Klimabonus application: energy renovation step by step, from approval in principle to payment
By Yacine Sahnoune, founder of renov.lu
In Luxembourg, to receive the 2026 Klimabonus for insulation, windows or MVHR, you must obtain the agreement in principle (MyGuichet.lu, DEPA-2026 form) before works begin, with an EPC before works in the pathway with energy advice; a heat pump or solar panels are applied for after installation. Payment must be requested within 4 years of the end of the invoice year, and by 31 December 2039 at the latest.
- Before works: insulation, windows and MVHR require the approval in principle (DEPA-2026 form on MyGuichet.lu) before the first day on site, with 4 to 8 weeks of processing (indicative); a heat pump or solar panels are applied for after installation.
- Energy advice: mandatory from 2 work measures; the grant is €1,700 for a house, or €2,000 if the approval in principle is requested by 30 June 2027, for an indicative cost of €800 to €2,000.
- Single measure: in the simplified procedure, occasional help from an energy advisor earns €500 more (€400 for the advice and €100 for the compliance check).
- Ceiling: grants are flat-rate, per m² or per installation; insulation is capped at 60% of costs excluding VAT.
- Payment: CONF-2026 sheet and DEPA-2026 form with the paid invoices, within 4 years of the end of the invoice year and by 31 December 2039 at the latest; bank transfer within 4 to 12 weeks (indicative).
- Pre-financing: since 4 January 2026, the installer deducts the Klimabonus from the solar panel invoice; for heat pumps and insulation, this will be possible for invoices issued from 1 January 2027.
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⚡ The essentials in 30 seconds
In Luxembourg, every Klimabonus 2026 grant application for insulation, windows or MVHR requires an agreement in principle obtained before works begin. Without this agreement, no subsidy can be paid for these works — regardless of their quality. Technical installations (heat pump, photovoltaics…), by contrast, are applied for after installation, without prior approval. The procedure is submitted on MyGuichet.lu via the DEPA-2026 form. For a renovation covering several elements, an energy advisory by an approved energy advisor is mandatory, with an EPC before and after works.
First steps: EPC, energy advice and approval in principle
As of September 2026 in Luxembourg, every well-run project starts with the same three steps: an up-to-date energy performance certificate (EPC) — about €500 to €600 incl. VAT for a single-family house, required before and after works for the Klimabonus with energy advice —, a certified energy consultation, subsidised at €1,700 for a house (€2,000 if the approval in principle is requested by 30 June 2027) and mandatory from 2 work measures onwards (400 € + a 100 € quote-compliance check for a single accompanied measure), then the Klimabonus approval in principle obtained BEFORE the first day on site. The technical order never changes: roof first (25–30 % of heat losses), then walls, windows, ventilation, and heating last.
| Your profile | First formalities | Watch-out |
|---|---|---|
| 1980s house, gas boiler at end of life | EPC → energy adviser → approvals in principle → insulation then heat pump | Heat pump: no approval in principle needed (apply after installation), but size it after insulation |
| Landlord, 1970s flat, class G | EPC + grant estimate → co-ownership rules → approval before works | A valid EPC is required to let; no rental ban based on the energy class is in force (September 2026) |
| Recent buyer, tight budget | EPC → single measure (loft insulation) by a “Klima-Agence certified” contractor | Check the contractor’s certification for the single-measure file |
| Targeting class A for resale | Full audit → 2-3 phase plan → multi-measure approval | Budget to pre-finance: 50 to 150 k€ |
| Co-owned 1960s building | General-assembly vote → syndic file (COLL-2026 form) → approval before works | PROC-2026 proxies from every co-owner, or general-meeting minutes authorising the works (co-ownership renovation) |
Three cross-cutting rules: the dwelling must be more than 10 years old counted from the building permit, the Klimabonus is granted only once per building element, and DIY renovation is not eligible (a company registered with the Chamber of Trades is mandatory). To obtain or update your EPC, see our energy performance certificate guide. The two administrative tracks (multi-measure or single measure) are detailed in the sections below.
First estimate your grants in under 5 minutes with the Renov.lu simulator.
The 2 Klimabonus 2026 pathways — which is yours?
Since 1 January 2026, the Klimabonus Wunnen scheme offers two procedures depending on the scope of your project. Choosing the right pathway determines the steps to follow and the grants you can claim. This distinction is fundamental and deserves to be well understood before starting anything.
| Pathway A — multi-element renovation | Pathway B — single-element renovation | |
|---|---|---|
| When to use it? | You are renovating several elements (e.g. insulation + windows + heat pump) | You are renovating only one thermal envelope element (e.g. only the windows OR only the roof insulation) |
| Energy advisory | Mandatory — by an approved energy advisor | Optional — but strongly recommended (+€500 grant if carried out) |
| Form to submit | DEPA-2026 + COAS-2026 sheet (renovation concept) + energy advisory report + EPC before works | DEPA-2026 + DESC sheet |
| Energy advisory grant | €1,700 for a house (€2,000 if the approval in principle is requested by 30 June 2027) | €400 for occasional advisory + €100 for compliance verification |
| Grant ceiling | Flat-rate amounts (per m² or per installation); insulation capped at 60% of costs excluding VAT | Flat rate per m²; insulation capped at 60% of costs excluding VAT |
| Technical installations | Included (heat pump, biomass boiler, PV, MVHR…) | Can be added separately via the « technical installations » section |
⚠️ Important
If you are planning multiple works on your home in due course, it is always more advantageous to choose Pathway A from the outset. Carrying out works in two separate stages without overall planning can cause you to miss grant synergies and force you to restart administrative procedures from the beginning. Consult our page on improving your energy class for an overview of the most impactful works.
Pathway A — multi-element renovation, step by step
This is the recommended pathway for any global or partial renovation involving several items. It guarantees the most significant grants and a coherent approach to your energy project.
Online simulation and pre-assessment
Before contacting any professional, use the Klima-Agence official simulator (aides.klima-agence.lu) to obtain a first estimate of available grants for your home. This step is free, anonymous, and lets you arrive prepared for the energy advisory.
Duration: 10 to 15 minutes. Cost: Free.
Free basic consultation at the Klima-Agence
Make an appointment with a Klima-Agence advisor for a free basic consultation. This can be done at home, by phone or video call. The advisor carries out an energy diagnosis, identifies priority works and informs you of all available grants. This first consultation is completely free, funded by the Klima-Agence and your municipality.
Contact: klima-agence.lu/fr/conseil or free hotline 8002 11 90 (Monday–Friday, 8am–12pm and 1pm–5pm). Service available in French, Luxembourgish, German and English.
Duration: 1 to 2 hours. Cost: Free.
In-depth energy advisory with report (mandatory for Pathway A)
For a multi-element renovation, you must commission a full energy advisory with report from an approved energy advisor. This report forms the centrepiece of your agreement in principle file. The advisory invoice must be dated between 1 January 2026 and 31 December 2030. The Klimabonus grant for the energy advisory is €1,700 for a house (€2,000 if the approval in principle is requested by 30 June 2027); it is paid as soon as the approval in principle is applied for.
Duration: 2 to 4 weeks. Indicative cost: €800 to €2,000 gross (grant of €1,700, or €2,000 until 30 June 2027).
Obtaining detailed quotes and comparison
Based on the energy advisory report, request at least 3 quotes per work item from tradespeople registered with the Luxembourg Chamber of Skilled Trades. Only works carried out by accredited companies are subsidised. Quotes must be sufficiently detailed — description of works, surfaces, materials with certified thermal performance (U or R value), amounts excl. and incl. VAT.
Duration: 2 to 6 weeks. Cost: Free (non-binding quotes).
Agreement in principle application — DEPA-2026 form ⚠️ Critical step
This is the most important step in the pathway. Before starting works, you must submit an agreement in principle application via MyGuichet.lu (DEPA-2026 form). The agreement must be obtained before any work starts. Documents to provide include the signed DEPA-2026 form, the COAS-2026 sheet (renovation concept), the energy advisory report, the EPC before works, contractor quotes, proof of building age (over 10 years) and material technical data sheets. The first application must be submitted between 1 January 2026 and 31 December 2030.
Processing time: 4 to 8 weeks. Cost: Free.
Parallel applications: Enoprimes and municipal grants
In parallel with the Klimabonus application, submit your Enoprimes application to Enovos or SUDenergie (enoprimes.lu). This also requires prior agreement before signing the quote — not just before works begin. Also check with your municipal administration: 98 of the 100 communes pay their own grant (amount and procedure: applying for your commune’s grant).
Duration: 1 to 3 weeks. Cost: Free.
Municipal building permit (if applicable)
Depending on your municipality’s building regulation, works may be exempt or require a declaration or a building permit from the mayor: check this in particular for ETI modifying the facade appearance, roof modification, or geothermal heat pump installation requiring ground drilling. Check with your municipal planning department before starting.
Duration: 2 to 8 weeks. Cost: Variable.
Carrying out works — in the correct order
Once the agreement in principle is obtained and quotes are signed, works can begin. Sequencing is fundamental: start with the envelope (roof insulation, then walls, then windows) before installing or replacing the heating system. A heat pump installed before insulation will be oversized afterwards. During works, keep all material delivery notes and request a works completion certificate from each tradesperson.
Duration: 2 to 6 months. Allow 2 to 8 months for tradesperson lead times.
Energy performance certificate (EPC) after works (mandatory in pathway A)
After the works, have a new energy performance certificate (EPC) drawn up by an approved expert or by an OAI architect or consulting engineer: in the pathway with energy advice, the post-works EPC is a mandatory document of the Klimabonus payment application, just as the pre-works EPC was for the agreement in principle. It also proves the class improvement that unlocks the energy class bonus.
Duration: 1 to 2 weeks. Cost: about €500 to €600 incl. VAT for a house (fees are not regulated).
Payment application — receiving Klimabonus grants
After receiving final paid invoices, submit the grant payment application via MyGuichet.lu (CONF-2026 sheet “Confirmation rénovation énergétique”, with the DEPA-2026 form and the post-works EPC). This file must be submitted within 4 years of 31 December of the invoicing calendar year. Grants are transferred directly to your bank account.
Processing time: 4 to 12 weeks. Cost: Free.
Simulate your Klimabonus grants in a few minutes before launching your procedures.
Simulate my grants →Pathway B — single-element renovation (simplified procedure)
If you only wish to renovate one thermal envelope element, you can use the simplified procedure without a mandatory energy advisory. This procedure is faster but grants are strictly limited to the item concerned.
Elements eligible under the simplified procedure (one at a time): external wall insulation, roof or loft insulation, floor insulation, replacement of windows and French windows.
Obtain a quote from a certified tradesperson
Have a quote drawn up by a company registered with the Luxembourg Chamber of Skilled Trades. The quote must state the materials used and their thermal performance (R-value in m².K/W or U-value in W/m²K). A tradesperson holding the « Klima-Agence certified Artisan » label can handle the administrative procedures directly for individual measures.
Complete the DESC sheet and submit DEPA-2026
Complete the annex sheet « Description of the measure for the construction element » (DESC). This sheet must be signed by you and the tradesperson. Submit the DEPA-2026 form with the DESC sheet on MyGuichet.lu. Include proof of building age (over 10 years) and the cost estimate or quote. This step must be completed before works begin.
Carry out works after the agreement in principle
Only start works after receiving the official agreement in principle notification. Keep all documents: material delivery notes, signed installation certificate, the contractor’s warranty documents.
Payment application after invoicing
Submit your payment application (CONF-2026 sheet and DEPA-2026 form) with paid invoices and proof of payment within 4 years of 31 December of the invoicing year. Payment is made directly to your bank account within 4 to 12 weeks.
💡 Tip
Even under the simplified procedure, calling on an energy advisor to verify quote compliance earns you an additional €500 grant (€400 for occasional advisory + €100 for compliance verification).
The order of works (roof, walls, windows, ventilation, then heating sized for the insulated house, with photovoltaics last) is explained in our guide: which works to prioritise in an energy renovation. On the paperwork side, align this schedule with your approvals in principle: for insulation, windows and MVHR, each approval is requested before the stage concerned, and each element is subsidised only once.
Assembling the administrative file — required documents
To avoid back-and-forth with the single housing grants window, here is the complete list of documents to prepare according to the chosen procedure. An incomplete file is the most common cause of additional delay.
| Document | Pathway A (multi-element) | Pathway B (simplified single-element) | Where to obtain it |
|---|---|---|---|
| DEPA-2026 individual person form | ✓ Mandatory | ✓ Mandatory | MyGuichet.lu |
| Energy advisory report | ✓ Mandatory | ✗ Not required (unless +€500 grant sought) | Approved energy advisor |
| Energy performance certificate (EPC) before works | ✓ Mandatory | Not required by guichet.lu | Approved expert, OAI architect or consulting engineer |
| DESC sheet (measure description) | ✗ Replaced by the COAS-2026 sheet (renovation concept) | ✓ Mandatory | MyGuichet.lu — to complete with tradesperson |
| Quote or cost estimate | ✓ Mandatory | ✓ Mandatory | Tradesperson registered with Chamber of Skilled Trades |
| Original building permit (proof of age >10 years) | ✓ Mandatory | ✓ Mandatory | Municipality, cadastral archives or notarial deed |
| Construction plans (if extension) | If applicable | If applicable | Architect or municipality |
| COLL-2026 sheet (co-ownerships) | If co-ownership | If co-ownership | MyGuichet.lu |
| PROC-2026 proxy for each co-owner, or general-meeting minutes | If co-ownership | If co-ownership | MyGuichet.lu |
| For the payment application (after works): | |||
| CONF-2026 sheet (confirmation after works) | ✓ Mandatory | ✓ Mandatory | MyGuichet.lu |
| Energy performance certificate (EPC) after works | ✓ Mandatory | Not required by guichet.lu | Approved expert, OAI architect or consulting engineer |
| Detailed paid invoices | ✓ Mandatory | ✓ Mandatory | Tradesperson |
| Invoice payment proof | ✓ Mandatory | ✓ Mandatory | Bank statement or payment receipt |
| Bank account details (IBAN) | ✓ Mandatory | ✓ Mandatory | Your bank |
⚠️ Proof of building age
If you cannot find the original building permit, other official documents may be accepted: notarial purchase deed mentioning the construction date, municipal certificate, cadastral extract or land register extract. As a last resort, an expert can certify the building’s age based on a technical inspection.
Submitting your application on MyGuichet.lu — step-by-step guide
The MyGuichet.lu platform is the official portal of the Luxembourg administration for all online procedures, including Klimabonus applications.
Create or activate your MyGuichet account
Go to myguichet.lu. Login is via LuxTrust (token or card), the Luxembourg government mobile app, or eID. If you do not yet have a LuxTrust account, allow 1 to 2 weeks to obtain one. For foreign residents, login via eIDAS (European electronic identity card) is also accepted.
Access the DEPA-2026 form
In the « Housing grants » section of MyGuichet.lu, select « Klimabonus Wunnen 2026« , then choose the appropriate procedure. The DEPA-2026 form is entirely online and can be completed in multiple sessions — save your entry at any time.
Upload supporting documents
Scan all required documents in PDF or JPG format. Clearly name your files (e.g. « QUOTE_roof_insulation_tradeX.pdf »). Scan quality must allow unambiguous reading.
Submit and keep the receipt
After submission, you receive an electronic receipt with a case number. Keep this receipt: it proves the submission date. Paper submission is also possible at the single grants window or by registered post with acknowledgement of receipt.
Case tracking and receipt of agreement in principle
Your case progress is viewable at any time on MyGuichet.lu. The agreement in principle is notified officially within a typical 4 to 8 weeks. Wait for this written confirmation before starting works — not before, and not on the very day of receiving the notification.
Official Klimabonus 2026 calendar and deadlines
The 2026 Klimabonus scheme offers a long time window, but several key deadlines must be strictly respected to avoid losing all or part of the grants. These are limitation deadlines — they cannot be extended after expiry.
| Event / Deadline | Deadline date | Note |
|---|---|---|
| First agreement in principle application (DEPA-2026) | 31 December 2030 | Agreement to be obtained before any work begins (insulation, windows, MVHR) |
| Eligible invoices (works carried out) | Insulation, windows, MVHR: 1 Jan. 2026 → 31 Dec. 2035 | Technical installations and energy advice: until 31 Dec. 2030 (31 Dec. 2035 if carried out with an energy renovation); photovoltaics: 4 Jan. 2026 to 31 Dec. 2029 (2031 if ordered by end-2029). Invoices before 1 Jan. 2026: 2022 scheme possible |
| Energy advisory invoice | 31 December 2030 | Must be issued within the eligibility period to be reimbursed |
| Payment application (liquidation) | 4 years after 31 Dec. of the invoicing year | 2026 invoices → file before 31 Dec. 2030. Absolute limitation deadline. |
| Absolute payment deadline | 31 December 2039 | No application accepted after this date under any circumstances |
| Agreement in principle — processing time (indicative) | 4 to 8 weeks | Variable depending on AEV administrative workload |
| Grant payment after application (indicative) | 4 to 12 weeks | Direct bank transfer — extended during high-demand periods |
ℹ️ PV pre-financing (since 4 January 2026)
For photovoltaic installations only, the pre-financing mechanism allows an officially registered installer to deduct the Klimabonus subsidy directly from the final invoice. You therefore pay the net amount immediately — without advancing the subsidy amount and without waiting for the state to pay. For heat pumps and insulation, this pre-financing will only be possible for invoices issued from 1 January 2027.
Combining with Enoprimes
Enoprimes are complementary grants paid by energy suppliers under their energy efficiency obligations (not by network operators such as Creos). They are stackable with the Klimabonus and cover in particular thermal insulation and some technical equipment; the amounts are set out in the scale published on enoprimes.lu.
Check your eligibility on enoprimes.lu
Visit enoprimes.lu. Contrary to common belief, you do not need to be an Enovos or SUDenergie customer to benefit from Enoprimes — they are accessible to all Luxembourg residents whose home is connected to the Luxembourg distribution network.
Request Enoprimes prior agreement BEFORE works AND before signing the quote
Enoprimes require prior agreement before signing the quote — not just before works begin. This rule is stricter than the Klimabonus. Submit your application on enoprimes.lu with your tradesperson’s unsigned quote. The application is typically processed within 1 to 2 weeks.
Send invoices after works for payment
After works are completed, submit paid invoices and proof of payment on enoprimes.lu. Payment typically occurs within 4 to 8 weeks. Enoprimes management is entirely independent of the Klimabonus.
Combining with municipal grants
In 98 of the 100 communes, the commune tops up the Klimabonus with its own grant, most often a percentage of the state grant (10% to 50%), often capped. Example: in Luxembourg City, an air-to-water heat pump ordered before 30 June 2027 receives €12,000 from the state and €6,000 from the City (50%). You apply to the municipal administration, usually after the state decision, with a copy of it and your invoices: amounts, rules and steps on our page on municipal grants in all 100 communes.
PV pre-financing — the 2026 major innovation
Since 4 January 2026, photovoltaic installations benefit from a pre-financing mechanism: the Klimabonus subsidy is deducted directly from the final invoice by the installer, without you needing to advance the subsidy amount and wait for state reimbursement.
Choose an installer registered in the official registry
To benefit from pre-financing, your installer must be registered in the registry of installers admitted to the pre-financing procedure, published by the Ministry of the Economy on guichet.public.lu. Check this registry before contacting any PV installer.
The installer submits the grant application
Under the pre-financing scheme, it is the installer who submits the financial aid application to the administration. They deduct the subsidy amount directly from your final invoice. You pay only the net amount after subsidy, upon completion of works.
Conditions to be met
The installation must have a minimum capacity of 2 kWp, with no maximum capacity (the maximum subsidy of €10,000 is reached at 15 kWp). It must operate in self-consumption mode and be connected to the grid. A domestic battery can be included in the pre-financing (max. subsidy €2,250 for 9 kWh capacity).
7 critical errors that cause grants to be lost
Starting works before the agreement in principle
This is error number one and it is irreversible. If works begin before the official agreement in principle notification, all Klimabonus grants are permanently lost for the elements concerned. No exceptions are provided for in the regulations, and no appeal is possible.
Having works carried out by a non-accredited company
Only tradespeople registered with the Luxembourg Chamber of Skilled Trades are eligible. A non-registered tradesperson, however skilled, does not give entitlement to any grant. Check the tradesperson’s registration number on each quote before approving it.
Forgetting to apply for Enoprimes BEFORE signing the quote
Enoprimes require prior agreement before signing the quote — not just before works begin. A homeowner who only applied for the Klimabonus permanently loses this supplementary grant.
Submitting the payment application too late
The 4-year deadline from 31 December of the invoicing year is a limitation deadline: after this deadline, the right to the grant is permanently lost. For 2026 invoices, the payment application must be submitted before 31 December 2030.
Not keeping proof of invoice payment
The single grants window requires detailed paid invoices accompanied by proof of payment. An invoice without corresponding proof of payment will not be accepted in the payment application file. Scrupulously keep all bank statements covering your works payments.
Carrying out several elements under the simplified procedure to circumvent the energy advisory requirement
The simplified procedure (Pathway B) only applies to a single thermal envelope element. As soon as you are working on two or more elements, Pathway A with energy advisory is mandatory.
Choosing a PV installer not registered in the pre-financing registry
To benefit from the pre-financing mechanism, the installer must be registered in the Ministry of the Economy’s official registry. An unregistered installer cannot offer pre-financing: you will need to advance the subsidy amount and wait for standard reimbursement.
Before any large quotes: the energy advisor. Their audit orders the works, quantifies the gains and files the subsidy applications — and it is heavily subsidised.
Frequently asked questions about energy renovation procedures
How long does the whole process take from first step to grant payment?
For a complete project with energy advisory, allow 6 to 18 months in total: 1 to 2 months for the advisory and quotes, 4 to 8 weeks for the agreement in principle, 2 to 6 months for works (tradesperson lead times included), then 4 to 12 weeks for payment application processing. The earlier you begin administrative procedures, the better your cash flow will be preserved.
Can my tradesperson manage all the procedures on my behalf?
Some certified tradespeople offer full administrative support. This is a practical option, particularly for Pathway B. However, for Pathway A, the agreement in principle remains an official procedure in your name: you sign and submit the DEPA-2026 form yourself (in MyGuichet.lu with your own login, or on paper). Your tradesperson or advisor can prepare the file, but the final submission is yours.
Can I receive grants if I rent out my property?
Yes, subject to conditions. Landlords can apply for Klimabonus grants for renovation works on their Luxembourg rental property. Improving the energy class of a rental property is particularly relevant given discussions on rent regulation according to CPE class.
What if I no longer have the original building permit?
Other official documents proving the building’s age (over 10 years) may be accepted: notarial purchase deed mentioning the construction date, municipal certificate, cadastral extract or land register extract. If you encounter difficulties, contact your municipality or the National Archives. Check with the single grants window before blocking your file on this point.
Is the Klimabonus taxable?
The Klimabonus texts (law of 24 July 2026, guichet.lu pages) do not address its taxation, and renov.lu has found no published official position on the matter. If the home is let or used for business purposes, have the tax treatment of the grant and of the works checked with the Direct Tax Administration (ACD) or a tax adviser.
What happens if works cost less than the approved quote?
The grant is calculated on actual costs stated on invoices, not on the estimated quote. As the Klimabonus has paid flat-rate amounts since 2026 (per m² insulated or per installation), lower costs only reduce the grant if it exceeds its cap (60% of costs excluding VAT for insulation, the cost excluding VAT for a technical installation). If works cost more (unforeseen site issues), you can in some cases submit a modification request to the agreement in principle before exceeding the initial budget.
Is the Klima-Agence basic consultation different from the energy advisory with report?
Yes, these are two distinct services. The basic consultation is free, informal and produces no official report usable in a Klimabonus file. The energy advisory with report (paid, subsidised at €1,700, or €2,000 until 30 June 2027) is a regulated service producing a formal report mandatory for Pathway A. If in doubt, start with the free basic consultation to assess the scope of your project.
What number should I call if I have questions about the procedures?
The Klima-Agence has a free hotline: 8002 11 90, available Monday to Friday from 8am to 12pm and 1pm to 5pm (excluding public holidays). The service operates in French, Luxembourgish, German and English.