This International Standard specifies the characteristics related to the dynamic thermal behaviour of a complete building component and provides methods for their calculation. It also specifies the information on building materials required for the use of the building component. Since the characteristics depend on the way materials are combined to form building components, this International Standard is not applicable to building materials or to unfinished building components. The definitions given in this International Standard are applicable to any building component. A simplified calculation method is provided for plane components consisting of plane layers of substantially homogeneous building materials. Annex A specifies simpler methods for the estimation of the heat capacities in some limited cases. These methods are suitable for the determination of dynamic thermal properties required for the estimation of energy use. These approximations are not appropriate, however, for product characterization. Annex B gives the basic principle and examples of applications of the dynamic thermal characteristics defined in this International Standard. Annex C provides information for programming the calculation method. Annex D gives examples of calculation for a building component.