Single-family house with barrier-free granny flat on the ground floor

A joint room program initially means taking into account the needs of the user groups parent-child family and resident parents in a common needs calculation for the room program.
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This has been neglected here (with the result of an extension) and afterwards (with the Z-tower shift) unsuccessfully attempted to be remedied. Hence also (among other things my) clear advice for a relaunch (which consistently implies refraining from bending the shown design).

Sorry, but of course we have considered this and discussed it with the architect. We didn’t just go to the architect and say "we are 2 normal, 2 small and 2 old people and need a house"? ;)
The shift was not present in the first preliminary draft (yes, you might not have called it that either), but we didn’t like it so much because the hallway was in the east and the children's bathroom in the west. We therefore prefer the new version, because the hallway gets more light in the afternoon/evening hours, which is important to us.

Only the house entrances must be on the ground floor. Stricter requirements could not have any legal basis known to me, technically they would be unfounded and thus exaggerated and impermissible.

Here is an excerpt from the TAG of the municipal utilities: "The installation room of the WEA is to be provided on the ground floor or basement and must be accessible via publicly accessible rooms, e.g. stairwell. The installation room is not intended to be located on an upper floor." An inquiry with the municipal utilities also revealed that installation on the upper floor will not be approved. If you have further information about this, please share.

Correctly formulated, the task is to plan a two-generation house for six residents in two households, whereby the living unit for the grandparents is to be barrier-free.

"... and the living-dining area of the main apartment is located on the ground floor." In my opinion, this comes to the same thing, but you are welcome to show me a floor plan that solves a similar situation "better" as an example.

It is difficult to see in the development plan. Are you even allowed to build 2 full stories + attic and 2 residential units? With your building, the parking spaces, terraces you exceed the 0.4 floor area ratio significantly. Is the exceeding allowed or is it excluded?

Yes, 2 full stories with a floor area ratio of 0.4 are allowed plus a 50% exceedance for garages, parking spaces, terraces, etc.

The design is not consistent for me. You build a large ground floor so that the granny flat fits. On the upper floor you step back so that half remains as a flat roof, and then you build out the peak? Is it only me who finds that strange? Why not build the upper floor completely as a gable roof with, for example, a knee wall of 1.40 m and leave out the peak? Who wants to walk up and down three floors for no reason, when two are obvious and probably cheaper?

An absolutely valid and comprehensible question and many thanks for suggesting an alternative. We actually considered both, but perhaps not enough. We might tackle that again. The reason for the current design is that we want 2 full stories on the upper floor. Building the entire area of 15.5 x 10 m also as a full story and then putting a gable or hip roof on top, because we don’t like the Bauhaus style, would probably exceed our budget.
Therefore, the idea was to only build part of the upper floor and since there is a roof anyway, to directly take a converted attic with a gable roof. The HO and fitness area is then located in the attic, which is used less frequently compared to the other living spaces. So not only the Märklin train runs its rounds up there.

Yes, 2 full stories with a floor area ratio of 0.4 are allowed and an exceedance of 50% for garages, parking spaces, terraces, etc.

Where do you read that? There are only exceptions concerning the terrace and the building boundary. At least, I have not been able to read anything else regarding Paragraph 9 of the Building Code. The terrace always belongs to the house and floor area ratio I.

Where do you read that

Completely forgot to link: And the employee from the building authority also confirmed it, albeit only orally.

The terrace always belongs to the house and GRZ I.

My mistake, you are right!

The design does not work with 600 k including garage. And from experience, no one builds right up to the limit; it always ends up more expensive than planned without you suddenly upgrading a KNX system for 50 k.

Take a look at Allkauf Haus Generation 5 BF (barrier-free). The somewhat more compact design suits your budget. I also find the granny flat has a few good ideas. And mentally run through all scenarios. How and how long your parents will be with you. Short-term care and especially respite care exist more on paper.

By the way, we use our unfinished attic as storage space; a large inflatable gymnastics mat is there, Carrera track and Gravitrax are set up upstairs. The advantage is that the dads and kids are upstairs and we women sit downstairs comfortably and quietly.

We did not go to the architect and say "we are 2 normal, 2 small and 2 old people and need a house"?

That's exactly what I would have recommended to you.

The shift was not present in the first preliminary draft (Yes, you wouldn’t have called it that either),

With technically sound design technique (youth has always believed it knows better), there is no serial sequence of preliminary drafts, but rather parallel preliminary drafts A to C (less often only A and B and even less often it goes up to E), and from these then directly the selective breeding, followed by the dough resting according to my recommendation. Afterwards, one (1,000 !) preliminary draft matures into the design: service phase 3 is too expensive to mess around here with counting rhymes. "Modern" architects of the CAD generation consider playing Infinite Monkey to be customer friendliness, but they are actually not doing themselves any favors with it. And the general contractor’s drafting slaves are notoriously saving at the wrong end anyway.

Here is an excerpt from the TAG of the municipal utilities: "The installation room of the WEA is to be provided on the ground floor or basement and must be accessible via publicly accessible rooms, e.g. stairwell. The arrangement of the installation room on an upper floor is not foreseen." An inquiry with the municipal utilities has also shown that installation on the upper floor will not be approved.

The municipal utilities only have a maximally advisory private opinion in the procedure. The approval authority may only adopt it within the legal framework. Unfortunately, sometimes a judicial authority is required to remind of the generally and bindingly applicable principles of proper administrative action; this must be, among other things, expedient and appropriate.