Heat bridges in passive houses

Design of passive houses requires project preparation above standard. It is necessary to deal with all heat bridges while designing. Creation of 2-D model of particular construction parts and computation of steady-state temperatures are standard methods using for computation of temperatures of inner surfaces in heat bridges. This way of computation seems to be sufficient for most of construction details, but its results are far away from reality when used for particular parts of construction. Connection of the enclosure wall, its foundation, the floor and the soil is one of them. In this article a comparison of two methods of computation is undertaken for the construction detail mentioned above. A computation of steady-state distribution of temperatures and a computation of transient heat transfer are compared. The computation of transient heat transfer simulates distribution of temperatures in the construction detail during four year period from the beginning of the using of the building. For this period the data of distribution of temperatures during typical meteorological year were used. The results show, that computation by standard method is very conservative and it can lead to overestimating of the problem, which the heat bridge between construction and the soil can make.