A brief update on our search: Viebrockhaus offered a Kfw 40 plus house (modified Maxime 305) at €358,000. We have now contacted an architect who has also built for acquaintances/relatives. His offer as a general contractor with a fixed price for KFW 55 is €239,000. Of course, KfW 40 plus cannot be compared with 55 and everything at Viebrockhaus is more complete and of higher quality, but for us, this will be the better alternative. We are adding a controlled residential ventilation system with heat recovery for €10,000 and will have him start the planning to see how far we still are from KfW 40. If it is possible with minimal effort, we will take care of it to secure the subsidy. If not, it stays at 55.