How to choose your contractor for energy renovation in Luxembourg: complete 2026 guide
Choosing the wrong contractor for your energy renovation in Luxembourg can cost far more than an underestimated quote: permanent loss of Klimabonus grants, defects not covered by insurance, full rework of the project. In Luxembourg, a single label unlocks access to state grants: the « Klima-Agence certified – Artisan », awarded after an exam by Klima-Agence and valid for 5 years. Without a valid certificate, no Klimabonus is possible — regardless of the actual quality of works. This guide explains exactly how to verify a contractor’s certification, compare quotes in Luxembourg, follow the correct sequence of steps to keep all your grants, and secure your project from A to Z.
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The essential label: « Klima-Agence certified – Artisan »
In Luxembourg, unlike in some neighbouring countries, there is no equivalent of the French « RGE » label or a comparable certification system managed by a private professional body. The reference certification for energy renovation is called « Klima-Agence certified – Artisan ». It is awarded by the Klima-Agence, the body mandated by the Luxembourg government, and is the absolute prerequisite for your works to qualify for Klimabonus Wunnen grants. This label is not a mere administrative formality: it guarantees that the contractor masters both the technical aspects of high-performance renovation and Luxembourg’s administrative procedures.
Accredited « Klima-Agence certified – Artisan » contractors can directly assist their clients through the grant application process on MyGuichet.lu. This is exclusively reserved for contractors accredited by the Ministry of the Environment, Climate and Biodiversity who participate in a quality assurance system (SAQ).
How does a contractor obtain this certification?
Module 1 – Building physics and sustainable construction techniques
In-depth knowledge of building pathologies, insulation materials, airtightness, moisture management and ventilation systems. The contractor must be able to diagnose weaknesses in an existing building envelope and propose coherent solutions to reach the energy classes targeted by the Klimabonus.
Module 2 – Renewable energy installation techniques
Mastery of heat pumps (Air/Water, geothermal), pellet boilers, solar thermal and photovoltaic systems, and their interfaces with heat emitters (underfloor heating, low-temperature radiators). This module guarantees the contractor knows the precise technical requirements — including correct equipment sizing and hydraulic balancing — without which Klimabonus is systematically refused.
Module 3 – Regulations, energy efficiency and financial grants
Knowledge of Luxembourg’s legal requirements (energy passports, NZEB standards), Klimabonus procedures (MyGuichet.lu, mandatory prior approval before works begin, DEPA form), Enoprimes from Enovos/Creos and SudEnergie, the Klimaprêt and Chambre des métiers obligations. A single procedural error can result in the permanent loss of thousands of euros in grants.
The « Klima-Agence certified – Artisan » certification is valid for 5 years. It must be renewed before it expires, either by passing a new exam or by providing proof of completed Klimabonus projects and validated continuing education. Always ask for the certificate’s expiry date when verifying. A contractor whose label has expired — even by a single day — is no longer authorised to submit Klimabonus applications, and your works would lose all rights to grants.
A contractor claiming to be « in the process of certification », whose label has expired, or who cannot provide a copy of the certificate cannot submit a Klimabonus application for your works. Never sign a quote or order any materials before verifying the certificate’s validity. If works begin without a valid Klimabonus prior approval, you permanently and irrevocably lose your rights to the grants.
Other labels and qualifications to know in Luxembourg
Alongside the Klima-Agence certified label, the Luxembourg renovation market recognises other certifications that attest to a contractor’s seriousness and competence. Some complement the Klima-Agence certification and reinforce the provider’s credibility; others are inescapable legal obligations.
« Nohalteg an d’Zukunft + » (NANZ+) — Chambre des Métiers
This label, established by the Luxembourg Chamber of Trades (Chambre des Métiers), replaces the former « Energie fir d’Zukunft + » label. It has two complementary specialisations: Passive House Contractor (with a Passivhaus Institut certificate, relevant for new-build or deep renovation targeting NZEB standard) and Energy Renovation Contractor (which automatically and simultaneously confers Klima-Agence certified status). Valid for 5 years, renewable via validated continuing education or documented proof of a completed Klimabonus project. When a contractor holds both NANZ+ and Klima-Agence certified, you benefit from two independent validations of their competence.
Chambre des métiers registration (mandatory for all contractors)
Any contractor legally operating in Luxembourg must be registered with the Chambre des Métiers (cdm.lu). For heat pump installations, the Chambre des métiers also oversees the building inspection and acceptance service: the installer must submit an acceptance request within the month following commissioning. Absence of registration is an absolute red flag. Always verify at cdm.lu.
Certified Passive House Tradesperson — Passivhaus Institut
Issued by the Passivhaus Institut in Darmstadt, this certificate demonstrates specialist expertise in very low energy construction and renovation. Relevant for renovation projects targeting energy class AAA or NZEB standard — particularly for comprehensive single-family home renovations.
Companies Register (RCS Luxembourg)
Any company carrying out works in Luxembourg must be registered with the Registre de Commerce et des Sociétés (RCS). Absence of registration is an immediate red flag that should lead to immediate elimination of the provider, regardless of how attractive their pricing. Check any company for free in seconds at lbr.lu.
Insurance: what you must require from your contractor in Luxembourg
Luxembourg’s legal framework on construction insurance has an important feature that distinguishes the Grand Duchy from France or Belgium: decennial insurance is not legally mandatory for craftsmen and building contractors. In Luxembourg, the legal obligation for professional insurance applies only to architects and consulting engineers (Law of 13 December 1989). This specificity of Luxembourg law demands heightened vigilance on your part as project owner, since in the event of a defect committed by an uninsured contractor, your immediate financial recourse is very limited.
The three coverages to systematically require
Exploitation liability insurance (RC exploitation)
Covers damage caused to third parties during construction works: a broken neighbouring pipe, water damage to the flat below, injury of a third party on site, damage to a nearby vehicle. Though not legally mandatory for contractors in Luxembourg, any serious professional holds it. Always demand a valid exploitation liability insurance certificate — with the insurer’s details, policy number and expiry date — before any works begin. In the event of an uncovered incident, you would bear the full remediation costs.
Decennial liability insurance (RC décennale)
Decennial liability is rooted in Luxembourg law through Articles 1792 and 2270 of the Luxembourg Civil Code. It covers serious defects compromising the structural integrity or intended use of the building for 10 years from project handover: structural settlement, infiltrations from defective waterproofing, facade insulation detachment, etc. This legal guarantee exists as a matter of law, but contractors have no legal obligation to insure against it. Without decennial insurance, you would need to initiate court proceedings against the contractor directly — a long, costly and uncertain process if the contractor is insolvent. Always require a valid decennial insurance certificate.
All-risks site insurance (TRC) — strongly recommended
This covers material damage occurring during the construction phase itself, regardless of liability: a storm damaging materials awaiting installation, accidental fire, theft of materials or equipment on site, accidental loss during works. It can be taken out by either the contractor or you as project owner (in the latter case, compensation is fast and does not require prior determination of responsibilities). Strongly recommended for any energy renovation project in Luxembourg exceeding €10,000.
Unlike France, in Luxembourg decennial insurance is not legally mandatory for contractors. The decennial liability (Articles 1792 and 2270 of the Civil Code) exists in law, but the legal obligation to insure it applies only to architects and consulting engineers. Always request certificates and be especially cautious if the contractor refuses to provide them — it is the first sign they are operating without a safety net.
How to compare energy renovation quotes effectively in Luxembourg
Comparing energy renovation quotes is not just about looking at the total at the bottom of the page. A misread quote can lead you to choose the most expensive option net of lost grants — or the cheapest on paper but incompatible with the Klimabonus. Here is the rigorous approach to apply systematically.
Request at least 3 quotes from different certified contractors
For an energy renovation project in Luxembourg, you must request at least three quotes from different contractors, all holding a valid Klima-Agence certified label. Plan to launch consultations at least 4–6 months in advance to have time to compare calmly, submit the Klimabonus prior approval, and wait for its validation before signing anything.
Build an identical specification for all bidders
For the comparison to be genuinely meaningful, quotes must cover identical scopes. Before requesting quotes, draft a precise specification that you provide to each contractor, covering: required works type and equipment with minimum performance specifications (COP/SCOP for heat pumps, thermal resistance R for insulation, Uw for windows), surfaces and spaces involved, access and logistical constraints, expected ancillary services, and desired timelines.
Compare quotes along three simultaneous axes
| Comparison axis | What to verify | Red flag |
|---|---|---|
| Klimabonus eligibility | Equipment on official list, hydraulic balancing included, valid contractor certification | Equipment not listed, missing balancing, uncertified contractor |
| Scope of services | All specification items present, removal and disposal included, admin steps covered | Missing items, waste management « as option », Klimabonus steps left to you |
| Net cost after grants | Price incl. VAT − Klimabonus − Enoprimes − municipal grants − 3% VAT saving | Cheapest gross quote but loss of Klimabonus = much higher actual net cost |
A quote much lower than the others almost always conceals one of the following: missing hydraulic balancing (required by Klimabonus for heat pumps), equipment not on the official eligible models list, deliberate undersizing of the required equipment, use of non-certified subcontractors, or absence of commissioning and administrative services. In all these cases, the Klimabonus will be refused and you will bear the full cost without any grant.
Concrete example: An air-water heat pump quote of €22,000 incl. VAT with Klimabonus €10,000, Enoprimes €1,500, municipal grants €2,000 and 3% VAT applied (saving ~€2,400 vs 17% VAT) → estimated actual net cost: approximately €6,100 only for a €22,000 installation.
Checklist: what a good energy renovation quote must contain in Luxembourg
An incomplete or poorly written quote is the first sign of an insufficiently rigorous provider. For a Klimabonus-eligible energy renovation project in Luxembourg, the quote must contain all of the following items without exception.
| Quote item | Why it’s essential |
|---|---|
| Full contractor identity (name, address, Chambre des métiers number, RCS number) | Legal verification of the company, its right to operate and its register entries |
| « Klima-Agence certified – Artisan » certification with validity date and certificate number | Absolute prerequisite for Klimabonus eligibility — cross-check against the official list |
| Detailed line-by-line description of works (materials, brands, quantities, performance levels) | Enables comparison between quotes and compliance checking against Klimabonus technical criteria |
| Precise equipment specifications (brand, exact model, COP/SCOP for heat pumps, R-value for insulation, Uw for windows) | Required to verify equipment eligibility on the official Klimabonus list published by Klima-Agence |
| Explicit mention of hydraulic balancing (for any heat pump) | Required by Klimabonus for any heat pump installation — its absence causes systematic refusal of the application |
| Separate pre-VAT and incl.-VAT prices, with applicable VAT rate (3% or 17%) | Verifies eligibility for the 3% super-reduced VAT (building over 10 years old, primary residential use) |
| Precise execution timeline and step-by-step payment conditions | Protects against scheduling issues, excessive advance payments and mid-project abandonment |
| Applicable warranties (biennial proper functioning, decennial) | Secures your legal recourse in case of defects or failure after project handover |
| Administrative steps to be handled by the contractor (Klimabonus prior approval, final application, Enoprimes) | Unambiguously clarifies who is responsible for each formality — prevents post-project disputes over uncollected grants |
| Mandatory legal mentions (company ID number, RC exploitation insurance details with insurer contact) | Minimum legal obligations allowing identification and contact of the contractor in case of dispute |
A two-line quote (« heat pump installation — flat rate €18,000 ») without material details, equipment references or mention of hydraulic balancing is systematically incompatible with a Klimabonus application. Refuse any quote that fails these criteria, however attractive the price: accepting such a quote means forfeiting all your grants upfront.
Order of steps: don’t miss your grants through a wrong sequence
In Luxembourg, subsidised energy renovation follows a strictly ordered and non-modifiable sequence of steps. Each missing or reversed step can result in permanently losing a grant, with no possible recourse. This procedural rigour is frequently underestimated by homeowners who discover too late that they can no longer claim the grants they were entitled to. Here is the correct order to follow scrupulously.
Request Enoprimes BEFORE signing the order form or quote
Enoprimes (grants from energy distributors Enovos/Creos and SudEnergie, paid as part of energy savings certificates) are irreversibly lost if you don’t apply before signing the order form or accepted quote. This rule is imperative and without exception. Contact your energy distributor as soon as you know which type of equipment you plan to install and have a provisional quote, even before you have chosen your contractor definitively.
Obtain the Klimabonus prior approval BEFORE starting works
The Klimabonus prior approval application (DEPA form) is submitted on MyGuichet.lu with your certified contractor. This approval must be validated by Klima-Agence before any work begins — even before ordering equipment. Starting works, ordering equipment or signing an order form before receiving and validating this approval permanently and irrevocably forfeits your Klimabonus.
Check and apply for available municipal grants
Many Luxembourg municipalities offer grants complementary to national schemes. For example, Luxembourg City offers an additional grant of up to 50% of the Klimabonus amount for certain work types. Some municipalities also require a prior application before works. Always check with your municipal administration before signing anything.
Sign the quote and officially launch works
Once Klimabonus prior approval is obtained and validated, and Enoprimes applied for, sign the final quote and schedule the project. Keep all documents (signed order form, quote, Klimabonus prior approval, Enoprimes confirmation) — they will be required for your final post-works application.
Apply for Klimaprêt if pre-financing is needed
The Klimaprêt is a subsidised loan available via BCEE (State Savings Bank) and other partner banks. It can finance all or part of the project not covered by grants, and is fully combinable with all grants (Klimabonus, Enoprimes, municipal grants). Its preferential rate and zero arrangement fees make it a particularly advantageous financing tool for Luxembourg homeowners.
Submit the final Klimabonus application after works handover
Once works are complete, accepted and fully invoiced, your certified contractor assists you in submitting the final application on MyGuichet.lu. The file must include original invoices, the equipment commissioning report, technical documents required by Klima-Agence, and the project handover report.
Calculate now the exact amount of your grants and simulate your net renovation cost in Luxembourg.
Simulate my grants →5 red flags to avoid at all costs when choosing your contractor
On Luxembourg’s energy renovation market, the surge in demand driven by Klimabonus grants has attracted unscrupulous providers with practices that are dangerous for your finances and your grant rights. These five red flags should lead to immediate and non-negotiable elimination of the contractor in question.
They cannot provide their valid Klima-Agence certified certificate
Any contractor authorised to submit Klimabonus applications holds this certificate and can provide a copy immediately, without delay. A contractor who « is looking for it », claims to be « in the process of renewal » for several weeks, says « my partner has it », or asks you to trust them on their word, is not authorised. Without a valid certificate, no Klimabonus is possible — and you will have to bear the full cost of your works without any grant.
They pressure you to sign before comparing other quotes
Serious contractors in Luxembourg know their clients compare multiple offers — it is a normal and healthy practice. A professional creating artificial urgency (« offer valid 48 hours only », « equipment prices go up next week », « I have a team free next week only »…) is deliberately trying to prevent competitive comparison. This sales pressure is almost always a sign of poor value or a provider who knows their offer would not withstand comparison.
They propose starting works before the Klimabonus prior approval
This is a serious fault and a certain sign of incompetence or dishonesty. Some unscrupulous contractors propose « getting started quickly to save you time » or promise to « regularise the situation with Klima-Agence afterwards ». This is totally incompatible with Klimabonus rules: prior approval is mandatory and must precede works. If you yield to this pressure, you lose the entire Klimabonus grant — often several thousands of euros — with no possible recourse.
Their quote is incomplete, only a few lines, or without precise equipment references
A Klimabonus-eligible energy renovation quote must be detailed enough to allow compliance checking against the Klima-Agence official list. A global two or three-line quote is incompatible with a valid Klimabonus application. Refuse any quote that does not clearly list equipment with brand, exact model and technical performance figures. A serious contractor has no reason to provide such a vague quote.
They refuse to provide insurance certificates
Even though decennial insurance is not legally mandatory for contractors in Luxembourg, any serious professional — working for any length of time — holds voluntary RC exploitation and RC decennial policies, and can provide a certificate on simple request within 24 hours. A categorical refusal is an immediate red flag: it means either that the contractor has no insurance (leaving you with no fast recourse in case of defect), or that the certificate content reveals a problematic situation (expired insurance, insufficient coverage, etc.).
Project handover: how to protect yourself effectively after the works
Project handover is the most important legal act in your relationship with the contractor. It starts the legal warranty periods running, triggers your rights of recourse in case of defects, and conditions the payment of the remaining balance. Never skip it just because you’re satisfied at first glance or want to maintain a cordial relationship with the contractor.
Express or tacit acceptance: always choose express acceptance
In Luxembourg, as in general civil law, acceptance can be express (written document signed by both parties, dated and detailing any reservations) or tacit (resulting from the parties’ behaviour — for example if you take possession and start using the property normally without raising any reservation). Always and without exception opt for express acceptance in the form of a written, dated and countersigned handover report, listing any reservations and the deadline for their resolution. This document is the official and incontestable starting point for all your legal warranties.
What to systematically check at handover
- Exact compliance of installed equipment with the signed quote: brand, exact model, rated power, colour and dimensions. Physically compare the equipment nameplates with your quote.
- Effective proper functioning during a full commissioning test in your presence, checking supply/return temperatures for a heat pump, airflow for a VMC, etc.
- Hydraulic balancing completion for any heat pump installation, and receipt of the corresponding balancing protocol signed by the technician.
- Complete cleanliness and restoration of the property after works: removal of construction waste, filling of drill holes, repainting or plastering if specified in the quote.
- Receipt of all technical documents: user and maintenance manuals for each piece of equipment, manufacturer warranty certificates, maintenance logbook, programming interface access codes.
- The official commissioning report, an essential document for the final Klimabonus application on MyGuichet.lu — without this document, your final application will be incomplete and may be refused.
For heat pump installations, Luxembourg law requires the installing company to submit an acceptance application to the Chambre des métiers’ Building Inspection and Acceptance Service within the month following commissioning. This step is not optional: it conditions the legal compliance of your installation and may be required during a subsequent sale of the property or in the context of an insurance claim. Verify your contractor has completed this step — and ask for written confirmation.
The retention payment: an effective and legally recognised protection
It is strongly recommended to retain a 5–10% holdback of the total incl.-VAT amount, payable only after you have verified proper functioning over a reasonable period (ideally a full heating season for a heat pump) and after formal resolution of all reservations raised at handover. This common and recognised practice in Luxembourg’s construction sector effectively protects you against situations where the contractor becomes difficult to reach once the balance has been received. Mention this retention explicitly in the quote and have it confirmed in writing before signing.
Systematically photograph the installation before, during and after works. Note all reservations in writing on the handover report with precise description and deadline for resolution. Send all post-handover claims by registered letter with acknowledgement of receipt (or email with read confirmation). In case of persistent disagreement on works quality or refusal to resolve reservations, you can refer to the Chambre des Métiers (for disputes between individuals and registered contractors) or the Union Luxembourgeoise des Consommateurs (ULC) for mediation prior to any legal action.
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Frequently asked questions on choosing a contractor for energy renovation in Luxembourg
Can a cross-border contractor (from France, Belgium or Germany) carry out my energy renovation in Luxembourg and give me access to the Klimabonus?
Yes, subject to strict conditions. A contractor based in a neighbouring country can legally operate in Luxembourg under the European freedom to provide services, but must hold a valid « Klima-Agence certified – Artisan » label without exception. Without this label, they cannot submit a Klimabonus application for your works, regardless of their reputation or qualifications in their home country. The cross-border contractor must also have declared their activity in Luxembourg with the relevant authorities and comply with Chambre des métiers obligations, particularly for heat pump acceptance within the month following commissioning.
Can I use multiple contractors (one for insulation, one for the heat pump) on the same Klimabonus project?
Yes, this is not only possible but sometimes recommended for comprehensive renovation projects. Each contractor working on a subsidisable work item must hold the Klima-Agence certified certification relevant to their specific field. For a comprehensive project, it is often simpler to designate a lead contractor (certified generalist or general renovation company) who coordinates the whole project and may subcontract — provided subcontractors are themselves certified for their respective domains. Clarify this clearly and obtain written confirmation before signing the quote.
Can a contractor subcontract my works to a non-certified company?
No, under no circumstances for Klimabonus-eligible work items. The « Klima-Agence certified – Artisan » certification is specific to the company. If the contractor subcontracts work to a non-certified company, that work cannot give rise to Klimabonus eligibility for that item, regardless of the final result. Always require in writing that any subcontracting is performed by companies themselves certified for the relevant domains, and have this requirement expressly written into the signed quote.
How long should I allow between the Klimabonus prior approval application and the start of works?
In 2026, processing times typically take several weeks to two months. Add to this the availability of the chosen certified contractor (often 1–3 months depending on the season and type of works) and equipment lead times (especially for air-water heat pumps, sometimes 6–12 weeks). Overall, it is prudent to start all your steps at least 4–6 months before your target start date.
What happens if my contractor goes bankrupt during or after the works?
Bankruptcy during works risks losing advance payments exceeding the value of works actually completed — hence the critical importance of never paying more than 30% upfront before works effectively begin, and maintaining a retention holdback until formal handover. For the post-handover period, if the contractor held voluntary decennial insurance, your recourse is against the insurer directly, completely independent of the contractor’s solvency. Without voluntary decennial insurance, recourse is limited to court proceedings against the contractor or their creditors — a long, uncertain and potentially fruitless process. This is precisely why verifying the existence of voluntary decennial insurance is a decisive selection criterion in Luxembourg.
Are there energy renovation works for which an architect is mandatory in Luxembourg?
Yes. Some energy renovation works require mandatory architect or consulting engineer involvement in Luxembourg, particularly when they involve structural modifications (openings in load-bearing walls, roof structure changes), a change of use of the building, or when the project exceeds certain floor area or works value thresholds requiring a building permit. For purely technical works such as a heat pump installation, window replacement or insulation, an architect is generally not required. Our guide on architect vs general contractor helps you identify which option is preferable in your situation.
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