RegulationFor architects
EcoDesign and EN 303-5 Class 5: the compliance that unlocks your Luxembourg building permit
Architects and project owners: what EcoDesign and EN 303-5 Class 5 require for a biomass project in Luxembourg, and how to turn compliance into higher grants.
Updated 20 July 2026·5 min read
What do EcoDesign and EN 303-5 Class 5 actually cover?
EU Regulation 2015/1189 sets ecodesign requirements for biomass boilers under 500 kW. EN 303-5 Class 5 layers on tight efficiency and emission thresholds.
- Seasonal space-heating efficiency ≥ 90 %.
- CO ≤ 500 mg/Nm³, NOx ≤ 200 mg/Nm³, particles ≤ 40 mg/Nm³.
- Applies to every new unit placed on the EU market.
What must the permit file include?
Luxembourg doesn't ask for compliance directly, but without the right paperwork the file stalls and the Klimabonus is lost.
- Manufacturer data sheet citing EcoDesign 2015/1189 and EN 303-5 Class 5.
- ENplus A1 certificate for the wood pellets.
- Boiler-room plan: safety distances, ventilation, silo access.
- Sizing note with a buffer tank ≥ 20 l/kW.
Does compliance unlock the grants?
Yes. The 2026 Klimabonus for pellets requires EcoDesign compliance and EN 303-5 Class 5 certification. A non-compliant boiler is not eligible.
- Up to €8,000 for a single-family home when replacing an old system (€4,000 without replacement).
- €6,000 per dwelling in multi-family housing, capped at €40,000.
- +15 % bonus with a buffer tank, €1,000 flat bonus with solar thermal.
- Communal top-ups are variable and stackable (simulator at aides.klima-agence.lu).
What should you do at the sketch stage?
Lock compliance into the brief and the design stage won't drift. Three moves are enough.
- Ask the manufacturer for the EcoDesign + EN 303-5 Class 5 datasheet before signing.
- Plan the boiler room to supplier dimensions + truck-silo access.
- Run a grant simulation on the official tool before the design development stage.
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