Modeling and Dimensioning Ground Heat Exchangers Principles: Influence of the soil's thermal proprieties

In the context of energy crisis and global warming, heating buildings with the solar energy stored in the soil rep- resents a very interesting alternative. Moreover, cooling buildings can also use the soil damping capacity. This paper presents our reflexion about the modeling and dimensioning of the ground heat exchanger part of ground-coupled heat pumps (GCHP). After a physical overview of the ground heat exchanger, we extract from analytical solutions practical consequences of the soil damping behavior and limits that provide guidelines for the dimensioning. We then question the default values of the numerical tools thermal parameters used for the simulation of GCHP. We illustrate this issue through a TRNSYS dynamic simulation of GCHP, demonstrating that soil's thermal parameters have a strong impact on the results. Finally, we give some perspectives for the determination of soil's characteristics in situ, but indirectly, thanks to geophysical prospection methods as ground penetrating radar, electromagnetic induction, or electrical resistivity tomography.