Renovating an Older Home in Luxembourg: The Klimabonus and How to Plan the Works

Start with a free energy check, not a contractor

Before touching any subsidy, it is worth calling Klima-Agence, the national energy and climate agency, for a basic energy advice session, which the agency describes as free and independent. A counsellor looks at the building, discusses your project and points you toward the type of work and the aid available. For a fuller, paid energy assessment carried out by an accredited advisor, a portion of the cost can itself be reimbursed under the Klimabonus.

This step matters because the Klimabonus 2026 scheme is built around it. Projects touching several elements of the building envelope (roof, walls, floor, windows) generally require a report from a certified energy counsellor before the work starts, while a renovation limited to a single element has a simplified route. Either way, approval has to be requested before signing contracts or starting work, through the online MyGuichet.lu portal. Work started first is not eligible retroactively.

What the Klimabonus actually pays for

The 2026 regime covers, broadly:

• Insulation of roof, walls and floor, paid per square metre and varying by the type of material used (standard, mineral or ecological insulants attract different rates, with ecological materials generally rewarded more generously).
• Window and door replacement, again calculated per square metre of surface replaced.
• Heating systems, in particular the replacement of an oil or gas boiler with a heat pump, where the requirement that the old boiler be at least ten years old has reportedly been dropped for the current regime.
• Renewable energy installations, such as photovoltaic panels, and technical equipment linked to renewable sources.
• The energy advice itself, partly reimbursed.

Rates, ceilings and any extra bonuses (for example for recycled or certified ecological materials) are adjusted periodically, so treat any percentage or euro figure you read, including here, as indicative. Confirm the exact current amounts for your project type on guichet.lu and klima-agence.lu before budgeting, since these are the authoritative, up-to-date sources and the ones your approval will be measured against.

One condition that has stayed consistent across recent versions of the scheme: the building generally needs to be more than ten years old to qualify for the energy renovation aid, which is logical since new builds are covered by different rules on energy performance. Work also has to be carried out by professionals registered with the Chambre des Métiers; do-it-yourself renovation is not eligible.

How the process runs in practice

1. Get the energy advice. Book the free basic consultation with Klima-Agence, or commission a full energy report if your project needs one.
2. Get quotes from registered contractors for the specific work you plan.
3. Apply for approval in principle via MyGuichet.lu before signing anything, attaching the energy report, the quotes and proof of the building's age.
4. Wait for the accord, then sign the contracts and schedule the work.
5. Keep every invoice. The reimbursement request is made after the work is completed and paid, within the time limit set by the scheme.

Because approval has to come first, buyers who want to renovate immediately after taking possession should start this process as soon as the compromis is signed, not after the notarial deed, so the accord is close to ready by the time keys change hands.

The right order of works

Contractors and Klima-Agence advisors generally recommend the same sequence for an older home, because each step changes what the next one needs to deliver:

1. Roof or attic insulation first. A poorly insulated roof is typically the single largest source of heat loss in an older house.
2. Wall insulation, ideally from the outside where the façade allows it, which avoids losing interior floor area.
3. Windows and doors, replaced once the envelope is otherwise sealed, so the new glazing is not undermined by draughts elsewhere.
4. Ventilation, upgraded alongside or after the envelope work, since a tighter building needs controlled air renewal to avoid condensation and mould (see our guide on condensation and mould in a rental for the underlying mechanics, which apply to owned homes too).
5. Heating last. A heat pump should be sized for the building's reduced heat demand after insulation, not for the old, leaky version of the house. Installing it first usually means oversizing it, which costs more and runs less efficiently.
6. Solar or other renewable generation, once consumption has been reduced as far as sensible.

Skipping this order is one of the most common expensive mistakes: buyers who install a heat pump before insulating end up with an oversized, inefficient system, then insulate afterwards and find the heating no longer matches the home's real needs.

Permits and the commune

Beyond the Klimabonus paperwork, structural changes such as replacing windows on a street-facing façade, adding external insulation that changes the building's outline, or installing a heat pump's outdoor unit can require a commune building permit or at least a notification, particularly in a protected streetscape or a co-ownership. Contact your commune's technical service (service technique or bâtisses) early in the planning stage; a permit that is missed is far more costly to fix after the fact than to request before work starts. In a co-ownership, works affecting common parts, such as external wall insulation or a shared roof, also need the general meeting's agreement; see the buying an apartment in a co-ownership guide for how that works.

VAT and other renovation costs

Separately from the Klimabonus, renovation work on a home used as a main residence can benefit from Luxembourg's super-reduced 3% VAT rate, instead of the standard rate, up to a lifetime ceiling per home. The conditions, the ceiling and how to apply the reduced rate at invoicing stage or claim it back afterwards are explained in our dedicated guide to the 3% housing VAT; the energy renovation aid and the VAT reduction are separate mechanisms that can generally both apply to the same project, so check both before signing quotes.

An older home's energy performance certificate is also worth requesting or updating before you plan the works, since it gives you a room-by-room and system-by-system baseline to measure the renovation against, and lenders and future buyers will ask for it regardless.

Budgeting realistically

Energy renovation of an older home is rarely a single, one-off invoice. A realistic budget allows for:

• the cost of the energy report itself, partly reimbursed;
• a contingency for what turns up once walls or floors are opened, such as old wiring, damp or asbestos-era materials that need separate handling;
• the time between paying the contractor and receiving the Klimabonus reimbursement, since the aid is paid after the work, not before;
• any permit fees or commune requirements.

Buyers financing the purchase and the renovation together should also flag the planned works to their bank early, since a mortgage offer can sometimes be structured to release funds in stages as work is invoiced; see our mortgage guide for how Luxembourg banks generally approach staged disbursements.

Our take

An older home with character in a quarter you actually want to live in is often a better long-term buy than a new build in a less convenient location, provided the energy renovation is planned properly and the Klimabonus paperwork is filed before, not after, the work starts. Get the free Klima-Agence advice early, even before you have made an offer, so you know roughly what a given house will cost to bring up to standard. If you are weighing an older property against a new one, our guide on house or apartment in Luxembourg covers the wider trade-offs, and our team can point you toward current listings where the energy class and renovation potential are already documented.

This article describes general rules and market practice in Luxembourg and is not legal, tax or financial advice. Rules and announced measures change; confirm the position that applies to you with a notary, your bank or a tax adviser before signing.