KfW 70 without ventilation system

... and the final heat determination will only take place after contract conclusion.

What a "heat determination" is supposed to be is not clear to me. Presumably, the standard heating load is meant. However, that is a power and not energy!

..."But a KfW 70 is always included!" according to the seller.

Then it should not be a problem at all to include "KfW 70" in the contract! Ultimately, only what is contractually agreed upon counts, not the pre-contractual seller talk of a general contractor/general entrepreneur! Not to forget, legally the responsibility externally lies solely with the client, not the agent he commissioned to perform! GU/GÜ certainly know that

...Is that common practice? Can one get KfW 70 without ventilation with geothermal energy?

KfW 70 is basically achievable even without controlled residential ventilation/heat recovery. However, whether it is possible here can only be known if recalculated. If the story is "cut tight" or "nicely calculated," there could be problems. As always, nothing is certain! "Geothermal energy" is also not by chance and by no means a guarantee for low subsequent consumption costs. The source must be dimensioned according to demand, otherwise one has to reckon with modest annual performance factors despite the initially high investment costs. Likewise, heating surfaces and hydraulics must be appropriately designed. Completely blindly, I would not trust a GU/GÜ seller. You can protect yourself by consulting an independent, external advisor/planner. If the GU/GÜ has significant problems with that, you quickly know what you are dealing with.

v.g.

We were proposed the following ventilation concept for a KFW70 house:

Window rebate ventilators (RegelAir) in all windows
Exhaust fans with humidity sensors in the bathrooms and in the utility room

A preliminary energy calculation showed that sufficient air exchange would be available for a ventilation concept. According to these calculations, there are numerical values indicating how much sqm air exchange / supply takes place.

Which information is relevant here? Then I would take a closer look at this calculation!

I understand that you still have to ventilate with such a ventilation concept. But would it possibly be sufficient if one does not manage to ventilate the house in the morning?

Doesn't anyone have a tip for me?

@Peppy1981
We will probably have an air-to-water heat pump installed at our place with ventilation.

You write in the opening post, definitely with solar. Our heating specialist told us – because we also wanted solar – that he would gladly combine solar with a heat pump because he earns well from it, but he does not recommend this combination to us because the heat pump does the same work as solar at the temperatures where a solar system is beneficial. Solar would then basically "work against the pump" and you don't really gain anything that way.

...- that he likes to combine solar with a heat pump because he makes good money from it, but he does not recommend this combination to us because the heat pump at the temperatures where a solar system is beneficial does the same work as solar.

Keep this advice, it will not be to your disadvantage! The actual benefit of solar thermal systems is often significantly overestimated, initially regardless of whether it is only for hot water or also with space heating. However, solar thermal systems are almost standard for every general contractor. The actual benefit, despite additional investment, is not contractually agreed upon. A knave who thinks ill of this The framework conditions of the Energy Saving Ordinance also contribute their share to this sham

best regards

We were proposed the following ventilation concept for a KFW70 house:

Window rebate ventilators (RegelAir) in all windows
Exhaust fans with humidity sensors in the bathrooms and in the utility room

A preliminary energy calculation showed that sufficient air exchange would be provided for a ventilation concept. According to these calculations, there are numerical values indicating how many square meters of air exchange / supply take place.

Which details are relevant here? Then I would take a closer look at this calculation!

I understand that one still has to ventilate with such a ventilation concept. But would it possibly be enough if one misses to ventilate the house in the morning?

Does no one have a tip?
We are currently facing a similar problem.
Yesterday there was a blower door test in the shell construction with a result of 1.2. Basically good, but we had just decided against the ventilation system (not necessarily because of the cost, rather no time for installation, cleaning, noise through the ducts, door gaps).
We are building a KfW 70 house in timber frame construction with an air heat pump without any solar use (solar pointless, photovoltaic currently unattractive without widely developed storage options, but might be retrofitted in the future) with a pellet stove (whether water-based must still be decided, we are also advised against that).
However, we don’t know how we can realistically comply with the "just ventilate three times a day by shock airing." Apart from the temperature drop in winter, simply the time is lacking. We both work and do not want to become slaves to ventilating.
Are there no sensible less comprehensive alternatives?