Mohammed AL-Qubtan

Central heating system

Central heating differs from local heating in that the heat generation occurs in one place, mechanical room in a large building . The most common method of heat generation involves the combustion of fossil fuel in a furnace or boiler. The resultant heat then gets distributed: typically by forced-air through duct work  by water circulating through pipes, or by steam fed through pipes. Increasingly, buildings utilize solar-powered heat sources, in which case the distribution system normally uses water circulation.

In Italy:
In Italy, district heating is used in some cities (Bergamo, Brescia, Turin and now Milan). The district heating of Turin is the biggest of the country and it supplies 550.000 people (55% of the whole city population).
They mostly use it on December and January

Reference: Wikipedia.com