This European Standard specifies a set of assumptions, requirements and validation tests for procedures used for the calculation of the annual energy needs for space heating and cooling of a room in a building where the calculations are done with a time step of one hour or less. This European Standard does not impose any specific numerical technique for the calculation of the room heating or cooling need and the internal temperatures of a room. The purpose of this European Standard is to validate calculation methods used to: assess the energy performance of each room of a building; provide energy data to be used as interface with system performance analysis (heating, cooling, ventilating, lighting, domestic hot water etc). The validation procedure is used to check the energy need for space heating and cooling based on a transient sensible heat balance model, taking into account: the external surface heat balance; the conduction through the building envelope; the thermal capacities of external and internal structures; the internal surface heat balance; the air heat balance; the heat balance solution method. All other aspects are given either by prescribed boundary conditions or by input data and are not part of the model validation. It is assumed, that for all these other matters e. g. embedded heating and cooling systems, prescriptive models have to be used according to existing European Standards. The system performance analysis and moisture balance are not within the scope of this European Standard.