This International Standard provides a systematic, comprehensive and modular overall structure on the integrated energy performance of buildings, in order to ensure consistency among all EPB standards required to calculate the energy performance of buildings. This Standard handles the framework of the overall energy performance of a building, covering inter alia: a) common terms, definitions and symbols; b) building and assessment boundaries; c) building partitioning into space categories; d) methodology for calculating the energy performance of a building (set of overall formulae on energy used, delivered, produced and/or exported at the building site and near-by); e) set of overall formulae and input-output relations, linking the various elements relevant for the assessment of the overall energy performance of buildings which are treated in separate EPB standards; f) general requirements to EPB standards dealing with partial calculations; g) rules for the combination of different spaces into zones; h) performance indicators; i) methodology for measured energy performance assessment. The procedures take into account the specific possibilities and limitations for the different applications, such as building design, new buildings 'as built', existing buildings in the use phase and renovation.