Which heating system? Air heat pump / Gas / Geothermal

Thanks for the photos explaining

Funny: do they all have the same houses there? Or is the roof pitch regulated?

There you hit our sore spot Yes, the municipality wants gray, nicely conservative pitched roofs..grumble...we actually wanted a flat roof.

I would tease them with possibilities that probably only the architect knows. For example, with a staggered desk or a beautiful house in the style of the 1950s (with glass in the gable)

So, we have 20-21 degrees throughout the whole house. We shower as usual, and the house has a size of 135m². Of course, the stove certainly helps a bit, but it actually only serves for "coziness."

And we always shower warm, not cold. I don’t know how it is with you. Fairly speaking, one must of course say that last winter was by no means particularly harsh for us.

And for your information: last summer was sunny. From June to the end of August, I used 3m² of gas. So the solar system does have some benefits...

I don’t know which air heat pump was installed, etc. Estimated size is also about 120-130m². And as I said, I don’t care. Everyone has to decide that for themselves. I was told 130 euros without household electricity. But be that as it may... Of course, I also understand that everyone who has invested in a heat pump naturally thinks it’s very good. I would too if I had invested so much money...

Oh, and regarding the "green" electricity. I obviously have to trust the "certificates." But at least I try and pay attention to it. I’m happy to pay a few cents more per kWh for that.

Ok, thanks for the info about the underfloor heating. The heating load calculation is clear, we will probably do that soon. However, I wonder how accurate such a thing can be when it is currently a two-person household, where both are mostly working, and that will change in a few years.

Yes, the architect and we have a few nice roof ideas, but the eaves height is also giving us trouble in this regard. From the front, however, we can even manage the flat roof view. :-/

Gas with solar sounds good, I think if we had solar in a sensible way, that might be the best alternative. But how can I still combine gas to stay sensible and comply with KFW?

Gas with underfloor heating, controlled residential ventilation with heat recovery and much better insulation e.g.

With proper insulation, one could also combine the following: gas boiler + [Warmwasser-Wärmepumpe] + photovoltaic = KfW55.

Controlled residential ventilation would then only be for comfort in the house, but not necessarily required for KfW. The [Warmwasser-Wärmepumpe] is even cheaper than solar thermal energy, and photovoltaic currently pays for itself (though there are no longer large profits).