Energy Renovation in Luxembourg: Where to Start in 2026?

Step 1 — Assess Your Property: The Initial Diagnosis

Before anything else, you need to know your starting point: your home’s current energy class, its main weaknesses, and realistic improvement potential. Three immediate questions: Do you have an EPC less than 4 years old? Is your property over 10 years old (date of building permit — the mandatory condition for Klimabonus)? Are you the owner? The Klimabonus is reserved for property owners; tenants cannot apply directly. In co-owned buildings, works on common parts (roof, façade) require a vote at the general assembly. Use the Renov.lu simulator to get a first personalised estimate in under 5 minutes — free, no commitment.

Step 2 — The Energy Performance Certificate: Mandatory or Optional?

The EPC (Energiepass) is issued by an OAI-registered architect or engineer, or an accredited expert, using the official LuxEeB-H method. It rates your home from A+ to I on three dimensions and identifies heat loss hotspots. For a single-element measure by a Klima-Agence certified contractor, no EPC is required before or after works. For multi-element projects (two or more measures), an energy advisor’s report is mandatory to access Klimabonus grants. After significant works, updating the EPC is legally required. For sale or rental: always mandatory (fine up to €5,000 if missing). Cost: €475–600 for a single-family home — covered by the Klimabonus energy advisory grant (up to €1,500).

Step 3 — Consult an Accredited Energy Advisor

The accredited energy advisor is the cornerstone of the Klimabonus system. For projects involving two or more elements, their involvement is mandatory to access grants. Only advisors accredited by the Minister of Environment under the law of 21 April 1993, and enrolled in a quality assurance system since 15 December 2018, are authorised to produce the required reports. In practice, the advisor visits your home, analyses the building envelope and technical systems, establishes or uses your existing EPC, simulates renovation scenarios with estimated class gains and grant amounts, writes the mandatory renovation logbook, and recommends the optimal order of works. The energy advisory fee is subsidised up to €1,500 via Klimabonus 2026. For a single measure with punctual advisory support: €400 grant (+ €100 for offer compliance check). Accredited advisors can be found at guichet.public.lu and klima-agence.lu.

Step 4 — Define Your Priority Works: The Golden Rule

The recommended order: (1) Roof/loft insulation — 25–30% of heat losses, lowest cost per gain, €15–35/m²; (2) External wall insulation (EWI) — 15–25% of losses, eliminates thermal bridges, €120–250/m²; (3) Triple-glazed windows — Uw ≤ 1.0 W/m²K, ideally done alongside EWI; (4) MVHR ventilation — mandatory for class B or above, efficiency ≥ 80%; (5) Heat pump — now that the building is insulated, the heat pump is correctly sized and efficient, up to €10,000 Klimabonus for air/water, €12,000 for geothermal; (6) Photovoltaics — last step, up to €10,000 Klimabonus with pre-financing since January 2026.

Step 5 — Get and Compare Quotes from Certified Contractors

For Klimabonus eligibility, the contractor must be registered with the Luxembourg Chamber of Crafts (Chambre des Métiers) and RCS/RNE. A foreign company without a Luxembourg establishment cannot make you eligible for grants. Look for the « Klima-Agence certified artisan » qualification (for single-element projects) or the « Nohalteg an d’Zukunft + » label (quality label, Chambre des Métiers + Klima-Agence, valid 5 years). Get at least 3 detailed quotes per trade — price variations in Luxembourg can be 2–3× for identical work. A valid Klimabonus quote must include the contractor’s RCS/RNE number, detailed material references, precise surfaces, prices at 3% VAT, and compliance with Klimabonus technical requirements.

Step 6 — The Klimabonus Prior Agreement: The Non-Negotiable Rule

The application is made via myguichet.lu. Required documents: official DEPA-2026 form, current EPC (or energy advisor’s report for multi-element projects), renovation logbook (multi-element projects), detailed contractor quotes, proof of ownership. Key deadlines: first prior agreement application between 1 January 2026 and 31 December 2030; invoices between 1 January 2026 and 31 December 2035; liquidation request within 4 years of 31 December of the billing year. The Klimabonus can only be claimed once per building element per building.

Step 7 — Submit the Enoprimes Application in Parallel

Enoprimes are grants from energy supplier Enovos/Encevo for efficient equipment (heat pumps, insulation, windows…). They are stackable with Klimabonus and can add several thousand euros in additional grants. Just like Klimabonus, the Enoprimes prior agreement must be obtained before accepting quotes and committing expenses — check enoprimes.lu. Other complementary grants: municipal grants (vary by commune); 3% VAT rate on renovation works for homes over 10 years old (vs standard 17%), capped at €50,000 recoverable VAT per property across all renovation work; landlord tax deduction: 6% accelerated depreciation over 10 years on eligible Klimabonus expenditure.

Step 8 — Finance the Remaining Cost

Even with maximum Klimabonus grants (in practice 30–45% of total project cost), there’s still a portion to finance yourself. Key options: Klimaprêt — subsidised loan from Luxembourg state-approved banks (1.5% interest subsidy, up to €100,000, max 15 years, mortgage-secured; partner banks: BCEE, BGL BNP Paribas and others); PV pre-financing — since January 2026, the Klimabonus grant for photovoltaics can be deducted directly from the installer’s invoice, so you only pay the net amount immediately; Standard renovation credit — from your regular bank for remaining portions. Important: Klimabonus grants are paid after works are completed — plan to pre-finance the full cost. Reimbursement typically takes 3–6 months after submitting the complete liquidation file.

Step 9 — Manage the Works and Meet Technical Requirements

Building permit in Luxembourg: interior works not affecting structure, roof or external appearance generally don’t require a permit. Façade modifications (EWI, rendering) typically require a works declaration or permit depending on the commune and scope — always check with your local authority. Extensions, roof changes and changes of use require a full building permit. Consult geoportail.lu for your commune’s General Development Plan (PAG). Klimabonus technical requirements to monitor on site: minimum insulation thicknesses per measure and performance level; windows Uw ≤ 1.0 W/m²K (triple glazing); heat pump COP ≥ 3.5, correctly sized; MVHR efficiency ≥ 80%; materials compliant with environmental requirements (≥50% recycled content for fossil-origin insulants). The energy advisor can perform on-site control visits (subsidised €75–200) — useful to catch non-compliances before they block your grant payment.

Step 10 — Update Your EPC and Collect Your Grants

Updating the EPC after significant performance-changing works is legally mandatory and strongly recommended to certify your new class and enhance property value. Without an updated EPC, you cannot prove your class gain for sale or rental purposes. Klimabonus liquidation file: submit on myguichet.lu with paid invoices and payment proofs, equipment technical datasheets, before/after photos, energy advisor’s verification report if applicable, and for co-owned buildings: COLL-2026 annex and PROC-2026 power-of-attorney from each owner. Deadline: within 4 years of 31 December of the billing year — missing this permanently forfeits your rights.

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