You’re replacing an old oil boiler with a heat pump in your home in Luxembourg. The quote comes to five figures. Before signing, you need to understand what the state will cover, under what conditions, and, above all, what changed on 1 January 2026 with the new Klimabonus Wunnen scheme.
Klimabonus pre-financing 2027: pay less upfront
The 2026 Klimabonus scheme works on a simple principle: you pay first, then apply to the state for reimbursement. This cash-flow gap creates a real problem for households without enough savings.
From 1 January 2027, an optional pre-financing mechanism will change things for certain types of work. The company carrying out the work deducts the grant directly from your bill. The state then reimburses the company, not you.
This pre-financing covers four categories of work:
- Thermal insulation work (façade, roof, floor slab), provided an application for preliminary approval was submitted before work began by an accredited energy adviser or an approved contractor
- Installation of an air-to-water or geothermal heat pump
- Installation of photovoltaic solar panels
- Installation of an electricity storage system, but only if purchased at the same time as a photovoltaic system
The standard grant application process will remain available alongside it. The amount paid is the same in either case. In practical terms, if you find a contractor listed in the register of intermediary applicants, you can reduce your upfront costs by several thousand euros.
One caveat, highlighted by Paperjam in October 2026: banks do not always factor renovation work into their loan calculations. The share of the work included in the property’s value varies according to each lender’s policy. Pre-financing reduces the bill, but does not guarantee a larger mortgage.
To better understand state energy grants in Luxembourg and the amounts available for each type of work, it is worth checking the flat-rate schedules before contacting an adviser.
2026 Klimabonus flat rates: insulation, windows and heat pumps
The 2026 scheme, introduced by the law of 24 July 2026, replaces percentage-based grants. No more “up to 62.5% of the cost.” The state now pays flat-rate amounts in euros per square metre or per installation.
Here are a few examples from the current scheme:
- Wood-fibre façade insulation: 140 euros per square metre
- Window replacement: 80 euros per square metre of glazing
- Air-to-water heat pump replacing a fossil-fuel heating system in a single-family home: 12,000 euros
These amounts are increased if an application for preliminary approval (for insulation, windows, mechanical ventilation or energy advice) is submitted, or if the heat pump is ordered, between 1 January 2026 and 30 June 2027. After that date, the flat rates decrease to 115 euros per square metre for façade insulation, 70 euros per square metre for windows and 10,000 euros for a heat pump.
Preliminary approval determines whether you qualify for the higher amount
This point is often misunderstood. The date that matters is not the start date of the work or the date on the invoice. It is the date the application for preliminary approval is submitted to the ministry by your accredited energy adviser or approved contractor.
A project starting in March 2027 with preliminary approval obtained in May 2027 will not qualify for the higher amount. A project starting in September 2027 with an application submitted in June 2027 will. Eligibility for the higher amount depends on the application date, not the date the work begins.
3% VAT and combining grants in Luxembourg
Alongside the Klimabonus, the super-reduced 3% VAT rate applies to renovation work on a home used as a primary residence. This rate covers labour and materials supplied by the company as part of the project.
The grants can be combined: you can receive the Klimabonus flat-rate grant and benefit from reduced VAT on the same project. For low-income households, a social top-up is added to the base amounts. The Klimaprêt, a preferential-rate loan, completes the package by helping finance the remaining costs.
Non-residential buildings: a separate scheme offering up to 300,000 euros
If you own an office, shop or workshop, another scheme has been available since 2026. This grant scheme for energy renovation of functional buildings can provide up to 300,000 euros per project. It aims to prepare for the new energy performance requirements for non-residential buildings due to take effect in 2030.
Energy renovation without an energy adviser: what the simplified process allows
Using an accredited energy adviser gives you access to the full range of grants and the highest amounts. However, the 2026 scheme also provides for an application process without an energy adviser, limited to a single building element.
Replacing only your windows, without making changes to the façade or heating system? You can apply for a grant for that item alone, without a full energy audit. You still need to meet the technical requirements for the element concerned, but the administrative process is simpler.
This option suits homeowners tackling a specific issue rather than carrying out a full renovation. The grant remains a flat-rate amount, calculated using the same schedules, but you cannot combine several items in a single application.
The 2026 Klimabonus calendar has two key dates: the higher grant amounts are available until 30 June 2027, and the pre-financing mechanism starts on 1 January 2027. If you are still undecided, submitting your application for preliminary approval before the first deadline is the most cost-effective step.
