Transfer functions method and sub-structuration technique for two-dimensional heat conduction problems in high thermal mass systems: Application to ground coupling problems

This paper describes the use of the two-dimensional transfer functions (TF) method and the sub-structuration technique for solving numerically two-dimensional heat conduction problems in large calculation domains. This technique consists of decomposing the studied system into rectangular blocks following the two directions of heat transfer. Each block is a sub-system characterised by its inputs and outputs and by its appropriate transfer function coefficients (TFC). The procedure described is applied to predicted heat exchanges between the building and the soil. So, three ground-coupled structures are studied: slab-on-grade floor, shallow basement and earth-sheltered building. The TFC generated are used to predict the temperature profiles at different levels of the studied configurations and the variation of the monthly heat flux exchanged between buildings and the soil in two typical climates. The pertinence of the technique presented is tested by comparing its results with those obtained using the alternative directions implicit (ADI) method.