You can rarely say in general terms: Save this, save that… take for example the lifting system, which you say you don’t need. If you had a plan including contour lines and access road, you could address that you don’t need it. As it is now, it’s back and forth questioning, which can ultimately annoy you and others. In the end, there are no constructive answers.
I go even further, that you need to know who wants to move in there, how old and with how many people (children). Because that decides, for example, how much circulation space and whether any at all needs to be generated. With living areas, meaning the floor plan, you can control many costs. Or how large the hot water tank needs to be…
The plan is not available yet, it is just being created, maybe I am still too early here, much of what you would like to have and know does not exist yet.
Moving in will be me and my girlfriend, both 30 years old and currently childless, and we actually want to remain childless or at most (!) have 1 child.
A layman does not plan optimized, usually either wastefully with room sizes or so that it works suboptimally.
Therefore, it makes sense to let a professional do it. He will get the money anyway – whether he thinks himself now or lets the builder think – he puts his name to it.
I do not want to optimize the floor plan yet, but rather exclude or include things in advance that do or don’t make sense, the planned ~120m2 are also realistic (I have been in several prefabricated houses from 80-200m2, 120/130m2 feels right)
Two-story gives a turret, hardly an approach to efficient storage areas in that size. 60 sqm per floor, that invites to kneel down.
Since neither the plot size nor the building envelope is known yet (see topic on essentials), I still suggest a one-story plus developed gable roof (e.g. 26-30 degrees roof pitch without knee wall): the roof can later, when a child arrives, be developed for children's rooms, well-accessible storage space, and hobby/office room.
On the ground floor parents, all-purpose room, and technical room. With 85/90 sqm you get along well, in the attic you come to 40/50 sqm, developed as needed.
Ok, I probably expressed myself wrongly there, we want 1 ground floor and then a developed roof truss on top, 60 sqm per floor is probably, as you say, suboptimal in terms of floor plan.
Putting everything on one floor probably makes the slope work much more expensive, as more area has to be created..
Many thanks for the other tips :)