At the latest, when the annual heating bill arrives, many people begin to wonder whether there might be an alternative to keeping the heating on constantly. If the apartment still does not feel properly warm despite the radiators working at full capacity, inadequate thermal insulation may be the reason. If draughty windows and doors are added to the problem, it is time to consider possible improvements. After all, a heating system that is constantly running also has a negative impact on your personal carbon footprint and environmental conscience.
Fortunately, there are now numerous options for retrofitting thermal insulation in your own apartment.
The first question that needs to be answered is: external or internal insulation?
External wall insulation is more commonly used, but it is not always feasible. This may be due to a listed façade, structural restrictions or simply because the external wall does not belong solely to you when you live in a condominium.
One possible form of external insulation is cavity wall insulation, which involves insulating the space between two masonry walls in a double-leaf external wall. Another option is a ventilated rainscreen façade, where the insulation forms part of a multi-layer external wall or façade construction. A third possibility is an external thermal insulation composite system. This consists of a fixing system, an insulating material, a reinforced base coat and a finishing layer.
Internal Insulation Measures
If these external insulation methods are not possible for one of the reasons mentioned above, retrofitting insulation to the interior may be a suitable alternative.
Until a few years ago, simple polystyrene boards were often glued beneath wallpaper to improve thermal insulation. Over time, however, insulation systems have become more complex. One reason for this is the need to prevent unpleasant side effects caused by choosing an unsuitable method, such as mould growth or thermal bridges. To avoid these problems, the measures must be precisely adapted to the respective property.
Various types of internal insulation may be considered. The first option is insulation using composite panels. This involves installing composite panels faced with insulating material, such as panels with a plasterboard surface and an insulating layer made of expanded polystyrene, or EPS.
The second option is insulation using a stud frame. In this method, a supporting frame is constructed and the insulating material is installed between the battens.
The third option is to bond the insulating material directly to the wall and then apply plaster over it. This is known as insulation with a plaster finish.
The fourth option is spray-applied insulation, in which cellulose insulation is sprayed directly onto the wall.
The most suitable method depends on the structural characteristics of the building and should be assessed by a qualified professional.
Support Through Funding Programmes
Please note that certain limits must also be observed when retrofitting thermal insulation in accordance with the German Energy Saving Ordinance, or EnEV. In some cases, additional insulation may even be mandatory for property owners, depending on the refurbishment standard currently prescribed for the respective property.
In this context, insulation measures may be eligible for support through funding programmes for energy-efficient refurbishment, as recommended by the German Federal Government through the KfW development bank. Regional funding programmes for thermal insulation may also be available. A prerequisite is generally that the relevant work is carried out by a qualified professional.
However, one important point must be considered: if windows and doors are not properly sealed, even the most effective internal insulation will provide limited benefits. Before starting any work, the areas requiring improvement should therefore be identified together with a specialist and a comprehensive approach should be adopted.
This can often address several issues at once. For example, replacing windows and doors can be combined with the installation of improved burglary protection.
Ultimately, new thermal insulation not only improves the overall indoor climate but can also sustainably increase the value of the property. Another positive side effect is that additional insulation can significantly reduce noise from neighbouring apartments.
