Heizung#

Heating: Rooms were formerly heated almost exclusively by individual heat sources (stoves, fireplaces) using wood, coal and coke; since around 1950 also by oil, gas or electricity. Collective heating of buildings became known around 1900, mostly in the form of steam heating, now mostly hot-water heating. District-heating stations for the heating of whole complexes or quarters of a city came into use around 1950. The required hot water or steam (industrial-waste steam) was generally transported in subterraneous pipelines. Alternative forms of energy such as solar energy ( Photovoltaics) or Geothermal Power are becoming increasingly popular.