FAQ

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In principle, a wall does not breathe. Air renewal and moisture removal are only achieved by ventilation (via windows or the installation of comfort ventilation, i.e. controlled mechanical ventilation – CMV). The effect of 'breathing' as mentioned above refers to the transfer of moisture by the diffusion of water vapour. In practice, this is minimal and does not play any role in moisture removal. On the other hand, it is important for interior plaster to be able to absorb moisture from the air and release it back into the interior after ventilation. The effect of moisture regulation effect therefore only operates within the first few centimetres (on the interior side) of a wall. For example, clay plaster on internal walls provides excellent moisture regulation.

Joints can cause significant heat loss. In winter, warm, moist air escapes to the outside via areas that are not tightly sealed, i.e. joints and cracks. This leads to the air cooling down and humidity condensing, which can give rise to the formation of mould in the recesses. In order to detect heat loss, thermal imaging is recommended.

An energy retrofit of a building (insulating the façade and roof, as well as replacing the windows) seals the building more tightly and can thus improve energy performance.

Buildings constructed between 1900 and 1970 have enormous potential for energy retrofitting. To find out the energy performance of your building’s insulation, it is necessary to analyse each project individually. Klima-Agence offers you a free energy diagnosis to check the state of your home's insulation.

Insulating materials are not all flammable. Insulating materials are divided into different fire protection categories. A European standard regulates the classification of materials and building types according to their fire behaviour.
In principle, insulating materials made out of minerals are non-flammable. They are taken into account in the Luxembourg sustainable housing certification (LENOZ) framework and can thus receive state financing as part of an overall concept. This also applies to retrofits: choosing insulating materials of mineral origin makes it possible to obtain higher financing compared to conventional materials.

Some materials used as façade coverings may be flammable. This is why it is important to take into account the overall make-up of the external wall. However, this may also include flame retardants (i.e. sealant, firewall, etc.) and thus provide protection against the spread of flames.

Insulation is one of the most important measures to take when boosting the energy efficiency of a building. No other measure can save as much energy for heating. 

Manufacturing the insulating materials consumes much less energy than the materials ultimately save. The energy used to manufacture insulation materials is marginal compared to the energy saved in a dwelling over a period of 20 to 30 years. As such, the energy consumed in manufacturing insulation does not constitute an argument against energy retrofitting, but it can very well influence the choice of insulating material. According to Klimabonus State aid criteria, environmentally friendly insulation requires little energy to produce.

The Klimabonus programme provides substantial subsidies for the use of environmentally friendly insulation.

In all cases, a properly executed energy retrofit improves the energy efficiency of the building and helps to reduce dependence on higher energy prices by reducing energy consumption for heating. In order to guarantee the sustainability of a dwelling and to maintain/increase its value, its maintenance and modernisation need to be considered in view of the long term. Whereas some retrofitted elements might depreciate in 10 or 20 years, for other elements this can happen much faster. To learn more about the potential for improving the energy efficiency of your home, request a free energy assessment with a Klima-Agence adviser.

Various State and municipal aid is also available to help finance your energy retrofitting project.

When replacing windows, one should take care to ensure that the walls are properly insulated. If the energy quality of the window is higher than that of the wall, humidity can condense on the walls, thus giving rise to the formation of mould. Condensation always appears in the coldest places.

To benefit from Klimabonus support, the performance of the wall insulation must be higher than that of the new window, or the windows must be replaced and controlled mechanical ventilation installed. When replacing windows, it may therefore also be necessary to insulate the façade. Contact your Klima-Agence adviser to determine the insulation performance of your building (free energy assessment).

In any case, after your windows have been replaced, proper daily ventilation must be ensured to maintain a healthy climate in your home.