ISO 50049:2020

Calculation methods for energy efficiency and energy consumption variations at country, region and city levels

This document gives guidelines for methods for analysing changes in energy efficiency and energy consumption, and for measuring energy efficiency progress, for countries, regions and cities. It is composed of three different calculation methods: — evaluation of structure effects in the variation of energy intensity; — calculation of energy efficiency indices; — decomposition analysis of energy consumption variation. This document is applicable to providing an aggregated statistical evaluation for a country, region or city. It does not apply to calculating changes in the energy consumption or in energy efficiency at the individual consumer's level (e.g. households, organizations, companies).

Méthode de calcul pour l'efficacité énergétique et les variations de consommation d'énergie aux niveaux national, régional et urbain

Le présent document fournit des lignes directrices sur les méthodes permettant d'analyser l'évolution de l'efficacité énergétique et de la consommation d'énergie, et de mesurer les progrès en matière d'efficacité énergétique, aux niveaux national, régional et urbain. Il se compose de trois méthodes de calcul différentes: — évaluation des effets de structure dans la variation de l'intensité énergétique; — calcul des indices d'efficacité énergétique; — analyse de la décomposition de la variation de la consommation d'énergie. Le présent document permet de fournir une évaluation statistique agrégée d'un pays, d'une région ou d'une ville. Il ne s'applique pas au calcul de l'évolution de la consommation d'énergie ou de l'efficacité énergétique au niveau de consommateurs individuels (par exemple, ménages, organisations, entreprises).

General Information

• Status: Published
• Publication Date: 24-Sep-2020
• ICS: 27.010 - Energy and heat transfer engineering in general
• Technical Committee: ISO/TC 301 - Energy management and energy savings
• Drafting Committee: ISO/TC 301 - Energy management and energy savings
• Current Stage: 6060 - International Standard published
• Start Date: 25-Sep-2020
• Due Date: 18-May-2019
• Completion Date: 25-Sep-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 50049
First edition
2020-09
Calculation methods for energy
efficiency and energy consumption
variations at country, region and city
levels
Méthode de calcul pour l'efficacité énergétique et les variations de
consommation d'énergie aux niveaux national, régional et urbain
Reference number
ISO 50049:2020(E)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 50049:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 50049:2020(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Factors to be calculated . 4
4.1 General . 4
4.1.1 Overview of methods included in the document . 4
4.1.2 Objectives of calculations . 4
4.1.3 Types of explanatory factors to be calculated . 5
4.2 Indicators, methods and applications . 7
4.2.1 Indicators . 7
4.2.2 Types of data used . 7
4.2.3 Structure effects . 8
4.2.4 Indicator choice for energy efficiency and energy savings calculation . 8
4.2.5 Climatic corrections of energy consumption . 9
5 Evaluation of structure effects in the variation of energy intensity .9
5.1 General . 9
5.2 Calculation methods .10
5.2.1 Introduction to the calculation of structure effect .10
5.2.2 Decomposition of the energy intensity variation with the Divisia method .11
5.3 Calculation issues related to structure effects .12
5.3.1 General.12
5.3.2 Options of calculation of the Divisia decomposition .13
5.3.3 Disaggregation level .14
5.3.4 Chained or unchained calculation .14
6 Calculation of energy efficiency indices .14
6.1 Objective and overview of calculation .14
6.2 General calculation .15
6.2.1 General.15
6.2.2 Step 1: Selection of subsectors or energy uses .15
6.2.3 Step 2: Choice of indicators .15
6.2.4 Step 3: Calculation of indicator values .16
6.2.5 Step 4: Calculation of indicator trends as index .16
6.2.6 Step 5: Calculation of weighting factors .16
6.2.7 Step 6: Calculation of energy efficiency indices by sector .17
6.2.8 Step 7: Calculation of an overall energy efficiency index .18
6.3 Computational issues in the calculation of the energy efficiency indices .18
6.3.1 General.18
6.3.2 Options for calculation.18
6.3.3 Indicators resulting in negative energy efficiency improvement .19
6.4 Reliability of energy efficiency indices .19
6.4.1 General.19
6.4.2 Status of data sources .20
6.4.3 Appropriateness of the indicator.20
6.4.4 Length of period .20
7 Decomposition analysis of energy consumption variation .20
7.1 Objective and overview of calculation .20
7.2 General calculation .21
7.2.1 General.21
7.2.2 Definition of explanatory factors .21
7.2.3 Calculation of the activity factor .22
© ISO 2020 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 50049:2020(E)

7.2.4 Calculation of the energy savings factor .23
7.2.5 Calculation of structure effects .24
7.2.6 Calculation of other factors.24
7.3 Other issues related to the decomposition of the energy consumption variation .24
7.3.1 General.24
7.3.2 Calculation over a period .25
7.3.3 Indicators resulting in negative energy efficiency improvement .25
Annex A (informative) Calculation of structure effects .26
Annex B (informative) Examples of energy efficiency indicators .34
Annex C (informative) Examples of explanatory factors .45
Annex D (informative) Climatic corrections of energy consumption .56
Bibliography .57
iv © ISO 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 50049:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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 ISO documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO 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).
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.
This document was prepared by Technical Committee ISO/TC 301, Energy management and energy
savings.
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.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO 50049:2020(E)

Introduction
Due to the increasing role of energy efficiency improvements and of controlling the energy consumption
growth in international climate and energy policies, there is a need for harmonization of methods to
evaluate the impact of these policies at the international level.
This document is concerned with the evaluation of energy consumption and energy intensity changes
through explanatory factors, as well as the calculation of an energy efficiency index, at national
and regional levels. The practical application can be different due to specific restrictions, such as
methodologies, availability of data at lower levels of disaggregation, or difficulty in understanding and
communicating.
The methods presented here can provide valuable insights into trends in energy use and factors linked
to those trends. Still, not all aspects of the phenomena that affect energy use are accounted for by the
methods in this document, as these methods are primarily descriptive. While the analysis presented
here can reveal patterns or shifts in patterns of energy use, they do not necessarily reveal causality, an
aspect that can also require additional analysis.
The user should be aware of some issues associated with the methods presented in this document.
Some of these arise from analytic issues. For example, whether to combine all fuels in a sector into a
single energy variable or to treat them separately is a question best addressed by clear reference to the
purpose of the analysis using the methods presented here. Other aspects are phenomena not explicitly
included in the methods presented here. An example is the role of the prices of energy or other goods,
which can require additional methods.
This document is composed of three different calculation methods:
— evaluation of structure effects in the variation of energy intensity;
— calculation of energy efficiency indices;
— decomposition analysis of energy consumption variation.
Energy intensity is often considered as an indicator of energy efficiency at aggregate level when limited
data are available. Their use as a proxy for energy efficiency can be improved by removing from their
variations changes in economic structures: this is the objective of the first part of this document.
With more detailed data on energy consumption available by subsectors or energy uses (e.g. space
heating) or by modes of transport (e.g. cars), it is possible to assess energy efficiency trends through a
more accurate indicator than energy intensity, called “energy efficiency indices”: this is the objective of
the second method of calculation presented in this document.
The variation of energy consumption can be related to change in economic activity, to energy savings
as well as to other explanatory factors: the purpose of the third method of calculation described in this
document is to present the method of decomposition of changes in energy consumption. It makes use
of indicator-based savings, i.e. energy savings calculated according to the indicator-based method, as
described in ISO 17742.
This document considers all end-use sectors, such as industry, transport, households, services (also
known as the “tertiary sector”) and agriculture. It does not generally incorporate the energy supply
sectors, such as power plants, refineries or coal mines. However, the integration of the power sector
can be considered in the decomposition of the primary energy consumption to account for the effect of
variations in energy efficiency and energy mix in the power sector.
Energy consumption considered in this document excludes feedstock energy, such as oil feedstock used
to produce plastics or natural gas used as a feedstock for the production of fertilisers, as they are not
affected by energy efficiency policies.
vi © ISO 2020 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 50049:2020(E)

This document can be used by any interested parties (decision-makers, companies, researchers, NGOs,
etc.) that want to understand changes in the energy intensity or the energy consumption, as well as to
assess energy efficiency by sector over a specific period.
This document is part of a set of documents developed by TC 301 (see Figure 1) and builds on the
general principles outlined in ISO 17743, including reporting and system boundaries, and on the energy
savings calculations presented in ISO 17742.
Figure 1 — Relationship between documents
The document covers more precisely three types of calculation methods based on energy efficiency
indicators. Compared to ISO 17742, it details more advanced methodologies that facilitate a more
comprehensive understanding of changes in: a) energy intensity, b) energy efficiency and, finally,
c) energy consumption. The evaluation of energy efficiency trends relies on the calculation of energy
efficiency indices. Variations in energy consumption are explained from a decomposition into different
explanatory factors, one of which being energy savings. Therefore, this document complements
ISO 17742 on energy savings calculation methods. More specifically, it complements how ISO 17742
deals with indicator-based methods. For each calculation method, examples of specific calculations are
presented separately in Annexes A to C.
When applying this document, the user can choose between different options of the methods proposed.
In order to be transparent in the way results have been obtained, the user of this document should
specify the methodology used when presenting the results.
The general methodologies to evaluate trends in energy intensity, energy efficiency and energy
consumption and its link to energy savings are presented in Clause 4. The calculation of the influence
of structural changes in the energy intensity variation is described in Clause 5. The calculation method
for the energy efficiency index is described in Clause 6. Finally, the method of decomposition of the
energy consumption is given in Clause 7. Annexes A to C provide examples to illustrate various types of
calculations. Annex D presents the methodology of climatic corrections, as most of these calculations
should be done with energy efficiency indicators adjusted to a normal climate.
© ISO 2020 – All rights reserved vii

---------------------- Page: 7 ----------------------
INTERNATIONAL STANDARD ISO 50049:2020(E)
Calculation methods for energy efficiency and energy
consumption variations at country, region and city levels
1 Scope
This document gives guidelines for methods for analysing changes in energy efficiency and energy
consumption, and for measuring energy efficiency progress, for countries, regions and cities. It is
composed of three different calculation methods:
— evaluation of structure effects in the variation of energy intensity;
— calculation of energy efficiency indices;
— decomposition analysis of energy consumption variation.
This document is applicable to providing an aggregated statistical evaluation for a country, region or
city. It does not apply to calculating changes in the energy consumption or in energy efficiency at the
individual consumer’s level (e.g. households, organizations, companies).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
activity factor
variation in the energy consumption levels of a sector or subsector due to the variation of the activity
of the sector for a given period
Note 1 to entry: The quantification of this factor depends on the driver used to measure the activity.
3.2
apparent energy efficiency improvement
increase in energy efficiency (3.5) without correction or adjustment (i.e. gross value resulting from a
calculation)
3.3
base year
reference year in the calculation
Note 1 to entry: It is usually the first year of calculation.
Note 2 to entry: The year can be calendar or fiscal. All data should have the same definition of year, whether
calendar or fiscal.
© ISO 2020 – All rights reserved 1

---------------------- Page: 8 ----------------------
ISO 50049:2020(E)

3.4
behavioural factor
factor that shows the impact on the variation of energy consumption or on an energy indicator of
changes in the behaviour of consumers
EXAMPLE Change in the level of thermal comfort with a higher or lower use of heating or air cooling
equipment.
3.5
energy efficiency
ratio or other quantitative relationship between an output of performance, service, goods, commodities
or energy and an input of energy
[SOURCE: ISO/IEC 13273-1:2015, 3.4.1, modified — The symbol has been deleted and “commodities”
has been added.]
3.6
energy efficiency improvement
increase in energy efficiency (3.5) as a result of technological, behavioural and/or economic changes
[SOURCE: ISO/IEC 13273-1:2015, 3.4.3, modified — “technological, behavioural and/or economic
changes” has replaced “technological, design, behavioural or economic changes”.]
3.7
energy efficiency index
index measuring the increase in energy efficiency (3.5) compared to a base year (3.3)
EXAMPLE 100 for base year.
3.8
energy intensity
quotient describing the total energy consumption per unit of economic output
Note 1 to entry: The economic output should be measured at a constant price.
Note 2 to entry: The intensity can be interpreted as the amount of energy required to produce one unit of activity
expressed in monetary terms (GDP or value added).
Note 3 to entry: The intensity can also be used at sector level (e.g. industry, residential, services). In that case, it is
often referred to as “sectoral energy intensity”.
Note 4 to entry: The term “energy intensity” is sometimes used with the same meaning as specific energy
consumption (3.17), but this is not the case in this document.
[SOURCE: ISO/IEC 13273-1:2015, 3.1.14, modified — The example has been deleted and Notes 1, 2, 3 and
4 to entry have been added.]
3.9
energy savings
reduction of energy consumption compared to an energy baseline at same level of service
Note 1 to entry: Energy savings are positive when they reduce consumption. Due to some external factors that
cannot be accounted for, consumption can increase instead of decrease: this phenomenon is referred to as
“negative energy savings”.
3.10
energy use
application of energy
EXAMPLE Ventilation; lighting; heating; cooling; transportation; data storage; production process.
Note 1 to entry: Energy use is sometimes referred to as “energy end-use”.
2 © ISO 2020 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 50049:2020(E)

[SOURCE: ISO 50001:2018, 3.5.4]
3.11
energy using system
physical items with defined system boundaries, using energy
EXAMPLE Plant, process, building, machines, equipment, product.
[SOURCE: ISO 50047:2016, 3.1, modified — The example has been replaced.]
3.12
explanatory factor
factor explaining the variation in an indicator or in the energy consumption
Note 1 to entry: It is different from the concept of “relevant variable” as defined in other standards as a
“quantifiable factor that impacts energy performance and routinely changes” (e.g. ISO 50006:2014, 3.14).
“Relevant variable” is more related to the performance of an energy using system (3.11), whereas “explanatory
factor” relates to a sector and to both its consumption and performance. “Relevant variable” is more a micro
concept, whereas “explanatory factor” is a macro concept.
3.13
final energy
energy as delivered to an energy using system (3.11)
Note 1 to entry: This concept is sometimes referred to as “delivered energy”.
[SOURCE: ISO/IEC 13273-1:2015, 3.1.11, modified — Note 2 to entry has been deleted.]
3.14
fuel substitution factor
factor that shows the impact of fuel substitutions between types of energy with very different end-use
efficiency on the variation of an energy indicator
3.15
indicator-based savings
energy savings (3.9) calculated by indicator-based methods (3.16)
[SOURCE: ISO 17742:2015, 2.28]
3.16
indicator-based method
determination of energy savings (3.9) from the variation of energy consumption indicators over a period
[SOURCE: ISO 17742:2015, 2.27, modified — The example has been deleted.]
3.17
specific energy consumption
quotient describing the total energy consumption per unit of output or service
2
EXAMPLE Gigajoule (GJ) per ton of steel, annual kilowatt-hour (kWh) per square meter (m ), litres of fuel
per 100 kilometre (km).
[SOURCE: ISO/IEC 13273-1:2015, 3.1.15]
3.18
structure effect
structural effect
measure of the variation in energy consumption or in energy intensity (3.8) due to a variation in
economic structures
Note 1 to entry: Structure effects may refer more generally to any changes in the share of different activities (e.g.
industrial branches in total value added of industry, transport modes in total traffic).
© ISO 2020 – All rights reserved 3

---------------------- Page: 10 ----------------------
ISO 50049:2020(E)

Note 2 to entry: “Hidden structure effect” refers to structure effects that exist but cannot be quantified due to a
lack of data.
4 Factors to be calculated
4.1 General
4.1.1 Overview of methods included in the document
This clause is an introduction to Clauses 5, 6 and 7 on methods to assess energy intensity and energy
efficiency trends and to analyse the energy consumption variation. It describes common issues, such
as the different explanatory factors that need to be considered in these assessments (case of energy
intensity and energy consumption) or excluded to measure energy efficiency improvements and the
various ways to calculate them. This clause clarifies what kind of explanatory factors are covered in
this document.
Explanatory factors of changes in energy intensity or in energy consumption and energy efficiency
trends are calculated for a given period of time, normally one or more calendar years. The methods
make use of statistical data and are normally applied to calculate explanatory factors, such as energy
savings or energy efficiency improvements made during the past years. However, if a comparable set of
data is available such as projections, e.g. from an energy scenario outlook, the methods can be applied
for future years.
This document refers to the so-called “top-down” method of calculating energy savings as reported in
ISO 17742 and ISO 17743, based on statistical energy efficiency indicators. The first and third methods
analyse observed trends in energy intensity indicators (see Clause 5) and in energy consumption (see
Clause 7) through the identification of some of the explanatory factors behind these trends. The second
method (see Clause 6) proposes an energy efficiency index that is as far as possible corrected for factors
that are not linked to energy efficiency.
4.1.2 Objectives of calculations
The main objective of this document is to help monitor energy efficiency targets, on energy intensity, on
energy consumption or on energy efficiency improvements. More generally, this document can help to
understand variations observed in energy intensity and energy consumption. It is critical for the analysis
presented in this document to be useful
...

NORME ISO
INTERNATIONALE 50049
Première édition
2020-09
Méthode de calcul pour l'efficacité
énergétique et les variations de
consommation d'énergie aux niveaux
national, régional et urbain
Calculation methods for energy efficiency and energy consumption
variations at country, region and city levels
Numéro de référence
ISO 50049:2020(F)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 50049:2020(F)

DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: [phone]
E-mail: [e-mail]
Web: www.iso.org
Publié en Suisse
ii © ISO 2020 – Tous droits réservés

---------------------- Page: 2 ----------------------
ISO 50049:2020(F)

Sommaire Page
Avant-propos .v
Introduction .vi
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Facteurs à calculer . 4
4.1 Généralités . 4
4.1.1 Vue d’ensemble des méthodes incluses dans le document . 4
4.1.2 Objectifs des calculs . 4
4.1.3 Types de facteurs explicatifs à calculer . 5
4.2 Indicateurs, méthodes et applications . 7
4.2.1 Indicateurs . 7
4.2.2 Types de données utilisés . 8
4.2.3 Effets de structure . 9
4.2.4 Choix de l’indicateur pour les calculs relatifs à l’efficacité énergétique et
aux économies d’énergie. 9
4.2.5 Corrections climatiques de la consommation d’énergie .10
5 Évaluation des effets de structure dans la variation de l’intensité énergétique .10
5.1 Généralités .10
5.2 Méthodes de calcul .11
5.2.1 Introduction au calcul de l’effet de structure .11
5.2.2 Décomposition de la variation de l’intensité énergétique à l’aide de la
méthode Divisia .12
5.3 Questions liées aux calculs des effets de structure .14
5.3.1 Généralités .14
5.3.2 Options de calcul de la décomposition de Divisia .14
5.3.3 Niveau de désagrégation .15
5.3.4 Calcul chaîné ou non chaîné .15
6 Calcul des indices d’efficacité énergétique .15
6.1 Objectif et vue d’ensemble du calcul .15
6.2 Méthode générale de calcul.16
6.2.1 Généralités .16
6.2.2 Étape 1: sélection des sous-secteurs ou usages de l’énergie .17
6.2.3 Étape 2: choix des indicateurs .17
6.2.4 Étape 3: calcul de la valeur des indicateurs .17
6.2.5 Étape 4: calcul des tendances des indicateurs sous forme d’indice .17
6.2.6 Étape 5: calcul des facteurs de pondération .18
6.2.7 Étape 6: calcul des indices d’efficacité énergétique par secteur .18
6.2.8 Étape 7: calcul d’un indice d’efficacité énergétique global .19
6.3 Questions liées au calcul dans la détermination des indices d’efficacité énergétique .20
6.3.1 Généralités .20
6.3.2 Options de calcul .20
6.3.3 Indicateurs entraînant une évolution négative de l’efficacité énergétique .21
6.4 Fiabilité des indices d’efficacité énergétique .21
6.4.1 Généralités .21
6.4.2 Statut des sources de données .22
6.4.3 L’adéquation de l’indicateur .22
6.4.4 Durée de la période .22
7 Analyse de la décomposition de la variation de la consommation d’énergie. .23
7.1 Objectif et vue d’ensemble du calcul .23
7.2 Méthode générale de calcul.23
7.2.1 Généralités .23
© ISO 2020 – Tous droits réservés iii

---------------------- Page: 3 ----------------------
ISO 50049:2020(F)

7.2.2 Définition des facteurs explicatifs .23
7.2.3 Calcul du facteur d’activité .24
7.2.4 Calcul du facteur d’économies d’énergie .25
7.2.5 Calcul des effets de structure .26
7.2.6 Calcul des autres facteurs.27
7.3 Autres questions liées à la décomposition de la variation de la consommation d’énergie 27
7.3.1 Généralités .27
7.3.2 Calcul sur une période .27
7.3.3 Indicateurs entraînant une évolution négative de l’efficacité énergétique .27
Annexe A (informative) Calcul des effets de structure .29
Annexe B (informative) Exemples d’indicateurs d’efficacité énergétique .37
Annexe C (informative) Exemples de facteurs explicatifs .48
Annexe D (informative) Corrections climatiques de la consommation d’énergie .59
Bibliographie .61
iv © ISO 2020 – Tous droits réservés

---------------------- Page: 4 ----------------------
ISO 50049:2020(F)

Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes
nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est
en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.
L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents
critères d'approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).
L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de
brevets reçues par l'ISO (voir www .iso .org/ brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion
de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir www .iso .org/ avant -propos.
Le présent document a été élaboré par le comité technique ISO/TC 301, Management de l’énergie et
économies d’énergie.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www .iso .org/ fr/ members .html.
© ISO 2020 – Tous droits réservés v

---------------------- Page: 5 ----------------------
ISO 50049:2020(F)

Introduction
Au vu du rôle croissant des améliorations de l’efficacité énergétique et de la maîtrise de la croissance
de la consommation d’énergie dans les politiques climatiques et énergétiques internationales, il est
nécessaire d’harmoniser les méthodes permettant d’évaluer l’impact de ces politiques au niveau
international.
Le présent document traite de l’évaluation de la consommation d’énergie et des variations de l’intensité
énergétique à travers des facteurs explicatifs, ainsi que du calcul d’un indice d’efficacité énergétique,
aux niveaux national et régional. L’application pratique peut être différente en raison de restrictions
spécifiques, telles que les méthodologies, la disponibilité de données à des niveaux de désagrégation
inférieurs ou la difficulté à comprendre et à communiquer.
Les méthodes présentées ici peuvent fournir de précieux renseignements sur les tendances de l’usage
de l’énergie et sur les facteurs qui y sont liés. Cependant, tous les aspects des phénomènes influant sur
l’usage de l’énergie énergétique ne sont pas pris en compte par les méthodes décrites dans le présent
document, celles-ci étant essentiellement descriptives. Bien que les analyses présentées dans ce
document puissent révéler des tendances ou des changements dans l’usage de l’énergie, elles ne révèlent
pas nécessairement de causalité. Cet aspect peut également exiger une analyse supplémentaire.
Il convient que l’utilisateur soit informé de certains problèmes liés aux méthodes présentées dans le
présent document. Certains relèvent de questions analytiques. Par exemple, savoir s’il faut combiner
tous les combustibles d’un secteur en une variable énergie unique ou les traiter séparément est une
question qu’il est préférable d’aborder en faisant clairement référence à l’objet de l’analyse à l’aide des
méthodes présentées ici. D’autres aspects sont des phénomènes qui ne sont pas explicitement inclus
dans les méthodes présentées ici. Par exemple, le rôle des prix de l’énergie ou d’autres biens, qui peuvent
nécessiter des méthodes supplémentaires.
Le présent document se compose de trois méthodes de calcul différentes:
— évaluation des effets de structure dans la variation de l’intensité énergétique;
— calcul des indices d’efficacité énergétique;
— analyse de la décomposition de la variation de la consommation d’énergie.
L’intensité énergétique est souvent considérée comme un indicateur de l’efficacité énergétique à
un niveau agrégé lorsque les données disponibles sont limitées. Son utilisation comme substitut à
l’efficacité énergétique peut être améliorée en supprimant de ses variations les changements survenant
dans les structures économiques: il s’agit de l’objectif de la première partie du présent document.
Avec des données plus détaillées sur la consommation énergétique disponible par sous-secteurs ou par
usages de l’énergie (par exemple, le chauffage des locaux) ou par modes de transport (par exemple, les
voitures), il est possible d’évaluer les tendances de l’efficacité énergétique au moyen d’un indicateur plus
précis que l’intensité énergétique, appelé «indices d’efficacité énergétique»: tel est l’objectif du second
mode de calcul décrit dans le présent document.
La variation de la consommation d’énergie peut être mise en relation avec l’évolution de l’activité
économique, les économies d’énergie, ainsi que d’autres facteurs explicatifs: l’objet de la troisième
méthode de calcul décrite dans le présent document est de présenter la méthode de décomposition des
variations de la consommation énergétique. Elle fait appel aux économies basées sur des indicateurs,
c’est-à-dire des économies d’énergie calculées selon la méthode fondée sur des indicateurs, telle que
décrite dans l’ISO 17742.
Le présent document prend en compte tous les secteurs d’usage final, tels que l’industrie, le transport, les
ménages, les services (également appelés «secteur tertiaire») et l’agriculture. Il ne prend généralement
pas en compte les secteurs de l’approvisionnement énergétique, tels que les centrales électriques, les
raffineries ou les mines de charbon. Toutefois, l’intégration du secteur de l’énergie peut être prise en
compte dans la décomposition de la consommation d’énergie primaire pour tenir compte de l’effet des
variations de l’efficacité énergétique et du bouquet énergétique du secteur de l’énergie.
vi © ISO 2020 – Tous droits réservés

---------------------- Page: 6 ----------------------
ISO 50049:2020(F)

La consommation d’énergie prise en considération dans le présent document exclut l’énergie liée
aux matières premières, telles que les matières premières pétrolières destinées à la production
de plastiques ou le gaz naturel destiné à la production d’engrais, ceux-ci n’étant pas affectés par les
politiques d’efficacité énergétique.
Le présent document peut être utilisé par toutes les parties intéressées (décideurs, entreprises,
chercheurs, ONG, etc.) qui souhaitent comprendre les changements de l’intensité énergétique ou de la
consommation énergétique et évaluer l’efficacité énergétique par secteur sur une période spécifique.
Le présent document fait partie d’un ensemble de documents élaborés par la TC 301 (voir Figure 1) et
s’appuie sur les principes généraux décrits dans l’ISO 17743, y compris les rapports et le périmètre du
système, ainsi que les calculs d’économie d’énergie présentés dans l’ISO 17742.
Figure 1 — Relation entre les documents
Le document couvre plus précisément trois types de méthodes de calcul basées sur des indicateurs
d’efficacité énergétique. Comparé à l’ISO 17742, il détaille des méthodologies plus élaborées qui
permettent une compréhension plus complète des changements a) de l’intensité énergétique, b) de
l’efficacité énergétique et, enfin, c) de la consommation énergétique. L’évaluation des tendances en
matière d’efficacité énergétique repose sur le calcul d’indices d’efficacité énergétique. Les variations
de la consommation d’énergie sont expliquées par une décomposition en différents facteurs explicatifs,
parmi lesquels figurent les économies d’énergie. Par conséquent, le présent document complète
l’ISO 17742 sur les méthodes de calcul des économies d’énergie. Plus précisément, il complète la façon
dont l’ISO 17742 traite des méthodes fondées sur des indicateurs. Pour chaque méthode de calcul, des
exemples de calculs spécifiques sont présentés séparément dans les Annexes A à C.
Dans le cadre de l’application du présent document, l’utilisateur peut choisir entre différentes
variantes des méthodes proposées. Pour garantir la transparence des résultats obtenus, il convient que
l’utilisateur du présent document indique la variante utilisée lors de la présentation des résultats.
Les méthodologies générales d’évaluation des tendances en matière d’intensité énergétique, d’efficacité
énergétique et de consommation énergétique, ainsi que leurs liens avec les économies d’énergie sont
présentés dans l’Article 4. Le calcul de l’influence des changements de structure sur la variation de
l’intensité énergétique est décrit à l’Article 5. La méthode de calcul de l’indice d’efficacité énergétique
est décrite à l’Article 6. Enfin, la méthode de décomposition de la variation de la consommation d’énergie
est décrite à l’Article 7. Les Annexes A à C illustrent différents types de calculs par des exemples.
© ISO 2020 – Tous droits réservés vii

---------------------- Page: 7 ----------------------
ISO 50049:2020(F)

L’Annexe D présente la méthodologie des corrections climatiques. Il convient en effet que la plupart de
ces calculs soit effectuée avec des indicateurs d’efficacité énergétique ajustés à un climat normal.
viii © ISO 2020 – Tous droits réservés

---------------------- Page: 8 ----------------------
NORME INTERNATIONALE ISO 50049:2020(F)
Méthode de calcul pour l'efficacité énergétique et les
variations de consommation d'énergie aux niveaux
national, régional et urbain
1 Domaine d’application
Le présent document fournit des lignes directrices sur les méthodes permettant d’analyser l’évolution
de l’efficacité énergétique et de la consommation d’énergie, et de mesurer les progrès en matière
d’efficacité énergétique, aux niveaux national, régional et urbain. Il se compose de trois méthodes de
calcul différentes:
— évaluation des effets de structure dans la variation de l’intensité énergétique;
— calcul des indices d’efficacité énergétique;
— analyse de la décomposition de la variation de la consommation d’énergie.
Le présent document permet de fournir une évaluation statistique agrégée d’un pays, d’une région ou
d’une ville. Il ne s’applique pas au calcul de l’évolution de la consommation d’énergie ou de l’efficacité
énergétique au niveau de consommateurs individuels (par exemple, ménages, organisations,
entreprises).
2 Références normatives
Le présent document ne contient aucune référence normative.
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions suivants s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp
— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/
3.1
facteur d’activité
variation des niveaux de consommation énergétique d’un secteur ou d’un sous-secteur liée à l’évolution
de l’activité du secteur sur une période donnée
Note 1 à l'article: La quantification de ce facteur dépend du paramètre d’influence utilisé pour mesurer l’activité.
3.2
amélioration apparente de l’efficacité énergétique
accroissement de l’efficacité énergétique (3.5) sans correction ou ajustement (c’est-à-dire une valeur
brute résultant d’un calcul)
3.3
année de référence
année de référence utilisée dans le calcul
Note 1 à l'article: Il s’agit généralement de la première année du calcul.
© ISO 2020 – Tous droits réservés 1

---------------------- Page: 9 ----------------------
ISO 50049:2020(F)

Note 2 à l'article: L’année peut être calendaire ou fiscale. Il convient que toutes les données adoptent la même
définition de l’année, qu’elle soit calendaire ou fiscale.
3.4
facteur comportemental
facteur qui montre l’impact du comportement des consommateurs sur l’évolution de la consommation
d’énergie ou sur un indicateur d’énergie
EXEMPLE Évolution du niveau de confort thermique suite à une utilisation plus ou moins importante de leur
équipement de chauffage ou de climatisation.
3.5
efficacité énergétique
ratio, ou autre relation quantitative, entre une performance, un service, un bien, des marchandises ou
une énergie produits et un apport en énergie
[SOURCE: ISO/IEC 13273-1:2015, 3.4.1, modifiée — Le symbole a été supprimé et le terme «marchandises»
a été ajouté.]
3.6
amélioration de l’efficacité énergétique
accroissement de l’efficacité énergétique (3.5) résultant de modifications technologiques,
comportementales et/ou économiques
[SOURCE: ISO/IEC 13273-1:2015, 3.4.3, modifiée — «modifications technologiques, comportementales
et/ou économiques» remplace «modifications technologiques, de conception, comportementales ou
économiques».]
3.7
indice d’efficacité énergétique
indice permettant de mesurer l’augmentation de l’efficacité énergétique (3.5) par rapport à une année de
référence (3.3)
EXEMPLE 100 pour l’année de référence.
3.8
intensité énergétique
ratio exprimant la consommation énergétique totale par unité de production économique
Note 1 à l'article: Il convient de mesurer la production économique à prix constant.
Note 2 à l'article: L’intensité peut être interprétée comme la quantité d’énergie requise pour produire une unité
d’activité, exprimée en valeur monétaire (PIB ou valeur ajoutée).
Note 3 à l'article: L’intensité peut également être utilisée à l’échelle d’un secteur (par exemple, industriel,
résidentiel, services). Dans ce cas, on parle généralement d’«intensité énergétique sectorielle».
Note 4 à l'article: Le terme «intensité énergétique» est parfois utilisé au sens de consommation énergétique
spécifique (3.17). Ce n’est pas le cas dans le présent document.
[SOURCE: ISO/IEC 13273-1:2015, 3.1.14, modifiée — L’exemple a été supprimé et les Notes 1, 2, 3 et 4 à
l’article ont été ajoutées.]
3.9
économies d’énergie
réduction de la consommation énergétique par rapport à une consommation de référence au même
niveau de service
Note 1 à l'article: Les économies d’énergie sont positives lorsqu’elles réduisent la consommation. La consommation
peut augmenter au lieu de diminuer en raison de certains facteurs externes ne pouvant être pris en compte: ce
phénomène est appelé «économies d’énergie négatives».
2 © ISO 2020 – Tous droits réservés

---------------------- Page: 10 ----------------------
ISO 50049:2020(F)

3.10
usage de l’énergie
ce qui utilise de l’énergie
EXEMPLE Ventilation, éclairage, chauffage, climatisation, transport, stockage de données, procédé de
production.
Note 1 à l'article: L’usage de l’énergie est parfois appelé «usage final de l’énergie».
[SOURCE: ISO 50001:2018, 3.5.4, modifiée]
3.11
système consommateur d’énergie
système physique ayant un périmètre défini et consommant de l’énergie
EXEMPLE Une installation, un procédé, un bâtiment, une machine, un équipement, un produit.
[SOURCE: ISO 50047:2016, 3.1, modifiée — L’exemple a été remplacé]
3.12
facteur explicatif
facteur expliquant l’évolution d’un indicateur ou de la consommation énergétique
Note 1 à l'article: Ce concept est différent de celui de «variable pertinente», défini dans d’autres normes comme
un «paramètre quantifiable ayant un impact sur la performance énergétique et soumis à des changements
réguliers» (par exemple ISO 50006:2014, 3.14). La «variable pertinente» est davantage liée à la performance
d’un système consommateur d’énergie (3.11), alors que le «facteur explicatif» est lié à un secteur, ainsi qu’à sa
consommation et à sa performance. La «variable pertinente» relève plutôt du micro-concept alors que le «facteur
explicatif» est un macro-concept.
3.13
énergie finale
énergie telle que fournie à un système consommateur d’énergie (3.11)
Note 1 à l'article: Ce concept est parfois désigné sous le terme «énergie fournie».
[SOURCE: ISO/IEC 13273-1:2015, 3.1.11, modifiée — La Note 2 à l’article a été supprimée.]
3.14
facteur de substitution énergétique
facteur qui montre l’impact des substitutions d’énergie entre des types d’énergie dont l’efficacité
énergétique finale diffère considérablement sur la variation d’un indicateur d’énergie
3.15
économies basées sur des indicateurs
économies d’énergie (3.9) calculées avec des méthodes fondées sur des indicateurs (3.16)
[SOURCE: ISO 17742:2015, 2.28]
3.16
méthode fondée sur des indicateurs
détermination des économies d’énergie (3.9) à partir de la variation d’indicateurs de consommation
énergétique sur une certaine période
[SOURCE: ISO 17742:2015, 2.27, modifiée — L’exemple
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 50049
ISO/TC 301
Calculation methods for energy
Secretariat: ANSI
efficiency and energy consumption
Voting begins on:
2020­06­16 variations at country, region and city
levels
Voting terminates on:
2020­08­11
Méthode de calcul pour l'efficacité énergétique et les variations de
consommation d'énergie aux niveaux national, régional et urbain
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/FDIS 50049:2020(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 2020

---------------------- Page: 1 ----------------------
ISO/FDIS 50049:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
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
CH­1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 50049:2020(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Factors to be calculated . 4
4.1 General . 4
4.1.1 Overview of methods included in the document . 4
4.1.2 Objectives of calculations . 4
4.1.3 Types of explanatory factors to be calculated . 5
4.2 Indicators, methods and applications . 7
4.2.1 Indicators . 7
4.2.2 Types of data used . 7
4.2.3 Structure effects . 8
4.2.4 Indicator choice for energy efficiency and energy savings calculation . 8
4.2.5 Climatic corrections of energy consumption . 9
5 Evaluation of structure effects in the variation of energy intensity .9
5.1 General . 9
5.2 Calculation methods .10
5.2.1 Introduction to the calculation of structure effect .10
5.2.2 Decomposition of the energy intensity variation with the Divisia method .11
5.3 Calculation issues related to structure effects .12
5.3.1 General.12
5.3.2 Options of calculation of the Divisia decomposition .13
5.3.3 Disaggregation level .14
5.3.4 Chained or unchained calculation .14
6 Calculation of energy efficiency indices .14
6.1 Objective and overview of calculation .14
6.2 General calculation .15
6.2.1 General.15
6.2.2 Step 1: Selection of subsectors or energy uses .15
6.2.3 Step 2: Choice of indicators .15
6.2.4 Step 3: Calculation of indicator values .16
6.2.5 Step 4: Calculation of indicator trends as index .16
6.2.6 Step 5: Calculation of weighting factors .16
6.2.7 Step 6: Calculation of energy efficiency indices by sector .17
6.2.8 Step 7: Calculation of an overall energy efficiency index .18
6.3 Computational issues in the calculation of the energy efficiency indices .18
6.3.1 General.18
6.3.2 Options for calculation.18
6.3.3 Indicators resulting in negative energy efficiency improvement .19
6.4 Reliability of energy efficiency indices .19
6.4.1 General.19
6.4.2 Status of data sources .20
6.4.3 Appropriateness of the indicator.20
6.4.4 Length of period .20
7 Decomposition analysis of energy consumption variation .20
7.1 Objective and overview of calculation .20
7.2 General calculation .21
7.2.1 General.21
7.2.2 Definition of explanatory factors .21
7.2.3 Calculation of the activity factor .22
© ISO 2020 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/FDIS 50049:2020(E)

7.2.4 Calculation of the energy savings factor .23
7.2.5 Calculation of structure effects .24
7.2.6 Calculation of other factors.24
7.3 Other issues related to the decomposition of the energy consumption variation .24
7.3.1 General.24
7.3.2 Calculation over a period .25
7.3.3 Indicators resulting in negative energy efficiency improvement .25
Annex A (informative) Calculation of structure effects .26
Annex B (informative) Examples of energy efficiency indicators .34
Annex C (informative) Examples of explanatory factors .45
Annex D (informative) Climatic corrections of energy consumption .56
Bibliography .57
iv © ISO 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/FDIS 50049:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non­governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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 ISO documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO 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).
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.
This document was prepared by Technical Committee ISO/TC 301, Energy management and energy
savings.
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.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO/FDIS 50049:2020(E)

Introduction
Due to the increasing role of energy efficiency improvements and of controlling the energy consumption
growth in international climate and energy policies, there is a need for harmonization of methods to
evaluate the impact of these policies at the international level.
This document is concerned with the evaluation of energy consumption and energy intensity changes
through explanatory factors, as well as the calculation of an energy efficiency index, at national
and regional levels. The practical application can be different due to specific restrictions, such as
methodologies, availability of data at lower levels of disaggregation, or difficulty in understanding and
communicating.
The methods presented here can provide valuable insights into trends in energy use and factors linked
to those trends. Still, not all aspects of the phenomena that affect energy use are accounted for by the
methods in this document, as these methods are primarily descriptive. While the analysis presented
here can reveal patterns or shifts in patterns of energy use, they do not necessarily reveal causality, an
aspect that can also require additional analysis.
The user should be aware of some issues associated with the methods presented in this document.
Some of these arise from analytic issues. For example, whether to combine all fuels in a sector into a
single energy variable or to treat them separately is a question best addressed by clear reference to the
purpose of the analysis using the methods presented here. Other aspects are phenomena not explicitly
included in the methods presented here. An example is the role of the prices of energy or other goods,
which can require additional methods.
This document is composed of three different calculation methods:
— evaluation of structure effects in the variation of energy intensity;
— calculation of energy efficiency indices;
— decomposition analysis of energy consumption variation.
Energy intensity is often considered as an indicator of energy efficiency at aggregate level when limited
data are available. Their use as a proxy for energy efficiency can be improved by removing from their
variations changes in economic structures: this is the objective of the first part of this document.
With more detailed data on energy consumption available by subsectors or energy uses (e.g. space
heating) or by modes of transport (e.g. cars), it is possible to assess energy efficiency trends through a
more accurate indicator than energy intensity, called “energy efficiency indices”: this is the objective of
the second method of calculation presented in this document.
The variation of energy consumption can be related to change in economic activity, to energy savings
as well as to other explanatory factors: the purpose of the third method of calculation described in this
document is to present the method of decomposition of changes in energy consumption. It makes use
of indicator-based savings, i.e. energy savings calculated according to the indicator-based method, as
described in ISO 17742.
This document considers all end-use sectors, such as industry, transport, households, services (also
known as the “tertiary sector”) and agriculture. It does not generally incorporate the energy supply
sectors, such as power plants, refineries or coal mines. However, the integration of the power sector
can be considered in the decomposition of the primary energy consumption to account for the effect of
variations in energy efficiency and energy mix in the power sector.
Energy consumption considered in this document excludes feedstock energy, such as oil feedstock used
to produce plastics or natural gas used as a feedstock for the production of fertilisers, as they are not
affected by energy efficiency policies.
vi © ISO 2020 – All rights reserved

---------------------- Page: 6 ----------------------
ISO/FDIS 50049:2020(E)

This document can be used by any interested parties (decision-makers, companies, researchers, NGOs,
etc.) that want to understand changes in the energy intensity or the energy consumption, as well as to
assess energy efficiency by sector over a specific period.
This document is part of a set of documents developed by TC 301 (see Figure 1) and builds on the
general principles outlined in ISO 17743, including reporting and system boundaries, and on the energy
savings calculations presented in ISO 17742.
Figure 1 — Relationship between documents
The document covers more precisely three types of calculation methods based on energy efficiency
indicators. Compared to ISO 17742, it details more advanced methodologies that facilitate a more
comprehensive understanding of changes in: a) energy intensity, b) energy efficiency and, finally,
c) energy consumption. The evaluation of energy efficiency trends relies on the calculation of energy
efficiency indices. Variations in energy consumption are explained from a decomposition into different
explanatory factors, one of which being energy savings. Therefore, this document complements
ISO 17742 on energy savings calculation methods. More specifically, it complements how ISO 17742
deals with indicator-based methods. For each calculation method, examples of specific calculations are
presented separately in Annexes A to C.
When applying this document, the user can choose between different options of the methods proposed.
In order to be transparent in the way results have been obtained, the user of this document should
specify the methodology used when presenting the results.
The general methodologies to evaluate trends in energy intensity, energy efficiency and energy
consumption and its link to energy savings are presented in Clause 4. The calculation of the influence
of structural changes in the energy intensity variation is described in Clause 5. The calculation method
for the energy efficiency index is described in Clause 6. Finally, the method of decomposition of the
energy consumption is given in Clause 7. Annexes A to C provide examples to illustrate various types of
calculations. Annex D presents the methodology of climatic corrections, as most of these calculations
should be done with energy efficiency indicators adjusted to a normal climate.
© ISO 2020 – All rights reserved vii

---------------------- Page: 7 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 50049:2020(E)
Calculation methods for energy efficiency and energy
consumption variations at country, region and city levels
1 Scope
This document gives guidelines for methods for analysing changes in energy efficiency and energy
consumption, and for measuring energy efficiency progress, for countries, regions and cities. It is
composed of three different calculation methods:
— evaluation of structure effects in the variation of energy intensity;
— calculation of energy efficiency indices;
— decomposition analysis of energy consumption variation.
This document is applicable to providing an aggregated statistical evaluation for a country, region or
city. It does not apply to calculating changes in the energy consumption or in energy efficiency at the
individual consumer’s level (e.g. households, organizations, companies).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
activity factor
variation in the energy consumption levels of a sector or subsector due to the variation of the activity
of the sector for a given period
Note 1 to entry: The quantification of this factor depends on the driver used to measure the activity.
3.2
apparent energy efficiency improvement
increase in energy efficiency (3.5) without correction or adjustment (i.e. gross value resulting from a
calculation)
3.3
base year
reference year in the calculation
Note 1 to entry: It is usually the first year of calculation.
Note 2 to entry: The year can be calendar or fiscal. All data should have the same definition of year, whether
calendar or fiscal.
© ISO 2020 – All rights reserved 1

---------------------- Page: 8 ----------------------
ISO/FDIS 50049:2020(E)

3.4
behavioural factor
factor that shows the impact on the variation of energy consumption or on an energy indicator of
changes in the behaviour of consumers
EXAMPLE Change in the level of thermal comfort with a higher or lower use of heating or air cooling
equipment.
3.5
energy efficiency
ratio or other quantitative relationship between an output of performance, service, goods, commodities
or energy and an input of energy
[SOURCE: ISO/IEC 13273-1:2015, 3.4.1, modified — The symbol has been deleted and “commodities”
has been added.]
3.6
energy efficiency improvement
increase in energy efficiency (3.5) as a result of technological, behavioural and/or economic changes
[SOURCE: ISO/IEC 13273-1:2015, 3.4.3, modified — “technological, behavioural and/or economic
changes” has replaced “technological, design, behavioural or economic changes”.]
3.7
energy efficiency index
index (such as 100 for base year) measuring the increase in energy efficiency (3.5) compared to a base
year (3.3)
3.8
energy intensity
quotient describing the total energy consumption per unit of economic output
Note 1 to entry: The economic output should be measured at a constant price.
Note 2 to entry: The intensity can be interpreted as the amount of energy required to produce one unit of activity
expressed in monetary terms (GDP or value added).
Note 3 to entry: The intensity can also be used at sector level (e.g. industry, residential, services). In that case, it is
often referred to as “sectoral energy intensity”.
Note 4 to entry: The term “energy intensity” is sometimes used with the same meaning as specific energy
consumption (3.17), but this is not the case in this document.
[SOURCE: ISO/IEC 13273-1:2015, 3.1.14, modified — The example has been deleted and Notes 1, 2, 3 and
4 to entry have been added.]
3.9
energy savings
reduction of energy consumption compared to an energy baseline at same level of service
Note 1 to entry: Energy savings are positive when they reduce consumption. Due to some external factors that
cannot be accounted for, consumption can increase instead of decrease: this phenomenon is referred to as
“negative energy savings”.
3.10
energy use
application of energy
EXAMPLE Ventilation; lighting; heating; cooling; transportation; data storage; production process.
Note 1 to entry: Energy use is sometimes referred to as “energy end-use”.
[SOURCE: ISO 50001:2018, 3.5.4]
2 © ISO 2020 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/FDIS 50049:2020(E)

3.11
energy using system
physical items with defined system boundaries, using energy
EXAMPLE Plant, process, building, machines, equipment, product.
[SOURCE: ISO 50047:2016, 3.1, modified — The example has been replaced.]
3.12
explanatory factor
factor explaining the variation in an indicator or in the energy consumption
Note 1 to entry: It is different from the concept of “relevant variable” as defined in other standards a as
“quantifiable factor that impacts energy performance and routinely changes” (e.g. ISO 50006:2014, 3.14).
“Relevant variable” is more related to the performance of an energy using system (3.11), whereas “explanatory
factor” relates to a sector and to both its consumption and performance. “Relevant variable” is more a micro
concept, whereas “explanatory factor” is a macro concept.
3.13
final energy
energy as delivered to an energy using system (3.11)
Note 1 to entry: This concept is sometimes referred to as “delivered energy”.
[SOURCE: ISO/IEC 13273-1:2015, 3.1.11, modified — Note 2 to entry has been deleted.]
3.14
fuel substitution factor
factor that shows the impact of fuel substitutions between types of energy with very different end-use
efficiency on the variation of an energy indicator
3.15
indicator-based savings
energy savings (3.9) calculated by indicator-based methods (3.16)
[SOURCE: ISO 17742:2015, 2.28]
3.16
indicator-based method
determination of energy savings (3.9) from the variation of energy consumption indicators over a period
[SOURCE: ISO 17742:2015, 2.27, modified — The example has been deleted.]
3.17
specific energy consumption
quotient describing the total energy consumption per unit of output or service
2
EXAMPLE Gigajoule (GJ) per ton of steel, annual kilowatt-hour (kWh) per square meter (m ), litres of fuel
per 100 kilometre (km).
[SOURCE: ISO/IEC 13273­1:2015, 3.1.15]
3.18
structure effect
structural effect
measure of the variation in energy consumption or in energy intensity (3.8) due to a variation in
economic structures
Note 1 to entry: Structure effects may refer more generally to any changes in the share of different activities (e.g.
industrial branches in total value added of industry, transport modes in total traffic).
Note 2 to entry: “Hidden structure effect” refers to structure effects that exist but cannot be quantified due to a
lack of data.
© ISO 2020 – All rights reserved 3

---------------------- Page: 10 ----------------------
ISO/FDIS 50049:2020(E)

4 Factors to be calculated
4.1 General
4.1.1 Overview of methods included in the document
This clause is an introduction to Clauses 5, 6 and 7 on methods to assess energy intensity and energy
efficiency trends and to analyse the energy consumption variation. It describes common issues, such
as the different explanatory factors that need to be considered in these assessments (case of energy
intensity and energy consumption) or excluded to measure energy efficiency improvements and the
various ways to calculate them. This clause clarifies what kind of explanatory factors are covered in
this document.
Explanatory factors of changes in energy intensity or in energy consumption and energy efficiency
trends are calculated for a given period of time, normally one or more calendar years. The methods
make use of statistical data and are normally applied to calculate explanatory factors, such as energy
savings or energy efficiency improvements made during the past years. However, if a comparable set
of data is available as projections, e.g. from an energy scenario outlook, the methods can be applied for
future years.
This document relates to the so-called “top-down” methods of energy saving calculations as reported in
ISO 17742 and ISO 17743, based on statistical energy efficiency indicators. The first and third methods
analyse observed trends in energy intensity indicators (see Clause 5) and in energy consumption (see
Clause 7)
...