The headline is, in my opinion, somewhat wrong and misleadingly chosen. If you build with an architect, then there is no contract for work, but the HOAI table (or am I wrong?). They do the tenders for the trades and so on. As a client, you probably still do the sampling yourself. Of course, an architect can also act as a general contractor or general contractor with subcontractors. But then it is this company with which you enter into a contract for work. They then build a turnkey house for you... according to the construction service description. And in this part of the house comes this heating system from company X and the sanitary installations from company Y. In case of changes, in my opinion, you have to inform correspondingly early: Hello, it shall not be X installed, I want Z. Counting is what is in the contract: Y or according to the client’s sampling. Cheap general contractors/subcontractors may possibly not take the client’s wishes for the technology into account, because the type house Sabrina simply works as a KfW House 70 exactly in this constellation with heating x and window sizes such and such. Changes mean extra effort, but who wants to pay for that? The higher the price segment of the general contractor/subcontractor (the word architect is left out in this question), the more flexible, the more choice and options you have. At least that was the impression I had from home builders and providers when we had gathered information. Although Mr. Viebrockhaus would certainly have been upset if he was not allowed to install his super-duper technology that he advertises, but something else. Do you actually have the right to sample??? I do not know what is in our construction service description now... Is that fixed somewhere? But I think if you agree to a turnkey house, then you also agree to the philosophy of the general contractor/subcontractor - and they have their usual technology (heating and co.) as well as their trade companies with whom they primarily work and (hopefully) achieve good results :)