A zero carbon emission plant for heating, cooling, humidity control and domestic hot water supply is designed, for a new building complex in Northern Italy. The plant is composed of: a ground coupled heat pump system for space heating and cooling, with electricity supplied by PV solar collectors; air dehumidifiers; thermal solar collectors and a wood pellet boiler for domestic hot water supply. Dynamic simulations of the building complex and of the borehole heat exchangers are performed by the software package TRNSYS. The economic feasibility of the proposed plant is analyzed by comparison with a conventional plant for heating, cooling and humidity control.