Standards & Technical Specifications

Over the last 20 years a comprehensive suite of standards relating to solid biofuels has been developed at first by the CEN Technical Committee TC335 Solid Biofuels, then by ISO TC238. These standards include many aspects of solid biomass, from terminology to physical and chemical properties. They also include quality requirements for fuel for smaller boilers as well as for quality assurance.

Copyright on standards is strictly enforced, so standards are available only from an official standardization body, which in Ireland is NSAI).

The ISO standards have been produced under the so-called Vienna Agreement, so they become automatically European standards, so they get the designation EN ISO. As such these standards then replace eventual existing European standards, so for example the EN 16964 Solid Biofuels, Requirements and classes has been replaced by the EN ISO 17225.

The development of a standard goes through several steps to ensure that the contents are alright and that a majority of the participating countries in ISO accept the standard. The development follows a strict time schedule. In general, it takes 3 to 4 years to produce a standard.


The steps are called:

  • Working Document (WD). A document which is being prepared by experts within a particular working group. This document is discussed in the working group until consensus is reached. The document is restricted to members of the working group
  • Committee Draft (CD): this is the final version of the working document that goes for ballot to the countries participating in the drafting. The document is not available to the general public.
  • Draft International Standard (DIS): this version goes for ballot to a much wider circle. Comments may be given on the technical content as well as editorial comments. The document is not available to the general public
  • Final Draft International Standard (FDIS). This is a document with the widest circulation in ISO member states. Only editorial comments can be made. It is not available to the general public.
  • EN ISO standard, the published version of standard, available to the general public. It is published in English, French and German and may be translated into the national language by the national standardization body. Where there are disputes; the English version takes precedence.
  • Below is a list of published and upcoming standards within TC335 and TC238 Solid Biofuels. Check the homepage of NSAI if the particular standard you are interested in has already been published.
  • Many of the standards in the EN ISO suite of solid biofuels have been published 5 years ago, which means that they come up for automatic revision. A revision is carried out if the majority of members of the TC vote for that in a ballot.
  • Besides standards there can also be Technical Reports (TR) or Technical Specifications (TS)
  • In the case that a measuring method is not entirely scientifically based, or the method is not used widespread, a Technical Report can be written. Such a TR explains the state of the art and the experiences gained with the method.
  • A Technical Specification is used when the method is more widely accepted, but there is insufficient data or experience with the method. A TS must be revised within 3 to 5 years and either it is then promoted to a standard or the subject is dropped altogether.

Published standards in CEN and ISO on Solid Biofuels, status September 2017

CEN/TR 15149-3:2014 (WI=00335084)
Solid biofuels - Determination of particle size distribution - Part 3: Rotary screen method

CEN/TR 15569:2009 (WI=00335033)
Solid biofuels - A guide for a quality assurance system

CEN/TS 15370-1:2006 (WI=00335015)
Solid biofuels - Method for the determination of ash melting behaviour - Part 1: Characteristic temperatures method

EN 15234-1:2011 (WI=00335072)
Solid biofuels - Fuel quality assurance - Part 1: General requirements

EN 15234-2:2012 (WI=00335073)
Solid biofuels - Fuel quality assurance - Part 2: Wood pellets for non-industrial use

EN 15234-3:2012 (WI=00335074)
Solid biofuels - Fuel quality assurance - Part 3: Wood briquettes for non-industrial use

EN 15234-4:2012 (WI=00335075)
Solid biofuels - Fuel quality assurance - Part 4: Wood chips for non-industrial use

EN 15234-5:2012 (WI=00335076)
Solid biofuels - Fuel quality assurance - Part 5: Firewood for non-industrial use

EN 15234-6:2012 (WI=00335077)
Solid biofuels - Fuel quality assurance - Part 6: Non-woody pellets for non-industrial use

EN ISO 14780:2017 (WI=00335127)
Solid biofuels - Sample preparation (ISO 14780:2017)

EN ISO 16559:2014 (WI=00335103)
Solid biofuels - Terminology, definitions and descriptions (ISO 16559:2014)

EN ISO 16948:2015 (WI=00335104)
Solid biofuels - Determination of total content of carbon, hydrogen and nitrogen (ISO 16948:2015)

EN ISO 16967:2015 (WI=00335105)
Solid biofuels - Determination of major elements - Al, Ca, Fe, Mg, P, K, Si, Na and Ti (ISO 16967:2015)

EN ISO 16968:2015 (WI=00335106)
Solid biofuels - Determination of minor elements (ISO 16968:2015)

EN ISO 16993:2016 (WI=00335135)
Solid biofuels - Conversion of analytical results from one basis to another (ISO 16993:2016)

EN ISO 16994:2016 (WI=00335136)
Solid biofuels - Determination of total content of sulfur and chlorine (ISO 16994:2016)

EN ISO 16995:2015 (WI=00335108)
Solid biofuels - Determination of the water soluble chloride, sodium and potassium content (ISO 16995:2015)

EN ISO 17225-1:2014 (WI=00335096)
Solid biofuels - Fuel specifications and classes - Part 1: General requirements (ISO 17225-1:2014)

EN ISO 17225-2:2014 (WI=00335097)
Solid biofuels - Fuel specifications and classes - Part 2: Graded wood pellets (ISO 17225-2:2014)

EN ISO 17225-3:2014 (WI=00335098)
Solid biofuels - Fuel specifications and classes - Part 3: Graded wood briquettes (ISO 17225-3:2014)

EN ISO 17225-4:2014 (WI=00335099)
Solid biofuels - Fuel specifications and classes - Part 4: Graded wood chips (ISO 17225-4:2014)

EN ISO 17225-5:2014 (WI=00335102)
Solid biofuels - Fuel specifications and classes - Part 5: Graded firewood (ISO 17225-5:2014)

EN ISO 17225-6:2014 (WI=00335100)
Solid biofuels - Fuel specifications and classes - Part 6: Graded non-woody pellets (ISO 17225-6:2014)

EN ISO 17225-7:2014 (WI=00335101)
Solid biofuels - Fuel specifications and classes - Part 7: Graded non-woody briquettes (ISO 17225-7:2014)

EN ISO 17827-1:2016 (WI=00335121)
Solid biofuels - Determination of particle size distribution for uncompressed fuels - Part 1: Oscillating screen method using sieves with apertures of 3,15 mm and above (ISO 17827-1:2016)

EN ISO 17827-2:2016 (WI=00335120)
Solid biofuels - Determination of particle size distribution for uncompressed fuels - Part 2: Vibrating screen method using sieves with aperture of 3,15 mm and below (ISO 17827-2:2016)

EN ISO 17828:2015 (WI=00335118)
Solid biofuels - Determination of bulk density (ISO 17828:2015)

EN ISO 17829:2015 (WI=00335119)
Solid biofuels - Determination of length and diameter of pellets (ISO 17829:2015)

EN ISO 17830:2016 (WI=00335125)
Solid biofuels - Particle size distribution of disintegrated pellets (ISO 17830:2016)

EN ISO 17831-1:2015 (WI=00335114)
Solid biofuels - Determination of mechanical durability of pellets and briquettes - Part 1: Pellets (ISO 17831-1:2015)

EN ISO 17831-2:2015 (WI=00335112)
Solid biofuels - Determination of mechanical durability of pellets and briquettes - Part 2: Briquettes (ISO 17831-2:2015)

EN ISO 18122:2015 (WI=00335113)
Solid biofuels - Determination of ash content (ISO 18122:2015)

EN ISO 18123:2015 (WI=00335117)
Solid biofuels - Determination of the content of volatile matter (ISO 18123:2015)

EN ISO 18125:2017 (WI=00335126)
Solid biofuels - Determination of calorific value (ISO 18125:2017)

EN ISO 18134-1:2015 (WI=00335111)
Solid biofuels - Determination of moisture content - Oven dry method - Part 1: Total moisture - Reference method (ISO 18134-1:2015)

EN ISO 18134-2:2017 (WI=00335137)
Solid biofuels - Determination of moisture content - Oven dry method - Part 2: Total moisture - Simplified method (ISO 18134-2:2017)

EN ISO 18134-3:2015 (WI=00335116)
Solid biofuels - Determination of moisture content - Oven dry method - Part 3: Moisture in general analysis sample (ISO 18134-3:2015)

EN ISO 18135:2017 (WI=00335128)
Solid Biofuels - Sampling (ISO 18135:2017)

EN ISO 18846:2016 (WI=00335122)
Solid biofuels - Determination of fines content in quantities of pellets (ISO 18846:2016)

EN ISO 18847:2016 (WI=00335124)
Solid biofuels - Determination of particle density of pellets and briquettes (ISO 18847:2016)

Standards under development, status September 2017

prEN ISO 20023 (WI=00335130)
Solid biofuels - Safety of solid biofuel pellets - Safe handling and storage of wood pellets in residential and other small-scale applications (ISO/DIS 20023:2017)

Under Approval

prEN ISO 20024 (WI=00335131)
Solid biofuels - Safe handling and storage of solid biofuel pellets in commercial and industrial applications

Under Drafting

prEN ISO 20049 (WI=00335132)
Solid biofuels - Determination of self-heating

Under Drafting

prEN ISO 21404 (WI=00335138)
Solid biofuels - Method for the determination of ash melting behaviour

Under Drafting

prEN ISO 21945 (WI=00335140)
Solid Biofuels - Simplified sampling method for small scale applications and stores

Under Drafting

Copyright COFORD 2006.