Energy standards for new construction in Luxembourg 2026
By Yacine Sahnoune, founder of renov.lu
Since 1 January 2017 (date of the building permit application), every new home in Luxembourg must be a nearly zero-energy building (NZEB). Learn about mandatory requirements for insulation, ventilation, heat pumps, solar panels and energy certificates to build legally in the Grand Duchy.
- NZEB requirement: every new home whose building permit was applied for since 1 January 2017 must be a nearly zero-energy building (NZEB): its primary energy and heating needs may not exceed those of a reference building.
- Reference building: since 1 January 2023 it is heated by an air-to-water heat pump: in practice, a gas boiler can no longer meet the building permit requirements.
- Energy performance certificate: mandatory for every new build, it is valid for 10 years and rates the building from A+ to I on 3 indicators; the “as built” calculation goes to the mayor within 2 months of final acceptance.
- Klimabonus for new builds: an air-to-water heat pump receives €3,000 per house; balanced ventilation and insulation are only subsidised in existing homes.
- “Sustainable housing” grant: only for building permits applied for by 31 December 2026, with at least 60% of LENOZ points per category; invoices accepted until 31 December 2029.
- Application: for a heat pump or photovoltaics, you apply after installation, within 4 years following the year of the invoice.
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Request a free quote- 1. NZEB standard: mandatory since 2017
- 2. NZEB level (formerly « AAA »): characteristics
- 3. Energy certificate: legal requirements
- 4. Thermal insulation: mandatory U-values
- 5. Air tightness (n50) and double-flow ventilation
- 6. Heat pumps and renewable energies
- 7. Solar panels for new construction
- 8. Klimabonus certification and financial aid
- 9. Grand Ducal regulation: reference texts
- Frequently Asked Questions
1. NZEB Standard: Mandatory Since 2017 in Luxembourg
Since January 1, 2017 (date of the building permit application), every new residential building construction in Luxembourg must be a Nearly Zero Energy Building (NZEB). This requirement stems from the European Directive 2010/31/EU on building energy performance, transposed into Luxembourg law.
The NZEB standard means that the building has very high energy performance and the remaining energy needs are largely covered by renewable energy. To obtain a building permit in Luxembourg, new buildings must demonstrate that their total primary energy demand and heating demand do not exceed those of a reference building, under the Grand-Ducal Regulation of 9 June 2021 (in force since 1 July 2021). Since 1 January 2023, this reference building has been heated by an air-to-water heat pump.
The NZEB standard does not impose a specific mandatory energy class, but rather overall energy performance. The « AAA » label comes from the former 2007 regulation: since the Grand-Ducal Regulation of 9 June 2021, the energy performance certificate rates buildings from A+ to I.
2. NZEB Level (formerly « AAA »): Characteristics and Requirements
The NZEB level, often called « AAA » after the 2007 regulation’s scale (the 2017 requirement actually matched class A for primary energy and class A for thermal insulation; the best certificate class is now A+), means excellent energy performance, very high thermal insulation, and low environmental impact. NZEB buildings combine insulation exceeding standards, high-performance windows, absence of thermal bridges, and use of renewable energies.
Main characteristics of the NZEB level:
Maximum thermal insulation: walls, roofs and floors insulated to the best standards (very low U-values)
Triple glazed windows: with Ug coefficient ≤ 0.5 W/(m²K) for optimal performance
No thermal bridges: thermally insulated balconies, reinforced frames
Enhanced air tightness: n50 ≤ 0.6 h⁻¹ to limit air leakage
Controlled ventilation: with heat recovery (double flow)
Renewable energies: a heat pump (the calculation reference since 2023), often combined with solar panels
3. Energy Passport: Legal Requirements and Procedure
The energy passport (or energy performance certificate – EPC) is a mandatory document in Luxembourg for any new construction, sale, rental or renovation of a residential building. It certifies the building’s energy performance on a scale from A+ to I.
Energy passport obligation:
- Mandatory when constructing a new building
- Mandatory when extending an existing building
- Mandatory on sale or rental of a property
- Mandatory during major renovation
Contents of the energy passport:
- Calculated energy requirement of the building
- Associated CO2 emissions
- Energy classification (from A+ to I, for 3 indicators)
- Improvement recommendations
- Details of technical installations
The energy passport remains valid for 10 years from the date of issue, unless major modifications to the building occur. For new construction, an « as built » calculation must also be sent to the mayor (bourgmestre) within 2 months of final acceptance or first use.
4. Thermal Insulation: Mandatory U-values for New Construction
Thermal insulation is one of the key elements to achieve the NZEB standard in Luxembourg. U-values (thermal transmission coefficient) define the insulation performance of each building element. Lower U-values mean better insulation.
U-values recommended for NZEB construction in Luxembourg:
| Building element | Recommended U-value (W/m²K) | Description |
|---|---|---|
| External walls | ≤ 0.15 | Very thick insulation, insulated frame |
| Roof / Attic | ≤ 0.13 | Maximum insulation, minimum 25cm |
| Ground floor | ≤ 0.12 | Insulation of floor on ground |
| Entry doors | ≤ 0.80 | Insulated doors with high-performance seals |
| Windows (Ug) | ≤ 0.50 | Triple glazed high-performance windows |
| Window frames (Uf) | ≤ 0.13 | Thermally insulated frames |
To achieve these optimal U-values, prefer external insulation (EWI) or distributed insulation within wall thickness. Internal insulation reduces usable space and is less effective.
5. Air Tightness (n50) and Double-Flow Ventilation
Air tightness and controlled ventilation are essential to guarantee the energy performance of an NZEB building. A poorly sealed building loses heat through air infiltration, which cancels out the benefits of insulation.
Air tightness (n50):
The n50 index measures the number of air changes per hour at 50 Pa pressure difference. For new NZEB construction in Luxembourg:
n50 ≤ 0.6 h⁻¹ for NZEB buildings
Mandatory air tightness test by pressurization (Blower Door Test) to certify performance
Sealing tapes, membranes, high-performance seals, careful window installation
Double-flow ventilation (HRV):
Double-flow ventilation is highly recommended and practically mandatory to achieve the NZEB level. It combines:
- Stale air extraction: warm air leaving the building
- Heat recovery: outgoing warm air heats incoming fresh air
- Filtration: incoming air is filtered (no pollen, pollution)
- Humidity control: maintaining healthy humidity (40-60%)
Ventilation ducts must be insulated and properly sized. Recovery efficiency must reach a minimum of 75-80% to contribute to NZEB performance.
6. Heat Pumps and Renewable Energies
To achieve the NZEB standard in Luxembourg, renewable energy sources are essential. Heat pumps (HP) are an essential solution for heating and domestic hot water production.
Types of heat pumps for new construction:
Air-to-air HP: extracts heat from outside air, economical and easy to install
Air-to-water HP: provides heating and hot water via radiators or floor heating
Geothermal HP: highly efficient, extracts heat from soil, COP up to 5
Water-to-water HP: uses groundwater source, excellent performance
Required efficiency:
COP (Coefficient Of Performance) measures heat pump energy efficiency:
- Air-to-air/air-to-water HP: minimum COP 3.5-4.0
- Geothermal HP: minimum COP 4.5-5.0
- These figures guarantee significant CO2 emission reductions
Combine the heat pump with photovoltaic solar panels to partially cover electricity consumption. This combination is ideal for achieving near-zero emissions.
7. Solar Panels for New Construction in Luxembourg
Photovoltaic solar panels are highly encouraged, though not mandatory, as part of NZEB construction in Luxembourg. They generate the electricity needed for heat pumps and electrical appliances.
Solar panel requirements:
- Recommended installation: roof, south-east to south-west orientation
- Minimum power: proportional to the building’s energy consumption
- Efficiency: modern panels 18-22% efficiency
- Storage battery: optional but recommended for self-sufficiency (lithium or LiFePO4)
Solar production in Luxembourg:
In Luxembourg, average sunlight is 1,200-1,400 kWh/m²/year, allowing good solar electricity production. A photovoltaic installation of 6-10 kWp can cover 50-80% of an NZEB house’s energy needs.
Solar panel integration is an eligibility criterion for certain Klimabonus aids. Panels must be certified and installed by approved professionals.
8. Klimabonus Certification and Financial Aid for Sustainable Construction
The Klimabonus program is a financial aid scheme from the Luxembourg government to promote sustainable construction and energy efficiency. For new construction compliant with NZEB, substantial subsidies are available.
Types of Klimabonus aid for new construction:
Sustainable housing aid (2022 scheme): for building permits applied for until 31 December 2026, provided at least 60% of the LENOZ points are achieved in each category
Renewable installations aid: photovoltaic panels, batteries, air-to-water heat pump (€3,000 per house); double-flow ventilation is only subsidised in existing homes
Certification and compliance: the energy performance certificate is not subsidised
Amounts and conditions:
- Subsidies vary according to elements installed and living space
- Since 2026, the Klimabonus pays flat-rate amounts (per installation) rather than percentages
- For a heat pump or photovoltaics, the application is filed after installation, within 4 years of the end of the invoice year
- Invoices accepted until December 31, 2029 for the sustainable housing aid and until December 31, 2030 for a heat pump
Check the emwelt.lu or Guichet.lu portal for precise conditions, current amounts and application forms. Rules change regularly.
9. Grand Ducal Regulation: Reference Texts for Construction in Luxembourg
Luxembourg building and energy regulations are defined by several legal texts. Here are the main reference documents:
Essential legislative texts:
- Directive 2010/31/EU (EPBD): European Directive on building energy performance, transposed into Luxembourg law
- Grand Ducal Regulation of June 9, 2021: Comprehensive regulation concerning building energy performance in Luxembourg
- Law of December 23, 2016: Establishes financial aid scheme for promoting sustainability and rational energy use (Klimabonus)
- Law of July 24, 2026: Klimabonus Wunnen 2026-2030 scheme, replacing since January 1, 2026 the scheme based on the 2016 law
- Luxembourg NZEB Rules: energy performance calculation method set out in the annexes of the Grand-Ducal Regulation of 9 June 2021
Administrative documents:
- Presentation and FAQ on the Grand-Ducal Regulation of 9 June 2021 published by the ministry in charge of energy
- Guichet.lu forms for permit and energy certificate applications
- Klima-Agence documentation (public advisory body)
- Technical specifications for energy certificate calculation
Regulations are updated regularly. Always consult official sources (gouvernement.lu, emwelt.lu, guichet.lu) before starting construction work.
Frequently Asked Questions about Energy Standards for New Construction
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