Floor plan of a 200m2 house, your assessment?

Measurements are missing. The house is not accessible at all or suitable for seniors with disabilities.

The elevator is an expensive solution to the obvious problem. However, the house will not be habitable at that time without major changes.

The bathrooms and toilets are only usable for healthy people. With a walker, needed assistance on the toilet, etc., that will not work.

I find the two toilets very small anyway. A spacious house and the toilet reminds one of the cramped space of a portable toilet.

I fear your cost-saving approaches are price drivers because they are not standard. can certainly name a few things.
Prices have been rising rapidly for some time. You can double your budget or reduce the house size as suggested by .

… that architects (can) apply several variants of calculation … Then I assume that my questions will not be answered?

The cost estimate we have was calculated according to NNF, GFA and GBA and then averaged. I answer each of your questions. I just consider the umpteenth comment (not from you) along the lines of "that will never work out" without any substantive contribution to be careless.

how is the architect's fee calculated? What does service phases 1-4 cost? Maybe a fixed price makes sense, then this item is already fixed. For the planning including the building application, I also got a fixed price for our house, billing according to HOAI, was somehow unbelievably expensive?!

The cost estimate we have was calculated according to NNF, BGF, and BRI and then averaged.

That may be so, but those are formulas. We have partly looked at the drawings. Essential factors that do not belong to the "usual" standard: [LIST] [*]The projections and recesses with supported lower level [*]the continuous room size without supports, which has higher static requirements [*]the glass railings [*]the elevator [*]the many large!!! window areas, which, even if fixed glazed, require additional installation effort. [*]and then the many other financing/construction contract contributions here in the forum, which give a certain overview of what amount is currently feasible for what [LIST] Especially the last point is a reason why very often here the assessment "not feasible for the price" comes, because the writer has seen the requirements/drawings and summarizes the experience in the most important sentence. And the fact that there are relatively many users like this should really make you think.

I would also be curious about his opinion.

The cost estimate we have was calculated according to NNF, BGF, and BRI and then averaged. I answer each of your questions. Only the x-th comment (not from you) along the lines of "that will never work out" without any substantial contribution, I consider forgivable.

Just read through the plans and the price per square meter. Why should it be cheaper for you than in the rest of Germany? And that even with a pool, elevator, etc. Even though you are already 58 (I am only 44), you trust your architect too much when it comes to cost calculation. You are somewhat naive there. I even check everything with my general contractor despite a fixed price guarantee. Because over 500,000 € is not exactly money to throw around for me :-)