House Construction Cost Estimation - Does this fit?

We built with gas heating in 2017 because it saved us many thousands of euros. Our entire underfloor heating system is designed for low temperature, it could be directly switched to a heat pump. However, I see no reason for that.

We have about 18000 kWh per year at 170 sqm with a fireplace and solar thermal with the basic supplier at 9.6 cents per kWh. (A high gas price unfortunately also drives up electricity.)
(...)

That's true. Most experts here neglect that we also want to phase out coal by 2035 when it comes to the electricity price. That means we will need enormous amounts of gas or hydrogen to cover the gaps in sun and wind.
There will easily be enough gas left for the few people who stick to their gas heating.

Your 18,000 kWh gas consumption is indeed quite high. Do you heat to 25°C room temperature?

What many probably don't know... the heat calculation according to the building energy law is done at 19°C... so at 21°C you already need 12-15% more energy than calculated...

The gas price will settle long-term at a level of 12-15 cents/kWh, provided we actually never import gas from Russia again. Where the electricity price will go, you'll be surprised when we actually want to do without coal alongside nuclear power by 2035

hm... So the gas price will be moderate in the future. Electricity from gas will probably be ridiculously expensive, if I understand you correctly. And why is that, if gas is cheap and we are also getting more and more electricity from renewable sources? What nonsense?!

... The immediate heat that a gas heater delivers "at the push of a button" is also nice...

Since when does a low-temperature underfloor heating system powered by gas deliver heat faster than an equivalent underfloor heating system powered by a heat pump? As for the rest of the nonsense regarding gas, I’ll say nothing (except: thinking about the next generation isn’t always a bad idea).

Our house is built according to the Energy Saving Ordinance minimum standard 2017. Triple-glazed windows, thermal blocks, and so on. In conversations with friends, family, and colleagues, the 18,000 KWH was generally regarded as good.

The value refers to 170 sqm of underfloor heating plus 300 liters of hot water.

The quick heat was once related to the underfloor heating, because yes, if I want heat, I raise the supply temperature within minutes, which we can already notice quickly, for example in the bathroom. But mainly hot water, as a thermal disinfection runs once a week and quickly brings the 300 liters to over 70 degrees. For heat pumps, this is presumably 100% electricity.

Please don’t misunderstand. Heat pumps are a great heating option, but I still wouldn’t demonize gas. By the way, about half of all German households heat with gas. The other half is divided among many other heating options. And there is little experience with heat pumps that are 20 years old or older. Our biggest fear back then was the risk of the investment if the pump stops working.

And honestly, all those with heat pumps are also the ones who got the short end of the stick, because they bought a significantly more expensive HP back then and are now financing the gas price cap for everyone through their high taxes. Because if a large part of Germany can no longer afford gas consumption, those with HP probably won't have a job either. That's why the government is now providing such massive assistance.

Our house is built according to the 2017 minimum standard of the Energy Saving Ordinance. Triple-glazed windows, thermal blocks, and so on. In conversations with friends, family, and colleagues, the 18000 KWH was generally considered good.

Well, how wrong one can be. The value is (terribly) bad. (But my 270-year-old house was even worse with about 25,000-30,000 KWh in the form of 2500-3000 liters of oil per year. But wind whistles through the attic and through the front door, windows are 35-40 years old, etc., but also about 170m² of living space.)

The quick heat was once related to the underfloor heating, because yes, when I want heat, I raise the flow temperature within minutes, we notice that quickly, e.g. in the bathroom. But mainly hot water, once a week there is a thermal disinfection that quickly brings the 300 liters above 70 degrees. With heat pumps, that is presumably 100% electricity.

Nope, that was the first thing that was programmed out (thermal disinfection, in a single-family house mEA nonsense and a waste of energy since there is no practical (only theoretical) legionella risk here. My brine-to-water heat pump therefore never runs 1:1 (with only electricity / heating rod).

Please don’t misunderstand. Heat pumps are a great heating option, but I still wouldn’t demonize gas. By the way, about half of all German households heat with gas. The other half is split among the many other heating options. And there is little experience with heat pumps that are 20 years old or older. Our biggest fear back then was the investment risk if the pump stops working.

Yes, and a quarter with oil. And that is also "still good"?
What is the difference between a non-functioning gas boiler and a non-functioning heat pump? Exactly 0 degrees ;-)