Last updated: official rules last verified on 17 October 2026. This guide summarises the 2026 Klimabonus scheme, whose higher rate applies to requests made by 30 June 2027. Before you sign anything, always check the current version on the official sites listed below.
Who this guide is for
- Owners of a house or a flat in Luxembourg who plan to replace their windows, French windows or front door in 2027.
- Landlords, because 3% VAT also applies to a rented home used as a main residence.
- Energy advisers, estate agents and journalists who need a clear summary with sources.
It does not replace the official texts or the administration’s decision. Every condition here is subject to eligibility.
The two grants for windows at a glance
Verified on 17 October 2026.
| Klimabonus for windows | 3% VAT | |
|---|---|---|
| What it is | A state grant calculated per m² of replaced window | A reduced VAT rate on renovation work |
| Amount | €70 per m², €80 for a request made from 1 January 2026 to 30 June 2027 | 3% instead of 17%, benefit capped at €50,000 per home |
| Age of the home | More than 10 years, counted from the building permit | At least 10 years, or renovation within 5 years of purchase |
| When to apply | Approval in principle granted before the work starts | Direct application filed before the work starts |
| Official source | guichet.lu | pfi.public.lu (AED) |
Klimabonus for windows: the conditions for 2027
Klimabonus Wunnen is the Luxembourg state grant for the energy renovation of homes. The scheme described here covers replacing a single element, without an energy adviser. Full details and an eligibility checker are on our Klimabonus windows page.
The building must be more than 10 years old
The age is counted from the date of the building permit, not from the date you bought the property.
The windows must insulate very well
| Criterion | Maximum value | What it means |
|---|---|---|
| Ug, the glazing alone | 0.6 W/(m²K) | In practice, triple glazing |
| Uw, the whole window | 0.85 W/(m²K) for a standard window of 1.23 × 1.48 m | The frame profile matters as much as the glass |
The Ug value comes from guichet.lu, the Uw value from the Klima-Agence cost sheet. The technical documents of the windows must state these values.
The outside wall must be insulated, or the home ventilated
Window replacement only qualifies if the outside wall has a U value of 0.85 W/m²K or lower, or if the home has mechanical ventilation.
Approval in principle must come before the work
No fitting may start before the administration has accepted the request for approval in principle (accord de principe). That is why we only place the final order once this approval is in.
The amount depends on the date of the request
| Request for approval in principle | Grant per m² of window |
|---|---|
| Made from 1 January 2026 to 30 June 2027, with an invoice issued by 31 December 2030 at the latest | €80 |
| Made outside this period | €70 |
3% VAT: the conditions
| Condition | Official rule |
|---|---|
| Rate | 3% instead of 17% |
| Age of the home | At least 10 years, or renovation within 5 years of purchase |
| Use | Main residence, lived in by the owner or by a tenant |
| Cap | €50,000 of VAT benefit per home |
| Direct application | Filed jointly by the company and the owner, before the work starts |
| Quote amount | At least €3,000 excluding VAT for the direct procedure |
| Eligible work | Windows and doors are on the list of eligible work |
Source: Administration de l’enregistrement, des domaines et de la TVA, on pfi.public.lu. More detail on our 3% VAT renovation page.
Combining Klimabonus and 3% VAT
The two grants can be added together if your project meets the conditions of each. They share one important rule: both requests are made before the work starts. The simplest way is to prepare them together, right after the quote. We prepare both files with you at the same time.
To understand what makes up the price of a window before any grant, read our window prices guide. We do not publish prices: every window is made to measure.
The steps, from first quote to fitting
- Check the age of the building (building permit) and the state of the wall or the ventilation.
- Free measurement visit at your home. We check the grant conditions with you. Book a visit.
- Detailed fixed-price quote, listing every window with its glazing and its Ug and Uw values.
- Klimabonus request for approval in principle and direct application for 3% VAT, before any final order.
- Approval from the administration, then the order.
- Manufacturing of your windows.
- Delivery.
- Fitting by our own team.
- Klimabonus payment request, with the invoice and the technical documents of the windows.
How a job runs from start to finish is explained on our window replacement page.
Checklist before you sign
| What to check | Why it matters |
|---|---|
| The building is more than 10 years old according to the building permit | Klimabonus age condition |
| The wall has a U value of 0.85 W/m²K or lower, or the home has mechanical ventilation | Without it, no Klimabonus for windows alone |
| The quote states Ug ≤ 0.6 and Uw ≤ 0.85 W/(m²K) | Values required for Klimabonus |
| Approval in principle has been granted | It must come before the work starts |
| The 3% VAT application has been filed with the company | It is made before the work, for a quote of at least €3,000 excluding VAT |
| The home is your main residence or a tenant’s | Condition for 3% VAT |
| Every window is listed with its size, profile, glazing and options | No surprises on delivery day |
| The price is fixed, after a measurement visit | No extras discovered on site |
Glossary
| Term | Meaning |
|---|---|
| Uw | Heat transfer coefficient of the whole window, frame and glazing, in W/(m²K). The lower it is, the better the window insulates. |
| Ug | The same coefficient for the glazing alone. |
| Uwall (Umur) | The same coefficient for the outside wall. It counts for the Klimabonus window grant. |
| Approval in principle (accord de principe) | The administration’s approval of your Klimabonus project, needed before the work starts. |
| Frame (dormant) | The fixed part of the window, fastened into the wall. The opening sash closes into it. |
| Triple glazing | Glazing with three panes separated by two insulating gaps. In practice, the condition for reaching the Klimabonus Ug value. |
| Mechanical ventilation | A system that renews the air in the home continuously. It can replace the insulated wall condition for Klimabonus. |
Official sources
- Klimabonus renovation: guichet.lu
- Technical values and cost sheets: Klima-Agence
- 3% housing VAT: pfi.public.lu (AED)
Rules last verified on 17 October 2026. Only the official texts and the administration’s decision are binding.
Press and reuse
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