The need to increase energy efficiency for heating and cooling has promoted the development of Ground-Source Heat Pumps; in particular a large number of vertical ground-coupled heat pumps have been installed thanks to their high energy efficiency and little land area requirement. This work, presents an overview of the numerical models available for the thermo-fluid dynamic phenomena which occur in the surroundings of Ground Heat Exchangers (GHEs). After a brief introduction on the subject, the available analytical and numerical models are summarized, underlining recent developments in modeling approach.