You need about 4.6 t of wood pellets a year (≈7.1 m³ bulk), costing 1,527 €. That is 7.6 cents per kWh of heat versus 10.9 with gas. It saves 517 €/yr compared with a gas boiler and recovers the extra investment in ≈17.9 years.
Fuel needed per year
4.63t
7.1 m³ bulk
Net calorific value
4.75kWh/kg
17.1 MJ/kg at 8% moisture
Annual fuel cost
€1,527
7.6 c/kWh of heat · 215 € per m³ bulk
Boiler size
13kW
11.1 kW average at 1,800 full-load h
Buffer tank (recommended)
350L
optional for modulating boilers
Fuel store volume
10.6m³
12 coldest month(s), 67% usable
Bulk density
652kg/m³
m³ bulk
Saving vs gas boiler
€517
incl. maintenance difference
Payback of extra cost vs gas
17 yr 10 mo
CO₂ saved vs gas
3.7t/yr
supply-chain emissions of wood ≈ 0.7 t counted
Wood fuel comparison for your heat demand
| Fuel | Moisture | NCV (kWh/kg) | Tonnes/yr | Volume/yr | Cost/yr |
|---|---|---|---|---|---|
| Split logs (stacked) | 20% | 4.04 | 6.18 | 19 stacked m³ | €1,237 |
| Wood chips (loose) | 30% | 3.45 | 6.82 | 31.8 loose m³ | €750 |
| Wood pellets (ENplus A1) | 8% | 4.75 | 4.63 | 7.1 m³ bulk | €1,527 |
| Wood briquettes | 9% | 4.69 | 5.2 | 7.4 m³ stacked | €1,560 |
- Net calorific value from ISO 17225 relation NCV = 18.8 MJ/kg × (1 − w) − 2.443 × w (evaporating the water costs energy). Bulk densities are typical; chip size and log length change them by ±20%.
- Comparison assumes gas boiler 92%, oil 88% at 10 kWh/L, heat pump at your SCOP. Wood combustion CO₂ is treated as biogenic (re-absorbed by regrowth); only processing and transport emissions are counted.
- Local air-quality rules may require low-emission (e.g. EN 303-5 class 5 / Ecodesign) appliances and regular particulate testing.