ISO/IEC 30134-7:2023

INTERNATIONAL ISO/IEC
STANDARD 30134-7
First edition
2023-03
Information technology — Data
centres key performance indicators —
Part 7:
Cooling efficiency ratio (CER)
Reference number
© ISO/IEC 2023
© ISO/IEC 2023
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© ISO/IEC 2023 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviations . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 2
3.3 Symbols . 2
4 Applicable area of the data centre . 3
5 Definition of the CER . 4
6 Measurement of CER .5
6.1 General . 5
6.2 Requirements . 5
6.3 Recommendations . 5
7 Application of CER . 5
8 Reporting of CER . 6
8.1 Requirements . 6
8.1.1 Standard construct for communicating CER . 6
8.1.2 Data for public reporting of CER . 6
8.2 Recommendations . 7
Annex A (informative) Correlation of CER and other KPIs . 8
Annex B (normative) Examples of usage of CER .10
Annex C (informative) Parameters influencing CER .11
Annex D (normative) Derivatives of CER . .12
Bibliography .16
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© ISO/IEC 2023 – All rights reserved

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 2023 – All rights reserved

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 and, with less than half (in 2014) of the world’s population
having access to an internet connection, that growth in data can only accelerate. 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 the reduction of CO emissions
essential.
Within the ISO/IEC 30134 series, the term “resource usage effectiveness” is more 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.
The cooling efficiency ratio (CER) allows data centre operators to quickly determine the efficiency of
their data centre cooling system, compare the results, and determine if energy efficiency improvements
need to be made. The impact of operational cooling efficiency is proving to be 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 CER’s use, along with its theoretical and mathematical development. This document concludes with
several examples of site concepts that could employ the CER metric.
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© ISO/IEC 2023 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 30134-7:2023(E)
Information technology — Data centres key performance
indicators —
Part 7:
Cooling efficiency ratio (CER)
1 Scope
This document specifies the cooling efficiency ratio (CER) as a key performance indicator (KPI) for
quantifying the efficient use of energy to control the temperature of spaces within a data centre (DC).
This document:
a) defines the CER of a DC;
b) describes the relationship of this KPI to a DC’s infrastructure, information technology equipment
and information technology operations;
c) defines the measurement, the calculation and the reporting of the parameter; and
d) provides information on the correct interpretation of the CER.
Annex A describes the correlation of the CER and other KPIs.
Annex B provides examples of the usage of the CER.
Annex C introduces the parameters that affect the CER.
Annex D describes requirements and recommendations for derivatives of KPIs associated with the CER.
This document is not applicable to cooling systems that are not powered by electricity (e.g. heat-driven
absorption chillers).
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
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 30134-1 and the following
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 2023 – All rights reserved

3.1.1
cooling efficiency ratio
CER
ratio of total heat removed and electrical energy used by a cooling system
Note 1 to entry: The value of "total heat annual removed" from the DC is measured in kWh.
3.1.2
cooling performance ratio
CPR
ratio of actual heat load and electrical power used by a cooling system
Note 1 to entry: The actual heat load is measured in kW.
3.1.3
energy loss
dissipation of energy caused by electric utilities
Note 1 to entry: The energy loss turned into heat are measured in kWh.
Note 2 to entry: Energy loss is caused, for example. by transformers, uninterruptible power supply (UPS), fans of
computer room air handling units (CRAH), pumps, lighting, power cables.
3.2 Abbreviated terms
For the purposes of this document, the terms and definitions given in ISO/IEC 30134-1 and the following
apply.
CEF cooling efficiency factor
CER cooling efficiency ratio
COP coefficient of performance
CPR cooling performance ratio
DC data centre
EER energ
...