District heating refers to a system where heat is generated in a central location and distributed to buildings through a network of pipes, typically in the form of hot water. You can think of it as a larger version of the 'central heating system' found in some buildings in our country. The construction of the necessary pipe network for the system to function is costly, hence, the investment is made only in areas with dense construction. As a result, district heating is predominantly found in the major cities of Norway and is virtually non-existent in rural areas.
The origins of district heating can be traced back to ancient Rome, where the Romans used a central heating system known as the 'hypocaust'. The hypocaust was a network of underground tunnels through which hot air was circulated using a series of ovens. This warm air was then directed into the floors and walls of buildings, heating them from the inside out. The Romans would also use a similar system to heat public baths and other public buildings.
In Norway, homes with district heating have radiators, much like the ones in our homes. These radiators carry the hot water that comes into the building into your home. Of course, thermostats are also found on these radiators. In addition to the thermostat, the amount of heat provided by district heating is regulated according to external temperatures.