ISO 13370:2017 provides methods of calculation of heat transfer coefficients and heat flow rates for building elements in thermal contact with the ground, including slab‐on‐ground floors, suspended floors and basements. It applies to building elements, or parts of them, below a horizontal plane in the bounding walls of the building situated

- at the level of the inside floor surface, for slab‐on‐ground floors, suspended floors and unheated basements;

NOTE 1 In some cases, external dimension systems define the boundary at the lower surface of the floor slab.

- at the level of the external ground surface, for heated basements.

ISO 13370:2017 includes calculation of the steady‐state part of the heat transfer (the annual average rate of heat flow) and the part due to annual periodic variations in temperature (the seasonal variations of the heat flow rate about the annual average). These seasonal variations are obtained on a monthly basis and, except for the application to dynamic simulation programmes in Annex D, ISO 13370:2017 does not apply to shorter periods of time.

NOTE 2 Table 1 in the Introduction shows the relative position of ISO 13370:2017 within the set of EPB standards in the context of the modular structure as set out in ISO 52000-1.