IEC GUIDE 121:2023

IEC GUIDE 121 ®
Edition 1.0 2023-11
GUIDE
Securing credible environmentally relevant performance assessment methods in
standards
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IEC GUIDE 121 ®
Edition 1.0 2023-11
GUIDE
Securing credible environmentally relevant performance assessment methods in

standards
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.020.01 ISBN 978-2-8322-7758-4

– 2 – IEC GUIDE 121:2023  IEC 2023
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions related to standards . 7
3.2 Terms and definitions related to the environment . 7
3.3 Terms and definitions related to credibility and metrology . 8
3.4 Other terms and definitions . 10
3.5 Abbreviated terms . 10
4 Principles for ensuring credible environmentally relevant performance
assessments . 10
4.1 General . 10
4.2 Representativeness . 11
4.3 Measurement repeatability . 11
4.4 Measurement reproducibility . 12
4.5 Measurement accuracy . 12
4.6 Cost of testing . 12
4.7 Anti-circumvention . 12
4.8 Review of standards . 13
5 Requirements for ensuring credible environmentally relevant performance
assessment methods . 13
5.1 General . 13
5.2 Identifying environmentally relevant assessment methods . 13
5.3 Drafting credible environmentally relevant performance assessment methods. 15
5.3.1 Overview . 15
5.3.2 Representativeness . 16
5.3.3 Measurement and costs . 17
5.3.4 Minimizing the risk of circumvention . 17
5.4 Review of standards . 18
6 Guidance for ensuring credible environmentally relevant performance assessment
methods . 18
6.1 General considerations when applying the principles of credibility. 18
6.2 Guidance on assessing the representativeness of environmentally relevant
performance assessment methods . 18
6.3 Guidance to reduce the risk of circumvention of environmentally relevant
performance assessment methods . 20
Annex A (informative) Practical examples . 22
Bibliography . 24

Figure 1 – Identification of an environmentally relevant assessment method or parts
thereof . 14
Figure 2 – Systematic approach for drafting standards with credible environmentally
relevant performance assessment methods . 16

Table A.1 – Examples of non-representativeness and circumvention . 22

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SECURING CREDIBLE ENVIRONMENTALLY RELEVANT
PERFORMANCE ASSESSMENT METHODS IN STANDARDS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC Guide 121 has been prepared by the Advisory Committee on Environmental Aspects
(ACEA).
The text of this IEC Guide is based on the following documents:
Draft Report on voting
SMBNC/43/DV SMBNC/52/RV
Full information on the voting for the approval of this Guide can be found in the report on voting
indicated in the above table.
The language used for the development of this Guide is English.

– 4 – IEC GUIDE 121:2023  IEC 2023
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2, and
developed in accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC
Supplement, available at www.iec.ch/members_experts/refdocs. The main document types
developed by IEC are described in greater detail at www.iec.ch/standardsdev/publications.

INTRODUCTION
The IEC has been developing and publishing standards to support industry and other
stakeholders for over 100 years, and the last few decades have seen an increase in the
importance of standards that address environmental matters. The protection of people from the
potential safety hazards of products has always been an important aspect in the portfolio of
standards developed by the IEC, and today society at large is also demanding that products do
not damage the world in which we live.
Therefore, there is a growing demand for publications that include assessment methods to
determine whether a product can cause harm to the Earth's ecosystem. For instance, the
quantification of hazardous emissions to the environment (for example, fluorinated or other
greenhouse gases) helps to counteract climate change.
The possible harm to the Earth's environment can be caused either directly by a product, for
example, through the emission of harmful substances such as greenhouse gases or other toxic
pollutants directly to land, water, or air during manufacture, use, or end-of-life phase, or
indirectly by the consumption of resources such as energy or water (called "inputs") by a
product. These can affect the environment through, for example, emissions coming from the
production of such inputs and the depletion of the Earth's resources.
IEC and other international standards are expected to provide commonly agreed, objective and
unbiased assessment methods to determine, amongst other things, quantitative properties of a
product or system, such as CO emission or energy consumption. The measurement result can
then be used to prepare an associated declaration to demonstrate the conformity of the product
to specified requirements. Even if IEC standards do not include assessment methods to assess
the direct impact of products on the environment, it is possible that they include methods
relating to a means to assess (or consider) the indirect impact of that product on the
environment, for example, energy consumed to deliver one or more product functions. In this
Guide, assessment methods of either the direct or the indirect environmental impact of products
are referred to as "environmentally relevant assessment".
Testing for environmental impacts, whether beneficial or detrimental, is not always easy. For
instance, such impacts cannot always be readily measured in a consistent and uniform manner.
This can lead to ambiguity and debate as to the usefulness of such a test.
When developing an assessment method, it is already general practice to consider classical
aspects such as measurement repeatability, reproducibility, and accuracy, as well as the costs
of testing. However, these considerations alone do not guarantee that such assessment method
is credible (from the environmental performance point of view). For an IEC standard to be
credible, it needs to ensure that its environmentally relevant performance assessments are
representative of how the product is used, maintained, and disposed of in real-life and to
prevent, as far as practicable, circumvention. Representativeness and (anti-)circumvention will
be extensively addressed in this Guide.
This Guide is complementary to IEC Guide 109. While IEC Guide 109 describes the general
principles of specifying environmental aspects in IEC publications, this Guide provides
principles and requirements to ensure that standards writers are made aware of and consider
the aspects of credibility described in this Guide.
In this Guide the term "committees" includes "technical committees, TCs", "project committees,
PCs", "subcommittees, SCs" and "systems committees, SyCs".
Since environmentally relevant performance assessment methods are present in standards
applicable to many committees, this Guide was prepared by ACEA and was circulated to all IEC
technical committees, some advisory committees, IEC Conformity Assessment Board and CEN-
CLC ECO-CG/TF2 for comments.
The following IEC committees are thanked for their active contribution to the preparation of this
Guide: NL NC, KR NC, JP NC, TC 59, TC 100, and TC 111.

– 6 – IEC GUIDE 121:2023  IEC 2023
SECURING CREDIBLE ENVIRONMENTALLY RELEVANT
PERFORMANCE ASSESSMENT METHODS IN STANDARDS

1 Scope
This Guide specifies principles, requirements, and guidance for standards writers to identify
whether an assessment method in their standard can be used to obtain an indication of the
environmental performance of a product and to ensure that such assessment is credible.
This Guide applies to standards covering environmental performance of new products and as
appropriate to standards covering environmental performance of second life products (for
example, refurbished or remanufactured).
This Guide is therefore intended to ensure that assessment methods developed by standards
writers are credible. The credibility of an environmentally relevant performance assessment
method is determined by taking into account all the related principles, namely
representativeness, measurement repeatability, measurement reproducibility, measurement
accuracy, cost of testing, anti-circumvention, as well as review of standards.
Environmentally relevant performance assessment methods can be present in many IEC
standards (for example, standards covering performance aspects of products), and not only
those focused on the environment. This Guide will be applicable to those as well.
This Guide is not applicable to standards containing environmentally relevant performance
assessment methods that are not assessed by test (for example, assessment by inspection or
simulation), nor is it applicable to other aspects not linked to environment, such as
electromagnetic compatibility (EMC) and electromagnetic fields (EMF).
This Guide does not include guidance on whether all environmentally relevant aspects are
covered by an IEC standard. This Guide also does not give guidance on whether a performance
assessment method was successfully identified as environmentally relevant.
NOTE The IEC Standardization Management Board (SMB) has decided that Guides such as this one can have
mandatory requirements which shall be followed by all IEC committees developing technical work that falls within the
scope of the Guide, as well as guidance which may or may not be followed. The mandatory requirements in this
Guide are identified by the use of "shall". Statements that are only for guidance are identified by using the verb
"should" (see IEC Directives Supplement Part 1, A1.1).
2 Normative references
There are no normative references in this Guide.
3 Terms, definitions and abbreviated terms
For the purposes of this Guide, the terms and definitions given in the ISO/IEC Directives, Part 2,
and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org

3.1 Terms and definitions related to standards
3.1.1
standard
document, established by consensus and approved by a recognized body, that provides, for
common and repeated use, rules, guidelines or characteristics for activities or their results,
aimed at the achievement of the optimum degree of order in a given context
Note 1 to entry: Standards should be based on the consolidated results of science, technology and experience, and
aimed at the promotion of optimum community benefits.
Note 2 to entry: The term "standard" in this document refers to IEC publications, for example, "International
Standard, IS", "Technical Specification, TS", "Publicly Available Specification, PAS", and "Technical Report, TR".
[SOURCE: ISO/IEC Guide 2:2004, 3.2, modified – Note 2 to entry was added to provide the
additional information contained in ISO/IEC Directives, Part 2:2021, 3.1.1, excluding the
reference to "Guides".]
3.1.2
Guide
document published by ISO or IEC giving rules, orientation, advice or recommendations relating
to international standardization
Note 1 to entry: Guides can address issues of interest to all users of documents published by ISO and IEC.
[SOURCE: ISO/IEC Directives, Part 2:2021, 3.1.7]
3.1.3
assessment
undertaking of an investigation in order to arrive at a judgement, based on evidence, of the
suitability of a product
[SOURCE: IEC 60050-821:2017, 821-12-04]
3.2 Terms and definitions related to the environment
3.2.1
environment
surroundings in which a product or system exists, including air, water, land, natural resources,
flora, fauna, humans and their interrelation
[SOURCE: IEC 60050-904:2014, 904-01-01]
3.2.2
environmental aspect
element of an organization's activities or products that can interact with the environment
[SOURCE: IEC 60050-904:2014, 904-01-02, modified – Note 1 to entry has been omitted.]
3.2.3
environmental impact
change to the environment, whether adverse or beneficial, wholly or partly resulting from
environmental aspects
EXAMPLE Typical environmental impacts are resource depletion, ozone depletion, smog formation, eutrophication,
climate change, alteration of habitats, reduction of biological diversity and human exposure.
[SOURCE: IEC 60050-904:2014, 904-01-03, modified – The example has been added.]

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3.2.4
performance
characteristics defining the ability of a product to achieve the intended functions
[SOURCE: IEC 60050-311:2001, 311-06-11, modified – The domain "" has been
added and, in the definition, "measuring instrument" has been replaced by "product".]
3.2.5
environmental performance
performance related to environmental impacts and environmental aspects
Note 1 to entry: The environmental performance is influenced by all processes related to the life cycle of the object
of consideration.
Note 2 to entry: Environmental performance can be expressed either quantitatively or qualitatively with reference
to performance requirements or possibly relative to a scale of values or a benchmark.
[SOURCE: ISO 21931-1:2022, 3.2.10]
Note 3 to entry: Environmental impacts can be either direct or indirect.
[SOURCE: ISO 15392:2019, 3.16, modified – Notes 2 and 3 to entry have been added.]
3.3 Terms and definitions related to credibility and metrology
3.3.1
circumvention
act that results in an invalid outcome to an assessment of a product that is advantageous for
the provider of that product
Note 1 to entry: The act of circumvention can be an intentional or an unintentional evasion of the provisions of a
standard, policy or legislation.
Note 2 to entry: The assessment is presumed to be carried out on a product or system. Consequently, if the
assessment is deemed to be advantageous, it benefits the provider of the product or system.
3.3.2
anti-circumvention
act aimed at preventing circumvention
3.3.3
defeat mechanism
mechanism that changes a product's performance, in particular under test conditions
Note 1 to entry: The mechanism can be hardware, software or firmware or a combination thereof.
3.3.4
representativeness
degree to which a quantitative property reflects the population of interest
Note 1 to entry: A "population of interest" refers to the group from which a conclusion is drawn.
3.3.5
measurement repeatability
closeness of agreement between the results of successive measurements of the same
measurand, carried out under the same conditions of measurement, i.e.:
– by the same measurement procedure,
– by the same observer,
– with the same measuring instruments, used under the same conditions,
– in the same laboratory,
– at relatively short intervals of time.
Note 1 to entry: The concept of "measurement procedure" is defined in VIM (ISO/IEC Guide 99:2007) 2.6.
[SOURCE: IEC 60050-311:2001, 311-06-06, modified – The term "repeatability (of results of
measurements)" has been replaced by "measurement repeatability".]
3.3.6
measurement reproducibility
closeness of agreement between the results of measurements of the same value of a quantity,
when the individual measurements are made under different conditions of measurement:
– measurement principle,
– measurement method,
– observer,
– measuring instruments,
– reference standards,
– laboratory,
– under conditions of use of the instruments, different from those customarily used,
– after intervals of time relatively long compared with the duration of a single measurement.
Note 1 to entry: The concepts of "measurement principle" and "measurement method" are respectively defined in
VIM (ISO/IEC Guide 99:2007) 2.4 and 2.5.
Note 2 to entry: The term "reproducibility" also applies to the instance where only certain of the above conditions
are taken into account, provided that these are stated.
[SOURCE: IEC 60050-311:2001, 311-06-07, modified – The term "reproducibility (of
measurements)" has been replaced by "measurement reproducibility" and, in the definition and
note, "principle of measurement" and "method of measurement" have been replaced with
"measurement principle" and "measurement method", respectively.]
3.3.7
measurement accuracy
closeness of agreement between a measured quantity value and a true quantity value of a
measurand
Note 1 to entry: The concept "measurement accuracy" is not a quantity and is not given a numerical quantity value.
A measurement is said to be more accurate when it offers a smaller measurement error.
Note 2 to entry: The term "measurement accuracy" should not be used for measurement trueness and the term
measurement precision should not be used for ‘measurement accuracy’, which, however, is related to both these
concepts.
Note 3 to entry: "Measurement accuracy" is sometimes understood as closeness of agreement between measured
quantity values that are being attributed to the measurand.
[SOURCE: ISO/IEC Guide 99:2007, 2.13, modified – Admitted terms "accuracy of
measurement" and "accuracy" have been omitted.]
3.3.8
cost of testing
cost of equipment and routine calibration, and cost of material and non-material resources
needed for determining conformity with a standard
Note 1 to entry: Examples of material resources can be test medium and consumables.
Note 2 to entry: Examples of non-material resources can be energy, time, and human resources.

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3.3.9
review
activity of checking a normative document to determine whether it is to be reaffirmed, changed
or withdrawn
[SOURCE: ISO/IEC Guide 2:2004, 9.4]
3.4 Other terms and definitions
3.4.1
product
goods or service
Note 1 to entry: This includes interconnected, interrelated goods or services.
Note 2 to entry: The goods or service can comprise processes, and combinations of processes, goods and services,
commonly known as "systems".
[SOURCE: IEC 62430:2019, 3.1.2, modified – in the definition the term "any" was deleted and
Note 2 to entry was added.]
3.4.2
test
testing
determination of one or more characteristics of an object of conformity assessment according
to a procedure
[SOURCE: ISO/IEC 17000:2020, 6.2, modified – added term "test" and notes to entry omitted.]
3.4.3
user
user of the product
one or more individuals or organizations that install, use, maintain, or finally dispose of the
product
3.5 Abbreviated terms
EMC Electromagnetic compatibility
EMF Electromagnetic field
4 Principles for ensuring credible environmentally relevant performance
assessments
4.1 General
When verifying whether an assessment method can be used to obtain information about the
environmental performance of a product, it is necessary to understand whether the quantitative
property assessed by such a test can have an impact on the environment.
The environmental impacts of products (including systems) are caused by inputs consumed and
outputs generated at all stages of a product's life cycle. Examples of inputs and outputs are:
– inputs: substances, materials (virgin or recycled), parts (new, reused or remanufactured),
subassemblies, consumables, water, and energy, etc.;
– outputs: products, substances, parts, subassemblies, semi-finished products, rejects during
production, emissions to air, water and soil, and waste, etc.

NOTE For further information on environmental impacts, see IEC Guide 109.
The environmental impacts can be direct or indirect. More details are provided in 5.2.
When developing an assessment method, it is already general practice to consider traditional
aspects related to the outcome of the test such as measurement repeatability, reproducibility,
and accuracy, as well as the costs of testing. However, these considerations alone do not
guarantee that such an assessment method is credible from the environmental performance
point of view. To ensure credibility, it is important that the assessment method is representative
of the use conditions as applied by the users in practice and that it takes into consideration the
associated state of the art and potential advances in technology.
Furthermore, in order to ensure that environmentally relevant performance assessment
methods are credible, it is necessary to consider and to limit the possibilities for circumvention
of such methods and the use of defeat mechanisms in particular. A review of the ways in which
tests can be circumvented should be integral to drafting and revising IEC standards.
Product-specific elements and ways to avoid circumvention can be extensively explored based
on, for example, previous experience and technical insights of committees.
These principles are explained in more detail in 4.2 to 4.8.
4.2 Representativeness
The assessment of representativeness, as defined in 3.3.4, is likely to result in an unbiased
estimate of the quantitative properties obtained in practice by users of that product, reflecting
use conditions and user behaviour. Thus, it is necessary to take into consideration, for example,
the geographical region of use, time interval, state of the art of the technology, and
technological coverage in different regions.
Deviations in manufacturing processes (compared to specification) could result in differences
in the manufactured products and so have an impact on the representativeness of the samples
under test. Understanding the manufacturing processes is, therefore, important when
accounting for representativeness (of products).
IEC standards may also cover (analytical) assessment methods of substances and materials
that have an environmental impact (for example, hazardous to the environment) and when
designing analytical assessment methods, the representativeness of such methods is normally
taken into account. To guarantee the representativeness of analytical testing of substances or
materials, reference substances or materials are necessary. The use of certified reference
materials will enhance the representativeness and reliability of the test.
NOTE Certified reference materials are 'controls' used to confirm the quality and metrological traceability of
products, to validate analytical measurement methods, or for the calibration of instruments. A certified reference
material is a particular form of measurement control.
Both sample selection and manufacturing variations are impacted by quality assurance
procedures in manufacturing and in the laboratory. Variations in manufacturing and sample
selection also have an impact on measurement repeatability and measurement reproducibility
of the measurement results
...