External wall insulation is the most cost-effective renovation measure for a Luxembourg home: it eliminates thermal bridges, protects the façade and qualifies for one of the most generous Klimabonus grants. In 2026, the grant can exceed €100 per m² insulated, with a bonus for bio-based materials and a top-up for low-income households. Here is the complete guide.
New: estimate your grants in 30 seconds. Our renovation aid calculator works out your Klimabonus, the bio-based bonus and the VAT saving based on the 2026 rates.
What is external wall insulation (ETICS)?
External wall insulation (ETICS) involves wrapping your home’s external walls in a layer of insulation, covered with render or cladding. Unlike internal wall insulation (IWI), it offers decisive advantages:
- Elimination of thermal bridges: the continuity of the insulation removes the areas of heat loss at junctions (floors, corners, lintels).
- No loss of living space: the thickness is added on the outside.
- Integrated façade refurbishment: you renovate the exterior appearance at the same time.
- Summer comfort: the thermal mass of the walls is preserved, which limits summer overheating.
It is also the measure that generates the most savings: walls account for 20 to 25% of heat loss in a poorly insulated home.
How much does external insulation cost in Luxembourg?
The price of ETICS is calculated per m² of façade treated and depends on the system (render or cladding) and the insulation chosen.
| System | Indicative installed price (per m²) |
|---|---|
| ETICS with render (polystyrene / mineral wool) | €150 – €220/m² |
| ETICS with render (bio-based insulation) | €180 – €260/m² |
| ETICS with ventilated cladding | €200 – €300/m² |
For a detached house with 150 to 200 m² of façade, the total budget generally lies between €25,000 and €50,000 before grants — an investment largely recouped through grants and heating savings.
The 2026 Klimabonus grant for ETICS
Insulating walls from the outside is one of the best-subsidised measures under the 2026 Klimabonus:
- Base amount: in the region of €80 to €115/m² depending on the material and the performance achieved.
- Bio-based materials bonus: eco-friendly insulation (wood fibre, cork, cellulose wadding, sheep’s wool) qualifies for a significant top-up.
- Required performance: for the maximum amount, the thermal transmittance coefficient must reach U ≤ 0.2 W/m²K.
- Low-income top-up: low-income households qualify for a 25% top-up on all insulation amounts.
On top of this comes the reduced-rate housing VAT (3%) on renovation work, a further significant saving.
Important: the exact amounts depend on the material, the performance and your income. Use our aid calculator to find out your precise grant, or check guichet.public.lu.
Worked example: a 180 m² façade
Take a house in Diekirch where 180 m² of façade is insulated with bio-based insulation, for a cost of €42,000:
- Cost of the work: €42,000
- Klimabonus grant (bio-based insulation, high performance): in the region of €18,000 to €20,000
- VAT saving (3% instead of 17%): several thousand euros
- Net cost to you: significantly reduced, for a heating saving of 20 to 30% per year
Indicative figures. The actual amount depends on the rate applied to your material and your performance — check it with our aid calculator.
Procedure: the order to follow
The golden rule of the Klimabonus: never start work before you have approval.
- Energy advice: basic advice is often required to validate the project.
- Approval in principle: obtain prior approval before the work begins.
- Carrying out the work by an approved company.
- Payment request via MyGuichet.lu, on presentation of the paid invoices. Payment usually comes 4 to 10 weeks after the complete file is submitted.
Choosing the right insulation company
ETICS is a technical project where the quality of the installation determines the performance and durability:
- Compare several quotes detailing the insulation, its thickness, the target U-value and the finishing system.
- Check the references and legal registration of the company — on tack.lu, every professional is a verified company in Luxembourg.
- Insist on quantified performance (U-value) to guarantee access to the maximum Klimabonus amount.
- Coordinate with other work: it’s the right time to replace the windows or install a heat pump.
To receive up to 6 quotes from verified insulation companies, request your free quotes — no obligation.
FAQ
What is the Klimabonus grant for external insulation in 2026?
The 2026 Klimabonus covers external wall insulation at around €80 to €115/m² depending on the material and performance, with a bonus for bio-based insulation and a 25% top-up for low-income households.
ETICS or internal insulation: which to choose?
External wall insulation (ETICS) is generally preferable: it eliminates thermal bridges, does not reduce living space and renovates the façade. Internal wall insulation (IWI) remains an option when the exterior appearance must be preserved or for a more limited budget.
How much does it cost to insulate a façade in Luxembourg?
Budget €150 to €300/m² installed depending on the system (render or cladding) and the insulation. For a house with 150 to 200 m² of façade, the budget lies between €25,000 and €50,000 before Klimabonus grants.
Do I need approval before starting work?
Yes, without exception. You must obtain the Klimabonus approval in principle before the work begins. Starting work without prior approval forfeits your entitlement to the grant.
Are bio-based insulation materials really more advantageous?
Yes. Bio-based insulation (wood fibre, cork, cellulose wadding, sheep’s wool) qualifies for a significant Klimabonus bonus, offers excellent summer performance and a better environmental footprint.
