This European Standard is part of a set of standards on the method for calculation of system energy requirements and system efficiencies. The scope of this specific part is to standardise the method of assessing the energy performance of district heating and cooling systems and to define: ? system borders; ? required inputs; ? calculation method; ? resulting outputs. The method applies to district heating and cooling systems and any other kind of combined production for space heating and/or cooling and/or domestic hot water purposes. Primary energy savings and CO2 savings, which can be achieved by district heating systems compared to other systems, are calculated according to prEN 15603.