Wood logs + pellets: the bivalence that secures a rural project

Wood logs + pellets: why does this bivalence secure a rural project?

In Luxembourg's rural areas, wood logs remain abundant and affordable, but supply depends on weather, manual labor, and local stère pricing.

A bivalent boiler accepts both fuels: logs in mid-season or as manual backup, ENplus pellets in deep winter on automatic mode. This redundancy shields the project owner from price volatility and logistics risks.

How to integrate bivalence from the design phase?

From APS onward, plan two separate spaces: a ventilated log room (dry, accessible via wide door) and a sealed pellet silo of 15-20 m², i.e. 1 to 3 tonnes of storage for a single-family home.

The single heat body requires a buffer tank of at least 500 L to absorb load variations. This tank, essential for bivalence, unlocks the +15% Klimabonus 2026 bonus.

• 1 stère of beech logs ≈ 1,500 kWh useful (75% efficiency).
• Silo volume = annual consumption (kWh) ÷ (4.9 kWh/kg × 0.65 t/m³).
• Silo-to-boiler distance: 6 m suction, 20 m auger.
• Log room access diameter: 90 cm for bulk delivery.

What Klimabonus 2026 aid applies to a bivalent installation?

The Klimabonus 2026 targets pellet boilers. For a bivalent installation, only the pellet function qualifies: up to €8,000 in a single-family home (€4,000 without replacement of an old system), €6,000/dwelling in collective housing (cap €40,000).

Adding a buffer tank unlocks a +15% bonus on the main aid. Adding thermal solar on the same tank triggers an additional €1,000 flat bonus. Municipal aid: variable by commune, check the official simulator.

• Klimabonus pellet boiler: up to €8,000 (single-family) / €6,000 (collective, cap €40,000).
• Buffer tank bonus: +15% on main aid.
• Thermal solar bonus: €1,000 flat.
• Municipal aid: variable and stackable, simulate on aides.klima-agence.lu.

What EcoDesign and regulatory checks before signing?

Any new biomass boiler sold in the EU must comply with EcoDesign Regulation 2015/1189 (seasonal efficiency ≥ 75%, PM ≤ 40 mg/Nm³, CO ≤ 500 mg/Nm³ at 10% O2). The EN 303-5 standard (CEN) classifies boilers from 1 to 5 and specifies test methods.

Requiring ENplus A1 certified pellets (LHV ≥ 4.6 kWh/kg, moisture ≤ 10%) ensures stable combustion, limits heat exchanger fouling, and preserves Klimabonus 2026 eligibility.

• EcoDesign 2015/1189: seasonal efficiency ≥ 75%, PM ≤ 40 mg/Nm³.
• EN 303-5 (CEN): classification 1 to 5 for solid fuel boilers.
• ENplus A1: LHV ≥ 4.6 kWh/kg, moisture ≤ 10%.
• Pick a manufacturer that documents bivalence compatibility (e.g. Tatano, Italy).