KfW - construction: is it necessary or not?

My question about the new construction of a KFW 55 or better house? What exactly does it mean? I spoke yesterday with the managing director of a public construction company, and he advised me not to build a KfW house.

a) you would need a construction supervisor (who is also specialized in this area)
b) if you insulate the house well, etc., the ancillary costs are low.

Furthermore, he recommended taking a gas boiler + solar including battery instead of an air-water heat pump + solar including battery. The acquisition costs are much lower, and you never get back the additional costs in the purchase.

I am a bit confused. I had actually planned to build at least a kfw55 house.

For your information, our plot is fully developed and has a gas connection.

It cannot be answered generally, as too many factors come into play. But you can find reading material here in the forum and in the rest of the internet for months... Therefore, regarding your questions: a) yes, but you also receive a repayment grant b) yes, but that has more of a secondary connection to KfW Air-water heat pumps or gas usually don't differ much. Batteries are pointless. I would rate kfw55 as a minimum standard better for maintaining value, but that is just my opinion.

Aside from whether the additional costs can be recouped (kfw and BAFA, that already adds up), the decision is also a subjective one. We wanted to make ourselves as independent as possible from electricity and gas or heating oil prices. We like the idea that our house is relatively autarkic. And yes, the ecological aspect also naturally plays a role. But the priority it holds for you is basically something you have to decide for yourself.

Putting aside whether you recoup the additional costs (KfW and BAFA, there is quite a bit coming together), the decision is also a subjective one.
We wanted to make ourselves as independent as possible from electricity, gas, and heating oil prices. We like the idea that our house is relatively self-sufficient. And yes, the ecological aspect also naturally plays a role. But which priority that holds for you is basically up to you to decide.

Ecology is always a question. You must not only calculate the savings, but also the environmental costs of production. See electric cars, for example. You do save CO2, but just the battery production for the car demands a lot of water and CO2.

Sure, the production of batteries is unfortunately still not particularly ecological (haben wir nicht). Especially in heating technology, I don't think there's really a big discussion about that (of course, I am happy to be proven wrong) - a fossil fuel (on which one is also so dependent on foreign countries) can in my opinion never be even remotely as ecological as a heat pump + photovoltaic system. Especially not when calculated over the expected lifespan.

Heat pump

... that gets its electricity during the heating period from fossil fuels? Or from the nuclear power plant? The photovoltaic system does not help in winter. Then the heat pump is ecological?