ENplus A1 explained
ENplus is a certification scheme for wood pellets with three quality classes, A1 being the highest. It is based on the standard ISO 17225-2 but is stricter: demolition wood and chemically treated wood are not permitted in any ENplus class.
The calorific value is the same in all three classes, at least 4.6 kWh per kilogram. What defines A1 is the rest: no more than 0.7 % ash, the highest ash melting point and, as raw material, only stemwood or untreated residues from wood processing.
The limits
Under ENplus ST 1001, valid since 1 January 2026. Percentages refer to weight.
| Property | A1 | A2 | B | Unit |
|---|---|---|---|---|
| Diameter | 6 ± 1 / 8 ± 1 | 6 ± 1 / 8 ± 1 | 6 ± 1 / 8 ± 1 | mm |
| Length | 3.15–40 | 3.15–40 | 3.15–40 | mm |
| Water content | ≤ 10 | ≤ 10 | ≤ 10 | % |
| Ash content, dry basis | ≤ 0.7 | ≤ 1.2 | ≤ 2.0 | % |
| Mechanical durability | ≥ 98.0 | ≥ 97.5 | ≥ 97.5 | % |
| Fines below 3.15 mm, loose goods | ≤ 1.0 | ≤ 1.0 | ≤ 1.0 | % |
| Calorific value | ≥ 4.6 | ≥ 4.6 | ≥ 4.6 | kWh/kg |
| Bulk density | 600–750 | 600–750 | 600–750 | kg/m³ |
| Nitrogen, dry basis | ≤ 0.3 | ≤ 0.5 | ≤ 1.0 | % |
| Ash deformation temperature | ≥ 1200 | ≥ 1100 | ≥ 1100 | °C |
No more than 1 % of the pellets may be longer than 40 mm, none longer than 45 mm. Durability is measured at loading in the plant, fines ex works or when loading the delivery lorry. For bagged goods, fines may be no more than 0.5 % (A1 and A2).
What may go in
A1: stemwood and chemically untreated residues from wood processing. A2 additionally allows whole trees without roots and logging residues, B also chemically untreated used wood. Demolition wood is excluded in all classes, as is rotten wood and raw material with a lot of bark.
Recognising genuine ENplus pellets
Certified goods carry the ENplus seal: the ENplus logo, the quality class and an ENplus ID. The ID begins with the country code; producers have the numbers 001 to 299, traders 301 to 899. Exception: non-certified traders of bagged goods may use the seal without an ID.
Whether a certificate is valid is shown by a search on enplus-pellets.eu by company name or ID. Only the status active permits sale under the mark; suspended and terminated do not.
On delivery to the store
Loose pellets are screened before loading so that fines are below 1 %, and blown in with low-abrasion vehicles. If there is more than 4 % fines in the store after a silo delivery, the supplier must accept a complaint. Conditions: the store complies with the ENplus storage guidelines and is regularly emptied and cleaned, was less than 10 % full before the delivery, less than a fifth of the delivery has been used, and the blowing hose was no more than 30 m long.
Sources
ENplus® ST 1001:2022, ENplus® wood pellets – Requirements for companies, Anhang A, 2. Ausgabe, in Kraft seit 01.01.2026
ENplus®, Suche nach zertifizierten Unternehmen, abgerufen 07.10.2026
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