What would you do differently in the next house construction?

I simply wouldn't have time to deal with it.

You don't have to either, everything is available ready-made according to the builder's wishes from the professional. You don't build a phone yourself either, you just buy one.

The sockets themselves do not obstruct the opening. Even with a normal plug, it's still okay. It was sold to us as a great invention for Christmas lights. It’s also quite practical if you don’t have to run three distribution boxes all the way to the window... but if you add a timer in between, that’s already a "chunk"...

It helps if you put all the sockets in the window recesses on one circuit, which then includes a timer module in the switch box. That’s how it’s solved in my apartment ... just Erzgebirge with the "obligation" of the Schwibbogen at Christmas time. And, very practical. And better off in the recess than in the wall section under the window, because this way the cables for the Schwibbogen are practically not noticeable.

A phone = €30
KNX = €30,000 (incl. electrical)

The offers here in the forum unfortunately illustrate this.

We received 7500 euros for the painting work and I managed it with about 500 euros ...

What?! For the whole house interior?!
We would have received over 20,000. Filling, wallpapering everything, painting twice, some rooms with textured plaster, whitewashing all basement rooms, waxing the wooden beam ceiling on the ground floor completely twice...
We have already paid 1000€ for materials (primer & paint) for the exterior wood coating!

No, just painting, priming, and 2x. [emoji4] Q3 plaster 7000 euros extra. Final coat on underside of roof 2500 euros We didn't do any wallpapering, so no prices there. So it probably all falls within your price range. [emoji6]

Our general contractor is charging an additional €17,000 for a central ventilation and exhaust system. Two other construction companies even quoted significantly higher (19,000, 20,000).

Wow, how different that is. We don't even have €14,000 for a central ventilation system for three floors [emoji15]