The scope of this specific part is to standardise the required inputs, the outputs and the links (structure) of the calculation method in order to achieve a common European calculation method. The energy performance may be assessed either by values of the heat emission system performance factor or by values of the heat emission system losses due to inefficiencies. The method is based on an analysis of the following characteristics of a space heating emission system including control, for non-uniform space temperature distribution, emitters embedded in the building structure and control of the indoor temperature. The energy required by the emission system is calculated separately for thermal energy and electrical energy in order to determine the final energy, and subsequently the corresponding primary energy is calculated. The calculation factors for conversion of energy requirements to primary energy shall be decided on a national level.