Single-family house with staggered floor, southwest location in Bonn

No idea why the drawings are so praised. At first glance, they are nicely colorful, but much is quite hard to recognize. Dimensions instead of so much color would be much better.

because dimensions hardly play a role at this size and this stage of idea planning. At this planning stage, there will not yet be anything important planned on 5 sqm that cannot work due to the lack of space.

only somewhat restricted

The development plan restricts surprisingly little.

build with setback floor

Where does it say that? Only the building height and number of full floors are fixed. Roof shape, orientation, pitch, eaves height - all free ...

The planning so far took place on a greenfield site, without consideration of costs or practical aspects. At least on our side.

... perhaps too free?

Flat roof results somewhat due to setback roof and the height restriction, which probably does not allow a gable roof.

That seems to me to be a misinterpretation.

Price estimate according to architect/planner: With general contractor and all additional costs >900,000€ Personal price limit for the house, including equipment: rather below that.

Without a number, no further discussion can take place. Not that in the end we end up with Town & Country.

because dimensions at this size and this stage of idea planning hardly play a role. There will not yet be anything important planned on 5 sqm here that cannot work due to the lack of space at this planning stage.

Well, the children's rooms are being discussed even though it is not clear whether they are about 3x5 or 2.5x7 m. That makes a big difference when furnishing.

Well, the children's rooms are being discussed, although you can't see whether they are about 3x5 or 2.5x7 m. That makes a big difference when furnishing.

For example, I discuss less about a number and more about a discrepancy.
Those who want to build over 200 sqm, more power to them. I also allowed myself half a meter more in width. It makes many things easier in planning, because there is a difference between having only 80 cm between wardrobes in the dressing room or over 1 meter. So 1.30 or 1.50 do not even need to be mentioned.
But is right: we don't need to continue discussing if the budget is unknown. I see the 230 sqm (without the basement) at 600,000 including additional building costs... the finished living basement does its part. And if you consider that architects in their creativity tend to forget 10-20% of the duration of the house construction, then we are looking at a house plan of over one million... although the OP only wants to spend 500,000? (including additional building costs and carport 600,000).

For measurements, the client has a ruler. Although at this stage, it's only about how a house could look. The planning is still far from whether my furniture fits. And with or without measurements, the children's rooms are small and poorly laid out in relation to the living area, the hallway, etc.

Of course, with measurements for us, there would be a whole series of other comments.

Well, the children's rooms are being discussed, even though you can't see whether they are about 3x5 or 2.5x7 m. That makes a big difference when furnishing.

But you can see that these have many edges and corners and thus, regardless of whether they are ultimately 13m2 or 17m2, they are not "nice rooms" ("nice" for me would be a rectangle with an aspect ratio of about 3:4). The corners by the doors do add square meters to the room but not actual space. I also find the trick with built-in wardrobes difficult for children's rooms because the requirements for these rooms (unlike other rooms in the house) change the most over the years. And if I later really want to realize my reading room/library, 60cm deep built-in wardrobes would just be in the way.