New build in Luxembourg: carbon footprint, permits and pellets — what architects lock in at sketch stage

How much CO₂ does a new build save with pellets?

On a ~150 m² new build (15–20 kW, ~9,000 kWh/yr), the numbers speak clearly. ADEME and IEA Bioenergy put wood energy at ~30–40 g CO₂/kWh, gas at ~220 g and heating oil at ~320 g — per useful kWh.

In practice: ~1.6 t CO₂/yr less than gas, ~2.5 t less than oil. That gap shows up on the energy certificate and affects resale value.

Leaving fossil fuels: regulatory timeline and property value

Since 2022, new oil boiler installations are banned in Luxembourg. Gas remains possible on new builds, but regulation is shifting toward low-carbon heat — pellets de-risk both permitting and resale.

An energy certificate tied to fossil heating drags on price. A project with a pellet boiler, buffer tank and local fuel (ENplus pellets) outperforms a system likely due for replacement within 10–15 years.

• Oil on new builds: banned in Luxembourg since 2022
• Gas: still allowed, but no Klimabonus equivalent to biomass
• Pellets: low carbon footprint + local supply from managed European forests

EcoDesign and EN 303-5: what goes in the permit file?

Architects should embed the heating choice at sketch stage in the permit package. EcoDesign Regulation 2015/1189 sets minimum thresholds; EN 303-5 Class 5 defines the performance benchmark.

For permitting and later Klimabonus: product sheet, manufacturer conformity declaration, energy label ≥ A+, plant room and silo layout, ENplus A1 pellet specification.

• EcoDesign 2015/1189: mandatory minimum efficiency and emissions
• EN 303-5 Class 5: efficiency ≥ 87%, CO ≤ 500 mg/m³, particles ≤ 40 mg/m³
• ENplus A1: moisture ≤ 10%, ash ≤ 0.7% — lock into the spec early

Klimabonus 2026: what to fix at design stage?

Grants follow design decisions. Klimabonus 2026: up to €8,000 for a single-family home with replacement, €4,000 without; €6,000/dwelling in multi-unit (€40,000 cap); €6,000 on district heat (€24,000 cap).

Bonuses: +15% with buffer tank, €1,000 flat with solar thermal. Communal grants vary by municipality and stack with state aid — check aides.klima-agence.lu.

• Plant room: 8–12 m² + 3–6 t silo (one-season autonomy)
• Delivery access: width ≥ 2.5 m, turning radius ≥ 6 m for blower trucks
• Buffer tank: +15% Klimabonus — draw into hydraulic plans
• Solar thermal: +1,000 — reserve roof area and pipe runs at sketch stage
• Only pellet boilers qualify — never log or chip boilers