ISO/FDIS 17225-5
(Main)Solid biofuels — Fuel specifications and classes — Part 5: Graded firewood
Solid biofuels — Fuel specifications and classes — Part 5: Graded firewood
This document determines the fuel quality classes and specifications of graded firewood. This document covers only firewood produced from the following raw materials (see ISO 17725‑1:2021, Table 1): — 1.1.1 Whole trees without roots; — 1.1.3 Stem wood; — 1.1.4 Logging residues (thick branches, tops etc.); — 1.2.1 Chemically untreated by-products and residues from wood processing industry.
Biocombustibles solides — Classes et spécifications des combustibles — Partie 5: Classes de bois de chauffage
Le présent document détermine les classes et spécifications de qualité du combustible pour le bois de chauffage. Le présent document couvre uniquement le bois de chauffage produit à partir des matières premières suivantes (voir ISO 17725-1:2021, Tableau 1): — 1.1.1 Arbres entiers sans racines; — 1.1.3 Grumes; — 1.1.4 Rémanents forestiers (grosses branches, cimes, etc.); — 1.2.1 Produits dérivés et sous-produits de l'industrie de transformation du bois sans traitement chimique.
General Information
- Status
- Not Published
- Technical Committee
- ISO/TC 238 - Solid biofuels
- Drafting Committee
- ISO/TC 238/WG 2 - Fuel specifications and classes
- Current Stage
- 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
- Start Date
- 06-Jan-2026
- Completion Date
- 06-Jan-2026
Relations
- Consolidates
ISO/IEC 24775-7:2021 - Information technology - Storage management - Part 7: Host elements - Effective Date
- 15-Mar-2025
- Revises
ISO 17225-5:2021 - Solid biofuels - Fuel specifications and classes - Part 5: Graded firewood - Effective Date
- 07-Jan-2025
Overview
ISO/FDIS 17225-5:2025 is an international standard defining the fuel specifications and classification of graded firewood. Developed by ISO Technical Committee ISO/TC 238, this document focuses specifically on firewood produced from raw materials including whole trees without roots, stem wood, logging residues, and chemically untreated by-products from the wood processing industry. This new edition updates and replaces the 2021 version, providing clear, harmonized quality classes to support efficient trading and reliable communication between producers, buyers, and equipment manufacturers.
The standard supports the use of graded firewood primarily for residential, small commercial, and public buildings, emphasizing higher quality fuels suitable for appliances like stoves, fireplaces, cookers, and boilers. It fosters improved fuel quality transparency, helps ensure safety, and encourages environmentally responsible biomass energy use.
Key Topics
Scope and Applicability
Only firewood from defined biomass categories is covered (whole trees, stem wood, logging residues, untreated wood industry residues). It excludes chemically treated or contaminated materials.Quality Classes
The firewood is classified into three main graded quality classes:- Class A1 and A2: Suitable for stoves and fireplaces requiring higher-quality fuel.
- Class B: Applicable for use in log wood boilers where fuel control is less stringent.
Specifications and Parameters
Fuel quality is specified based on:- Moisture content (wet basis ranges from 8% to 35% depending on the class)
- Diameter and length of logs (with defined minimum proportions for specific size fractions)
- Origin and raw material type
- Physical properties such as energy density and net calorific value (optional but recommended)
Measurement and Testing Methods
Methods conform to related ISO standards including:- ISO 21945 for sampling
- ISO 14780 for sample preparation
- ISO 18134-1 and ISO 18134-2 for moisture content determination (reference and simplified methods)
- ISO 18125 for calorific values
Additional Informative Annexes
- Moisture content comparisons (as received vs dry basis)
- Firewood measurement techniques
- Energy density calculation
Firewood Dimensions
Defined by maximum diameter and length parameters following specific maximum and minimum dimensional criteria to ensure uniformity in grading.
Applications
ISO 17225-5:2025 addresses practical needs relevant to:
Residential Heating
Ensuring the provision of clean, energy-efficient fuel for household appliances such as wood-burning stoves and fireplaces that typically lack advanced emission controls.Small Commercial and Public Buildings
Provides guidelines for fuel suitable for boilers and heating systems in various building types where fuel quality impacts operational efficiency and air quality.Fuel Trading and Certification
Facilitates transparent communication between suppliers and buyers by defining unambiguous firewood quality classes, assisting official market regulation and consumer protection.Environmental and Safety Compliance
Helps minimize emissions and contamination risks by excluding chemically treated or potentially contaminated wood and defining moisture limits for optimized combustion.Manufacturer Communication
Supports appliance manufacturers in specifying fuel requirements to maximize device performance and durability.
Related Standards
ISO/FDIS 17225-5 builds upon and complements several international standards, including:
- ISO 17225-1:2021 - General requirements for solid biofuels, providing foundational principles for classification and fuel quality.
- ISO 18134 series - Determination methods for moisture content, critical for fuel quality assessment.
- ISO 21945 - Sampling procedures tailored for small-scale solid biofuel applications like firewood.
- ISO 14780 - Sample preparation for solid biofuels ensuring consistency during analysis.
- ISO 18125 - Methods for net calorific value analysis, important for energy content determination.
These related standards form a comprehensive framework for managing solid biofuel quality - essential for ensuring compliance, safety, and performance in biomass utilization.
Keywords: ISO 17225-5, graded firewood, solid biofuels, fuel specifications, firewood quality classes, moisture content, biomass fuel standards, residential heating fuel, firewood grading, wood fuel specifications, ISO solid biofuels, biomass energy, pellet and log stove fuel standards.
ISO/FDIS 17225-5 - Solid biofuels — Fuel specifications and classes — Part 5: Graded firewood Released:23. 12. 2025
REDLINE ISO/FDIS 17225-5 - Solid biofuels — Fuel specifications and classes — Part 5: Graded firewood Released:23. 12. 2025
ISO/FDIS 17225-5 - Biocombustibles solides — Classes et spécifications des combustibles — Partie 5: Classes de bois de chauffage Released:12. 01. 2026
Frequently Asked Questions
ISO/FDIS 17225-5 is a draft published by the International Organization for Standardization (ISO). Its full title is "Solid biofuels — Fuel specifications and classes — Part 5: Graded firewood". This standard covers: This document determines the fuel quality classes and specifications of graded firewood. This document covers only firewood produced from the following raw materials (see ISO 17725‑1:2021, Table 1): — 1.1.1 Whole trees without roots; — 1.1.3 Stem wood; — 1.1.4 Logging residues (thick branches, tops etc.); — 1.2.1 Chemically untreated by-products and residues from wood processing industry.
This document determines the fuel quality classes and specifications of graded firewood. This document covers only firewood produced from the following raw materials (see ISO 17725‑1:2021, Table 1): — 1.1.1 Whole trees without roots; — 1.1.3 Stem wood; — 1.1.4 Logging residues (thick branches, tops etc.); — 1.2.1 Chemically untreated by-products and residues from wood processing industry.
ISO/FDIS 17225-5 is classified under the following ICS (International Classification for Standards) categories: 27.190 - Biological sources and alternative sources of energy; 75.160.10 - Solid fuels; 75.160.40 - Biofuels. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO/FDIS 17225-5 has the following relationships with other standards: It is inter standard links to ISO/IEC 24775-7:2021, ISO 17225-5:2021. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO/FDIS 17225-5 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
FINAL DRAFT
International
Standard
ISO/TC 238
Solid biofuels — Fuel specifications
Secretariat: SIS
and classes —
Voting begins on:
2026-01-06
Part 5:
Graded firewood
Voting terminates on:
2026-03-03
Biocombustibles solides — Classes et spécifications des
combustibles —
Partie 5: Classes de bois de chauffage
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
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING 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.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 238
Solid biofuels — Fuel specifications
Secretariat: SIS
and classes —
Voting begins on:
Part 5: 2026-01-09
Graded firewood
Voting terminates on:
Biocombustibles solides — Classes et spécifications des
combustibles —
Partie 5: Classes de bois de chauffage
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.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 2
5 Specification of graded firewood . 2
Annex A (informative) Comparison of moisture content as received and dry basis. 6
Annex B (informative) Measurement of firewood . 8
Annex C (informative) Calculation of energy density . 9
Bibliography .11
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 238, Solid biofuels and Pyrogenic Biocarbon, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 335,
Solid Biofuels and Pyrogenic Biocarbon, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 17225-5:2021), which has been technically
revised.
The main changes are as follows:
— moisture in Table 1 has been changed.
A list of all parts in the ISO 17225 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
The objective of the ISO 17225 series is to provide unambiguous and clear classification principles for solid
biofuels, to serve as a tool to enable efficient trading of biofuels, to enable good understanding between
seller and buyer and as a tool for communication with equipment manufacturers. It also facilitates authority
permission, procedures and reporting.
This document supports the use of graded firewood for residential, small commercial and public building
applications which require classified firewood quality.
Residential, small commercial and public building appliances require higher quality fuel for the following
reasons:
— small-scale equipment does not usually have advanced controls and flue gas cleaning;
— appliances are not generally managed by professional heating engineers;
— appliances are often located in residential and populated districts.
NOTE 1 Firewood produced according to this document can be used in stoves, fireplaces, cookers, room heaters
[1] [2] [3]
and multifired sauna stoves, which are tested according to European standards EN 13229, EN 12815, EN 12809,
[4] [5] [6] [7] [8] [9] [10]
EN 13240, EN 15250, EN 15821, EN 16510–2–1, EN 16510–2–2, EN 16510–2–3, EN 16510–2–5, EN 16510–
[11] [12] [13] [14]
2–7, EN 16510–2–10, and boilers systems tested according to EN 303–5, EN 16510–2–4 .
NOTE 2 For individual contracts, ISO 17225-1 can be used.
Although this document can be used separately, it requires a general understanding of the standards based
on and supporting ISO 17225-1. It is recommended to obtain and use ISO 17225-1 in conjunction with this
document.
v
FINAL DRAFT International Standard ISO/FDIS 17225-5:2026(en)
Solid biofuels — Fuel specifications and classes —
Part 5:
Graded firewood
1 Scope
This document specifies the fuel quality classes and specifications of graded firewood. This document
applies only to firewood produced from the following raw materials (see ISO 17225-1:2021, Table 1):
— 1.1.1 Whole trees without roots;
— 1.1.3 Stem wood;
— 1.1.4 Logging residues (thick branches, tops, etc.);
— 1.2.1 Chemically untreated by-products and residues from wood processing industry.
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 14780, Solid biofuels — Sample preparation
ISO 16559, Solid biofuels — Vocabulary
ISO 17225-1:2021, Solid biofuels — Fuel specifications and classes — Part 1: General requirements
ISO 18134-1, Solid biofuels — Determination of moisture content — Part 1: Reference method
ISO 18134-2, Solid biofuels — Determination of moisture content — Part 2: Simplified method
ISO 21945, Solid biofuels — Simplified sampling method for small scale applications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16559 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
firewood
cut and split oven-ready fuelwood used in household wood burning appliances like stoves, fireplaces and
central heating systems
Note 1 to entry: Firewood usually has a uniform length, typically in the range of 15 cm to 100 cm.
Note 2 to entry: Cut-offs from virgin wood can also be used as a firewood.
3.2
commercial application
facility that utilizes solid biofuel burning appliances or equipment that have similar fuel requirements as
residential appliances
Note 1 to entry: Commercial applications are not to be confused with industrial applications, which can utilize a much
wider array of materials and have vastly different fuel requirements.
4 Symbols and abbreviated terms
The following symbols and abbreviated terms are used in this document and conform with the SI system of
units, except where noted.
ar as received
D Designation for diameter (D) as received [cm]
d dry (dry basis)
3 3
E Designation for energy density as received, E [MJ/m or kWh/m loose or stacked volume or MJ/kg,
ar
kWh/kg]
L Designation for length (L) as received [cm]
M Designation for moisture content as received on wet basis, M [% in mass]
ar
q Designation for net calorific value as received, q [MJ/kg or GJ/t or kWh/kg or MWh/t] at constant
p,net,ar
pressure
U Designation for moisture content on dry basis, U [% in mass]
d
NOTE 1 1 MJ/kg or GJ/t equals 0,277 8 kWh/kg (1 kWh/kg equals 1 MWh/t and 1 MWh/t is 3,6 MJ/kg). 1 g/cm
equals 1 kg/dm . 1 mg/kg equals 0,000 1 %.
NOTE 2 Designation symbols are used in combination with a number to specify property levels in Table 1.
5 Specification of graded firewood
Specification of the firewood shall be stated in accordance with Table 1 and Figure 1. Sampling shall be
carried out in accordance with ISO 21945, sample preparation in accordance with ISO 14780 and analysis
of the properties of solid biofuels, specifically moisture, shall be carried out in accordance with ISO 18134-1
(reference method) or ISO 18134-2 (simplified method).
Ash, N, S, Cl and minor elements are not required as firewood is produced from virgin material which has
been grown in uncontaminated soil and therefore the likelihood of contamination is very low.
Firewood specified according to classes A1 and A2 are suitable to be used in stoves and fireplaces and class
B in log wood boilers.
How to state the dimensions of firewood is expressed in Figure 1.
...
ISO/TC 238
Secretariat: SIS
Date: 2025-10-2912-22
Solid biofuels — Fuel specificationspecifications and classes —
Part 5:
Graded firewood
Biocombustibles solides — Classes et spécifications des combustibles —
Partie 5: Classes de bois de chauffage
FDIS stage
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ISO/DISFDIS 17225-5:202x2025(en)
© 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: + 41 22 749 01 11
Fax: +41 22 749 09 47
EmailE-mail: copyright@iso.org
Website: www.iso.orgwww.iso.org
Published in Switzerland
ii © ISO 2025 – All rights reserved
ii
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Specification of graded firewood . 2
Annex A (informative) Comparison of moisture content as received and dry basis . 6
Annex B (informative) Measurement of firewood . 8
Annex C (informative) Calculation of energy density . 10
Bibliography . 12
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Specification of graded firewood . 2
Annex A (informative) Comparison of moisture content as received and dry basis . 6
Annex B (informative) Measurement of firewood . 8
Annex C (informative) Calculation of energy density. 9
Bibliography . 10
iii
ISO/DISFDIS 17225-5:202x2025(en)
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.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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 238, Solid biofuels and Pyrogenic Biocarbon, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 238,
Solid Biofuels and Pyrogenic Biocarbon, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 17225-5:2021), which has been technically
revised.
The main changes are as follows:
— — moisture in Table 10 has been changed.
A list of all parts in the ISO 17225 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.
Field Code Changed
iv © ISO 2025 – All rights reserved
iv
Introduction
The objective of the ISO 17225 series is to provide unambiguous and clear classification principles for solid
biofuels, to serve as a tool to enable efficient trading of biofuels, to enable good understanding between seller
and buyer and as a tool for communication with equipment manufacturers. It also facilitates authority
permission, procedures and reporting.
This document supports the use of graded firewood for residential, small commercial and public building
applications which require classified firewood quality.
Residential, small commercial and public building appliances require higher quality fuel for the following
reasons:
— — small-scale equipment does not usually have advanced controls and flue gas cleaning;
— — appliances are not generally managed by professional heating engineers;
— — appliances are often located in residential and populated districts.
NOTE 1 Firewood produced according to this document can be used in stoves, fireplaces, cookers, room heaters and
[1] [ ] [2] [ ] [3]
multifired sauna stoves, which are tested according to European standards EN 13229 , , 0 EN 12815 , , 0 EN 12809 ,
[ ] [4] [ ] [5] [ ] [6] [ ] [7] [ ] [8] [ ] [9]
, 0 EN 13240 , , 0 EN 15250 , , 0 EN 15821 , , 0 EN 16510–2–1 , , 0 EN 16510–2–2 , , 0 EN 16510–2–3 ,
[ ] [10] [ ] [11] [ ] [12] [ ]
, 0 EN 16510–2–5 , , 0 EN 16510–2–7 , , 0 EN 16510–2–10 ,, 0 and boilers systems tested according to EN 303–
[13] [ ] [14] [ ]
5 , , 0 EN 16510–2–4 . 0 .
NOTE 2 For individual contracts, ISO 17225--1 can be used.
Although this document can be used separately, it requires a general understanding of the standards based on
and supporting ISO 17225-1. It is recommended to obtain and use ISO 17225-1 in conjunction with this
document.
v
DRAFT International Standard ISO/FDIS 17225-5:2025(en)
Solid biofuels — Fuel specificationspecifications and classes — —
Part 5:
Graded firewood
1 Scope
This document specifies the fuel quality classes and specifications of graded firewood. This document applies
only to firewood produced from the following raw materials (see ISO 17225--1:2021, Table 1):
— — 1.1.1 Whole trees without roots;
— — 1.1.3 Stem wood;
— — 1.1.4 Logging residues (thick branches, tops, etc.);
— — 1.2.1 Chemically untreated by-products and residues from wood processing industry.
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 14780, Solid biofuels — Sample preparation
ISO 16559, Solid biofuels — Vocabulary
ISO 17225--1:2021, Solid biofuels — Fuel specifications and classes — Part 1: General requirements
ISO 18134--1, Solid biofuels — Determination of moisture content — Part 1: Reference method
ISO 18134--2, Solid biofuels — Determination of moisture content — Part 2: Simplified method
ISO 21945, Solid biofuels — Simplified sampling method for small scale applications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16559 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/obphttps://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
3.1 3.1
firewood
cut and split oven-ready fuelwood used in household wood burning appliances like stoves, fireplaces and
central heating systems
Note 1 to entry: Firewood usually has a uniform length, typically in the range of 15 cm to 100 cm.
Note 2 to entry: Cut-offs from virgin wood can also be used as a firewood.
3.2 3.2
commercial application
facility that utilizes solid biofuel burning appliances or equipment that have similar fuel requirements as
residential appliances
Note 1 to entry: Commercial applications are not to be confused with industrial applications, which can utilize a much
wider array of materials and have vastly different fuel requirements.
4 Symbols and abbreviated terms
The following symbols and abbreviated terms are used in this document and conform with the SI system of
units, except where noted.
ar as received
D Designation for diameter (D) as received [cm]
d dry (dry basis)
3 3
E Designation for energy density as received, E [MJ/m or kWh/m loose or stacked volume or MJ/kg,
ar
kWh/kg]
L Designation for length (L) as received [cm]
M Designation for moisture content as received on wet basis, M [% in mass]
ar
Qq Designation for net calorific value as received, qp,net,ar [MJ/kg or GJ/t or kWh/kg or MWh/t] at constant
pressure
U Designation for moisture content on dry basis, U [% in mass]
d
NOTE 1 1 MJ/kg or GJ/t equals 0,277 8 kWh/kg (1 kWh/kg equals 1 MWh/t and 1 MWh/t is 3,6 MJ/kg). 1 g/cm
equals 1 kg/dm . 1 mg/kg equals 0,000 1 %.
NOTE 2 Designation symbols are used in combination with a number to specify property levels in Table 1.0.
5 Specification of graded firewood
Specification of the firewood shall be stated in accordance with Table 10 and Figure 1.0. Sampling shall be
carried out in accordance with ISO 21945, sample preparation in accordance with ISO 14780 and analysis of
the properties of solid biofuels, specifically moisture, shall be carried out in accordance with ISO 18134--1
(reference method) or ISO 18134--2 (simplified method).
Ash, N, S, Cl and minor elements are not required as firewood is produced from virgin material which has been
grown in uncontaminated soil and therefore the likelihood of contamination is very low.
Firewood specified according to
...
PROJET FINAL
Norme
internationale
ISO/TC 238
Biocombustibles solides —
Secrétariat: SIS
Classes et spécifications des
Début de vote:
combustibles —
2026-01-06
Partie 5:
Vote clos le:
2026-03-03
Classes de bois de chauffage
Solid biofuels — Fuel specifications and classes —
Part 5: Graded firewood
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Numéro de référence
PROJET FINAL
Norme
internationale
ISO/TC 238
Biocombustibles solides —
Secrétariat: SIS
Classes et spécifications des
Début de vote:
combustibles —
2026-01-06
Partie 5:
Vote clos le:
2026-03-03
Classes de bois de chauffage
Solid biofuels — Fuel specifications and classes —
Part 5: Graded firewood
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
DOCUMENT PROTÉGÉ PAR COPYRIGHT
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
© ISO 2026 INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
PROJETS DE NORMES
TRAITEMENT PARALLÈLE ISO/CEN
INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
DU POINT DE VUE DE LEUR POSSI BILITÉ DE DEVENIR DES
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NORMES POUVANT
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
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Publié en Suisse Numéro de référence
ii
Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Symboles et abréviations . 2
5 Spécification des classes de bois de chauffage . 2
Annexe A (informative) Comparaison de la teneur en humidité à réception et sur masse
anhydre . 6
Annexe B (informative) Mesurage du bois de chauffage . 8
Annexe C (informative) Calcul de la densité d’énergie . 9
Bibliographie .11
iii
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’ISO attire l’attention sur le fait que la mise en application du présent document peut entraîner l’utilisation
d’un ou de plusieurs brevets. L’ISO ne prend pas position quant à la preuve, à la validité et à l’applicabilité
de tout droit de brevet revendiqué à cet égard. À la date de publication du présent document, l’ISO n’avait
pas reçu notification qu’un ou plusieurs brevets pouvaient être nécessaires à sa mise en application.
Toutefois, il y a lieu d’avertir les responsables de la mise en application du présent document que des
informations plus récentes sont susceptibles de figurer dans la base de données de brevets, disponible à
l’adresse www.iso.org/brevets. L’ISO ne saurait être tenue pour responsable de ne pas avoir identifié tout ou
partie de tels droits de brevet.
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 le lien suivant: www.iso.org/iso/fr/avant-propos.html.
Le présent document a été élaboré par le comité technique ISO/TC 238, Biocombustibles solides et biocarbone
pyrogène, en collaboration avec le comité technique CEN/TC 335, Biocombustibles solides et biocarbone
pyrogène, du Comité européen de normalisation (CEN) conformément à l’Accord de coopération technique
entre l’ISO et le CEN (Accord de Vienne).
Cette troisième édition annule et remplace la deuxième édition (ISO 17225-5:2021) qui a fait l’objet d’une
révision technique.
Les principales modifications sont les suivantes:
— les spécifications relatives à l’humidité ont été modifiées dans le Tableau 1.
Une liste de toutes les parties de la série ISO 17225 se trouve sur le site web de l’ISO.
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.
iv
Introduction
L’objectif de la série ISO 17225 est de fournir des principes clairs et univoques de classification des
biocombustibles solides, de servir d’outil pour permettre des échanges commerciaux efficaces et une bonne
compréhension entre vendeur et acheteur, ainsi que de moyen de communication avec les fabricants de
matériel. Elle facilite également les procédures d’autorisation administrative et l’établissement de rapports.
Le présent document couvre l’utilisation de classes de bois de chauffage pour des applications dans les
habitations, les petits commerces et les bâtiments publics, qui requièrent une qualité de bois de chauffage
classifiée.
Les appareils utilisés dans les habitations, les petits commerces et les bâtiments publics nécessitent un
combustible de haute qualité pour les raisons suivantes:
— les équipements à petite échelle ne disposent habituellement pas de commandes sophistiquées ni
d’épurateurs de fumées;
— les appareils ne sont généralement pas gérés par un spécialiste du chauffage;
— les appareils sont souvent situés dans des zones résidentielles et habitées.
NOTE 1 Le bois de chauffage produit conformément au présent document peut être utilisé dans des poêles, des
cheminées, des cuisinières, des calorifères et dans des poêles de saunas polycombustibles qui sont soumis à essai
[1] [2] [3] [4] [5] [6] [7]
conformément aux EN 13229 , EN 12815 , EN 12809 , EN 13240 , EN 15250 , EN 15821 , EN 16510-2-1 ,
[8] [9] [10] [11] [12]
EN 16510-2-2 , EN 16510-2-3 , EN 16510-2-5 , EN 16510-2-7 , EN 16510-2-10 , et dans les chaudières qui sont
[13] ' [14]
soumises à essai selon l'EN 303-5 , l EN 16510-2-4 .
NOTE 2 Pour des contrats individuels, l’ISO 17225-1 peut être utilisée.
Bien que le présent document puisse être utilisé séparément, il nécessite une compréhension globale des
normes basées sur l’ISO 17225-1 et de celles qui la complètent. Il est recommandé de se procurer l’ISO 17225-1
et de l’utiliser conjointement avec le présent document.
v
PROJET FINAL Norme internationale ISO/FDIS 17225-5:2026(fr)
Biocombustibles solides — Classes et spécifications des
combustibles —
Partie 5:
Classes de bois de chauffage
1 Domaine d’application
Le présent document spécifie les classes et spécifications de qualité du combustible pour le bois de
chauffage. Il s'applique uniquement au bois de chauffage produit à partir des matières premières suivantes
(voir l’ISO 17225-1:2021, Tableau 1):
— 1.1.1 Arbres entiers sans racines;
— 1.1.3 Grumes;
— 1.1.4 Rémanents forestiers (grosses branches, cimes, etc.);
— 1.2.1 Produits dérivés et sous-produits de l’industrie de transformation du bois sans traitement chimique.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l'édition citée s'applique. Pour
les références non datées, la dernière édition du document de référence s'applique (y compris les éventuels
amendements).
ISO 14780, Biocombustibles solides — Préparation des échantillons
ISO 16559, Biocombustibles solides — Vocabulaire
ISO 17225-1:2021, Biocombustibles solides — Classes et spécifications des combustibles — Partie 1: Exigences
générales
ISO 18134-1, Biocombustibles solides — Dosage de la teneur en humidité — Partie 1: Méthode de référence
ISO 18134-2, Biocombustibles solides — Dosage de la teneur en humidité — Partie 2: Méthode simplifiée
ISO 21945, Biocombustibles solides — Méthode d'échantillonnage simplifiée pour les applications à petite échelle
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions de l’ISO 16559 ainsi que les 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 https://www.electropedia.org/
3.1
bois de chauffage
bûches coupées en rondins ou fendues prêtes à l’emploi utilisées dans des applications domestiques de
combustion du bois comme les poêles, les cheminées et les systèmes de chauffage central
Note 1 à l'article: Le bois de chauffage a une longueur uniforme, habituellement dans la plage comprise entre 15 cm
et 100 cm.
Note 2 à l'article: Les coupes de bois vierge peuvent également être utilisées comme bois de chauffage.
3.2
application commerciale
installation qui utilise des appareils ou des équipements brûlant des biocombustibles solides ayant des
exigences relatives aux combustibles similaires à celles des appareils domestiques
Note 1 à l'article: Ne pas confondre les applications commerciales avec les applications industrielles, qui peuvent
utiliser un éventail plus large de matériaux et qui possèdent des exigences relatives aux combustibles très différentes.
4 Symboles et abréviations
Les symboles et abréviations suivants sont utilisés dans le présent document et sauf indication contraire, ils
sont conformes au système international (SI) d’unités de mesure.
ar à réception
D désignation du diamètre (D) à réception [cm]
d anhydre (sur une base dite à sec)
3 3
E désignation de la densité d’énergie à réception, E [MJ/m ou kWh/m de volume apparent ou empilé,
ar
ou MJ/kg, kWh/kg].
L désignation de la longueur (L) à réception [cm]
M désignation du taux d’humidité à réception sur masse humide, M [% en masse]
ar
q désignation du pouvoir calorifique inférieur à réception, q [MJ/kg ou GJ/t ou kWh/kg ou MWh/t]
p,net,ar
à pression constante
U désignation de la teneur en humidité à réception sur masse anhydre, U [% en masse]
d
NOTE 1 1 MJ/kg ou GJ/t équivaut à 0,277 8 kWh/kg (1 kWh/kg équivaut à 1 MWh/t et 1 MWh/t correspond
3 3
à 3,6 MJ/kg). 1 g/cm équivaut à 1 kg/dm . 1 mg/kg équivaut à 0,000 1 %.
NOTE 2 Dans le Tableau 1, les symboles de désignation sont suivis d’un nombre spécifiant le niveau de la propriété.
5 Spécification des classes de bois de chauffage
La spécification du bois de chauffage doit être établie conformément au Tableau 1 et à la Figure 1.
L'échantillonnage doit être effectué conformément à l'ISO 21945, la préparation des échantillons
conformément à l'ISO 14780 et l'analyse des propriétés des biocombustibles solides, en particulier l'humidité,
conformément à l'ISO 18134-1 (méthode de référence) ou à l'ISO 18134-2 (méthode simplifiée).
Les teneurs en cendres, N, S, Cl et les éléments mineurs ne sont pas exigés du fait que le bois de chauffage
est produit à partir de matériaux vierges, qui proviennent de terrains non contaminés. Par conséquent, la
probabilité d’une contamination est très faible.
Les bois de chauffage spécifiés conformément aux classes A1 et A2 sont appropriés à un usage dans des
poêles et des cheminées, et ceux de la classe B sont appropriés à un usage dans des chaudières à rémanents
forestiers.
La Figure 1 présente la façon d’exprimer les dimensions du bois de chauffage.
Légende
D diamètre, diamètre maximal de D ou D
1 2
L longueur
Figure 1 — Dimensions du bois de chauffage prêt à l’emploi
NOTE Les quantités de bois de chauffage sont données en mètres cubes ou en k
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