Use of a slab foundation is very common in construction of residential buildings, and could also serve as a shallow ground heat exchange to address with a joint use of air source in a dual air and ground source heat pump. That thermal behaviour is here simulated using a commercial software FEFLOW, while the well-known building energy simulation software EnergyPlus is employed to produce the time series parameters serving as the boundary conditions in FEFLOW simulation. The overall coefficient of performance (COP) of the dual source heat will be estimated according to the simulation results. In addition, the simulation results also allow to evaluate how much the frosting problem could be avoided by use of the dual source heat pump. Therefore, the potential benefit of the dual source heat pump could be figured out.