Wood pellet certificates: ENplus, DINplus, ISO 17225-2, FSC and PEFC

Bags of wood pellets can carry several different marks. It is easy to treat them as equivalent, but that is a mistake: each one answers a different question. ENplus and DINplus relate to fuel quality and are awarded after an audit. ISO 17225-2 is a standard that defines quality classes, but it is not a mark in itself. FSC, PEFC and SBP relate to the origin of the wood. The 2025 Polish regulation, for its part, sets a legal minimum — not a “premium” quality standard.

Wood pellet certificates compared

The table sets out the most important marks. The “Relates to” column is the key one — it separates fuel quality certificates from certificates covering the origin of the raw material.

Alongside FSC and PEFC there is also SBP (Sustainable Biomass Program) — a scheme for the responsible sourcing of woody biomass, mainly pellets and wood chips, used above all in industrial and large-scale energy generation. The programme itself publishes the list of certificate holders^[35]. Like FSC and PEFC, SBP does not describe combustion properties.

Product certificates vs wood origin certificates

For a buyer, this is the most important distinction. A product certificate (ENplus, DINplus) answers the question: how will these pellets burn? — how much ash they will leave, how much water they contain, whether they will crumble in the auger, whether the ash will form clinker. An origin certificate (FSC, PEFC, SBP) answers a different question: where does the wood come from, and is the supply chain documented?^[31],[33]

FSC requires chain-of-custody certification at every stage at which a company takes legal ownership of the material — only then can the product carry the FSC label^[31]. This is valuable information about the legality and responsible sourcing of the raw material, but it is no substitute for testing ash content or mechanical durability.

ENplus: how the scheme works

ENplus is the most widely recognised wood pellet certification scheme in Europe. The current document is ENplus ST 1001:2022, edition 2, approved on 18 June 2025 and applicable from 1 January 2026. As the document itself states, its requirements are based on ISO 17225-2^[1]. The second edition did not change the limit values; what changed is the method for determining fines (from ISO 18846 to ISO 5370), and “coarse fines” were renamed coarse pellet fines (CPF) (The 3.15–5.6 mm fraction, i.e. pellet fragments larger than dust. ENplus requires its value to be stated, without a limit.)The 3.15–5.6 mm fraction, i.e. pellet fragments larger than dust. ENplus requires its value to be stated, without a limit.^[1].

Who manages the scheme

• ENplus International Management — Bioenergy Europe AISBL, represented by the European Pellet Council (EPC). It manages the scheme in all countries except Germany.
• DEPI (Deutsches Pelletinstitut) — manages the scheme in Germany, where it also acts as a certification and inspection body.
• National Licensers — appointed by the international management to run the scheme in a given country.
• Certification bodies — these are the organisations that issue certificates. They must be accredited to ISO/IEC 17065 (The standard setting out requirements for bodies that certify products, processes and services.)The standard setting out requirements for bodies that certify products, processes and services. by a national accreditation body that is a signatory to the EA/IAF agreements.
• Testing bodies — laboratories accredited to ISO/IEC 17025 (The standard setting out requirements for the competence of testing and calibration laboratories.)The standard setting out requirements for the competence of testing and calibration laboratories. (EA/ILAC agreements).

Sources: definitions in ST 1001 and the list of conformity assessment bodies on the ENplus website^[1],[8].

The whole supply chain, not just the plant

ENplus certifies not only producers but also distributors and service providers. This matters in practice: pellets can lose quality after they leave the plant — during transhipment, transfer or poor storage. One requirement that applies to both groups is the temperature rule: pellets delivered in bulk must not be warmer than 40 °C, and if they are, they must not be delivered to the end customer — this applies equally to producers and distributors^[1].

ENplus ID format

Every certified company receives a unique ENplus ID assigned by the scheme management. The consumer section of the website describes it as a country code followed by three digits^[5]. The number range reveals the company’s role^[3],[4]:

ENplus in Poland

According to the list of partners on the ENplus website, Poland currently has no National Licenser; the list includes twelve licensers, among them ones from Austria, the Czech Republic, France, Germany and Italy^[9]. In the past, the Polish Pellet Council (Polska Rada Pelletu) held the status of a National Promoting Association (NPA) in the scheme^[60], but we have not been able to confirm its current statusData require verification: Current status of the Polish Pellet Council in the ENplus scheme not confirmed. It is worth checking the current position directly on the ENplus website. The list of certification and testing bodies — including those operating in Poland — is published on the conformity assessment bodies page^[8].

Certification is not standard practice on the Polish market. A study by Drobniak et al., citing Bioenergy Europe data, reports that in 2022 the ENplus certificate covered around 30% of Polish wood pellet production^[47].

ENplus classes A1, A2 and B

The three ENplus classes differ mainly in the permitted ash, nitrogen and chlorine content, the minimum mechanical durability and the ash deformation temperature. Moisture content, net calorific value, bulk density and sulphur are the same for all classes^[1].

ENplus also requires pellets to be free of non-wood materials and of wood fibres in any form other than pellets (e.g. wood chips). The heavy metal limits (dry basis, mg/kg) are the same for all three classes^[1]:

Permitted raw materials

The classes also differ in the type of raw material permitted (designations according to ISO 17225-1)^[1],[13]:

• A1: 1.1.3 Stemwood (a); 1.2.1 Chemically untreated by-products and residues from the wood-processing industry (b).
• A2: 1.1.1 Whole trees without roots (a); 1.1.3 Stemwood (a); 1.1.4 Logging residues (a); 1.2.1 Chemically untreated by-products and residues from the wood-processing industry (b).
• B: 1.1 Forest, plantation and other virgin wood (a); 1.2.1 Chemically untreated by-products and residues from the wood-processing industry (b); 1.3.1 Chemically untreated used wood (c).

(a) Wood that has been externally treated with an insecticide is not regarded as chemically treated, provided that all the chemical parameters of the pellets are within the limits or the concentrations are negligible. (b) Negligible amounts of glue, grease and other additives used in the production of sawn timber and virgin-wood products are acceptable, provided that the chemical parameters of the pellets are clearly within the limits. (c) Demolition wood is excluded. (ENplus ST 1001:2022, Annex A, Table 5)

In all classes, the raw material must not be rotten or contaminated, or contain a high proportion of bark. Permitted additives (up to 2.0% in total) must come from agricultural or forestry products — e.g. starch, maize flour or vegetable oil^[1].

ISO 17225-2:2021 and ENplus — the differences

The current edition of the standard is ISO 17225-2:2021 (edition 2), which replaced the 2014 version. Among other changes, the new edition introduced a normative requirement for ash deformation temperature and an upper limit for bulk density, and added particle density and coarse pellet fines as informative parameters. Class B of the standard permits chemically treated by-products of the wood-processing industry and chemically untreated post-consumer wood, provided that heavy metals and halogenated organic compounds do not exceed levels typical of virgin wood^[11].

On several points, ENplus is more demanding than the standard. The ISO values in the table come from the final draft (FDIS), because the full text of the 2021 edition is only available for purchase — the final figures may differ slightly^[12].

For the other key parameters — moisture content ≤ 10%, net calorific value ≥ 16.5 MJ/kg as received, bulk density 600–750 kg/m³, ash 0.7 / 1.2 / 2.0% — the draft standard and ENplus are aligned^[1],[12].

DINplus

DINplus is a product certification run by DIN CERTCO, part of the TÜV Rheinland group. It covers A1-class pellets according to DIN EN ISO 17225-2 and adds to the standard’s requirements an annual inspection of production, sampling of the fuel and mandatory internal quality control. Holzforschung Austria acts as an external inspection body reporting to DIN CERTCO, which takes the certification decision^[28].

According to the index of the scheme document “Wood Pellets Class A1 – DINplus”, the scheme requires, among other things, mechanical durability ≥ 98.0% for the 8 mm diameter as well (the ISO standard allows 97.5% for D08) and fines ≤ 0.5% in small bags (up to 20 kg) at the end of production^[29]Data require verification: DIN CERTCO document unavailable at the time of verification — values taken from the search engine index. The 2021 version of the scheme is also cited by the authors of the study of the Polish market^[47].

A DINplus certificate is checked in the DIN CERTCO database by searching for the company name or registration number^[30]Data require verification: How the database works has not been checked directly. Unlike ENplus, we do not describe the DINplus requirements for distributors or its bag-labelling rules here — we have not confirmed them in the scheme documents.

Legal requirements in Poland: a minimum, not a certificate

Since 24 May 2025, the Regulation of the Minister of Climate and Environment of 8 May 2025 on quality requirements for biomass in the form of briquettes or pellets (Dz.U. 2025 poz. 618 — Polish Journal of Laws 2025, item 618) has been in force. It applies to pellets and briquettes placed on the market for households and for installations with a capacity below 1 MW^[36]. The ministry states that the values are consistent with the requirements of EN ISO 17225^[37].

The regulation sets two sets of requirements for pellets — one for appliances of class 3, 4 and 5 or those meeting ecodesign requirements (including ash ≤ 0.70% and durability ≥ 98.00%) and a general one (ash ≤ 1.20%, durability ≥ 97.50%). However, it contains no limits for heavy metals or ash deformation temperature, no separate fines limit for bags and no references to test methods^[36].

Who issues the certificate

A mark on a bag is only credible when an independent assessment stands behind it. This is how it works in each scheme:

• ENplus — the certificate is issued by a certification body accredited to ISO/IEC 17065, and samples are tested by a testing body accredited to ISO/IEC 17025. The ENplus ID is assigned by the scheme management (EPC, or DEPI in Germany)^[1],[8].
• DINplus — the certification decision is taken by DIN CERTCO on the basis of reports from inspection bodies^[28].
• FSC and PEFC — the chain-of-custody certificate covers the company, not an individual batch of fuel; you can check its number in the relevant scheme’s search tool^{[31],[32],[34]}.
• ISO 17225-2 — nobody issues an “ISO certificate” for pellets. A claim of conformity with a class in the standard is backed up by a test report; see laboratory testing for more.

Phrases such as “premium quality”, “class A1” or “compliant with the standard”, without a certificate number or a test report, are the seller’s own claims — not a certificate.

How to verify wood pellets before you buy

Checking an ENplus certificate takes a few minutes and requires no technical knowledge. All you need is the bag (or a photo of it) and a phone.

What must be on a bag of ENplus pellets

The mandatory elements are set out in ENplus ST 1003:2022 (ed. 2), section 7.2.3, Table 3^[2]:

All information must be printed directly on the bag. Stickers and handwritten additions are prohibited, and the bag design must be approved and published on the ENplus website^[2]. A bag with the number on a sticker, or with the calorific value given “on a dry basis” — always higher than as received, and therefore more flattering — should raise suspicion.

Why you should not rely on the ENplus print on the bag alone

The ENplus mark has commercial value, so it is sometimes counterfeited. The ENplus Fraud Management programme has recorded more than 1,500 cases of misuse since 2014. Half involved unauthorised use of the mark in marketing, 20% fake ENplus seals on bags, 14% forged certificates and 16% other infringements. Around 70% of cases are settled amicably; the remaining cases are placed on a public blacklist, and legal action is also possible^[6]. The authors of the study of the Polish market point to a marked rise in the number of forged certificates in the two years before its publication^[47].

The ENplus blacklist covers the following categories: marketing misuse, improper use of the mark on the product (bag) and certificate forgery. It also includes companies from Poland. We do not name names — you can find the current list directly on the ENplus website^[7].

Nor does a certificate remove the need to assess the product itself. Even with a valid number, pellets can be damaged in transport or absorb moisture in a warehouse, and an A1 result can sit close to the limit or well within it. We explain how we assess these differences in our methodology.