Three-dimensional modelling of heat transfer from slab floors

Earth-coupled heat transfer processes have been recognized in recent years as a potential source of significant energy savings in both conventional and earth-sheltered designs. Because of the complexity of the building/soil/atmosphere interaction, however, important aspects of earth-coupled heat transfer are not well understood. There is a particular lack of three-dimensional foundation heat loss data. In this study, a detailed three-dimensional finite difference model of a slab floor was used to generate 93 annual simulations in parametric groups focusing on effects of size and shape, soil properties, boundary conditions, climate, insulation, and building shadow. These results indicate that soil thermal conductivity, ground surface conditions, foundation design, and floor shape/size are essential elements of a general change in heat transfer rate. Effects of thermal diffusivity, and lower boundary condition variation were small (on the order of 10%) for the range of conditions considered.