KfW 55 - Ventilation system yes/no? - Experiences

How are we supposed to tell you if it is possible price-wise? It only depends on what your provider charges. If it is the one who already wanted 29000 for [Wärmepumpe], then rather not.

Honestly, no idea, since it was planned in my fixed price from the beginning. I have a Zehnder Q350 myself, but the surcharge for the enthalpy heat exchanger was definitely under €1,000

How are we supposed to tell you if it's possible price-wise? It only depends on what your provider charges. If it's the one who already wanted €29,000 for a heat pump, then probably not

Definitely. But I should also know what the reference prices are like, so that I can estimate whether I'm being ripped off or not The one who wanted €29k for the heat pump offered me the KFW 55 stuff with a ZK system for over €22k in total

Reference prices are not really effective.

For example, if I pay 1000 euros for something in S.H., it may cost 2500 euros in Bavaria.

Both prices can be expensive or cheap.

Why are you so fixated on KfW 55 + controlled residential ventilation?

Make Energy Saving Ordinance/KfW 70 a reasonable controlled residential ventilation with enthalpy and that's it. That keeps the costs within limits and the comfort gain is enormous.

What I would rather plan for is a split air conditioner for bedrooms on the upper floor. In insulated houses, the heat hardly gets out once it's inside. Unfortunately, I overlooked that and will accordingly integrate a retrofit solution.

Why are you so fixated on KfW 55 + controlled residential ventilation?

Do the Energy Saving Ordinance/KfW 70 with a proper controlled residential ventilation with enthalpy, and that's fine. That keeps the costs within limits and the comfort gain is enormous.

What I would rather plan for is a split air conditioner for bedrooms in the upper floor. In insulated houses, heat hardly escapes once it’s inside. Unfortunately, I overlooked that and will accordingly integrate a retrofit solution.

KfW 70 and controlled residential ventilation? But then I don’t get a repayment subsidy of €18,000.?

Even though some things have already been said, I still have to give my two cents.

Can someone tell me roughly how high the follow-up costs of a central ventilation system are?

No one can tell you that exactly. But as a rule, the operating costs should not be higher than what you save on heating costs through heat recovery.

Heat pump, ventilation system and possibly photovoltaic? 3 technically maintenance-intensive devices..

Please first familiarize yourself with the subject before you talk such nonsense!
A proper photovoltaic system requires no maintenance at all. You can clean the modules occasionally, but it is not necessary.

Heat pumps should be serviced regularly.

For a ventilation system, the filters should be changed/cleaned and the pipes should be cleaned about every 10 years. That’s about it.

I would like to do without all of them, if possible

Of course that’s possible! But then you can forget about KFW and in my opinion it is no longer state of the art.

I somehow have concerns in this area... Maybe it’s because this is simply still a "novelty" and is slowly becoming more of an issue due to the plastic foils currently being used

And again you can see that you have no idea!
Ventilation systems, heat pumps, etc. have long since ceased to be a novelty, but are absolutely state of the art in new buildings!
And the plastic foils you mentioned are by now outdated. Good timber house builders no longer work much with large foils but only seal the joints, etc. with adhesive tape. Airtightness on the surfaces is often achieved with OSB, solid wood or similar.
If "plastic foils" was meant as a synonym for "airtight," that is not a novelty either, but long since state of the art and also sensible.

I know... There are simply very different opinions on this topic, which makes it incredibly difficult.

That’s not true either. Almost everyone who has a ventilation system says they are super satisfied and would do it again.
Only many who don’t have one speak badly of it.
And yes, you DO NOT have to have one, but you achieve a better energy standard (KFW) which goes along with lower heating costs and you have a big gain in comfort.