Windows
Window subsidies in Luxembourg 2026: 80 € per m² from the Klimabonus
New windows and French windows get 80 € per m² when the approval in principle is requested by 30 June 2027, and 70 € after that, as long as the glass reaches Ug ≤ 0,6 and the wall around them is insulated. The conditions and the steps.
- 80 €/m²
- approval requested by 30 June 2027
- 70 €/m²
- after that
- Ug ≤ 0,6
- glass requirement
- 10 years
- minimum age of the building
The short version
- New windows and French windows get 70 € per m² of window, or 80 € when the approval in principle is requested between 1 January 2026 and 30 June 2027.
- The glass must reach Ug ≤ 0,6 W/(m²K), in practice triple glazing.
- The wall or heated roof must already be insulated to U ≤ 0,85, or the home must have controlled mechanical ventilation, to avoid condensation.
- Apply for the approval in principle before the work. Window replacement on a main residence older than 10 years can be invoiced at 3 % VAT.
How much the state pays
| Element | Klimabonus 2026 |
|---|---|
| Windows and French windows, glass Ug ≤ 0,6 W/(m²K) | 70 € per m² of window |
| Same, approval in principle requested 1 January 2026 to 30 June 2027, invoice by 31 December 2030 | 80 € per m² of window |
Example: 18 m² of new windows get 18 × 80 € = 1.440 € when the approval in principle is requested by 30 June 2027, and 18 × 70 € = 1.260 € after that.
With a full energy assessment, the windows count towards the class bonus: the aid for the building envelope rises by 20 %, 30 % or 50 % when the building improves by at least two energy classes and reaches C, B or A.
Conditions
- Glass: Ug ≤ 0,6 W/(m²K), which in practice means triple glazing.
- No condensation risk: the outside wall, or the roof of a heated attic, must reach a U-value of 0,85 W/(m²K) or better, or the building must have controlled mechanical ventilation. New tight windows in an uninsulated wall can cause mould.
- Building age: more than 10 years from the building permit when you apply.
- Approval first: the approval in principle must be requested before the work starts.
- Who does the work: an approved business, or work monitored by an approved energy consultant.
- Roof windows: when the roof of a heated attic is renovated, roof windows older than 10 years with a U-value above 1,4 must be replaced by windows with U ≤ 1,4.
- Check the wall firstWithout an insulated wall or roof (U ≤ 0,85) or controlled mechanical ventilation, new windows are not subsidised.
- Quote with m² and UgAsk for the window area in m² and the Ug value of the glass for each window.
- Approval in principleBefore the work, a registered energy adviser or tradesperson applies for the approval in principle.
- Work and paymentAfter installation by an approved business, apply with the CONF-2026 confirmation and the paid invoices, at the latest 4 years after 31 December of the invoice year.
Commune top-ups and 3 % VAT
Many communes add a share of the state aid for windows, most often 10 %, 25 % or 50 %, with a cap. Klima-Agence's aid simulator shows the amounts for your commune. Replacing windows is listed as eligible renovation work for the 3 % VAT rate on a main residence older than 10 years; see 3 % VAT on renovation.
What to ask for in your quotes
- The window area in m² and the Ug value of the glass for each window.
- The Uw value of each roof window, if the roof is being renovated too.
- Who files the approval in principle.
- Whether the wall around the windows meets U ≤ 0,85, or whether ventilation is planned.
Insulating the walls and roof first is covered on the insulation subsidies page.
Questions
Is double glazing subsidised?
Not in general: the Klimabonus 2026 requires Ug ≤ 0,6 W/(m²K) for the glass, which double glazing does not normally reach.
Why does the wall need to be insulated first?
New airtight windows in an uninsulated wall move condensation to the wall surface. The aid therefore requires an insulated wall or heated roof (U ≤ 0,85) or controlled mechanical ventilation.
Is a new entrance door subsidised?
No. The Klimabonus 2026 lists windows and French windows, not entrance doors.
Can I order the windows before the approval in principle?
The approval in principle must be requested before the work starts. Ask the installer to file it before installation, and keep the quote dated before the work.
Sources
- Guichet.lu — Energy efficiency renovation limited to a single element (Klimabonus 2026)
- Guichet.lu — Energy efficiency renovation based on an energy performance assessment (Klimabonus 2026)
- Guichet.lu — VAT refund or direct application of the super-reduced 3 % rate
- Klima-Agence — Aid simulator (state and commune aid)