Bio-sourced (wood fibre)
STEICO Protect, Gutex Ultratherm, hemp-lime. 14-18h thermal lag. Negative CO₂ footprint. Exceptional summer comfort. Price: €25-45/m² insulation.
Guide comparatif
Bio-sourced (wood fibre)
Mineral (rockwool/EPS)
STEICO wood fibre vs Rockwool rock wool — thermal lag, carbon footprint and summer comfort: the real differences.
- Wood fibre thermal lag: 14-18h vs 3-4h for rockwool
- Bio-sourced carbon footprint is negative — it stores CO₂
- +15-40% extra cost potentially offset by Klimabonus grants (see myenergy.lu)
Analyse QUASART
Thermal lag changes the equation
Rockwool is the historical insulator of EWI — high-performing, economical, non-combustible (A1). Wood fibre is the bio-sourced alternative — superior thermal lag (14-18h vs 3-4h), negative carbon footprint, exceptional summer comfort.
The premium on wood fibre (15-40%) is partially offset by the enhanced grants available in Luxembourg. A complete analysis must factor in summer comfort and the impact on air-conditioning bills — a criterion that is often overlooked.
Comparatif point par pointOption A Option B
Bio-sourced (wood fibre) Mineral (rockwool/EPS)
Criteria
Bio-sourced (wood fibre)
Mineral (rockwool/EPS)
Lambda
0.038-0.042
0.031-0.036✓ Advantage
Thermal lag (200mm)
14-18h✓ Advantage
3-4h
Fire classification
E (wood fibre) / B (hemp)
A1 (rockwool) / E (EPS)✓ Advantage
Carbon footprint
Negative (CO₂ storage)✓ Advantage
Positive (high embodied energy)
Insulation price
€25-45/m²
€12-25/m²✓ Advantage
Summer comfort
Excellent✓ Advantage
Moderate
Luxembourg grants
Potentially enhanced subsidies✓ Advantage
Standard
Service life
50+ years✓ Advantage
50+ years✓ Advantage
Moisture resistance
Hygroscopic (regulator)
Impermeable
Mineral (rockwool/EPS)
Rockwool, Knauf, grey EPS. Lambda 0.031-0.036. A1 non-combustible classification. Economical, proven. Price: €12-25/m² insulation.
Notre recommandation
Bio-sourced for comfort, mineral for budget
For single-family homes and low-energy/passive projects: wood fibre is superior thanks to thermal lag and summer comfort. The extra cost is repaid in 10-15 years through the absence of air conditioning.
For collective developments on a tight budget: rockwool or grey EPS remain the most economical choices with excellent thermal performance.
A frequent hybrid solution at QUASART: 80mm grey EPS + 80mm wood fibre — optimises cost while maintaining a 10-12h thermal lag. The best of both worlds.
Questions fréquentes
Tout ce que vous devez savoir
Réponses directes aux questions que nos clients nous posent le plus souvent sur ce sujet.
Are Klimabonus grants really higher for bio-sourced materials?
The Klimabonus programme in Luxembourg offers enhanced grants for bio-sourced materials under current criteria. The exact amount depends on the latest scales — consult myenergy.lu. QUASART provides the technical data sheets required for the application (R calculations, ACERMI certificates).
Does wood fibre struggle with moisture in EWI applications?
No. Wood fibre boards for EWI (STEICO Protect, Gutex Ultratherm) are hydrophobic and vapour-open. They temporarily absorb moisture and release it without damage. In ventilated cladding, the air gap ensures permanent evacuation.
Is wood fibre compatible with all render systems?
Yes, subject to conditions. Wood fibre requires a specific base coat (reinforced undercoat with 300g/m² mesh to absorb substrate movement). Weber, Sto and Baumit offer ETICS systems certified for wood fibre. QUASART uses exclusively manufacturer-certified systems.