The architect did not plan the costs; the prefabricated house manufacturer did. My answer in the questionnaire was probably ambiguous or incomplete.
The costs for the architect are not included in the house price, although they are reasonable.
So far, I know that the living area is 158.25 m^2. I would have to ask the architect about the enclosed space. Is that simply another measurement for the house, or can I derive further information from it?