Freezing in cities is not a lot of fun. This happened during the breakup of Yugoslavia. Every tree in every park gets cut down for firewood. Heirloom furniture is burned. Door frames. Interior doors.
Not to mention the fire and carbon monoxide risk of improvised fireplaces in apartment buildings.
In Stalingrad, they were eating the wall paper paste off off the walls before they tore them down for wood to burn.
https://www.youtube.com/results?search_query=waste+oil+heater
Some folks may build a used oil furnace
November in Germany and Europe is about to get interesting. Thank God we are in The USA with all our anarchy and oil/gas producers.