Cost estimate architect single-family house. Your assessment

As others have already mentioned, it is difficult to say anything without floor plans, site plans, and more details about the equipment. However, I have a bit of the impression that the architect is "letting himself go" a little, so you have to rein him in accordingly. From a distance, I find that overall much too expensive/generously calculated. Item 400 (heating, etc.) alone is generous at 45K. But have you checked the development plan to see if it is even allowed to build a shed roof house there?

I hope I was able to make it somewhat understandable without plans?!

If what I am making out of your description corresponds to reality: yes

Can you say something about the costs? Are they realistic?

I only know when I see the drafts and the section. A shed roof is not just a shed roof; a butterfly roof is basically a shed roof too; it just slopes to the "wrong" side, but is considerably more expensive. Also, I currently don't know how to interpret your statement: "2 building bodies." I’d rather wait with my estimate until you post the plans online; I assume it’s not a "terrible" agony for you either or do you want to sign the construction contract tomorrow? Easter greetings

But have you ever checked the development plan to see if you are even allowed to build a shed roof house there?

If necessary, it will be declared as a "pitched roof"

Easter greetings

2 building structures, 2 shed roofs, split level... I think it is a house meant, which you can find on Google Images under Studiohaus 2002... Haha, most pictures there show my house

But maybe the 350m3 per built-up space is set too high or, as someone already said, the technical systems might also be overestimated?

Regarding the pitched roof, we are allowed to build that. We are free in the design because it is not a new development area.
And no, it does not look similar to the Studio 2002. The house is arranged like an L. From the front, one story and to the left of it, two stories. Hard to explain.

As I said, for now I am generally concerned about the cost calculation and whether it can actually work out like that. I just find it very high.

As I understand the description, the building structure seems to be somewhat more complex, so I do not initially consider the mentioned amount to be too high; however, the exterior facilities are clearly underestimated. Your architect owes you a plan that stays within the budget, and besides, this is only the first draft, so there is no reason to panic. However, it is unfortunate for both sides if the first draft is knowingly doomed to fail.