Avoiding CO2 emissions and saving energy are essential requirements for achieving climate protection targets. In this context, optimised structural thermal insulation in particular ensures the required reduction in energy demand and ultimately that heat pumps can provide heat efficiently and with good annual coefficients of performance. As far as the heat requirement is concerned, the window component is of particular importance, as not only heat losses occur here, but also usable solar heat input. The higher the thermal insulation level of a building, the greater the proportion of the heating requirement that can be covered by utilisable solar heat input. In addition to winter thermal insulation, summer thermal insulation is also becoming increasingly important as climate change continues ...