Supplying customers with heating and cooling energy from district energy systems contributes to the rational use of energy and to environmental protection. In the past few years, the use of district cooling has significantly increased in some countries. In the last decade, the use of absorption chillers for district cooling has increased. These chillers need a heat source for their operation. It can be gas, fuel oil, steam or hot water. This paper presents the results of research on the parameters which influence the specific heat losses in a district heating network and the overall efficiency of the system.