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Cooperative research for small biomass fired boilers for the Ecodesign Directive

RISE, together with the boiler manufacturers Ariterm, Nibe and Värmebaronen, have conducted a joint research effort aimed at optimizing the environmental performance of new and future products to meet the new stricter requirements set out in the Ecodesign Directive for small-scale boilers

Aim and goal

In the present project boiler manufacturers and research institutes have collaborated in response to the combustion engineering challenges that face the boiler manufacturers.


Newly manufactured small-scale biomass-fired boilers must meet the Ecodesign requirements by 2020. In a market survey from 2014, none of 11 tested pellet boilers did meet all requirements, clearly indicating a developmental need. For wood log boilers, it is a challenge to comply with the NOx requirements of the Ecodesign Directive.

Work performed

In this project two different types of modern pellet boilers have been used. After optimization, sufficiently combustion performance could be achieved with both types. However, the burner with a protected combustion zone exhibited considerably lower emissions at partial loads.

Comprehensive temperature mapping in a wood log boiler showed that thermal NOx formation could be ruled out. By using barked birch wood, NOx emissions could be reduced to below the limit because the nitrogen content of the wood is concentrated to the bark. Even log of spruce showed low NOx emissions, but that fuel resulted in increased CO and OGC emissions. For wood log boilers to meet the requirements for CO, OGC and particles, operational optimization is required during the wood's final combustion phase. At that stage excess air supply tends to cool down the flue gas before the combustible gases are burnt out. Particle emissions and efficiency have also been surveyed within the project.


The project has provided participating companies with valuable knowledge and experience that can be used to develop future boilers that will comply with the Ecodesign Directive.

In the long run, the Ecodesign Directive implies that low performance boilers are excluded from the market, which means that both emissions and environmental impact from small-scale boilers will decrease.


Project name

Bioboiler 2020



RISE role in project

Project leader

Project start


2016-06-15 -- 2018-06-30

Total budget

3 150 000 SEK


Ariterm, NIBE, Värmebaronen


The Swedish Energy Agency

Supports the UN sustainability goals

7. Affordable and clean energy

Contact person

Fredrik Niklasson


Read more about Fredrik

Contact Fredrik
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