Is house construction possible without solar and renewable energies?

Yes, it is generally possible through better insulation. We have done that too. We have a gas condensing boiler without solar. However, we have a ventilation system with heat recovery. But we also achieve KFW70 this way.

We build like Jochen:

good stone, no insulation, air-to-water heat pump, without solar, photovoltaics or ventilation, and easily achieve Kfw 70 with a tendency towards KFW55.

Have an air-to-water heat pump calculated against a normal gas heating system. Ask your supplier beforehand how much the gas line connection will cost. In some cities, the cost of the gas connection already covers the extra price of an air-to-water heat pump – and on top of that, you also save the annual visits from the chimney sweep.

The idea with the air-to-water heat pump might not be so bad after all.
With 90 sqm of living space, it doesn't have to be that big. Can someone tell me how high their electricity consumption is with an air-to-water heat pump system?
I probably still can't do without the chimney sweep, since I wanted to have a fireplace.

Best regards
Hartmut

We build according to the Energy Saving Ordinance 2009. Only with gas boiler. No solar, photovoltaic, controlled residential ventilation, heat pump, etc. The house must be insulated well enough to comply with the so-called 15% rule. Your energy consultant will know the rule.