Environmental impact and management of energy is a highly topical issue in today's society. Climate impact must be reduced. The Government has set a target to reduce energy consumption in buildings by 20 % by 2020 and 50 % by 2050 compared to the energy use in 1995. With this in mind, we chose to examine how property owners can work on improving energy efficiency in existing apartment buildings. We also wanted to investigate profitability of different increasing energy efficiency measures and the calculation methods and the risk assessment performed by such investments. To tie in with government objectives, we also saw the possibilities of achieving these goals. 20 companies were interviewed, of which 14 were property owners and 6 were consulting firms that works with energy efficiency. All property owners were familiar with the importance of energy work but they worked very different with it. The interviewed companies work with energy efficiency measures in the building envelope, HVAC , household and residential electricity and solar energy. The companies have chosen to implement various extensive measures and outcome measures differ between objects of different conditions. Also the choice of calculation method for the calculation varied between companies. Much of the results were due to the tradition and resources. Many of the larger companies have come a long way in their work toward the energy targets and some already achieves the goals by 2020. Others are not as advanced, because they do not see sufficient profit to invest in energy efficiency measures.