ISO 50002-3:2025

Energy audits - Part 3: Guidance for conducting an energy audit using ISO 50002-1 in processes

This document gives guidance on how to apply ISO 50002-1 to carry out energy audits of a process. It is intended to be used in conjunction with, and is supplementary to, ISO 50002-1. If buildings are included in the scope of the energy audit, the energy auditor can choose to apply ISO 50002-2.

Audits énergétiques — Partie 3: Recommandations pour la conduite d'un audit énergétique selon l'ISO 50002-1 dans des processus

Energetske presoje - 3. del: Navodilo za izvajanje energetskega pregleda v procesih z uporabo standarda ISO 50002-1

General Information

• Status: Published
• Publication Date: 01-Jun-2025
• ICS: 27.015 - Energy efficiency. Energy conservation 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: 02-Jun-2025
• Due Date: 06-Dec-2024
• Completion Date: 02-Jun-2025
• Ref Project: SIST ISO 50002-3:2025 - Energy audits - Part 3: Guidance for conducting an energy audit using ISO 50002-1 in processes

Relations

• Revises: ISO 50002:2014 - Energy audits - Requirements with guidance for use
• Effective Date: 06-Jun-2022

Overview

ISO 50002-3:2025 - Energy audits - Part 3 provides practical guidance for conducting energy audits of industrial and commercial processes using ISO 50002-1. It is a supplementary document intended to be used alongside the Part 1 general requirements. The standard covers how to define audit scope and boundaries for processes, collect and verify process energy data, plan measurements, perform on-site activities, analyse energy performance and report findings tailored to process environments.

Key topics and requirements

• Scope and boundaries: Guidance on defining process boundaries, inclusion of utilities and outsourced services, and coordination when buildings are also in scope.
• Planning and roles: Clarification of relationships among audit client, auditee and operators where ownership, operation and maintenance can be split.
• Data collection: Recommended types of data to collect (site, utility, production process, energy sources), verification, plausibility checks and handling of missing data. (See Annex A for examples.)
• Measurement plan: How to review existing data, identify measurement needs, develop measurement plans and perform preliminary data analysis to determine significant energy uses (SEUs) and relevant energy performance indicators (EnPIs).
• Site work and analysis: Guidance on site visits, management of fieldwork, energy balance estimation, identification and evaluation of energy performance improvement opportunities.
• Reporting and meetings: Requirements for content of audit reports and conduct of opening/closing meetings.
• Competence: Statements on the competence requirements for the energy auditor.
• Informative annexes: Includes guidance on data collection (Annex A), measurement quality (Annex B) and representative sampling for multi-site organizations (Annex C).

Practical applications and users

Who benefits:

• Energy auditors and consultants conducting process-focused energy audits
• Industrial facility engineers and operations managers (e.g., manufacturing lines, utilities, steam systems, dryers, furnaces)
• Organisations implementing or integrating energy audits into an Energy Management System (EnMS)
• Multi-site organizations seeking representative sampling approaches

Practical uses:

• Structuring process energy audits to identify SEUs and EnPIs
• Preparing measurement plans and data verification procedures specific to process equipment and operational conditions
• Evaluating energy performance improvement opportunities (process optimization, utility interaction, changeover impacts)

Related standards

• ISO 50002-1 - Energy audits: general requirements with guidance for use (normative reference)
• ISO 50002-2 - Guidance for building-related energy audits (use when buildings are included in the audit scope)

Keywords: ISO 50002-3, energy audit, processes, energy performance, energy auditor, EnMS, measurement plan, data collection, SEU, EnPI.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2025
Energetske presoje - 3. del: Navodilo za izvajanje energetskega pregleda v
procesih z uporabo standarda ISO 50002-1
Energy audits - Part 3: Guidance for conducting an energy audit using ISO 50002-1 in
processes
Audits énergétiques - Partie 3: Recommandations pour la conduite d'un audit
énergétique selon l'ISO 50002-1 dans des processus
Ta slovenski standard je istoveten z: ISO 50002-3:2025
ICS:
03.100.70 Sistemi vodenja Management systems
27.015 Energijska učinkovitost. Energy efficiency. Energy
Ohranjanje energije na conservation in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

International
Standard
ISO 50002-3
First edition
Energy audits —
2025-06
Part 3:
Guidance for conducting an
energy audit using ISO 50002-1 in
processes
Audits énergétiques —
Partie 3: Recommandations pour la conduite d'un audit
énergétique selon l'ISO 50002-1 dans des processus
Reference number
© ISO 2025
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
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of energy auditing . 2
5 Performing an energy audit . 2
5.1 General .2
5.2 Planning .2
5.3 Opening meeting .3
5.4 Data collection .3
5.5 Measurement plan .4
5.5.1 General .4
5.5.2 Preliminary data analysis .4
5.5.3 Data measurement plan .4
5.6 Site visit . .5
5.6.1 Site visits .5
5.6.2 Management of field work .5
5.7 Analysis .5
5.7.1 General .5
5.7.2 Analysis of current energy performance .5
5.7.3 Identification of energy performance improvement opportunities .6
5.7.4 Evaluation of energy performance improvement opportunities .7
5.8 Reporting .7
5.8.1 General .7
5.8.2 Report content .7
5.9 Closing meeting .7
6 Competence of the energy auditor . 7
Annex A (informative) Data which can be collected . 8
Annex B (informative) Quality of measurement plan .15
Annex C (informative) Representative energy sampling approach for multi-site organizations . 17
Bibliography . 19

iii
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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO 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, ISO 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
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
A list of all parts in the ISO 50002 series can be found on the ISO website.
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.

iv
Introduction
An energy audit can help an organization identify opportunities to improve energy performance. It can be
part of a site-wide energy management system (EnMS). This document provides guidance for conducting an
ISO 50002-1-based energy audit of processes.
There are many types of processes in industry and commerce. In general, energy is used:
— directly by a process (e.g. furnaces, direct fired dryers);
— indirectly by a process (e.g. heat exchange, distillation, extrusion), including the specific conditions of
production (e.g. start-up, shut-down, product change over, cleaning, maintenance, laboratory and product
transfer);
— directly by a commercial organization, (e.g. meal preparation process, TV broadcasting process, data
centre process, coffee roasting);
— utility processes (e.g. motor driven systems (fans, pumps, motors, compressors, etc.), steam, hot water),
including on-site power plants;
— product or service changeover, (e.g. change of production feed or production quality, start-up, shut down,
cleaning-in-place, sterilization);
— other processes (e.g. sterilization in hospitals, fume cupboards, laboratories).
The energy audits covered by this document may be independent from energy performance certification.

v
International Standard ISO 50002-3:2025(en)
Energy audits —
Part 3:
Guidance for conducting an energy audit using ISO 50002-1 in
processes
1 Scope
This document gives guidance on how to apply ISO 50002-1 to carry out energy audits of a process. It is
intended to be used in conjunction with, and is supplementary to, ISO 50002-1.
If buildings are included in the scope of the energy audit, the energy auditor can choose to apply ISO 50002-2.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 50002-1, Energy audits — Part 1: General requirements with guidance for use
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 50002-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
audit client
person or organization that commissions an energy audit
Note 1 to entry: to entry. The audit client can be the owner, operator, process licensor and/or the service provider.
3.2
process
set of interrelated or interacting activities that use inputs to deliver an intended result
Note 1 to entry: to entry. This can include one or more production lines, laboratories, research centres, packaging and
warehouse sections with specific operational conditions and site transportation. An energy audit can be conducted on
selected processes or systems in an organization or site (3.4) or on all processes in an organization or site.
3.3
production process
all the steps, or some of the steps, necessary to manufacture a product, intermediate product, by-product or
co-product, or to deliver a service
Note 1 to entry: Production process can include specific facilities for health, safety and environmental pollution
control.
3.4
site
processes (3.2) within the boundary of the organization
Note 1 to entry: This may include processes for pollution treatment, energy recovery and waste management.
3.5
utility
generation and distribution of energy necessary for the process (3.2) and auxiliary
4 Principles of energy auditing
The principles of ISO 50002-1 apply.
5 Performing an energy audit
5.1 General
The general requirements of ISO 50002-1 apply.
5.2 Planning
In processes, the audit client and the auditee can be different. Their roles and responsibilities in the process
can also be different. For example, a process can be owner operated and maintained by a single organization.
The process can also be owned, operated and maintained by different organizations.
The energy auditor should obtain a preliminary description of the site and the process from the organization
or from a site visit.
NOTE 1 The preliminary contact can be by telephone, webinar, meeting or other remote interactive discussions.
The energy audit scope and boundaries should be defined and agreed between the energy auditor and the
audit client. At a minimum:
a) the audit client should have operational control of the process, or should have the ability to influence
and seek the cooperation of the operator;
b) the energy audit scope should cover energy use within the process and/or the interaction of energy use
with other energy use within the process. Optimization of some energy use while excluding others can
give misleading results.
Considerations for the audit scope and boundary include:
— processes included in the energy audit;
NOTE 2 A process can be defined as the whole process, part of a process, part of a system or a component.
— whether or not outsourced utilities are included in the energy audit;
— depending on the thoroughness of the energy audit, the need for a detailed energy audit to be carried out
for specific processes should be checked; in this case, reference should be made to the relevant standard.
For energy use not directly related to the process (e.g. storing, packaging, logistics, offices, research centres,
laboratories, transport), the energy auditor should agree with the organization on the applicability of
ISO 50002-2 (buildings) or ISO 50002-3 (processes); depending on the nature of the activities, the auditor
may also rely on the general framework of ISO 50002-1. This decision and the agreed scope should be clearly
stated in the final energy audit report (see 5.8).

ISO 50002-1:2025, Annex A, describes three different types of energy audit, each having a different level of
detail and thoroughness. The level of detail agreed by the parties will have an impact on:
— application;
— business needs;
— data collection;
— analysis;
— opportunities identification;
— opportunities evaluation;
— outputs;
— the time on-site.
For each audited process, the energy auditor and organization should agree on the relevant personnel, and
their roles which have an impact on energy consumption, and should propose a preliminary list of data to be
collected.
5.3 Opening meeting
No additional guidance to ISO 50002-1.
5.4 Data collection
The data collection can be carried out over several stages during an energy audit.
During data collection, the energy auditor should:
a) collect and collate appropriate energy data that support the audit objectives, the required audit scope
and the level of thoroughness of the energy audit, including:
1) site information including building, boundary and other relevant information;
2) utility information;
3) production process information;
i) product specification;
ii) main processes equipment involved in the process (drawings, other relevant technical data and
datasheets);
iii) current operating conditions (set points) of utilities and production process;
iv) other considerations that can impact energy performance on a non-routine basis (static factors);
v) specific conditions and constraints for process and environment (security, pollution, health, etc.);
4) information on energy source types;
b) verify the data and information provided by the organization (e.g. the power or the number of pieces of
equipment);
c) obtain any missing data;
d) check the quality and plausibility of the data, and ask for correction if significant mistakes or inaccuracies
are identified.
NOTE 1 The collected data can be based on invoices, contracts, measurements, calculations from given operating
hours and installed capacity (technical characteristics), operation and maintenance documents, meeting with
operations and maintenance personnel, etc.
NOTE 2 See Annex A for examples of data that can be collected.
5.5 Measurement plan
5.5.1 General
The energy auditor should review the information collected and provided by the organization. This is carried
out to ensure that the information is complete and representative and to identify further information and
measurement needs. If the data requested are not available, the energy auditor should define the method to
obtain the necessary information (e.g. measurements, estimates, modelling).
It is also possible to identify preliminary opportunities for energy performance improvement or areas for
investigation during the site visit.
5.5.2 Preliminary data analysis
The energy auditor should carry out an analysis of the data collected to:
a) undertake a preliminary analysis of the process energy balance on the basis of energy data;
b) establish the relevant variables and static factors;
c) identify significant energy uses (SEUs);
d) establish the relevant energy performance indicators (EnPIs);
e) evaluate the distribution of energy consumption (consumption breakdown) if possible, depending on
the measured data available;
f) if there is sufficient information, establish an initial energy reference (energy baseline) to be used for
quantifying the impacts of energy performance improvement actions (EPIAs);
g) plan further data collection and measurement to be carried out during field work.
The energy auditor should develop a preliminary list of EPIAs.
5.5.3 Data measurement plan
If there are missing data and information, depending on the scope of the energy audit and level of
thoroughness, the energy auditor should:
a) request the missing information from the organization;
b) carry out additional measurements during the site visit;
c) make an assumption about the data based on experience and competence (and provide details in the
energy audit report).
Where additional on-site measurement is determined to be feasible, ISO 50002-1 outlines a short list of data
that can be measured while on-site.
The energy auditor should also review the collected data (and eventual data measurement) to see whether
the energy audit objective(s) and audit scope are still appropriate and can be achieved. If the audit objective
and audit scope cannot be achieved, the energy auditor should discuss and agree on an alternative with the
organization.
NOTE See Annex B for quality data measurement plans.

5.6 Site visit
5.6.1 Site visits
No additional guidance to ISO 50002-1.
5.6.2 Management of field work
The energy auditor should inspect the processes within the audit scope in order to achieve the audit
objective. This includes:
a) collecting any missing data needed for analysis;
b) confirming the suitability of energy baseline if available;
c) confirming the energy consumption, energy balance, relevant variables and static factors if an EnMS
has already been introduced;
d) confirming the current operating conditions (set points) of utilities and production processes and the
impact on energy use and consumption;
e) collecting relevant information from identification plates, runtime information, interviews with
operators, etc;
f) identifying EPIAs and related constraints and restrictions.
5.7 Analysis
5.7.1 General
No additional guidance to ISO 50002-1.
5.7.2 Analysis of current energy performance
Analysis of current energy performance is described in ISO 50002-1.
The energy auditor provides:
a) a breakdown of the energy consumption by energy type;
b) a breakdown of the energy consumption into a company energy structure (e.g. main activities, auxiliary
services, general services) to a cost-effectiveness level;
c) a breakdown of the energy consumption by processes in absolute number and in consistent energy unit
(if the activity is time varying, it is recommended to establish the energy consumption at different time
periods in relation to the processes);
d) a demonstration of an energy balance between energy consumption and energy losses
...

International
Standard
ISO 50002-3
First edition
Energy audits —
2025-06
Part 3:
Guidance for conducting an
energy audit using ISO 50002-1 in
processes
Audits énergétiques —
Partie 3: Recommandations pour la conduite d'un audit
énergétique selon l'ISO 50002-1 dans des processus
Reference number
© ISO 2025
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
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of energy auditing . 2
5 Performing an energy audit . 2
5.1 General .2
5.2 Planning .2
5.3 Opening meeting .3
5.4 Data collection .3
5.5 Measurement plan .4
5.5.1 General .4
5.5.2 Preliminary data analysis .4
5.5.3 Data measurement plan .4
5.6 Site visit . .5
5.6.1 Site visits .5
5.6.2 Management of field work .5
5.7 Analysis .5
5.7.1 General .5
5.7.2 Analysis of current energy performance .5
5.7.3 Identification of energy performance improvement opportunities .6
5.7.4 Evaluation of energy performance improvement opportunities .7
5.8 Reporting .7
5.8.1 General .7
5.8.2 Report content .7
5.9 Closing meeting .7
6 Competence of the energy auditor . 7
Annex A (informative) Data which can be collected . 8
Annex B (informative) Quality of measurement plan .15
Annex C (informative) Representative energy sampling approach for multi-site organizations . 17
Bibliography . 19

iii
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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO 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, ISO 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
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
A list of all parts in the ISO 50002 series can be found on the ISO website.
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.

iv
Introduction
An energy audit can help an organization identify opportunities to improve energy performance. It can be
part of a site-wide energy management system (EnMS). This document provides guidance for conducting an
ISO 50002-1-based energy audit of processes.
There are many types of processes in industry and commerce. In general, energy is used:
— directly by a process (e.g. furnaces, direct fired dryers);
— indirectly by a process (e.g. heat exchange, distillation, extrusion), including the specific conditions of
production (e.g. start-up, shut-down, product change over, cleaning, maintenance, laboratory and product
transfer);
— directly by a commercial organization, (e.g. meal preparation process, TV broadcasting process, data
centre process, coffee roasting);
— utility processes (e.g. motor driven systems (fans, pumps, motors, compressors, etc.), steam, hot water),
including on-site power plants;
— product or service changeover, (e.g. change of production feed or production quality, start-up, shut down,
cleaning-in-place, sterilization);
— other processes (e.g. sterilization in hospitals, fume cupboards, laboratories).
The energy audits covered by this document may be independent from energy performance certification.

v
International Standard ISO 50002-3:2025(en)
Energy audits —
Part 3:
Guidance for conducting an energy audit using ISO 50002-1 in
processes
1 Scope
This document gives guidance on how to apply ISO 50002-1 to carry out energy audits of a process. It is
intended to be used in conjunction with, and is supplementary to, ISO 50002-1.
If buildings are included in the scope of the energy audit, the energy auditor can choose to apply ISO 50002-2.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 50002-1, Energy audits — Part 1: General requirements with guidance for use
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 50002-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
audit client
person or organization that commissions an energy audit
Note 1 to entry: to entry. The audit client can be the owner, operator, process licensor and/or the service provider.
3.2
process
set of interrelated or interacting activities that use inputs to deliver an intended result
Note 1 to entry: to entry. This can include one or more production lines, laboratories, research centres, packaging and
warehouse sections with specific operational conditions and site transportation. An energy audit can be conducted on
selected processes or systems in an organization or site (3.4) or on all processes in an organization or site.
3.3
production process
all the steps, or some of the steps, necessary to manufacture a product, intermediate product, by-product or
co-product, or to deliver a service
Note 1 to entry: Production process can include specific facilities for health, safety and environmental pollution
control.
3.4
site
processes (3.2) within the boundary of the organization
Note 1 to entry: This may include processes for pollution treatment, energy recovery and waste management.
3.5
utility
generation and distribution of energy necessary for the process (3.2) and auxiliary
4 Principles of energy auditing
The principles of ISO 50002-1 apply.
5 Performing an energy audit
5.1 General
The general requirements of ISO 50002-1 apply.
5.2 Planning
In processes, the audit client and the auditee can be different. Their roles and responsibilities in the process
can also be different. For example, a process can be owner operated and maintained by a single organization.
The process can also be owned, operated and maintained by different organizations.
The energy auditor should obtain a preliminary description of the site and the process from the organization
or from a site visit.
NOTE 1 The preliminary contact can be by telephone, webinar, meeting or other remote interactive discussions.
The energy audit scope and boundaries should be defined and agreed between the energy auditor and the
audit client. At a minimum:
a) the audit client should have operational control of the process, or should have the ability to influence
and seek the cooperation of the operator;
b) the energy audit scope should cover energy use within the process and/or the interaction of energy use
with other energy use within the process. Optimization of some energy use while excluding others can
give misleading results.
Considerations for the audit scope and boundary include:
— processes included in the energy audit;
NOTE 2 A process can be defined as the whole process, part of a process, part of a system or a component.
— whether or not outsourced utilities are included in the energy audit;
— depending on the thoroughness of the energy audit, the need for a detailed energy audit to be carried out
for specific processes should be checked; in this case, reference should be made to the relevant standard.
For energy use not directly related to the process (e.g. storing, packaging, logistics, offices, research centres,
laboratories, transport), the energy auditor should agree with the organization on the applicability of
ISO 50002-2 (buildings) or ISO 50002-3 (processes); depending on the nature of the activities, the auditor
may also rely on the general framework of ISO 50002-1. This decision and the agreed scope should be clearly
stated in the final energy audit report (see 5.8).

ISO 50002-1:2025, Annex A, describes three different types of energy audit, each having a different level of
detail and thoroughness. The level of detail agreed by the parties will have an impact on:
— application;
— business needs;
— data collection;
— analysis;
— opportunities identification;
— opportunities evaluation;
— outputs;
— the time on-site.
For each audited process, the energy auditor and organization should agree on the relevant personnel, and
their roles which have an impact on energy consumption, and should propose a preliminary list of data to be
collected.
5.3 Opening meeting
No additional guidance to ISO 50002-1.
5.4 Data collection
The data collection can be carried out over several stages during an energy audit.
During data collection, the energy auditor should:
a) collect and collate appropriate energy data that support the audit objectives, the required audit scope
and the level of thoroughness of the energy audit, including:
1) site information including building, boundary and other relevant information;
2) utility information;
3) production process information;
i) product specification;
ii) main processes equipment involved in the process (drawings, other relevant technical data and
datasheets);
iii) current operating conditions (set points) of utilities and production process;
iv) other considerations that can impact energy performance on a non-routine basis (static factors);
v) specific conditions and constraints for process and environment (security, pollution, health, etc.);
4) information on energy source types;
b) verify the data and information provided by the organization (e.g. the power or the number of pieces of
equipment);
c) obtain any missing data;
d) check the quality and plausibility of the data, and ask for correction if significant mistakes or inaccuracies
are identified.
NOTE 1 The collected data can be based on invoices, contracts, measurements, calculations from given operating
hours and installed capacity (technical characteristics), operation and maintenance documents, meeting with
operations and maintenance personnel, etc.
NOTE 2 See Annex A for examples of data that can be collected.
5.5 Measurement plan
5.5.1 General
The energy auditor should review the information collected and provided by the organization. This is carried
out to ensure that the information is complete and representative and to identify further information and
measurement needs. If the data requested are not available, the energy auditor should define the method to
obtain the necessary information (e.g. measurements, estimates, modelling).
It is also possible to identify preliminary opportunities for energy performance improvement or areas for
investigation during the site visit.
5.5.2 Preliminary data analysis
The energy auditor should carry out an analysis of the data collected to:
a) undertake a preliminary analysis of the process energy balance on the basis of energy data;
b) establish the relevant variables and static factors;
c) identify significant energy uses (SEUs);
d) establish the relevant energy performance indicators (EnPIs);
e) evaluate the distribution of energy consumption (consumption breakdown) if possible, depending on
the measured data available;
f) if there is sufficient information, establish an initial energy reference (energy baseline) to be used for
quantifying the impacts of energy performance improvement actions (EPIAs);
g) plan further data collection and measurement to be carried out during field work.
The energy auditor should develop a preliminary list of EPIAs.
5.5.3 Data measurement plan
If there are missing data and information, depending on the scope of the energy audit and level of
thoroughness, the energy auditor should:
a) request the missing information from the organization;
b) carry out additional measurements during the site visit;
c) make an assumption about the data based on experience and competence (and provide details in the
energy audit report).
Where additional on-site measurement is determined to be feasible, ISO 50002-1 outlines a short list of data
that can be measured while on-site.
The energy auditor should also review the collected data (and eventual data measurement) to see whether
the energy audit objective(s) and audit scope are still appropriate and can be achieved. If the audit objective
and audit scope cannot be achieved, the energy auditor should discuss and agree on an alternative with the
organization.
NOTE See Annex B for quality data measurement plans.

5.6 Site visit
5.6.1 Site visits
No additional guidance to ISO 50002-1.
5.6.2 Management of field work
The energy auditor should inspect the processes within the audit scope in order to achieve the audit
objective. This includes:
a) collecting any missing data needed for analysis;
b) confirming the suitability of energy baseline if available;
c) confirming the energy consumption, energy balance, relevant variables and static factors if an EnMS
has already been introduced;
d) confirming the current operating conditions (set points) of utilities and production processes and the
impact on energy use and consumption;
e) collecting relevant information from identification plates, runtime information, interviews with
operators, etc;
f) identifying EPIAs and related constraints and restrictions.
5.7 Analysis
5.7.1 General
No additional guidance to ISO 50002-1.
5.7.2 Analysis of current energy performance
Analysis of current energy performance is described in ISO 50002-1.
The energy auditor provides:
a) a breakdown of the energy consumption by energy type;
b) a breakdown of the energy consumption into a company energy structure (e.g. main activities, auxiliary
services, general services) to a cost-effectiveness level;
c) a breakdown of the energy consumption by processes in absolute number and in consistent energy unit
(if the activity is time varying, it is recommended to establish the energy consumption at different time
periods in relation to the processes);
d) a demonstration of an energy balance between energy consumption and energy losses based on an
appropriate method.
EXAMPLE Material and energy balance, Sankey diagram, steady-state computer simulation.
If feasible, the energy auditor should determine the energy consumption without production or activity
(baseload).
The energy balance and breakdown should be representative of the energy input and energy use. It should
be clear which is based on measurement, estimation or accurate calculation in accordance with the level of
thoroughness of the energy audit.
...