KfW55 with 36 cm brick (im)possible?

I was told that KfW55 can only be achieved with renewable energies. With gas, you are automatically out. My info.

You can't say that in such a general way. More interesting is the question whether one is even cheaper off with just gas and without KfW55 than with better insulation and/or other additions.

It's doable, but you have to assist with solar and [Kontrollierte-Wohnraumlüftung]. Since [Kontrollierte-Wohnraumlüftung] is already a given with us, the additional costs shouldn't be too bad. I can say more once the first offers come in.