Facade insulation and cladding in Luxembourg: EWI, techniques, prices and Klimabonus 2026
External walls account for 20 to 25% of heat loss in a Luxembourg home — the second largest source of heat loss after the roof. External wall insulation (EWI), whether installed under cladding or render, is the most effective technique to address this weakness: it eliminates thermal bridges, preserves all interior living space, and transforms the exterior appearance of your home while insulating it. In 2026, the Luxembourg Klimabonus reaches up to €115/m² for EWI with ecological insulation and non-fossil cladding — a subsidy that can cover a significant share of the works cost, especially when combined with Enoprimes and 3% VAT. This guide details each technique, each material, prices in Luxembourg, and the exact breakdown of available subsidies.
Estimate your Klimabonus subsidies for your facade insulation
Our simulator calculates in a few minutes the exact amount of your Klimabonus and Enoprimes based on your facade area and insulation choice.
Why insulate facades from the outside in Luxembourg?
In the Luxembourg housing stock, the vast majority of homes built between 1950 and 2000 have uninsulated or under-insulated external walls. These brick, block or concrete walls directly transmit heat to the outside and create thermal bridges at floor-wall junctions, facade corners, and around glazed openings. Our dedicated page on external wall insulation complements this guide with a broader approach. External wall insulation (EWI) is the most effective technical response to this problem.
EWI wraps the entire building in a continuous insulating layer applied directly to the existing facade. Unlike internal wall insulation, it does not reduce living space, it protects the building structure from temperature fluctuations, and it addresses thermal bridges at their source — by eliminating rather than working around them.
| EWI benefit | Quantified detail |
|---|---|
| Reduction of wall heat loss | 20 to 25% of total losses eliminated or greatly reduced |
| Heating bill savings | Up to 25–30% annual reduction depending on insulation level achieved |
| Elimination of thermal bridges | Cold spots, condensation and mould risks removed |
| Summer thermal comfort | Thermal inertia preserved, heat peaks dampened (especially with bio-based insulation) |
| Acoustic insulation | Significant reduction of external noise (road, neighbours) |
| Wall protection from weather | Structural lifespan extended by 20 to 30 years |
| Property value increase | +5 to +15% depending on energy class improvement — see the impact of the EPC on property prices |
✓ Ideal time for EWI in Luxembourg
EWI is particularly cost-effective when combined with a necessary facade refurbishment or window replacement. By combining these works, you spread fixed site costs (scaffolding, removal of shutters and gutters) across several interventions — which significantly reduces the total cost per m². It is also the opportunity to maximise Klimabonus subsidies by presenting a multi-element application. Consult our page on where to start your energy renovation to sequence your works correctly.
EWI or IWI: which technique to choose for your facade in Luxembourg?
Before choosing a cladding or render system, the first question is whether to insulate from the outside (EWI) or from the inside (IWI). This choice determines final performance, cost, Klimabonus subsidies and site constraints.
External wall insulation (EWI) — cladding or render
- Performance: maximum — no residual thermal bridges
- Living space: fully preserved
- Occupant disruption: none — works entirely external
- Thermal inertia: optimised — the wall stores heat on the interior side
- Cost: €180 to €280/m² (cladding) — €140 to €220/m² (render)
- Klimabonus: full amounts (€60 to €115/m²)
- Constraints: municipal permit often required, facade alignment changed
Internal wall insulation (IWI) — internal lining
- Performance: good but persistent thermal bridges at slabs and internal walls
- Living space: loss of 6 to 12 cm per insulated wall
- Occupant disruption: significant — partial relocation, interior refurbishment
- Thermal inertia: reduced — the wall is cut off from the heating
- Cost: €60 to €130/m² (cheaper, but reduced living space)
- Klimabonus: amounts reduced by 25% compared to EWI
- Constraints: no municipal permit, but heavy interior logistics
📋 When IWI is preferable to EWI
Certain situations impose or recommend internal wall insulation (IWI): visible stone facades to be preserved (old houses, listed Luxembourg villages), semi-detached houses where only one gable is accessible, constraints of the Municipal Particular Development Plan (PAP) prohibiting modification of the exterior appearance, or apartments in co-ownership where a collective decision is required. In these cases, IWI remains a valid solution — with a 25% reduction in Klimabonus amounts compared to EWI.
Unsure between EWI and IWI for your facade? Ask certified tradespeople for advice. Free quotes, no commitment.
Request quotes →EWI under cladding — the dry method
External wall insulation under cladding — also called the dry method or ventilated facade — is the technique that combines insulation fixed to the facade with a cladding creating a ventilated air gap between the insulation and the external facing. It is the flagship solution for Luxembourg homes seeking to combine maximum energy performance with aesthetic facade renewal.
Principle and advantages of the ventilated air gap
The 2 to 4 cm air gap between the insulation and the cladding is a decisive technical asset. It allows water vapour to evacuate naturally by convection, preventing any moisture accumulation in the insulation or the wall. This is why the ventilated facade is particularly suited to old brick or masonry walls that are hygroscopic — they can continue to breathe naturally behind the cladding.
Installation steps for EWI under cladding
Diagnostic and substrate preparation
The existing wall must be sound, flat and structurally solid. The tradesperson checks for the absence of active cracks, detached render or moisture problems. Crack treatment and high-pressure cleaning are carried out if necessary. Shutters, gutters, rainwater downpipes and exterior lights are removed before starting.
Installation of the starter rail and framework
A starter profile is fixed at the base of the wall to receive and support the insulation. A timber (vertical or horizontal battens) or metal (aluminium or galvanised steel) framework is then plugged to the wall with brackets. The spacing between uprights is calculated according to the width of the insulation panels and the type of cladding selected.
Installation of insulation between framework uprights
Insulation panels or rolls (rock wool, wood fibre, semi-rigid glass wool) are inserted between the framework uprights. For ecological insulations (wood fibre, hemp) that benefit from maximum Klimabonus subsidies, mechanical fixing has been mandatory since 2026 — bonding alone is no longer accepted for access to the « non-fossil cladding » premium. A breathable breather membrane (HPV membrane) is then stapled to the framework to protect the insulation from water infiltration while allowing vapour to pass through.
Counter-battens and ventilated air gap
Counter-battens 27 to 40 mm thick are fixed to the framework over the breather membrane. They create the essential ventilated air gap. The ventilation openings at the bottom (air inlet) and top (air outlet) are protected by insect mesh to prevent wasps or rodents nesting in the ventilated space.
Cladding installation and detail finishing
Cladding boards, panels or cassettes are fixed to the counter-battens. Corners, window surrounds, plinth and wall base junctions are carefully treated with finishing profiles. This is the stage where joinery may be repositioned and window sills extended to account for the thickness added to the facade (generally 14 to 22 cm depending on the system).
✓ Klimabonus 2026 specificity — non-fossil mechanically fixed cladding
Since 1 January 2026, the Klimabonus has introduced a specific premium for EWI with ecological thermal insulation and non-fossil cladding fixed exclusively by mechanical means. In practice: if you choose a bio-based insulation (wood fibre, hemp, certified cellulose) and a wood, fibre-cement or metal cladding (without fossil materials), and everything is mechanically fixed (not bonded), you access the maximum Klimabonus premium of €115/m². Cladding containing fossil materials (certain PVC composites) is not eligible for this enhanced premium.
EWI under render — the wet method (ETICS)
External wall insulation under render, also known by its European acronym ETICS (External Thermal Insulation Composite System), is the most widespread EWI technique in Europe and Luxembourg for individual homes. It consists of bonding and plugging insulation panels directly to the existing facade, then covering them with a reinforced finishing render.
Installation of EWI under render
Insulation panels are bonded with adhesive mortar to the existing wall, then mechanically plugged with fixing anchors (the « bonded and plugged » technique, mandatory for mineral insulations under Klimabonus since 2026). A first basecoat render is applied to the insulation, reinforced with a fibreglass mesh. After drying, the finishing render (mineral, organic or silicone depending on the desired finish) is applied. The result is a facade with a smooth or textured appearance, similar to traditional render, without an air gap.
| Criterion | EWI under render (ETICS) | EWI under ventilated cladding |
|---|---|---|
| Final appearance | Render, smooth or textured — traditional look | Wood, metal, fibre-cement boards — contemporary look |
| Ventilated air gap | No — no natural ventilation | Yes — vapour evacuation by convection |
| Suitability for damp walls | Limited — risk if wall not perfectly dry | Excellent — air gap protects insulation |
| Price per m² Luxembourg 2026 | €140 to €220/m² | €180 to €280/m² |
| Max Klimabonus (eco insulation) | €93/m² (certified eco insulation without cladding) | €115/m² (eco insulation + non-fossil mechanical cladding) |
| Lifespan | 30–40 years (render requires maintenance) | 30–50 years depending on cladding |
| Works duration | 3 to 5 weeks (including drying time) | 3 to 6 weeks |
| Permits | Often required (change of appearance) | Often required (change of appearance and alignment) |
⚠️ EPS insulation (expanded polystyrene) and Klimabonus
Expanded polystyrene (EPS), the cheapest insulation and widely used in ETICS in France and Belgium, is not subsidised by the Luxembourg Klimabonus, as it is a fossil material. Only EPS containing more than 50% recycled materials can benefit from an additional €15/m² on the base subsidy. To maximise your subsidies, opt for rock wool (mineral insulation, €60/m²) or wood fibre (ecological insulation, €93 to €115/m² depending on the system). See our complete insulation materials comparison.
EWI under overcladding — the intermediate solution
Overcladding is a hybrid solution between render and cladding: prefabricated panels integrating both the insulation layer and the finishing facing are fixed directly to the existing wall, without a secondary framework. This technique is faster to install than conventional cladding and offers a varied aesthetic finish (reconstituted stone, polished concrete, textured wood).
Its advantages are fast installation (no drying time as with render), aesthetic diversity of available panels, and the absence of a complex framework. Its limitations: the insulation thickness is less than with a full framework, performance is slightly lower than ventilated cladding on facades very exposed to rain, and the cost per m² is close to that of render (approximately €140 to €200/m²). Overcladding is eligible for the Klimabonus under the same conditions as other EWI systems.
Insulation materials for facades — complete comparison 2026
The choice of insulation is strategic: it determines thermal performance, the hygrothermal behaviour of the facade, eligibility for maximum Klimabonus subsidies, and the system’s lifespan. Here is the comparison of materials suitable for EWI in Luxembourg. Our insulation comparison page develops these criteria for all work items.
| Material | λ (W/m·K) | Typical EWI thickness | Klimabonus 2026 | Cladding compatible | Key points |
|---|---|---|---|---|---|
| Wood fibre (rigid board) | 0.038–0.045 | 16–22 cm | Max — €115/m² with non-fossil cladding | Yes — ideal for ventilated cladding and ETICS | Bio-based, moisture regulation, exceptional thermal lag (~12h), eligible for non-fossil cladding premium 2026 |
| Hemp wool (semi-rigid board) | 0.038–0.046 | 16–22 cm | High — €93–€115/m² depending on system | Yes — ventilated cladding recommended | 100% natural, good thermal lag (~8h), less common in Luxembourg, higher price |
| Rock wool (rigid or semi-rigid board) | 0.033–0.042 | 14–20 cm | Standard — €60/m² | Yes — suitable for ETICS and cladding | Excellent A1 fire rating, good acoustic performance, moisture resistance, accessible price |
| Glass wool (rigid board) | 0.030–0.040 | 14–18 cm | Standard — €60/m² | Yes — ETICS mainly | Cheapest mineral insulation, lightweight, but moisture-sensitive if poorly protected |
| Recycled EPS (>50% recycled) | 0.030–0.036 | 12–18 cm | +€15/m² on base (recycled fossil insulation) | ETICS mainly | Lightweight, easy to install, good price/performance ratio, but fossil even when recycled |
| Standard EPS (expanded polystyrene) | 0.031–0.038 | 12–18 cm | Not subsidised (fossil) | ETICS mainly | Very common in France and Belgium, but excluded from Luxembourg Klimabonus unless >50% recycled |
| PIR / Polyisocyanurate | 0.022–0.028 | 10–14 cm (thin) | Not subsidised (fossil) | Specific cases (thickness constraints) | Best performance per cm, useful if architectural constraint, but non-recycled fossil |
Sources: Klima-Agence Luxembourg — Klimabonus Wunnen regime 2026; Guichet.lu — technical conditions external wall insulation; λ values according to CE ACERMI certifications and manufacturer markings.
✓ 2026 recommendation — wood fibre + wood or fibre-cement cladding
To simultaneously maximise performance, summer comfort and Klimabonus subsidies, the combination of wood fibre boards + natural wood or mechanically fixed fibre-cement cladding is the reference solution in 2026. It accesses the maximum subsidy (€115/m²), offers a thermal lag of 10 to 12 hours (protection against summer overheating), naturally regulates moisture and has the best carbon footprint of all EWI solutions. For facades that must retain a traditional render appearance (PAP constraints), rock wool in ETICS at €60/m² Klimabonus remains the most accessible solution.
Types of cladding — wood, metal, composite, fibre-cement
Cladding fulfils two roles: protecting the insulation from weather and defining the home’s exterior aesthetics. The choice of cladding material directly influences the price, lifespan, maintenance and eligibility for the Klimabonus 2026 « non-fossil cladding » premium. See also our page on facade refurbishment prices in Luxembourg to compare with a refurbishment without insulation.
| Cladding type | Materials | Average LU price 2026 (facing only) | Lifespan | Maintenance | Klimabonus « non-fossil » |
|---|---|---|---|---|---|
| Natural wood cladding | Douglas fir, larch, spruce, red cedar | €35 to €90/m² | 30–50 years depending on species | Oiling or staining every 5–10 years | Yes — non-fossil ✓ |
| Fibre-cement cladding | Cement + cellulose (e.g. Eternit, Cedral) | €40 to €80/m² | 40–60 years | Periodic cleaning, very low | Yes — non-fossil ✓ |
| Aluminium or zinc cladding | Metal boards or cassettes | €60 to €120/m² | 50–80 years | Almost none | Yes — non-fossil ✓ |
| Lacquered steel cladding | Lacquered galvanised steel boards | €50 to €100/m² | 30–50 years | Coating check every 10–15 years | Yes — non-fossil ✓ |
| Wood-plastic composite cladding (WPC) | Wood and polymer mixture | €45 to €85/m² | 20–30 years | Very low | To verify — fossil content depends on product |
| PVC cladding | Polyvinyl chloride boards | €25 to €55/m² | 20–40 years | Cleaning, very low | No — fossil material ✗ |
📋 Cladding admitted and excluded by the Klimabonus 2026
The Klimabonus 2026 explicitly states that cladding containing fossil materials is not eligible for the « ecological insulation + non-fossil cladding » premium of €115/m². This notably excludes pure PVC cladding. Wood cladding, fibre-cement, aluminium, zinc and lacquered steel are all eligible. For wood-plastic composites (WPC), verify the exact composition with your tradesperson before confirming the choice for your Klimabonus application.
EWI prices in Luxembourg in 2026
Prices for external wall insulation in Luxembourg are significantly higher than averages observed in France or Belgium, due to local labour costs and the quality requirements of the Luxembourg market. The price ranges below come from our collection from certified partner tradespeople in Luxembourg. See also our page on insulation prices in Luxembourg for a global view of all items.
| EWI system | Insulation | All-inclusive price per m² (inc. VAT, 3% VAT) | Budget for 100 m² of facade |
|---|---|---|---|
| EWI under render (ETICS) | Rock wool 14–18 cm | €140 to €190/m² | €14,000 to €19,000 |
| EWI under render (ETICS) | Wood fibre 16–20 cm | €175 to €230/m² | €17,500 to €23,000 |
| EWI under ventilated cladding | Rock wool + fibre-cement cladding | €180 to €240/m² | €18,000 to €24,000 |
| EWI under ventilated cladding | Wood fibre + natural wood cladding | €210 to €280/m² | €21,000 to €28,000 |
| High-end EWI under ventilated cladding | Wood fibre + zinc or aluminium cladding | €250 to €340/m² | €25,000 to €34,000 |
| EWI under overcladding | Rock wool or wood fibre | €145 to €205/m² | €14,500 to €20,500 |
| IWI (internal lining) | Rock wool or wood fibre | €65 to €130/m² | €6,500 to €13,000 |
Indicative prices inc. VAT with 3% VAT applicable to properties over 10 years old in Luxembourg. Collected from certified partner tradespeople. Scaffolding, removal and reinstallation of shutters and gutters included.
Additional costs to plan for
| Additional item | Estimated cost |
|---|---|
| Window sill extensions | €80 to €200 per window |
| Facade corner treatment | €30 to €80 per linear metre |
| Rainwater downpipe relocation | €200 to €600 per downpipe |
| Balcony, terrace and canopy reworks | On quote depending on configuration |
| Prior thermal diagnostic (recommended) | €500 to €1,500 |
| Prior active crack treatment | €200 to €800 depending on extent |
✓ Measure your facade area correctly
The area to insulate is the actual area of external walls — not your home’s living space. For a 120 m² two-storey home with 4 facades, the external wall area is often 150 to 200 m². For a house with neighbours on both sides, it can drop to 80–120 m². Only a precise measurement by your tradesperson will produce a reliable quote. Be wary of tradespeople who quote by m² of living space — which underestimates the real cost by 20 to 40%. Our guide on how to compare energy renovation quotes helps you detect these practices.
Get comparative quotes from certified tradespeople for your facade EWI in Luxembourg. Free, no commitment.
Request quotes →Klimabonus and Enoprimes subsidies for facade insulation 2026
The Klimabonus Wunnen 2026 scheme, in force since 1 January 2026, offers fixed flat rates in €/m² for external wall insulation. The grid is differentiated according to the insulation category and technique used, with a system of cumulative bonuses rewarding the most ecological choices. For an overview of all subsidies, consult our page on Klimabonus subsidies and grants.
Klimabonus amounts grid — external wall insulation 2026
| Insulation category | Technique | Klimabonus amount (€/m²) | Additional conditions |
|---|---|---|---|
| Standard insulation (non-eco-certified mineral) | EWI or IWI | €60/m² | λ ≤ 0.13 W/(m·K) — mechanical fixing mandatory for EWI |
| Standard mineral insulation (rock wool, glass wool) | EWI or IWI | €60/m² | λ ≤ 0.13 W/(m·K) — mechanical fixing mandatory for EWI |
| Certified ecological insulation (wood fibre, hemp, cellulose) | EWI under render or IWI | €93/m² | Ecological certification required — mechanical fixing for EWI |
| Certified eco insulation + non-fossil cladding, mechanical fixing | EWI under cladding only | €115/m² | Wood, fibre-cement, metal cladding only — no PVC |
| IWI only (interior side) | Internal lining | −25% on applicable amount | Automatic 25% reduction if exclusively internal insulation |
Source: Guichet.lu — Klimabonus Wunnen 2026 (scheme in force since 01/01/2026). Values to verify on guichet.public.lu before submitting your application.
Additional cumulative bonuses
| Bonus | Additional amount | Condition |
|---|---|---|
| Fossil or mineral insulation composed of >50% recycled materials | +€15/m² | Recycled content certification mandatory |
| Certified ecological insulation (sustainably certified components) | +€15/m² | Sustainable cultivation certification (e.g. FSC for wood) |
| Green facade combined with EWI | Specific premium (amount to confirm on myguichet.lu) | Substrate ≥ 5 cm, living plants on facade |
Subsidies that can be combined with Klimabonus
| Subsidy source | Amount | When to apply |
|---|---|---|
| Klimabonus Wunnen | €60 to €115/m² | Agreement in principle on MyGuichet.lu, before works |
| Enoprimes (Enovos/Creos or SudEnergie) | €4 to €12/m² | Before signing the order with the tradesperson |
| Super-reduced 3% VAT | 14% saving vs standard VAT | Automatic if property >10 years — tradesperson must file approval |
| Municipal subsidies | Variable (approx. €500 to €3,000) | Enquire with municipality before works |
| BCEE Klimaprêt | Preferential rate loan + partial subsidy | To finance the part not covered by subsidies |
Calculation example — EWI under wood cladding, 100 m² facade, wood fibre
System: 18 cm wood fibre boards + douglas cladding — mechanical fixing
Works price inc. VAT (3% VAT): ~€240/m² × 100 m² = €24,000
― Maximum Klimabonus (eco insulation + non-fossil mechanical cladding): €115/m² × 100 m²
⚠ Cap at 50% of total cost: 50% × €24,000 = €12,000
→ Klimabonus = €11,500 (115 × 100 = €11,500, below cap of €12,000)
― Enoprimes (€12/m²): €1,200
― 3% vs 17% VAT saving: ~€3,360
Total subsidies: ~€16,060
Estimated remaining cost: ~€7,940 for 100 m² wood fibre facade + wood cladding
Excluding potential municipal subsidies. Indicative simulation — exact amounts vary by municipality and conditions in force.
Precisely simulate your remaining cost after Klimabonus and Enoprimes based on your area and insulation. Free, a few minutes.
Simulate my subsidies →Planning permissions and constraints in Luxembourg
In Luxembourg, any modification of a building’s external appearance may require a building permit issued by the municipal administration. EWI, whether under cladding or render, changes the appearance, sometimes the colour, and systematically the external alignment of the building — it therefore falls within the scope of works subject to authorisation in most municipalities. Consult our page on building permits and works declarations to understand the general procedure.
Cases requiring authorisation
Modification of exterior appearance or facade colour
In virtually all Luxembourg municipalities, installing cladding or render of a different colour from the existing constitutes a modification of the exterior appearance subject to authorisation. The Particular Development Plan (PAP) of your zone defines permitted materials, colours and finishes. Natural wood cladding on a house whose facade was smooth render will always constitute an appearance modification subject to authorisation.
Exceeding the legal facade alignment
EWI increases wall thickness by 14 to 22 cm depending on the technique. If this thickness encroaches on public space (pavement, road), a specific authorisation is required. In the narrow streets of Luxembourg city centres, this constraint can make EWI technically impossible on the street side — directing towards IWI for that facade section.
Protected zones and listed buildings
Buildings located within the protection perimeter of a listed site or registered in the Luxembourg architectural heritage inventory are subject to strict restrictions on facade modifications. In some cases, EWI may be refused if it compromises the architectural character of the building or neighbourhood. Consult the National Sites and Monuments Service if your property is concerned.
⚠️ Check before signing the order
Never sign an order for EWI without having previously verified the authorisation conditions with your municipal administration. Some less rigorous tradespeople start works without authorisation, which can force the owner to demolish the completed works and results in the loss of the Klimabonus. The municipality’s agreement must precede both the Klimabonus agreement in principle and the start of works.
✓ Good to know
Since the 2021 building law reform in Luxembourg, municipalities have simplified standardised forms for small energy renovation works. Processing times are generally 4 to 8 weeks. Your tradesperson can help you compile the file — before/after facade plans, chosen materials, dimensions of the planned insulation.
Step-by-step procedures for your EWI in Luxembourg
The procedure for obtaining the Klimabonus is strictly sequential. Each step must be followed in order — any reversal results in the permanent loss of one or more subsidies. Our complete guide on the steps and procedures for energy renovation in Luxembourg details the entire administrative journey.
Simulate your subsidies and choose your EWI system
Use the official simulator at aides.klima-agence.lu to estimate your subsidy amounts based on your facade area, insulation and cladding. This first calculation helps you compare the cost-effectiveness of a wood fibre + cladding system (€115/m² Klimabonus) versus EWI under render with rock wool (€60/m²) for your specific situation.
Apply for Enoprimes BEFORE any order
Contact Enovos/Creos (north and central Luxembourg zone) or SudEnergie (south zone) to submit your Enoprimes application at enoprimes.lu before signing anything with your tradesperson. This application must imperatively precede the signing of the order — any application made after is automatically rejected.
Verify municipal authorisation conditions
Enquire with your municipal administration about the need for a building permit and PAP constraints (permitted colours, materials). Factor this administrative delay into your planning: Luxembourg municipalities generally process these applications in 4 to 8 weeks.
Obtain at least 3 quotes from certified tradespeople
Request several quotes from tradespeople registered with the Luxembourg Chambre des métiers. The quote must mention the insulation material with its CE certification and λ value, the type of cladding with its composition, the planned thickness, and a detailed breakdown of supplies, installation and scaffolding. Only a certified tradesperson allows you to access the Klimabonus. See our guide on how to compare energy renovation quotes.
Obtain Klimabonus agreement in principle on MyGuichet.lu — BEFORE works
Submit your application via form DEPA-2026 on MyGuichet.lu. For facade insulation alone (simplified single-element procedure), the required documents are: detailed quote, CE-certified technical data sheets for insulation materials, and cladding sheet if applicable. Await written agreement before signing your order or starting works.
Carry out works and submit payment application
Once the agreement in principle is received, sign your order. After works completion, submit your payment application on MyGuichet.lu with: bank details, paid invoices, technical data sheets, photos if requested. Payment generally occurs within 4 to 12 weeks following validation of the complete file.
📋 Procedural reminder — mandatory order
Enoprimes before order → Klimabonus agreement before works → payment after works. Any reversal of this order results in permanent loss of the relevant subsidy. In case of doubt, contact the Klima-Agence (free hotline 8002 11 90) or consult the portal klima-agence.lu.
Mistakes to avoid for your EWI in Luxembourg
Choosing a fossil insulation without checking Klimabonus eligibility
Standard expanded polystyrene (EPS), very common in France and Belgium, is excluded from the Luxembourg Klimabonus. If your tradesperson proposes an ETICS system with standard EPS without mentioning this exclusion, that should alert you. Always demand the CE technical data sheet for the insulation with its classification and verify its eligibility before signing.
Carrying out EWI without prior municipal authorisation
Some tradespeople propose starting works directly, with regularisation afterwards. This is a serious mistake in Luxembourg: unauthorised works can be subject to a demolition order and automatically result in Klimabonus exclusion. The municipality’s agreement must precede both the Klimabonus agreement in principle and the start of works.
Neglecting thermal bridge treatment at junctions
The junctions between EWI on walls and insulation of the roof, ground floor or joinery are the zones most exposed to residual thermal bridges. If these junctions are not carefully treated, up to 40% of the theoretical thermal gain from EWI can be lost. Require a junction detail plan in your quote and verify their treatment at works acceptance.
Insulating a damp or cracked facade without prior treatment
Covering a facade with rising damp, untreated water infiltration or active cracks with EWI will trap moisture in the wall and cause rapid deterioration — mould, structural rot, cladding blistering. A prior diagnostic of the supporting wall condition is essential. If pathologies are present, they must be treated before insulation is installed.
Forgetting mechanical ventilation after improving airtightness
EWI significantly improves the airtightness of the building envelope. If your home is not equipped with controlled mechanical ventilation, the improved airtightness can lead to water vapour accumulation and degraded indoor air quality. Plan double-flow MVH alongside EWI — the Klimabonus covers it too within a multi-element renovation.
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Frequently asked questions — facade insulation and cladding in Luxembourg
What is the Klimabonus amount for facade insulation in Luxembourg in 2026?
Since January 2026, the Klimabonus for external wall insulation is a fixed flat rate of €60/m² for standard insulation (rock wool, glass wool), €93/m² for certified ecological insulation (wood fibre, hemp) under render EWI, and €115/m² for certified ecological insulation combined with non-fossil mechanically fixed cladding (wood, fibre-cement, metal). IWI (internal insulation) benefits from the same base amounts reduced by 25%. These amounts are subject to a cap of 50% of total works cost.
What is the difference between EWI under cladding and EWI under render?
EWI under cladding (dry method) creates a ventilated air gap between insulation and an applied facing (wood, metal, fibre-cement). It is the most effective technique on damp or highly exposed facades, and the one that benefits from the highest Klimabonus subsidies (up to €115/m²). Its cost is higher: €180 to €280/m² in Luxembourg. EWI under render (wet method, ETICS) bonds insulation panels directly to the wall and covers them with finishing render. It is less expensive (€140 to €220/m²), gives a traditional render appearance, but does not benefit from the cladding premium — capped at €93/m² for eco insulation under render.
Is polystyrene (EPS) subsidised by the Luxembourg Klimabonus?
No, not in its standard form. Expanded polystyrene (EPS) is a fossil insulation excluded from the Luxembourg Klimabonus since 2024. Only EPS containing more than 50% recycled materials can benefit from an additional €15/m² on the base subsidy. To maximise your subsidies, opt for rock wool (€60/m²) or wood fibre (€93 to €115/m² depending on the system).
Is municipal authorisation required for EWI in Luxembourg?
In the vast majority of cases, yes. EWI modifies the building’s external appearance and facade alignment, which falls within the scope of works subject to municipal building authorisation in Luxembourg. Conditions vary by municipality and the Particular Development Plan (PAP) of your zone. Additional restrictions apply in protected sites and for heritage buildings. Always verify with your municipal administration before starting works.
What insulation thickness is required for the Klimabonus?
To benefit from the Klimabonus for external wall insulation, the insulation must achieve a thermal conductivity λ ≤ 0.13 W/(m·K) CE-certified. In practice, this corresponds to a thickness of 14 to 20 cm of rock wool or 16 to 22 cm of wood fibre. For the highest subsidies, even greater thermal resistance R is required. For external walls, a thickness of 16 to 20 cm is generally recommended in Luxembourg.
How long does an EWI project on an individual house take?
For a standard individual house with 100 to 150 m² of facade, allow 3 to 6 weeks depending on the technique. EWI under render requires more time due to drying delays between layers. EWI under cladding is generally faster once the framework is in place. A major advantage of both techniques: works are entirely external — you can remain in your home for the entire duration without major daily disruption.
Can the facade Klimabonus be combined with the roof Klimabonus?
Yes, absolutely. The Klimabonus is granted per building element, and only once per element. You can therefore obtain the Klimabonus for roof insulation AND that for facade insulation within a multi-element renovation. An energy advisory by a Klima-Agence accredited consultant is then mandatory — it also allows access to higher subsidy amounts. The advisory cost (~€1,500) is itself subsidised by the Klimabonus.
Is EWI possible on a semi-detached house in Luxembourg?
Yes, but with specific constraints. On the two shared gable walls of a house flanked by two neighbours, EWI is excluded — you cannot encroach on the neighbour’s property. Insulation of these walls must be done internally (IWI). However, the front facade (street side) and rear facade (garden side) are accessible to EWI subject to municipal authorisations. For typical Luxembourg terraced houses, a mixed strategy of EWI on front/rear facades and IWI on shared gables is often the optimal solution.
Which cladding to choose to maximise Klimabonus subsidies in 2026?
To access the maximum premium of €115/m², you must choose a non-fossil mechanically fixed cladding. Eligible claddings are: natural wood (douglas fir, larch, red cedar, spruce), fibre-cement (type Cedral, Eternit), aluminium, zinc and lacquered steel. PVC cladding is explicitly excluded by the Klimabonus 2026 regulations. Wood-plastic composite cladding (WPC) must be verified case by case according to its exact composition.
Does EWI increase the value of my home in Luxembourg?
Yes. EWI carried out with quality materials improves the building’s energy class, which has a direct and measurable impact on property value in Luxembourg. An improvement of one or two energy classes (e.g. from E to C) can represent a value increase of 5 to 15% depending on location and property type. Consult our page on the impact of the EPC on property prices in Luxembourg for figures by region.
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