Construction costs are currently skyrocketing

Maybe the plans to make energetic renovation of old buildings mandatory are not so bad after all...

mimimi ... Normally, I would completely agree with you and immediately call for social justice. But the alternative that we continue as before and thus let the next (last?) generation perish?

The problem is that we are now subsidizing these 300kWh/sqm houses and their "I don't necessarily have to renovate" owners through the gas/electricity/oil/pellet price caps, although the relief would be significantly more sustainable if the energy consumption of these houses were reduced.

And a second problem, dear Till, is that the market is distorted if we leave such houses unrenovated. We have also looked at some existing houses, but if you factor in a renovation, you are always outbid by someone who calculates the renovation cheaply. As a society, that is not desirable and it has not made the houses more affordable.

Retrofitting measures in existing buildings are mostly a loss-making business without strong subsidies; making them mandatory is socially unfair and also ecologically questionable – so it would fit well with the current political zeitgeist.
Most older buildings have weak points that are worth addressing. Usually, this is not done, not because people so willingly want to bless the environment with the waste heat from their house, but simply because 1. the knowledge and 2. the money are missing.
Creating incentives through sensible support (especially in rented properties) and educating people makes a lot of sense to me, especially through uncomplicated, low-threshold subsidies. But a compulsory implementation of retrofit measures that go beyond existing requirements is, in my opinion, wrong. Sitting in a newly built house, such a mandate is very easy to demand; retiring in a 1970s old building means goodbye prosperity, welcome rental barracks and investors rubbing their hands.
That does not help the climate.

There is a tendency here to frequently criticize residents of old houses with high energy demand. Sometimes openly, sometimes the moral superiority only shines through the one love facade. However, the crux of climate protection does not lie in the mass barracking of less affluent population groups, but also in restricting owners of double garages and swimming pools with Weber grill beef rump steak parties, and especially those who drive their Porsche to the bakery and for shopping weekends in London; this is not so gladly acknowledged here. Old building heaters contribute to climate change as well. However, this does not justify the claim to a monopoly on climate-damaging comfort by new building eco-freaks or young renovators.

Likewise, one could as a climate protection measure demand the use of bicycles for distances under 5 km or compulsory vegan nutrition. Ultimately, that would be significantly less socially unfair, better for the common good (and animal welfare), and would probably have a much greater effect on the climate – yet it would not be a peace-establishing measure for society.

Maybe we should all point fingers less at others and especially kick less downward with our feet, but rather let weapons rest and create a mood of solidarity and common good thinking. In the current system, the exploitation of which is also encouraged here, we won’t be able to achieve real climate protection even with a styrofoam mandate.