How to change the floor plan?

The legitimation comes directly from the city council. They do cut out a green corner here for new buildings, that took years. The compromise was to build something high-quality, to take nature into account, be energetically exaggeratedly modern, and so on. The committee itself is a private-law body, not a building authority, without whose approval the city is not allowed to sell the plot.

There have been such committees in this region before. Drafts were rejected because one of the participating artists didn’t like a window (floor-to-ceiling in the utility room, he didn’t like it). So highly individual things that were not previously found in the requirements catalog. That ends badly.
In another neighboring town, it was simply badly organized. The committee met only once a quarter, then appointments were canceled. The next year no budget was planned for external consultants (they thought everything could be done in one year or four meetings), and that during times of budget freezes.
As a result, the entire new development area was dead because nothing could be approved. Damage to the city, damage to the builders who, like apo, had advanced payments.

We received a cost estimate from him with a total volume of about 460k including incidental construction costs, garage, and outdoor facilities...

I personally find it scandalous how architects can whisper dreamed-up numbers into their clients' ears without any personal liability.

Yes, they should be forced to deliver at this price.

Cost explosion at the Elbphilharmonie! Who is happy? The architect and the planning office, I believe from the 20 million estimated, it became 70 million.