The dominating fuel initially was oil. In the beginning of the 1970-ies there was an oil crisis in the world resulting in rapidly increasing prices. As Sweden has no own oil production, a lot of energy saving activities had to be started. This work was carried out in close co-operation between DH companies and the industry. Different energy saving techniques were developed.

In 1980, 85% of the used fule was oil. Today oil constitutes only 6-7% of the used fuel. Beside the development of energy saving technique, a lot of efforts have also been spent on development of alternative sources for production of heat. The increasing use of nuclear power plants together with the use of heat pumps, the use of renewable fuels and heat surplus from industries have been hepful tools to decrease the dependence on oil.