Economic and exergy analysis of alternative plants for a zero carbon building complex

The feasibility of zero carbon emission plants for heating, air conditioning and domestic hot water (DHW) supply, is analyzed, with respect to conventional plants, for a new residential building complex to be constructed, in Northern Italy. Two zero carbon plants are considered: the first is composed of air-to-water heat pumps for space heating and cooling, PV solar collectors, air dehumidifiers, thermal solar collectors and a wood pellet boiler for DHW supply; in the second, the air-to-water heat pumps are replaced by ground-coupled heat pumps. The conventional plant is composed of a condensing gas boiler, single-apartment air-to-air heat pumps, and thermal solar collectors. The economic analysis shows that both zero carbon plants are feasible, and that the air-to- air heat pumps yield a shorter payback time. The exergy analysis confirms the feasibility of both plants, and shows that the ground-coupled heat pumps yield a higher exergy saving.