After the quality of the architectural design, it is in particular the energetic optimisation of the building envelope that is at the centre of attention of architects and consultant planners today and which thus represents one of the central planning criteria. The prerequisite for a balance between thermal effectiveness on the one hand and economy of the thermal insulation measures on the other is thereby the most precise possible determination of the calculatory parameters – in façades this is the thermal transmittance, in practise also known as the U-value for short. For façades made of reinforced concrete sandwich elements, this U-value must be determined from three individual components: the unimpaired heat flow in the area of the homogeneous layer structure as well as the additional heat losses due to the system dependent anchor and joint systems. In practise, these additional influences in the area of the discontinuities are frequently accounted for by fixed allowances which, although they keep the calculation method relatively simple, lead to falsified results that are generally also economically unfavourable. Against this background, a practicable calculation method is presented below that enables, with relatively little calculation effort, the precise determina - tion of the heat losses from anchor and joint systems as well as for both individual element configurations and arbitrarily designed facades.
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