This European Standard is part of a set of standards covering methods for calculation of system energy requirements and system efficiencies of heating systems in buildings. In particular this European Standard is one of a number of standards dealing with domestic hot water systems. The scope of this specific part is to standardise the methods for determining the energy needs for do-mestic hot water. This European Standard covers the domestic hot water needs in buildings. The calculation of the energy needs for domestic hot water applies to a dwelling, a building or a zone of a building. In order to be coherent with calculation methods for space heating systems, emission losses represent-ing taps and control should be taken into account