The document specifies methods of calculation of heat transfer coefficients and heat flow rates, for building elements in thermal contact with the ground. It applies to building elements, or parts of them, below a horizontal plane in the bounding walls of the building situated for slab-on-ground floors and suspended floors, at the level of the inside floor surface and for basements, at the level of the external ground surface. It includes calculation of the steady-state part of the heat transfer and the part due to annual periodic variations in temperature. These seasonal variations are obtained on a monthly basis; the document does not apply to shorter periods of time.