How does one correctly balance between the Building Energy Act and KfW 55, 40, and 40 Plus?

Are the subsidies for this then higher than the repayment subsidies from the combined programs?

Of course not.

We faced the same question at the beginning of 2020. A prefabricated house or timber frame construction was not an option. The solution was then to apply for two residential units with 2x120k KFW55 loans. The loan is then completely repaid within 4 years. There remains a net advantage of around 32k. From the building standard we planned to build anyway to the KFW55 standard, there was not much difference. The only thing that comes to mind is the brick insulated with 36.5 cm of rock wool. But we probably would have taken that anyway. And the blower door test costing 450 euros. KFW40 was never an option for me. I don't want an external thermal insulation composite system (WDVS).

One more thing comes to mind: A controlled residential ventilation system is highly recommended in a modern new building. It also helps to bring your energy calculation up to KFW55 standard. If it is an integrated system within the heat pump, the controlled residential ventilation system, together with the heat pump, is subsidized at least 35%, including the entire distribution system such as pipes, ceiling outlets, etc.

A controlled residential ventilation system is highly recommended in a modern new building. If it is an integrated system within the heat pump, the controlled residential ventilation system together with the heat pump is subsidized by at least 35%.

Yes, controlled residential ventilation is recommended.
No, it is no longer subsidized.

KFW40 was never an option for me. I don't want an ETICS.

ETICS is not necessarily required, nor is timber frame. We will achieve KfW40 standard with 40cm Ytong. Those who don't like Ytong can also use filled bricks without making the walls extremely thick.

We are currently considering KFW40 EE in the planning phase - here (my current opinion, which might change ;) there is a very good ratio of additional investment expenses / funding amounts / heating costs.

I would choose controlled residential ventilation alone for the reason that we cannot ensure airing out the entire house every 2 hours with windows open.