Pellets or logs: how to choose

The real debate isn't about the fuel

When a customer asks us "pellets or logs?", the real question behind it is almost always the same: how much time will I have to spend looking after my heating? The fuel is just one variable among five that matter: autonomy, seasonal efficiency, running cost, storage space and compatibility with my existing setup (buffer tank, solar, underfloor).

In Luxembourg as in Belgium, both technologies coexist perfectly well, and the choice depends as much on the home as on the lifestyle of its occupants. Here are the elements that tip the decision one way or the other.

Seasonal efficiency and emissions

Modern pellet boilers (for example Kalorina Série 22 CL5 Pellet or Mini K Low Emission) reach a seasonal efficiency of 92 to 95 % with CO emissions below 15 mg/Nm³ — they easily meet EN 303-5 Class 5 and the A++ energy class.

Log gasification boilers (the Kalorina Série 21 or LE-PA range) approach the same figures under stable operation, but their actual efficiency depends heavily on the moisture content of the wood (ideally <20 %) and on how the loading is managed manually. In real-world conditions, expect 85–90 %.

Autonomy and ease of use

This is the criterion that most often settles the question. A pellet boiler fed from a 4 to 6 tonne silo can run an entire season without any manual intervention — fill it in autumn, then forget about it. Time scheduling, automatic ignition, continuous modulation: the experience comes close to that of a gas boiler.

A log boiler typically needs 1 to 3 loadings per day in the depths of winter. For many owners it's a cherished ritual; for others it's a deal-breaker. Wood remains, however, the cheapest fuel per kWh when you have your own cut or a reliable local supplier.

Fuel cost: an honest calculation

In Luxembourg in 2026, expect around €350/tonne for ENplus A1 pellets delivered in bulk (with strong seasonal swings of +/-15 %). With an average PCI of 4.8 kWh/kg, the cost works out at roughly 7.7 cents/kWh of useful heat (95 % efficiency).

For seasoned, stored logs, the price runs around €75–90 per stere depending on species and region. The useful cost comes out at 5–6 cents/kWh, i.e. 20 to 30 % cheaper than pellets — but that calculation ignores the time spent handling the wood.

For comparison, heating oil in 2026 sits around 9–11 cents/kWh useful, and natural gas (Creos LU network) between 8 and 10 cents/kWh useful depending on the tariff. Both biomass options remain more economical over the long term.

Buffer tank, solar and underfloor heating compatibility

Any modern biomass boiler can be integrated with a buffer tank (recommended), solar thermal panels (Tatano forced or natural circulation solar systems) and a low-temperature underfloor heating circuit. Bi-fuel models such as the Kalorina LE-PA Cippato or Série 22 also accept cippato (chips), wood AND pellets on the same combustion chamber.

For a heavy renovation project in Luxembourg with a heat pump providing winter backup or a hybrid setup, we steer customers toward a modulating 4-30 kW pellet boiler (Mini K Low Emission or Kalorino KS Pellet/Bois) which talks to the heat pump via a smart thermostat.

Our recommendation by profile

New build or BENs renovation (≤30 kW), busy occupants with little time to spare: modulating pellets such as Mini K Low Emission or Kalorina Série 22 CL5 Pellet.

Older stone house or renovated farmhouse, owner with access to local wood: Kalorina Série 21 (logs) or Kalorino KS Pellet/Bois for flexibility.

Commercial building or community facility ≥50 kW: Kalorina LE-PA Class 5 (pellets/logs) or Série 22 CL5 Cippato (chips) depending on the local fuel supply.