Construction costs are currently skyrocketing

I absolutely do not consider that contrived. When I look at what was happening with existing properties needing major renovations at the end of 2020 and how much was bid. That was only possible if you had either cooked the renovation numbers or simply ignored them.

I always wonder with these extreme examples whether it is the state's job to protect the harakiri financiers. In my opinion, anyone who finances up to their limit and far beyond without keeping an eye on the renovation is ultimately just to blame themselves. Why should you protect them? They themselves took out the risky financing. But I do see a need for protection for the grandma with a small pension, living in the house for 40 years.

Of course, the state does not have to protect people from themselves in every case, and those who enter into kamikaze financings should also be able to live with the consequences. As an Ordo-liberal, I am in favor of a lot of personal responsibility in life. On the other hand, personal responsibility also requires that the state creates reliable and sensible framework conditions (this is the Ordo) and does not constantly change the rules. It is also easy to forget that until recently gas heating systems were still subsidized. And this 180-degree turnaround is not justifiable on factual grounds; the facts were already on the table beforehand. In addition, there is much more to gain with old buildings if the building envelope is first appropriately upgraded; the energy carrier only plays a subordinate role in terms of environmental friendliness (it is also important to me here not to narrow the discussion only to CO2).

What is he supposed to do? Of course, the decisions in the past were wrong, but now to keep saying "Gas heating, no problem. If it gets too expensive, we’ll just cap the prices again" would be even more disastrous.

I described this yesterday. Cross-sector emissions trading (and without a price cap). Then the market regulates it. Maybe not in the building sector, but elsewhere where it is cheaper. In the end, it is relatively irrelevant whether pollutants are released into the environment when heating or when flying to the Maldives.
Additionally, support for upgrading building envelopes through subsidized loans with low repayment and easy access. Simplifications in monument preservation. Cost-covering renovation levy for rented properties. But: no bans or explicit promotion of energy carriers. No regulations on renovation standard X outside of funding programs.

And we are introducing trade here in DE bindingly for the whole world? Everything is taxed multiple times here and then I get to choose whether I drive to work by car or fly on vacation every 2 years, otherwise it costs extra? Give me a break...

I believe the bitter truth is that when it comes to CO2 reduction / climate protection, it will not work without bans and clear (transition periods). I am certainly not an apocalyptic thinker – but unfortunately we don’t have a lot of time left because the last 30 years have unfortunately been very much (partially intentionally) wasted. And the longer we wait, the more drastic the measures will eventually have to be. And even though the discussion has fortunately shifted in favor of climate protection among the broad masses of society in recent years, some people still unfortunately do not understand what is quite certainly coming to us (or our children/grandchildren) in the next 50 - 100 years. Usually it goes like this: There is a ban on the table, the outcry is huge. Eventually day X comes when it is enforced, and somehow everything turns out to be not nearly as bad. Hardship cases need to be cushioned, of course. But I see it exactly as written above: The people who finance a house from the ’60s without renovation buffer, there is no help for them anyway. The state can do little for them. Their heating could break down at any time anyway.