You can't really say that with us, since we are building our house ourselves, or rather my cousin has a construction company and is building the house for us. We have an energy consultant involved who advised us on the materials, but whether we achieve KfW 55 or if the flow temperature is even better or much worse, I can't say. Of course, we are building most of it according to the latest standards, and I think the heating system would not jeopardize KfW 55. Unfortunately, I am not an expert enough on that, sorry.