Which heating system? Air heat pump / Gas / Geothermal

In summer, that is correct (even though at night I like to keep the pollen outside and use the filtered air from the [Kontrollierte-Wohnraumlüftung]), but summer is only short here. How is it with the mentioned smells from October to May, when it is not high summer?

Among other things, the initial post contains this statement:

5. I like to ventilate a lot.

At least in summer, I won’t be able to change my ventilation habits. We have cats, cat food stinks, and I’m allergic to cooking fumes, so I like to open the window immediately. I want to live in my house the way I want and I am also willing to pay more money for that.

And based on this statement, I assume that one can save on a controlled residential ventilation system. Those who emphasize ventilation behavior (this is meant completely without judgment) will not give up fresh air in the house in autumn and winter either. And this does not mean any kind of mechanical ventilation system, but fresh air from an open window.

You get even more fresh air only by having windows and doors constantly open – which gets pretty cold in winter.

And that is completely counterproductive for the energy comfort of a new building. We all want to build energy-efficiently so that heat stays inside and cold stays outside.

I am not an expert in heating technology, but I would like to ask those here who know better:

Basically, can one dispense with KfW55 with the above statements?

asks Yvonne

Yes; economically speaking anyway ...

Rhineland greetings from on the road
Construction expert

A geothermal heat pump would have cost a lot here, including drilling, since surface installation is not possible and I don’t want that either. (as described above, an offer was available) It may be true that electricity consumption is factored into the annual figure, but I still believe that electricity has to be generated as well. And very few people pay attention to "green" electricity.
550 euros refers to the entire gas bill for the whole last year. Of course, including hot water. We have solar thermal on the roof, since we have to comply with the "rules." However, that is not economically viable either... But it is the cheapest of all solutions in our case to satisfy the legislator.
Acquaintances have an air heat pump and currently pay 130 euros in electricity costs per month. Whether it is incorrectly set or something else, I do not know, of course. I don’t care either.

Ultimately, everyone has to decide for themselves.

Of course, a house, car, or phone is not profitable, but in our case it is actually so that we do not have unlimited financial resources. At some point, you have to think "economically," too. If that didn’t play a role, we would all be driving Porsches or similar. But in fact, there are people who pay attention to reasonable and economical consumption with their cars, because of the follow-up costs.

I am just curious about how the whole thing will develop. I am not against alternative energies (on the contrary, I get my electricity exclusively from certified green providers and am personally involved in a wind power plant), but I am against all the nice calculations and talk.
A heat pump, therefore, in my eyes can only be regarded as an "alternative energy" if it is actually operated "green" and not with electricity from the coal power plant 100 km away.

That, of course, is a fundamental view.

Among other things, there is this statement in the opening post:

And based on this statement, I assume that one can save oneself a controlled residential ventilation system. Those who emphasize ventilation behavior (this is meant completely neutrally) will not do without fresh air in the house even in autumn and winter. And this does not mean any kind of system ventilation, but the fresh air from an open window.
Basically, can you not do without Kfw55 with the above statements?

asks Yvonne

That is a question I have been asking myself all along. The problem is, my boyfriend has really fixated on this KFW thing. Initially and also until recently, we had a provider in mind who advertises with KFW55. We share the opinion to build an energetically sensible house. Whether it has to be KFW55 is another matter. It is not about the "ecological conscience," which I put in quotation marks here because I realize it is just window dressing. There are other issues that our society should work on first. It is rather about the running costs as well as value stability and resale value.
And yes, it is about fresh air; a controlled residential ventilation system is not really my favorite. Our property is also right by the forest, and I like how the air smells there, even if probably everyone is rolling their eyes now

550 euros refers to the entire gas bill for the whole last year. Of course including hot water. We have solar thermal on the roof because we have to comply with the "rules." Economically, it's not that great either...But the cheapest solution in our case to satisfy the legislator..

What kind of house did you build? KFW or Energy Saving Ordinance?

Yes, the solar thing seems to be the crux. Without solar, KFW70 will not even be possible, and it probably should be (as of 2016, as far as I know, it’s basically the Energy Saving Ordinance, so it makes sense because of the value).
I’m currently thinking about whether solar might make sense in some form after all. I want to emphasize again that our house is located on a steep north-facing slope. I’m attaching the architect’s pictures; you can see the natural slope quite well. From the street (=north), it first goes up 3 meters. The garage will be embedded there with a staircase leading up to the house. Then the house is half embedded so that we have some outdoor space at the back, as mentioned before (namely only 90 cm rise over 9 m, which is doable). Further up (=right in the side view = south), after about 200–300 m, the forest with tall trees begins. From October to March, there is accordingly not much sun except at noon. However, I think solar is not really a great thing in winter in other locations either. Or am I mistaken? But it is kind of obvious when no one in the community has solar except the community across the river on the other side.

Many thanks so far for your answers

From October to March, there is accordingly not much sun except at noon.

But on the south roof, though?