Buildings consume more than 40% of total energy expenditure and most of the buildings belong to a lower energy class. This paper analyzes multi-dwelling building in Funtana, Istria in Coastal region of Croatia. An analysis of all parameters of the building´s existing condition is displayed, respectively gross and net area, analysis of existing outer sheath of the entire building so that the existing heat transfer coefficient ˝U˝ could be calculated for the entire multi-dwelling building. Furthermore, the layout, size, the amount of every window type and the window materials are all presented. Also, the photo documentation of the existing building´s condition is shown. After establishing that the existing buildings´s condition are not satisfying current requirements of heat transfer and energy expenditure, the measures for improving energy efficiency of multi-dwelling building are suggested. Using the KI Expert Plus computer program, the suggested measures of energy efficiency improving have been calculated, that is, the best solution for long-term reduction of CO2 emission and the reduction of electric energy expenditure which is the only way of heating, cooling and preparing warm water in the observed multi-dwelling building. The bill of quantities has been made for all suggested measures of improving energy efficiency of the observed multi-dwelling building. Also, the simple rate of return and the payback period have been calculated.