This article investigated the energy performance of CO2 (R744) ground-coupled heat pumping system for heating and cooling application for different buildings under the climate of Oslo, Norway. The developed heat pumping system, employing a reverse CO2 transcritical cycle, utilizes ground as a heat source in heating mode. The separated gas coolers also enable simultaneous space heating and hot water supply in the heating mode. It is also possible to use ground as heat sink in cooling mode. This CO2 hybrid ground coupled heat pumping system is constructed and modelled in the Modelica/ Dymola environment, and several types of arrangement according to the building heat load demands are suggested for the energy performance investigation. Simulation result shows the COPspace&shw, which is more than 3.0, is superior comparing with traditional heating system. The developed CO2 ground-coupled heat pumping system shows great potential on the simultaneous space heating and hot water supply, especially for the buildings with higher hot water demand.