KfW55 with air/water heat pump and decentralized ventilation system possible

My question, however, is whether this specific case, air-to-water heat pump in combination with a decentralized ventilation system, can also be subsidized, or whether one of the six mentioned concepts must necessarily be implemented.

Attention, you have to read the information sheet correctly. Either a calculation is done or it goes according to reference values, the six points can be found under "Alternativer Nachweis eines KfW-Effizienzhauses 55 nach Referenzwerten" It also says "The requirements for a KfW Efficiency House 55 are met if the following structural and technical system requirements (reference values) are implemented. In diesem Fall ist ein rechnerischer Nachweis für das KfW Effizienzhaus 55 nicht erforderlich."

Since the alternative according to reference values is not met, the following applies: The proof of the energy standard of a KfW Efficiency House 40, 40 Plus, or 55 is provided by an energy demand calculation. (preferably DIN18599) This should not pose a problem for the energy consultant. This also allows for more leeway with thermal bridges, as these always have to be verified by calculation; the alternative does not provide relief here either.

I would not do without a ventilation system in any form in a timber frame house, and I never have.

Instead of KfW 40(+), I would rather invest in a passive house, especially if you have children, as there is no loss in value after 2 years. Where the combination with e-mobility is headed will only be shown in the coming years.