Thermal Calculation of Ground Contact Structures: New Methods Based on Parametrized Transient Finite Element Thermal Modeling

The heat loss at ground contact structures is taken into consideration in building heat loss calculations. However, it implies uncertainties due to the physical properties of the soil as well as the building structure. In this paper, new methods are introduced for calculating the heat loss at ground contact structures. Firstly, it examines the presently used and general calculation methods and their shortcomings. Then a simple-to-use method based on thousands of results of parametrized transient finite element thermal models is shown. In this research, the calculations take the middle-eastern European climate conditions, geothermal gradient and soil properties as well as the relevant harmonized EU standards into account. The equivalent linear heat transfer coefficients, which in this method also contain the effects of thermal bridges, occurring in various conditions are summarized in a table and can be calculated by new formulae also shown in the paper using condition-dependent constants, the ground floor's heat transfer coefficient and the length between the floor and ground level