In energy-saving measures, the exterior walls are of particular importance. They form the largest part of the boundary surface of the building envelope and thus the largest part of the heat exchange surface.
For old buildings with a 24 cm thick brick wall, U-value approx. 2.0 W/m²K, the required U-value of 0.24 W/m²K according to the Building Energy Act can be achieved with an additional thermal insulation layer of ETICS of 16 cm (see GEG 2021).
Energy-saving measures are therefore economically and ecologically efficient. The required heat transfer coefficients for walls can only be achieved with additional thermal insulation.
Various analysis methods, e.g. thermography and blower door, can be used to visualize heat losses in the area of the building envelope.
The Blower-Door method checks the airtightness of a building and thus detects heat leaks through which warm air flows uncontrolled from the inside to the outside.
The method is explained in more detail in a video at:
Before applying the thermal insulation, the walls must be inspected for any existing structural damage.
The picture shows moisture damage.
surface, and moisture damage in the exterior wall can have many different
To carry out a permanent, proper renovation, the damage must be repaired.
Various methods are available to repair the damage: mechanical methods and injection methods
In mechanical processes, continuous horizontal slits are made through the wall of approx. 1m length and sealing materials are installed.
The joints must overlap sufficiently to achieve the moisture barrier.
Moisture penetrating laterally from outside into the basement walls can rise to the first-floor area by capillary action.
Heat losses are also given via the basement walls. If basement rooms are used as utility and recreation rooms, heat insulation measures reduce energy losses.
For reasons of building physics, exterior insulation is preferable.
Only moisture-resistant thermal insulation materials are suitable.
Insulation on the outside wall prevents the penetration of moisture.
After completion of the necessary renovation work, the thermal insulation measures can be carried out. It is possible to insulate outside or inside.
With external insulation, there are fewer thermal bridges and building physics problems, so it should be preferred. The thermal insulation can consist of different building constructions and building materials, e.g.:
External thermal insulation composite systems consist of thermal insulation, reinforcement, and final coating.
Polystyrene, mineral wool, mineral foam, or cork can be chosen as the insulation material.
Depending on the load-bearing capacity and surface quality of the wall, the panels are fastened using adhesive mortar, dowels, or rails.
To prevent cracking in the outer wall, a reinforcement layer is applied to the entire surface of the thermal insulation boards and a reinforcement fabric is inserted.
Afterwards, the final coating, which is resistant to driving rain and permeable to water vapor, is applied.
insulation plaster consists of the thermal insulation layer and the exterior
It is applied in one or two layers on a dry and load-bearing wall, depending on the chosen thickness.
The external plaster is applied to the thoroughly dried thermal insulation plaster.
In addition to single-layer external walls, multi-layer external walls with thermal insulation can be selected.
External walls with a light facing layer consist of a load-bearing external wall, the thermal insulation, and the facing layer.
In these methods, the thermal insulation, e.g. mineral wool, is placed between the supporting framework of the curtain wall.
The facing layer can be made of wood, metal, plastic, or slate, and it forms the end of the ventilated façade.
rear-ventilated systems with a heavy facing layer of brick, lime sand, or
natural stone, the insulation boards are attached seamlessly to the exterior
wall in a bond.
The distance between the facing layer and insulation must be at least 4 cm to ensure sufficient rear ventilation.
In the case of double-shell walls, core insulation is a good choice as thermal insulation fill.
This can consist of cork shot, polystyrene beads, perlite, or cellulose.
that are listed as historical monuments may only be insulated on the
Internal insulation creates thermal bridges in the area of the interior walls and ceilings; it must be checked whether a vapor barrier or vapor control layer is required.
Timber frame buildings may not be covered by wall coverings; the original architectural design must be preserved.
Energy-saving measures can be achieved by replacing the infill with well-insulating materials.
If renovation measures are necessary, infillings made of clay should be retained.
Heat losses are also given via the basment walls.
If basement rooms are used as utility and recreation rooms, heat insulation measures reduce energy losses.
For reasons of building physics, exterior insulation is preferable. Only moisture-resistant thermal insulation materials are suitable.