For the control of lamps, shutters and sockets is a variety of switches KNX available. Unfortunately, these are outrageously expensive and due to the required amount, they are are the reason for a huge part of the hardware costs.

If you instead relies on a combination of KNX universal interface and conventional buttons, you save a lot of money and and it looks very subtly.

In all places where I do not need more than 4 buttons, I could rely on the above-named combination. Only in 2 places I had to use 8x KNX push buttons to avoid my wall to be covered with unnecessarily many switch boxes.

The switching operations are performed by actors. Details can be found on pages about lighting and shutters.