The Assessment of Construction Details in Terms of 3D Thermal Fields and the Impact on Building Design

Abstract

Thermal bridge is a very common and undesirable phenomenon in a building. Thermal joint (bridge) is usually based on material or geometry reasons or their combinations. Many types (connection of window – wall, pillar – wall), can be calculated and evaluated sufficiently in 2D section, but in some types it is necessary to take into account 3D heat conduction. For example: a corner with ceiling (roof) and two walls where is strong deformation of isotherms and the internal surface temperature is definitely lower than in 2D section. According to the Czech Technical Standard it is necessary to fulfil law requirement – Temperature Factor at internal surface lowest temperature „at each location“. Recommendation is solving of “differential equation multi-dimensional of thermal field”. In this case of “building corner” project engineer has to decide for 3D modelling. In the contribution there is presented a mistake in 2D model, the situation when it is necessary to use 3D model. Additionally, there are recommendations to eliminate the risk of condensation and mould.