ISO/IEC 30134-7:2023

Information technology — Data centres key performance indicators — Part 7: Cooling efficiency ratio (CER)

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).

Titre manque — Partie 7: Titre manque

General Information

• Status: Published
• Publication Date: 09-Mar-2023
• ICS: 35.020 - Information technology (IT) in general
• ICS: 91.120.10 - Thermal insulation of buildings
• Technical Committee: ISO/IEC JTC 1/SC 39 - Sustainability, IT and data centres
• Drafting Committee: ISO/IEC JTC 1/SC 39/WG 1 - Resource Efficient Data Centres
• Current Stage: 6060 - International Standard published
• Start Date: 10-Mar-2023
• Due Date: 09-Jan-2024
• Completion Date: 10-Mar-2023

Standards Content (Sample)

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
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii
© 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
iii
© 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.
iv
© 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.
v
© 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 energy efficiency ratio
HVAC heating, ventilation, air conditioning
iCER interim cooling efficiency ratio
NSenCOP net sensible coefficient of performance
PUE power usage effectiveness
pCEF partial cooling efficiency factor
pPUE partial power usage effectiveness
pPUE partial power usage effectiveness for heating, ventilation and air conditioning systems
HVAC
SEER seasonal energy efficiency ratio
UPS uninterruptible power supply
3.3 Symbols
For the purposes of this document, the following symbols apply.
© ISO/IEC 2023 – All rights reserved

E cooling system energy consumption (annual) in kWh
cooling
E part of E that is attributed to the DC in kWh
cooling,DC cooling
E part of E that is not attributed to the DC in kWh
cooling,other cooling
E part of E that is allocated to one room of the DC in kWh
cooling,room cooling
E electrical energy use of the sub-system in kWh
cooling,subsystem
E electrical energy transferred to heat in kWh
heat
E electrical energy allocated to one room transferred to heat in kWh
heat,room
E electrical energy of the DC that is transferred to heat (annual) in kWh
heat,DC
E IT equipment energy consumption (annual) in kWh
IT
E IT equipment energy consumption (annual) allocated to one room in kWh
IT,room
E electrical energy losses (annual) in kWh
losses
E electrical energy losses (annual) allocated to one room in kWh
losses,room
E total energy consumption allocated to one room (annual) in kWh
total,room
E total DC energy consumption (annual) in kWh
DC
F cooling efficiency factor
EC
F partial cooling efficiency factor
EC,p
P actual electrical power of the cooling system in kW
cooling
P actual heat load in kW
heat
R cooling efficiency ratio
CE
R cooling performance ratio
CP
η power usage effectiveness, PUE
U,P,p
η partial power usage effectiveness, pPUE
U,P
4 Applicable area of the data centre
The CER as specified in this document:
— is associated with the DC infrastructure within its boundaries only;
— describes the efficiency of a cooling system with respect to its electrical energy use.
Derivatives of the CER which are useful in certain circumstances are described in Annex D.
© ISO/IEC 2023 – All rights reserved

5 Definition of the CER
The CER, R , is defined according to Formula (1):
CE
E
heat
R = (1)
CE
E
cooling
Both E and E shall be measured in kWh and for the same time period.
heat cooling
NOTE Within ISO/IEC TS 22237-7:2018, Formula (1) is designated as the energy efficiency ratio (EER). This
will be corrected with the revision of ISO/IEC TS 22237-7.
The following applies to dedicated DC infrastructures:
E = E
heat heat,DC
E = E
cooling cooling,DC
Figure 1 shows the relationship between the different energy forms for dedicated DC infrastructures.
where
E = E + E + E
DC IT losses cooling, DC
Figure 1 — Dedicated cooling system
The calculation of the heat load of the DC is based on the assumption that all electrical energy used in
the DC is transferred to heat:
E = E + E
heat,DC IT losses
E shall be measured in accordance with ISO/IEC 30134-2.
IT
If available, E shall include all other electrical losses, e.g. electrical energy of UPS, energy storage,
losses
transformers, power cables or lighting transferred to heat within the DC boundaries.
For shared cooling systems in multi-purpose buildings, which include a DC, the energy consumption of
the cooling system is determined from the energy consumption from the shared cooling system.
Figure 2 shows the relationship between the different energy forms for shared cooling systems in
multi-purpose buildings including a DC.
© ISO/IEC 2023 – All rights reserved

Where
E
cooling,DC is the part of the energy use for the entire shared cooling system to remove the DC related heat loads;
E
cooling,other is the part of the energy use for the entire shared cooling system to remove non-DC related heat loads.
Figure 2 — Shared cooling system
6 Measurement of CER
6.1 General
The calculation of CER requires the recording and documenting of total heat removed and electrical
energy used for cooling over a coincident period of 12 months. This document does not specify the
frequency of measurements of total heat removed and electrical energy used for cooling, since CER is
calculated on an annual timeframe. However, the frequency of measurement employed will define the
timing of subsequent CER calculations on a rolling annual basis.
6.2 Requirements
The measurement of CER requires the measurement of the total heat removed and the electrical energy
used in the same period.
In order to measure the heat removed, the volume of the coolant and its heat capacity shall be measured.
In cases like direct free cooling, every parameter influencing the heat capacity (like humidity) shall be
measured for an acceptable accuracy of the calculation of the heat removed. In case of redundant pipes,
every pipe shall be measured.
For the electrical energy use all components of the cooling infrastructure (like pumps) valves etc., shall
be measured and included in the energy used. Electrical metering shall be based on kWh, not on power
in kW. In the case of energy reuse, the energy consumption of additional systems for distributing the
reused heat in the building shall not be part of the electrical energy consumption. Annex B shall apply.
In cases where it is necessary to describe versions of the CER for measurement periods of less than 12
months or for DC subsystems, the measurements described in Annex D shall be used.
6.3 Recommendations
DCs should implement meters with remote reading and data history storage capabilities.
7 Application of CER
CER can be used by DC managers to report the efficiency of the cooling system used to control the
temperature of the spaces within the DC. This KPI can be used independently, but to achieve a more
holistic picture of the resource efficiency of the DC, other KPIs described in the ISO/IEC 30134 series
should be considered. When using CER, the PUE in particular should be considered. Where CER is
reported, the corresponding PUE value should also be reported.
© ISO/IEC 2023 – All rights reserved

8 Reporting of CER
8.1 Requirements
8.1.1 Standard construct for communicating CER
For a reported CER to be meaningful, the reporting organization shall provide the following information:
a) the DC under inspection;
b) the CER value [or cooling performance ratio (CPR) value; see D.4];
c) the termination date of the period of measurement using the format of ISO 8601-1 (e.g. yyyy-mm-
dd).
8.1.2 Data for public reporting of CER
8.1.2.1 Required information
The following data shall be provided when publicly reporting CER data:
a) contact information;
NOTE 1 Only the organization’s name or contact are recommended to be displayed in public inquiries.
b) DC location information (address, county or region);
NOTE 2 Only state or local region information is required to be displayed in public inquiries.
c) measurement results: CER with appropriate nomenclature;
d) use case: dedicated DC infrastructures or shared cooling systems in multi-purpose buildings
including a DC.
8.1.2.2 Required supporting evidence
Information on the DC which shall be available upon request as a minimum includes:
a) organization’s
...