This part of ISO 15928 sets out a method for describing the operating energy performance of houses. It covers user needs, provides performance descriptions and outlines evaluation processes. It includes the description of relevant parameters for external and internal climatic conditions, user functional requirements, energy used by the house and energy generated by the house. This part of ISO 15928 is intended to be used for houses that may be separated from, or linked horizontally to, another house(s). Where houses are linked, and some sharing of services occurs, it is intended that energy usage performance may be assessed both for individual houses, as well as a group of houses that are linked together. The ISO 15928 series is intended for use in the evaluation of the design and construction of houses and in the international trading of houses or their sub-systems. The ISO 15928 series does not specify a level of performance and it is not intended to provide a design method and/or criteria. NOTE Structural performance and other attributes are covered in other parts of ISO 15928.