Energetic house renovation: our experiences

I just have significantly higher prices. Are Chinese workers really doing that badly?

Measured against our free and socially oriented conditions, the individual person there is fundamentally already "worse off." Even if he had proportionally more money, his entire life is still impaired by dictatorial conditions, constant fear of state violence, intimidation of all kinds, state brainwashing, etc. If it were actually better in China, we would have a measurable number of people moving there, and you should ask yourself why you are still stuck here in this "bad" situation. I would look forward to positive reports from that distant country.
Such a comparison is sought with the biggest possible apples and oranges and rather sounds cynical.

Many workers in China have earned themselves a small prosperity.

What you call "work" here would mostly be perceived as dressage or coercion according to our, and thus also your, standards. I therefore recommend a one-year internship there or, if you are sure, I suggest moving there straight away.
Your cynical comparisons indicate little personal experience and rather parroting from the comfort of a warm sofa. You would be the first to sit on the plane again and settle here; no, you wouldn’t even take off.
Unless a new boxwood has actually grown there.
In general, what also applies to the spam callers from the alleged stock exchange with their groundbreaking investment tips applies: If you are convinced of it, why don’t you do it yourself?

And to put it into perspective, my annual salary is only 21,600 euros. But I have significantly higher prices. Is the Chinese worker really doing that badly?

Wow, as a full-time worker with 40 hours/week, that's really meager? Because that is officially the average hourly rate per week in China. unofficially they work significantly more.

You can watch the film "Alphabeth" to see some background on this topic.

The main reason for my contribution was to illustrate what can be achieved through renovation, what energy and ultimately costs can be saved in the long term. I originally did not have this information.