Improving the energy efficiency of the building envelope

Optimising the operating costs associated with the energy efficiency of your company’s building envelope

Much of the heating energy is lost through leaks in the poorly insulated or non-insulated building envelope. Improving the building envelope will therefore lead to considerable savings in heating and/or cooling requirements.

Definition of requirements for improving the energy envelope of buildings

Determination of the need for improvements to the building envelope

Careful analysis by an engineering office (technical consultant) is strongly recommended. Improvements can be detected using thermal imaging, drilling samples of the external walls or simply estimates of the constitution of the building envelope based on the year of construction and the experience of the envelope specialists.

The answers to the following questions will help to determine the renovation strategy and the need for envelope improvements

• What are the heating requirements in relation to the heated surface area?
• What are the heating costs?
• How much can I save on heating costs thanks to these improvements?
• Can I get financial subsidies?
• What is the condition of the building envelope, foundations, cellar and roof?
• Are there problems with draughts, cold rooms or overheating?
• Are there any long-term plans to expand (or redevelop) the premises?

Implementation of specific measures

The following points should be borne in mind when planning and implementing the project:

Roof

• Combine with the construction of a solar thermal (hot water production) or photovoltaic (electricity production) system.

• The correct construction from a building physics point of view must be ensured by a specialist.

• Flat roofs: green roofs regulate the climate, create additional ecological living space and relieve the drainage system.

• Pitched roof: Insulation can be installed between the rafters, between and below the rafters, or above the rafters.

• In all cases, the airtight layer must be checked

Windows and facade

• If possible, combine façade insulation with the installation of new windows.

• Ideally, the width of the frame should allow the window reveal to be insulated at a later date.

• Façade insulation is generally fitted externally; in exceptional cases (heritage, etc.), it may be necessary to fit insulation internally. In this specific case, it is strongly recommended that you contact an engineering office, as the installation is more technical.
• Façade insulation can be installed as a compact system or as a ventilated curtain wall, depending on the final cladding chosen.

Cellar ceiling and attic slab insulation

• Avoid heating unused rooms (cellars and attics) from adjacent heated rooms.

• Don’t forget to insulate doors, staircases and walls between heated and unheated rooms.

• Use the maximum possible thickness of insulation, without covering heating pipes or other technical installations.

Installation of controlled ventilation

• The more airtight the building, the lower the natural air exchange. To guarantee air quality within the building, it can be useful to install controlled ventilation.

• Controlled ventilation also serves to recover heat from stale air (only its heat, transmitted to fresh air via a heat exchanger), prevent damage from humidity and ensure good, constant air quality as required.

Subsidy application

Government subsidies

Temporary environmental impact aid

Extended “SME Packages Sustainability” aid scheme, to give companies greater incentives to invest in measures that significantly improve their environmental impact. Investments under this climate protection measure amount to 70 % for small businesses, 60 % for medium-sized businesses and 50 % for large businesses for projects costing more than €7 500, with a maximum subsidy amount of €100 000.

• Verification of company eligibility and costs: Ministry of the Economy (Department for Support to SMEs)
• Application deadline: 30 June 2025
• Any questions?
  • Chamber of Commerce
  • Chambre des Métiers (Chamber of Skilled Trades and Crafts)

SME Packages – Sustainability

Aide forfaitaire de 5 000 € destinée aux petites et moyennes entreprises pour des projets permettant de réduire leur impact environnemental, d’un montant compris entre 6 650 € et 25 000 € HTVA

• Des questions ?
  • Chambre des Métiers pour les artisans
  • Chambre de Commerce pour les entreprises des secteurs hors-artisanat

SME aid scheme – Aid for miscellaneous investments

Subsidies for small and medium-sized businesses, up to 10 % or 20 % of the amount of miscellaneous investments aimed at promoting the modernisation and competitiveness of the Luxembourg economy.

• Verification of company eligibility and costs: Ministry of the Economy (Department for Support to SMEs)
• Any questions?
• Chamber of Commerce
• Chambre des Métiers (Chamber of Skilled Trades and Crafts)

N.B. State subsidies cannot be combined for the same project.

Application for subsidies from electricity and natural gas suppliers

Since 2015, natural gas and electricity suppliers have been required to make energy savings for consumers under the obligation scheme. Since then, energy suppliers have been offering support and advice, as well as subsidy programmes for consumers to implement energy efficiency measures.

The following suppliers offer this service for companies:

• Enoprimes Enovos + SUDenergie
• SUDenergie
• Sudstroum

N.B. Supplier subsidies can be combined with any state subsidies for the same project.

After completion of the works

Heating replacement

Heat requirements fall sharply after a building has been insulated. It is therefore advisable to wait until the building envelope improvements have been completed before replacing the heating system, to avoid oversizing the new heat production unit.