Do I need to apply before the works start?

Yes. An application for an agreement in principle must be submitted before the works begin, by an approved energy adviser or by the company. Do not sign an order to start works without talking to us first.

How much funding is there to insulate a facade with rock wool?

Rock wool is a mineral insulation. For a wall insulated from the outside, the basic grant ranges from €60 to €85/m² depending on the performance achieved, and from €70 to €100/m² if the application for an agreement in principle is submitted no later than 30 June 2027.

My house is fairly new. Am I entitled to the Klimabonus?

The scheme covers residential buildings more than 10 years old, counted from the date the building permit was issued.

Can the grant be deducted directly from the invoice?

From 1 January 2027, pre-financing becomes possible for insulation works: the grant is paid to a company listed in the register of intermediary applicants, which deducts it from your invoice. The standard procedure remains available.

Guide · Updated 31 October 2026

Klimabonus 2026: grants to insulate your home

Q: Is polystyrene insulation eligible?

For an external wall or a roof, fossil-based insulation such as polystyrene is only eligible if it contains more than 50% recycled material. This is one of the reasons why we insulate facades with rock wool.

Insulating a 120 m² facade with rock wool can earn you up to €8,400 in government funding. Here is a plain-English guide to how the Klimabonus 2026 works and what you need to do to benefit from it.

Who is eligible?

Any owner who improves the energy performance of their home in Luxembourg: private individuals, co-ownerships and companies alike. The building must be more than 10 years old, counted from the date the building permit was issued.

The works must be carried out by an approved company or supervised by an approved energy adviser. Each element (facade, roof, windows, etc.) can only receive funding once.

Two ways to apply

A single element, without energy advice: for example, you insulate the facade or the roof. This is the most common case.
With energy advice: an adviser assesses the whole house and proposes a package of works to move up one or more energy classes. The advice itself is subsidised: €2,000 for a house if the application for an agreement in principle is submitted no later than 30 June 2027 (€1,700 after that).

How much for rock wool insulation?

The grant is calculated per square metre insulated. Rock wool is classed as a mineral insulation. The amount depends on the performance achieved (performance standard III, II or I, standard I being the most demanding).

Element insulated (mineral insulation)	Standard III	Standard II	Standard I
External wall, roof, slab exposed to the outside	60 (70) €/m²	70 (80) €/m²	85 (100) €/m²
Cellar ceiling, wall against the ground or an unheated area	25 (30) €/m²	35 (40) €/m²	50 (60) €/m²
Windows and patio doors	—	70 (80) €/m²	—

In brackets: the increased amount if the application for an agreement in principle is submitted no later than 30 June 2027 and the invoice is issued no later than 31 December 2030. Mineral insulation containing more than 50% recycled material qualifies for an extra €15/m².

For a wall insulated from the outside, the minimum thickness is 15 cm (for insulation with a thermal conductivity of 0.035 W/mK). For a roof, it is 20 cm.

Example: a 120 m² facade insulated from the outside with rock wool, to standard III, application submitted before 30 June 2027: 120 m² × €70 = €8,400 in funding. Submitted after that date: 120 × €60 = €7,200. This example is for guidance only: the exact amount depends on your application.

What about polystyrene?

For external walls and roofs, fossil-based insulation (polystyrene, polyurethane, etc.) is only eligible if it contains more than 50% recycled material. This is one of the reasons why we insulate facades with rock wool, using just one row of special base insulation at the foot of the wall, against the ground, where this type of insulation is still permitted.

Windows

Window replacement is eligible (€70/m², or €80/m² with the increase) with Ug ≤ 0.6 W/m²K glazing, provided the wall is already properly insulated (U-value ≤ 0.85 W/m²K) or the house has mechanical ventilation. The aim is to prevent condensation and mould. If you insulate a heated attic, roof windows more than 10 years old must be replaced at the same time.

Key dates

Before the works: application for an agreement in principle.
Until 30 June 2027: increased amounts if the agreement in principle is applied for by then.
From 1 January 2027: pre-financing becomes possible, with the grant deducted directly from the invoice by a company listed in the register of intermediary applicants.
After the works: grant application within 4 years of the end of the year in which the invoice was issued.

What we do for you

During the free survey, we measure the surfaces, recommend an insulation thickness that meets the Klimabonus requirements and give you a quote with one line per element, as the authorities require. We then provide the technical data sheets for the insulation and windows we install.

For free, independent advice, you can also contact the Klima-Agence on 8002 11 90.

Sources: the French pages of guichet.lu, Klimabonus 2026 – energy renovation and renovation of a single element, updated on 10 and 11 August 2026 and consulted on 31 October 2026. Amounts and conditions may change: only the official administration is authoritative.