Is it sensible to build a new semi-detached house without the KfW standard?

One should not generalize that all ETICS facades develop more algae than those with monolithic construction. As already mentioned, a properly constructed facade (window sills, roof overhang, proper top coat, etc.) has no disadvantages compared to monolithic construction. One can just as well say, I chose gas because my neighbor pays too much electricity for a heat pump without knowing if the system fits the house.