Planning with an older development plan

In my opinion, all 3 wishes could also be argued with the (increasingly important) topic of climate protection

No, you don’t want to be ahead of one of the next development plans in its time, but exemptions from this development plan. So leave climate protection out of it. The larger roof overhang (on the eaves side) is good to visually lower the eaves height – consider benevolently foregoing an increase of the overhang on the gable side. Argue with the reduction of the height level of the ground floor and the ceiling between ground floor and attic for focusing on the eaves height instead of the knee wall, and then with modesty in the roof pitch “in the service of adhering to the building height” as further accommodation regarding this eaves height (as said, 20 cm plus sounds moderate, and relinquishing roof additions shows your accommodation). I would leave out the higher photovoltaic yields there. Let the municipality think that you mainly do not want to stand out with your higher knee wall.

To come back to my first question: Should I first discuss my wishes (including arguments) with the municipality, come directly with the building application, or commission an architect for a building inquiry?

Follow my quote in post #5 and then also read Katja’s explanations there – you do not need an architect for the building inquiry. Draw a volume model of the building body into the cadastral map, show your willingness to integrate. Basically demonstrate that your house wants to follow the spirit of the development plan in an alternative way.

Ultimately, you as a future builder are also protected, so that, for example, no 4-story apartment building is imposed on you. In principle, the public interest always counts, not the personal one.

Well. In my neighborhood, exactly that has happened. An old plot where two old two-story houses were demolished. Then a development plan change within two years by the city council and now there are two 3-story apartment buildings with a recessed top floor, giving the impression of a four-story building with a height of 14m and just 5m distance to the old villas in the urban area. But that's just how it is. Nothing lasts forever. Of course, the owners of the houses there are upset.

But the owners of the houses there are of course annoyed.

I can understand that. If they were only semi-detached houses, meaning a more efficient use of building plots, it would be comprehensible. In our village center, many older houses are being demolished. Ten years ago, I would have called that a "sin" because the houses have a lot of potential. However, nowadays it is a very big energy challenge. Well, so they are demolished, but they are rebuilt with single-story construction, only with 2 residential units. A good compromise, I think.

I can understand that. If it were only semi-detached houses, thus a more efficient use of building plots, it could be understood. In our village center, many older houses are being demolished. Ten years ago, I would have called that a "sin," because the houses have a lot of potential. Meanwhile, though, it's a very big energy challenge. Well, so they are being demolished, but they are rebuilt with single-story construction, just with 2 residential units. A good compromise, I think.

Yes, but here it is common that in large multi-family housing projects the development plans are often changed in order to use the plots as efficiently as possible. Keyword: infill development. That way, not so much land outside urban areas is designated for building. Something I find quite sensible. Better to have another story inside the built-up area (as long as legal limits are respected) than to keep building more on the greenfield far away from infrastructure and supermarkets. And the two multi-family houses also look really nice (no flat roofs and with light brick slips). They were also built with underground garages, so the cars don't get in the way and even the roof of the underground garage had to be greened. Overall clearly more sustainable than other cities that still squeeze a development area onto the city outskirts.