The construction industry has demands on energy use in permanent buildings. How much energy that is permitted to use during the time the building is produced has no requirements. The purpose with this study is to learn how far Skanska has come with the work of making the building site more energy efficient. A literature study has been performed in the beginning of the study to survey what energy efficient arrangements that can be applied and how they operate. Using site visits and interviews the situations on the building sites have been studied as well as the energy efficient measure that are in use. Skanska has come a long way with the work of energy efficient building sites and they keep improving. They have improved half of their cabins so they use 50 % less energy. In the near future a cabin that use 84 % less energy can be used on the building sites. Skanska applies several different measures to reduce their energy consumption. The study has shown that a good way to save energy is to turn off the lights at the building sites when the staffs are not working. However, there is also the question about the working environment so it is up to the individual building site make the decision. A conclusion of the survey is that it is important to engage the employed in the work with energy efficient measure and get them to understand why the measure is used.