Sustainability evaluation of a medium scale GSHP system in a layered alluvial setting using 3D modeling suite

•Sustainability evaluation of a vertical closed-loop GSHP system is performed.•A newly developed modelling suite is validated for low enthalpy simulations.•Effects of main subsurface and design parameters are studied.•Interference is amplified by strong heterogeneity of Po Plain alluvial deposits.•Homogeneous model assumption underrates the magnitude of thermal imbalance issues.