This European Standard describes a method to calculate the power and the storage volume required for the dimensioning of domestic hot water systems (DHW). The applicability ranges from direct water heaters (no storage volume and a comparatively large effective heating power) to larger storage systems with a comparatively small heating power and large storage volumes.This European Standard is applicable to the following water storage systems:-storage systems characterized by a minimal mixing zone, (such as stratified charging storage tanks or storage tanks with external heat exchangers): these systems are nominated in this standard as "charging storage systems";-storage tank water heaters and warm water storage tanks with a pronounced mixing zone (such as DHW storage tanks with internal heat exchangers), nominated in this standard as "mixed storage systems";and for different uses.The Scope also includes standardization methods for determining the energy need for domestic hot water. This European Standard covers the domestic hot water needs in buildings.The calculation of the energy needs for DHW-Systems applies to residential and non-residential buildings, a building or a zone of a building.Figure 1 shows the relative position of this standard within the set of EPB standards in the context of the modular structure as set out in EN ISO 52000-1.NOTE 1In CEN ISO/TR 52000-2 the same table can be found, with, for each module, the numbers of the relevant EPB standards and accompanying technical reports that are published or in preparation.NOTE 2The modules represent EPB standards, although one EPB standard may cover more than one module and one module may be covered by more than one EPB standard, for instance a simplified and a detailed method respectively. See also Clause 2 and Tables A.1 and B.1.Table 1 shows the relative position of this standard within the EPB package of standards.(...)