Energy efficiency of buildings is becoming more and more common as a step towards decreasing the amount of climate emissions in the world. In the Swedish city Gothenburg, there are many existing buildings that soon faces extensive renovations due to age and therefore they have a lot of potential to, at the same time, improve the energy efficiency. Some of the buildings uses district heating as heating system and therefore this project has included an investigation of how the energy efficiency of a building affects the delivery of the district heating. The project also included an investigation of how energy efficiency of existing buildings affects the planning of the future needs of district heating.By applying energy saving measures on a reference building that can represent all the buildings in an area can the maximal power use at the DVUT be forecasted. The energy savings impact on the building’s energy- and power signatures is also a part of the study. The result of the energy savings measures is then used in an example of Gothenburg´s urban development by applying the results of the reference building on an area called Heden.The project includes a study, a model in VIP-Energy, an economic analysis of the energy savings and the example of the urban development of Heden. The results shows that the suggested measures reduce the primary energy number by 47 % and that the maximal power use reduced by 50 %. For property owners the economic analysis showed that the measures were not enough profitable. On the other hand, did the result, by the example with Heden also showed that Göteborg Energi can profit by reducing the energy use in existing buildings because it reduces the future additional net power.