Construction costs are currently skyrocketing

I don't fully agree with you. The question of how is largely foreseeable, bringing a house from the 70s with 300 kWh/sqm into the 2020s, what does that mean? It means: new windows, insulating the façade, basement ceilings and upper floor ceiling. For an inhabited attic, roof insulation usually means external roof insulation and thus a new roof covering, since the old rafters are too thin for insulation between rafters according to today's standards, and rarely does anyone want to lose ceiling height. All of that is clear, even without any concrete regulations. The majority of the costs are caused by the work itself. The regulations usually only make a difference of a few centimeters in the actual insulation thickness.

Anyone who buys a house from the 70s and wants to bring it energetically up to par with today's energy-efficient houses is even told by the energy consultant between the lines that they can do this for their green conscience, but financially and despite subsidies it will not pay off. The average residential buildings in Germany have a demand of about 150 kWh/(m2a) and are in class E (source: Verbraucherzentrale). That can perhaps still be expected as a standard from the buyer of an existing property, but certainly not the leap from an energy guzzler to energetic modernity.

The question of when is equally clearly visible. Politics signs agreements to reduce from X, and that then has to be implemented in practice. With 40 million housing units and a corresponding share of unrenovated old buildings, it is perfectly clear that you cannot start only in 15 years if you want to reach a certain target by 2040, 2045, or 2050. The politics that signs these agreements, by the way, is democratically elected. Except for the AfD, all parties basically support CO2 reduction, and in all polls still a majority of the population speak out in favor. Only when this approval results in concrete consequences for everyday life, everyone is against it and tells themselves the tale of evil politics and the order taker. To me, that is a classic case of cognitive dissonance.

So far, energy transition policy has been rather nebulous. Hardly anyone knew what the best solution for their house was, nor what the measures would cost in total. Only now, as the fog is clearing and people are gaining an overview of legal requirements, the market, and technical possibilities, talking with craftsmen, getting offers, etc., it dawns on them that they will not get off with just a few thousand euros. Accordingly, the anger is great, as you can very clearly see in the current surveys. Saying “It’s all democratically elected” is too simplistic. As a buyer of an existing property, you almost have to feel stupid that because of your past decision for an old town center and against sealing ground on the outskirts, you are now being held on a short leash and required to have the settlement house play energetically at the top within the next 10 years. Especially in regions with already low real estate prices, banks will not provide endless amounts of money for that. Nothing against climate protection, but reason and proportionality must always be maintained.

That's exactly it. Political guidelines change every year, but you only install a heating system every 20 years. I'm seeing this right now in the neighborhood. The young family has their prefab house from the '80s, which they bought about 8 years ago and have been renovating every year. But they haven't done a complete renovation. They have painted, installed new bathrooms and new windows, but the insulation isn't good. And making such a house suitable for heat pumps for €50,000 is now definitely unaffordable for this middle-class family. Even with 30% subsidies. And they didn't know that 8 years ago. That's why I am very skeptical and believe you shouldn't treat people's life's work like that. They are panicking now, anyway. And honestly: There is no heat pump mandate yet, but besides expensive pellets, there isn't much else left. And with district heating, politics only think about their own Berlin-Mitte faction with rental apartments and financially strong investors. It's not feasible or affordable in rural areas. The heating law will lead to many social tensions in the future. And whether we achieve climate neutrality in Germany by 2045 is at least uncertain.

And only one thing about democratic decisions. A large part of the Germans reject the Building Energy Act (76%). We have to limit global warming in Germany, but distributed socially fairly and economically sensibly. This is now clearly seen with heat pumps. As soon as there should be a 50% subsidy for almost everyone, prices suddenly rise by 50% as well. The heating lobby pockets the subsidies. Incentives instead of bans are the means of choice here.

Anyone who buys a house from the 70s and wants to bring it energetically on par with today's energy-efficient houses is told by the energy consultant between the lines that they can do it for their green conscience if they like, but financially and despite subsidies it won't pay off. The average residential building in Germany has a demand of around 150 kWh/(m2a) and falls into class E (source: Verbraucherzentrale). This can perhaps still be expected as a standard from the buyer of an existing property, but certainly not the leap from an energy guzzler to energetic modernity.

It doesn't seem to be that far off. Nordanney is also bringing his house from the 60s into the modern age, and I doubt he is putting money in purely out of hobby. I also deliberately left out a concrete number at this point. It is clear that the big jump is from 300 to 80 kWh and any further optimization then has an increasingly unfavorable cost-benefit ratio. But costs do not scale linearly either.
By the way, dealing with average values doesn't help anyone. Anyone insulating the facade will not stop at 6cm just because they have reached the average of all buildings, but will use more material. The effort for bonding and plastering remains the same, whether it is 6cm or 16cm insulation.

So far, energy transition policy has been rather nebulous. Hardly anyone knew what the best solution for their house was, nor what the measures would cost them in total. Only now, as the fog is clearing and people are gaining an overview of the legal requirements, the market and the technical possibilities, having conversations with craftsmen, getting quotes, etc., are they realizing that they won't get away with just a few thousand euros.

I can partly understand that, and I also have little understanding for the back and forth in politics while at the same time creating artificial time pressure (before the summer break, starting 2024...). I am also annoyed by the strong focus on heat generation instead of the building envelope.
But when you look at the end goal, net zero in 20-30 years, it should be clear to everyone that this cannot be achieved with a few small improvements. This is a major effort for the whole country. That has been clear for a long time if one wanted to listen.

And just one thing on democratic decisions. A large part of Germans reject the Building Energy Act (76%).

Sure. As long as it's abstractly about "more climate protection," everyone is for it. As soon as it concerns their own wallet, everyone thinks someone else should pay for it. Cognitive dissonance and the St. Florian principle, after all. This is true for every specific measure proposed so far. Whether wind farms or power lines nearby, driving or flying less, driving more efficient cars, insulating houses...
Only photovoltaic systems on one’s own roof seem to receive approval. At least as long as the bill for the feed-in tariff is not shown separately as a Renewable Energy Act surcharge.

Anyone who buys a house from the 70s and wants to bring it energetically up to the level of today's energy-efficient houses is told by the energy consultant, tacitly, that they can do it for their green conscience, but financially and despite subsidies it will not pay off. The average residential building in Germany has a demand of around 150 kWh/(m2a) and is in class E (source: Verbraucherzentrale). This can maybe just be expected as a standard from the buyer of an existing property, but certainly not the leap from an energy guzzler to energetic modernity.

If we are talking about a completely unrenovated property. Then, just because of the maintenance reserve, one should have between 100k and 150k ready to resolve the backlog of renovation, and investing such an amount in a house without it having positive energetic effects is simply unrealistic. Even in the conservative calculation, before the whole inflation spiral, something in the range of 1€ per m² per year was considered. If the house has 150 m² and is 50 years old, you can roughly see what is necessary for its upkeep.

As a buyer of an existing property, one must almost feel stupid that for their previous decision in favor of the old town center and against sealing off land at the edge of town, they are now being put on a tight rein and required to bring the settlement house energetically up to par within the next 10 years. Especially in regions with already low property prices, banks will not release unlimited amounts of money for this.
Nothing against climate protection, but reason and proportionality must always be maintained.

Could you clarify that? I am not quite up to date with the currently starting regulations, what else besides heating adjustments is additionally planned.

We also bought a house with energy class G (240/sqm) and end up after renovation at B (68/sqm) for the final energy demand (new roof, new windows, insulated basement ceiling, 8cm external insulation from the mid-90s remains).

And on topic, we have the last major item of our renovation on offer: painting work.

Prices net:

Inside:
Felt plaster including primer, grain size 1-1.5mm: 15€/sqm
2 coats with silicate paint: 7€/sqm
Sanding floorboards (3 passes) and varnishing: 30€/sqm
Baseboard: 8€/m

Exterior painting: 2x primer + 2x coating with silicate paint: 16€/sqm

Work charged by the hour: 45€

We found that relatively fair. Previously, we did not accept an offer where the prices were significantly higher (e.g. coatings with silicate paint 10€/sqm). That was almost 40% more expensive with spatula application instead of plastering.