Ground plan design single-family house 165 sqm without basement on 400 sqm plot

Thank you, a few points cannot be implemented, but I will keep some in mind.

By now, it should be clear to you that you should let an expert handle this. This is not meant in a negative way!

Yes, that is clear. But who is an expert? That's not written on anyone's forehead. Some have certificates, diplomas, and architectural firms with several employed architects in the office who plan, but obviously that means nothing, as I am just realizing.

Well, whatever. The issue will somehow work itself out.

Every architect should be able to do that better. Was your building application prepared by an architect?

Yes, of course. I left the planner of the construction company very, very early. After the first proposals, I stopped, the architect took over and ultimately also prepared the building application.

There are quite a few 1 x 1 m windows. That leaves an effective glass area of at best 0.8 x 0.8 m. With such small windows, a lot of area is simply taken up by the frame.

Many windows have a top edge at 1.9 m. Assuming a window frame width of 10 cm, the glass pane ends at 1.8 m above the floor. That would be way too low for me. On the other hand, there are windows with a top edge at 2.38 m, which in my view is the other extreme.

There is just ineffective window planning, and that has been realized in several places in your case.