District heating

The Klemetsrud facility produces district heating for Oslo.

Oslo’s district heating network is a closed system, with heat exchangers located around the city. 

The Klemetsrud facility is able to supply around 80,000 homes with heat from the energy recovery plant. Oslo is known for being one of the most environmentally-friendly cities in the country, partly due to its use of district heating.

How district heating is produced

The process starts with water from the municipal network being chemically treated at an internal water treatment plant, to prevent corrosion of the pipes and steam turbine. After treatment, the water is stored in tanks and used to heat the water in the district heating network.

The chemically-treated water circulates in a closed system between two heat exchangers. In the first exchanger, a gas-water heat exchanger, the treated water is heated using the heat from the waste gases from the incinerator. The main function of this heat exchanger is to reduce the temperature of the waste gases, so that materials and components are not damaged in later stages of the treatment process.

The heat from the waste gases is transferred to the treated water, which then continues to the other heat exchanger, a water-water heat exchanger. The main function of the second heat exchanger is to heat the water in the district heating network, which simultaneously reduces the temperature of the treated water, which shall again be used to reduce the temperature of the waste gases.

The water that is heated during combustion is transformed into steam, which transfers heat to Hafslund Varme AS’s district heating network. The water is transported in pipes from the Klemetsrud facility, via Hafslund’s network, at a temperature of around 95-120 °C. When the heat is transferred to apartments, houses and other buildings, the water returns to the facility to be reheated, before being sent out to the district heating network again. The temperature of the water that returns to the facility is around 55-62 °C.

Heat loss in Fortum Oslo Heats pipe network is 5 %.

806 GWh district heating
in 2016!
Fjernvarmerør inn og ut

Fortum Oslo Varme AS, Avd. Klemetsrud


Klemetsrudveien 1
1278 Oslo


Postboks 13
Mortensrud, 1215 Oslo


+47 815 000 53



Org.nr.: 977 296 919