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Standards are required to describe biomass equipment, and biomass fuels. They are vital if forms of biomass are to become commodity fuel that users can buy with confidence of trouble free operation. They are there to ensure reliable, efficient, trouble free operation.

The need for standards

There is a wide range of biomass potentially suitable for energy use, however most types of conversion equipment works effectively with a very few types and forms of biomass fuel.

Even with a specific form of fuel, such as wood chips, there can be major differences in characteristics and properties between different batches chipped using different chippers, from different material, with different moisture content.

This means that while it is all eminently usable, one batch will allow a particular piece of equipment to operate according to specification, but another may cause blockages in the fuel feed line, inefficient operation, emissions, condensation in the flue, or automatic shut down of the equipment as it moves outside its design operating regime. In different equipment, however, the second batch of fuel may be perfectly acceptable.

Sustainability standards too are required, and gradually being developed to ensure that biomass is only derived from sustainable, legal sources. CPET, the Central Point of Expertise on Timber Procurement, provides detailed information and advice on how public sector buyers and their suppliers can meet the UK Government’s timber procurement policy requirements in practice, and demonstrate that timber supplied is legal and sustainable.

British Standards (BS),European Norms (EN) and the International Organization for Standardization (ISO)

CEN/TC335 was the technical committee responsible for developing the European Norms (EN) to describe all forms of solid biofuels within Europe, including wood chips, wood pellets and briquettes, logs, sawdust and straw bales. These have been adopted by the British Standards Institution (BSI) to form BS EN.

The ISO extends these standards beyond Europe, and now many of the BS EN standards have been superseded by BS EN ISO standards.

These standards allow all relevant properties of the fuel to be described, and also the internationally accepted test procedures to measure the various properties. As well as the physical and chemical characteristics of the fuel as it is, they also provides information on the source of the material.


Woodsure is an accreditation scheme for assuring the quality and suitability of wood chip, pellets, briquettes, logs and hog fuel (shred).

Woodsure Accreditation of a woodfuel supplier means that these products have been tested to ensure they meet the BS EN or Önorm woodfuel standards that have become the established measure in the European biomass industry.

Woodsure accredited woodfuel assures customers that the fuel they are purchasing fulfils the appropriate specification for their equipment. It helps to guarantee a high standard and reliability in the supply chain.


While the CEN/TC 335 suite of standards are intended to be the universal standards for solid biofuels across Europe, prior to these many countries developed their own standards. The Austrian Standards Institute is ÖNORM. While ÖNORM is now adopting its own implementations of the CEN/TC 335 standards, many Austrian boilers have been installed in the UK and specify fuel according to ÖNORM M7 133 for wood chips (Woodchips for energy generation: quality and testing requirements) and ÖNORM M7 135 for pellets. Sizes such as G30 are ÖNORM sizes and still regularly encountered.


The German Standards Institute (Deutsches Institut fur Normung) also developed its own biomass fuel standards DIN 66 165, and these too are sometimes encountered.

BS EN 303-5:2012

In addition to specifications for biomass fuels, there are also specifications for biomass combustion equipment. BS EN 303-5:2012 applies to heating boilers for solid fuels, hand and automatically fired, nominal heat output of up to 300kW. It is the local UK implementation by the BSI of EN 303-5.

BS EN 303-5:2012 covers properties such as performance, efficiency, emissions, thermal output, pressure testing, safety measures and testing.

Standards testing

In order to demonstrate compliance with any standards system it is necessary to have independent testing

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