FAQ

For a new building, the construction elements of the thermal envelope (= external structure) as well as internal walls and slabs are taken into account.

For the elements of the external structure, all the layers taken into consideration for calculation of the U value are also taken into consideration for calculation of the I _env and I_prim indicators.

Party walls and partition walls between different units in a block of flats should be considered internal walls (within the building envelope).

For existing buildings, only new insulating materials used during the retrofitting works are taken into consideration.

For existing buildings, only the primary energy requirement of the technical installations for conditioning the building should be considered for the I_prim indicator (Chapter 4.2). The primary energy expenditure of the existing building is not taken into account. 

A LENOZ certificate can be issued for all residential buildings with an energy passport, whether they are new or existing residential buildings. Issuance of the certificate is associated with Class 4 "minimum sustainability" (Chapter 0.2 of the Annex to the Grand Ducal Regulation on housing sustainability certification). Existing residential buildings can achieve this "minimum sustainability" by means of comprehensive retrofitting works.

The possibility of developing integrated housing in single-family homes is dealt with in the Particular Development Plan (PAP). For PAGs that have been completely revised since 2011, the development of an integrated dwelling is permitted unless the municipality expressly rejects it in the PAP.

According to the Grand Ducal Regulation in force, an integrated dwelling is defined as additional accommodation forming part of a single-family house and belonging to the owner of the main dwelling. In theory, integrated dwellings allow for a soft densification of existing structures.

• Demolition: sale of a ruin or a building that does not have a heating installation and which will be demolished after purchase.
• Inheritance or gift.

• New building: any building that is subject to a building permit application. (A feasibility study concerning the use of renewable energies should be appended to the building permit application.)
• Extension of an existing building.
• Modification of an existing building (building permit required), if the surface area of the modified element of the thermal envelope exceeds the surface area of the same existing element (walls, windows, roof, etc.) by 10% and if the modification has an impact on the energy performance of the building. (Issuance of an energy performance certificate for the new planned situation.)
• Substantial alterations to an existing building (without a building permit), if the surface area of the altered element of the thermal envelope exceeds the surface area of the same existing element (walls, windows, roof, etc.) by 10% and if the alteration has an impact on the energy performance of the building. (Issuance of an energy performance certificate for the new planned situation.)
• Change of owner or tenant.
• Demolition: sale of a building that will be demolished after purchase, if the building has a heating installation, exterior walls and a roof.
• Modification of technical facilities, if the modifications of these technical facilities exceed €1,500 (for a single-family house) or €3,000 (for a multi-family house).

The energy performance certificate is a regulatory obligation, therefore no subsidy is provided for its establishment.
The energy performance certificate is issued according to precise rules set out in the amended Grand Ducal Regulation of 30 November 2007 on the energy performance of residential buildings. It is valid for 10 years from the day of its issue. The issuance of an energy performance certificate and the information it contains shall not result in any direct obligation for energy retrofitting.

The energy performance certificate (EPC) or energy passport is the quality label that defines the energy performance of a residential building. The certificate provides information on the energy efficiency of residential buildings and thus allows comparisons to be made with other residential buildings. Thus, even without technical knowledge, the consumer can assess the energy quality of a residential building.