1, the CO emissions of all internal and external power supplies are considered, taking into

account electricity only. In the event that different energy sources are used, Annex B provides examples

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ISO/IEC FDIS 30134-8:2021(E)

for energy conversion factors. For instance, internal power supply can come from diesel engines

whereas external power supply can from acquired electricity from the grid.
The category 1 CO emissions cover only CO as one of the GHGs.
2 2
For category 1, CUE can be calculated using Formula (2):
Ef× + Ef×
C () ()
ex,ele,ex,el int,el e,int,el
η == (2)
U,C,1
E E
IT IT
6.2.2.3 CUE category 2: CO emissions from all energy

The category 2 CO emissions cover CO e for all external and internal power supplies, for all additional

2 2
energy supplies and for all additional CO e-related emission sources.

For example, CO e are considered for external electricity from the grid, additional data centre energy

from internal combined heat and power stations based on natural gas, refrigerant losses or static

transfer switches isolation gases.
For category 2 CUE can be calculated by Formula (3).
EE × ff + ×
C () ()
ex,el,ad e,intint,el,ad e,ex
η == (3)
U,C,2
E E
IT IIT
6.2.2.4 CUE category 3: reserved for future use
Categroy 3 is reserved for future use.
7 Application of CUE

CUE can be used by data centre managers to monitor and report CO emissions in relation to IT

energy consumption in the data centre. This KPI can be used independently but to achieve a more

holistic picture of the resource efficiency of the data centre, other KPIs of the ISO/IEC 30134 series

should be considered. Using CUE particularity PUE should be considered. Where CUE is reported, the

corresponding PUE value should also be reported.
8 Reporting of CUE
8.1 Requirements
8.1.1 Standard construct for communicating CUE data

For a reported CUE to be meaningful, the reporting organization shall provide the following information:

a) the DC under inspection,
b) the CUE value,
c) the CUE category,

d) the termination date of the period of measurement using the format of ISO 8601-1 (i.e. yyyy-mm-

dd).

The CUE category shall be provided as a subscript to the name of the metric, e.g. CUE for a category 2

value.
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ISO/IEC FDIS 30134-8:2021(E)
8.1.2 Data for public reporting of CUE
8.1.2.1 Required information
The following data shall be provided, when publicly reporting CUE data:

a) contact information (only the organization’s name or contact should be displayed in public

inquiries);

b) data centre location information (address, county or region; only state or local region information

are required to be displayed in public inquiries);
c) measurement results: CUE with appropriate nomenclature;
d) factors, values and year for calculating CO emissions.
8.1.2.2 Required supporting evidence

Information on the DC which shall be available upon request as a minimum includes:

a) organization’s name, contact information and regional environmental description;

b) measurement results: CUE with appropriate nomenclature;
c) E and DC CO ,
IT 2
d) measurement(s) start dates and assessment completion dates;
e) the accuracy level;

f) report on the size of the computer room, telecom room and control room spaces;

g) external environmental conditions consisting of minimum, maximum and average temperature,

humidity and altitude;
h) corresponding PUE value and category;
i) factors reference according to Annex C.

NOTE 1 The PUE category provides information on the accuracy of measuring IT energy consumption.

NOTE 2 The IEC 62052 series and IEC 62053 series provide a reference for measurement of electrical energy.

8.2 Recommendations
8.2.1 Trend tracking data
The following information can be useful in tracking the CUE trends within a DC:
a) DC size (facility m );
b) total DC design load for the facility (e.g. 10 MW);
c) name of the possible auditor and method used for auditing;
d) DC contact information;
e) DC environmental conditions;
f) DC location and region;
g) DC's mission;
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ISO/IEC FDIS 30134-8:2021(E)
h) DC archetype percentages (e.g. 20 % web hosting, 80 % email);
i) DC commissioned date;
j) numbers of servers, routers, and storage devices;
k) average and peak server CPU utilization;
l) percentage of servers using virtualization;
m) average age of IT equipment by type;

n) average age of facility equipment by type (cooling and power distribution equipment);

o) DC availability objectives (see ISO/IEC 30134-1:2015, Annex A);
p) cooling and air-handling details.

NOTE Other KPIs within the ISO/IEC 30134 series can assist in the recording of the above information.

8.3 Examples of reporting CUE values

Using the construct of 8.1.1, this subclause provides two examples of specific CUE designations and

their interpretation:
EXAMPLE 1
Sample CUE designations:
DC X: CUE (2018-12-31) = 0,90 kg CO per kWh
1 2
Interpretation:
In the year 2018 the CUE value of DC X was 0,90. It was a category 1 CUE.
EXAMPLE 2
Sample CUE designations:
DC Y: CUE (2018-06-30) = 1,1 kg CO e per kWh
2 2
Interpretation:

In the period 2017-07-01 – 2018-06-30 the CUE value of data centre Y was 1,1. It was a category 2 CUE.

8.4 CUE derivatives
8.4.1 Purpose of CUE derivatives
Often, CUE values are needed:
a) to indicate CUE for periods less than 12 months; and/or

b) to provide the CUE for separated, non-standalone data centres (i.e. mixed building); and/or

c) to predict a desired CUE value during the design stage of the data centre.

For this purpose, CUE derivatives are introduced in 8.3.3 to 8.3.5, which address these specific needs.

Each derivative shall be accompanied with specific information that describes the specific situation.

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ISO/IEC FDIS 30134-8:2021(E)
8.4.2 Using CUE derivatives
CUE reporti
...

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