scope:

Sets out the specifications on a 3-D and 2-D geometrical model of a thermal bridge for the numerical calculation of: - heat flows in order to assess the overall heat loss from a building; - minimum surface temperatures in order to assess the risk of surface condensation. These specifications include the geometrical boundaries and subdivisions of the model, the thermal boundary conditions and the thermal values and relationships to be used. The standard is based upon the following assumptions: - steady-state conditions apply ; - all physical properties are independent of temperature; - there are no heat sources within the building element. It may also be used for the deriviation of linear and point thermal transmittances and of surface temperature factors.