The purpose with this project is to explore and verify three renovating systems for Miljonprogrammet (common expression forbuildings constructed during the years 1965-1975 when over a million houses where built in Sweden) to take measure to thelargely transmission losses of these buildings. Many of the buildings from this period have similar constructions and thereforethe same techniques can be used to renovate several of them. This project only considers the climate scale, although thereare many more factors to concern for to efficient the buildings of Miljonprogrammet.This thesis presents examples of renovations carried out using two of the three renovation systems.The essay presents a reference house of choice on which we apply the three systems and calculate the new U-values,consumption of energy and the investment costs. The new U-values the building is given is matched to the values ofrecommendation for passive houses. Our reference house is a two story apartment building, located in the village ofLammhult, with brick facades at the ends and plaster at the long sides.