When I see this kind of comments "-20C" in Europe, I always wonder where exactly? In Spain, Italy? Even in Belgium or Netherlands it rarely snows and drops below 0. The only part of Europe to experience these kind of temperature is Northern Europe, who are always well prepared and mostly use district heating. And maybe some parts of Poland and in Alpes.

Temperature map of Europe in January https://www.dwd.de/EN/ourservices/rcccm/int/rcccm_month_ttt.html