This article is an empirical study of the whole energy system development in the European Union. The analysis covers the years 1960-1998. The decomposition analysis of energy and CO2 intensities of the different EU countries and Norway reveal large differences between the individual countries. The reasons For the differences in energy intensity changes are explained by the structural changes of the economies. The changes in CO2 intensities are explained by the energy intensity changes and by the changes is fuel switching. The study verifies the conclusion that there are still big challenges in the harmonisation of energy and climate policy in the EU.