Change heating "after" building permit?

and whether I read. And I read that it won’t work like that. They want to submit the air-to-water heat pump to the office and still do the calculations and in the end then indicate that they are taking gas after all, and KFW 55 is supposed to be achieved. It will end like this: they submit the air-to-water heat pump, they say unfortunately gas and solar don’t work, they can’t reach the 55 unless we take thicker walls or another expensive base plate, and then? Then you can either abandon the 55 or swallow the air-to-water heat pump. Therefore, I advise to just go for the 55 immediately, submit gas and that’s it.

Or properly insulate it right away so that it is sufficient for [KfW55] despite the gas