Which KFW standard and which technology in new construction

Is it actually clear which construction type the OP wants to build? I mean, with a timber frame construction you are often already directly at KfW55. That was the case with us, the additional cost compared to KfW40 was then manageable and gave me a better feeling, even if the energy savings compared to KfW55 will be small. But we also had a higher repayment grant.

In winter, I basically heat with electricity, and all the wishful thinking of air-to-water heat pump enthusiasts doesn't change that!!

I believe all air-to-water heat pump owners are aware of this fact. However, I do not understand why that should be considered a bad thing...

I believe all air-to-water heat pump owners are aware of this fact. However, I do not understand why this should be considered bad...

I never said it was bad. It’s just more expensive than gas because 1 kW of heat costs around 30 cents with electricity and about 6 cents with gas. Since the air-to-water heat pump is also more expensive to purchase, you should keep that in mind. That’s all I wanted to say, neither more nor less.

Thank you for all the previous suggestions, tips, and advice. The design is not yet completely clear. As it often happens, about a year ago I was in favor of a prefabricated house and my girlfriend was against it. Like in a bad soap opera, today it is exactly the opposite. Noise insulation inside, the load-bearing capacity of the walls regarding shelves etc., as well as fire and water cause me headaches with a prefabricated house.

I think a ventilation system might then actually be an option. I found an excellent comparison on the website inventer that takes all points into account. There, the decentralized ventilation system comes out as the winner. Do you have any objections to this?

I never said it was bad. It’s just more expensive than gas because 1 kW of heat with electricity costs around 30 cents and 1 kW of heat with gas about 6 cents. Since the air-water heat pump is also more expensive to purchase, one should keep that in mind. I meant no more, but also no less.

Yes. Of course gas is cheaper per kW.

But there are costs for the connection (or tank), the chimney, and the chimney sweep. Then one should note that only very few of the mentioned kilowatts are needed in new buildings. So the leverage is quite small now (in the range of a few hundred euros per year).
Moreover, there is dependence on two energy sources as well as on third countries. The possibility of self-sufficiency is never given. If the underfloor heating is incorrectly designed, it is not possible to switch to electricity later.

And all of this must be taken into account. No more, but also no less.

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I think a ventilation system then seems to be an option after all. I found an excellent comparison on the website inventer that takes all points into account. There, the decentralized ventilation system comes out on top. Do you have any objections to that?

cool. so the producer of decentralized ventilation systems thinks decentralized ventilation systems are better than central ones?