What exactly is "well insulated"?

.

Walls with 36 cm T9 are not exactly looking rosy either. That results in a U-value of ~23.5. That is rather the lower end nowadays.

So what? It's not just the bricks now, but the overall package. Together with the air-water heat pump and the insulation of the floor slab, as well as good (better than just standard) triple-glazed windows, according to calculations we are not far from Kfw55. That's enough for us.

Yes, of course that can be enough if in other areas significantly more than necessary is done. The heat pump then takes care of the rest for Qp. Just wanted to mention it since the OP specifically noted

Min. KfW 70 over insulation not technology

. All good! ;)

Insulation is paid for only once, heating (regardless of the technology) always & continuously

Sorry, but before talking about U-values of 23.5 and U-values of thermal insulations of 0.4 without specifying the thickness, one should first get informed. The targeted U-value for vertical exterior walls is 0.24 W/m2*K and a thermal insulation has a thermal conductivity class of e.g. 035 and thus a thermal conductivity of 0.035 W/m*K. Regards

Don't need to inform me, I simply overlooked the powers of ten briefly... happens when you're in a hurry... Thanks for the clarification. ^^

:-)