Unfortunately, I cannot answer that.

Maybe my gut feeling ist wrong and we indeed have a significant number of people living at dangerous temperatures. But from my perspective the entire statistic is useless if we don't have more information. I just tried to find statistics with groups of the household incomes along with the number of households in that group. If we knew the average household income of someone who is +/- in the 38th percentile of people in Germany, that might be a starting point. However that would still contain many simplifications (How modern is the flat in terms of isolation? What's the primary energy source etc.? How big is the flat? How many people live in the household?).

It is very difficult to judge on a total number of a statistic unless you know the assumptions and methodologies behind it. In this case they apparantly didn't even try to work with scientific evidence. They just wanted to create a clickbaity article and thus made the question as broad as possible so as many people as possible will anwer with "yes, I'm affected".

By the way: wasn't this thread originally liked to an article from the newspaper "Die Welt" rather than DeStatis? DeStatis from my perspective is much more reliable souce than "Die Welt". Also the original post reported 38% of people freezing while DeStatis writes about 5.5 million people. 5.5 million would be around 7% which is a HUGE difference and sounds far more realistic.