Gas heating + photovoltaics possible without proof

It is exactly the same with us. If gas, then only with solar support. A ventilation system provides additional improvements but unfortunately does not save us from solar thermal. Photovoltaics would be great, but that does not apply with gas, since you cannot support the gas heating with electricity, but only with solar and a water heat storage tank.

As Dr. Hix writes, gas + controlled residential ventilation is not impossible, even with, for example, insulation worse than KfW55. I would avoid solar thermal and leave the space for photovoltaics.

So 2 out of 3 GCs that we already shortlisted in 2016 build their standard 08/15 Energy Saving Ordinance houses with gas and controlled residential ventilation, the previous ST was just replaced with controlled residential ventilation in 2016. Both are not large GCs, no special houses, doesn’t seem to be rocket science.

Well, for us (Stadtvilla 2 Geschosse 137qm mit Keller) it seems to be a witch's brew without solar. If you can believe the energy consultant. Maybe it’s due to your house (KFW-Dämmungsstandard) or the heating system itself. What kind of heating (KW and storage size) is supposed to be installed and how many sqm is your house planned to be?

Plan the whole thing with 36.5 Ytong instead of Poroton. I think then it will work out.

Well, for us (two-story city villa 137 sqm with basement) it seems to be a witchcraft without solar power. If you can believe the energy consultant. Maybe it's due to your house (KFW insulation standard) or the heating system itself. What kind of heating system (kW and storage size) is supposed to be installed and how many sqm is your house planned for?

If you mean me, we built a one-story city villa 160 sqm with an extension in KFW 55 with a heat pump and centralized controlled residential ventilation. Since it was fixed centrally, KFW 55 was overall the cheapest due to the conditions and we found a heat pump more appealing, so gas was not an option for us anyway. But every normal standard house or ours as a standard Energy Saving Ordinance is equipped with a standard gas condensing boiler and decentralized controlled residential ventilation from Lunos. Take a look at Tönjes and Meichsner or Ernst and Ernst on their websites and show it to your energy consultant.