Rönnbyskolan and Rönnby förskola is a school area situated in the city of Västerås, Sweden that consist of a total of five buildings. The main buildings are built in 1973 which makes their energy use of interest. Due to the individual goals for Sweden to lower its energy use by 2020, the city of Västerås has begun an energy efficiency process to reduce energy use in potential buildings. In this degree project, a survey of the buildings’ energy consumption has been reviewed and possible energy reduction methods have been presented. This was made by studying the surveys of the buildings ventilation systems, the heating systems, the envelope and the buildings application by taking measurements. The results from the measurements have been studied and confirmed with the literature study and suggestions of energy effective solutions are presented based on energy calculations. Based on the results, four different technological installations and four building engineering actions have been evaluated. The calculations were supplemented with a model built and simulated in the simulation tool IDA ICE. Economical aspects were taken into account, which shows the connection between energy savings and economic profit. Due to high investment costs, only a few actions were cost effective. The result of the study showed that the buildings can reduce their energy consumption by 17 % or 34 kWh/ m2, year using the measures that turned out profitable.