The Paul Scherrer Institut analyses the structures and impacts of national and international energy systems. In 2007, for example, a study was carried out in which PSI makes recommendations as to what the national climatic targets of Switzerland could be. The study also highlighted the facts on which the Swiss energy system is based and indicated which targets can be achieved and how. Protection of the climate is, after all, one of the most important areas of national energy policy for the coming years, and the emission of CO2 in Switzerland should be at least halved by the year 2050. Better energy efficiency is an important factor towards this goal – but not the only one.