The aim of this thesis work is to analyse the trends in heat use among Borlänge Energis district heating customer over the last 20 years. Several reports show that in general the buildings stock get more and more efficient, both in Sweden and other European countries, but will the same trend be seen among Borlänge Energis customer? Data of delivered heat to 324 customers, both single-family houses and multifamily houses, for the period of 1998-2018 is used in this study. The heating that is assumed for domestic hot water is calculated and the heat used for heating is temperature corrected so the heat needed for a normal year could be calculated. The investigated customers are divided into different groups representing various types of buildings with different building years. From this data it’s possible to see trends in heat usage in kWh/building, and year for various types of buildings over the period. Other studies on how trends for heating usage in buildings have report heating usage in kWh/(m2,year). It wasn’t possible in this work to get data of the size of each building, which means that it’s not possible to compare the result from this study with other studies. However, assuming that the building area have been the same and that no extensions of the buildings have been done during the period, the trend in changed heat use should be the same, unless the result is presented in kWh/m2, year and kWh/building, year. The overall results show that there is a reduction in energy use in the buildings in Borlänge during the period 1998-2018. The decrease in heat use are in the order of 0.3 – 0.4 %/year, with larger decrease in multi-family houses. This is considerably less than the decrease of heat use in the buildings stock of 0.9 – 1.2 %/year reported for the entire building stock in Sweden during approximately the same period.