Utilisation of groundwater heat pumps for the decarbonisation of heating and cooling sector: the analysis of an Italian case study

In this paper, the utilisation of groundwater heat pumps for residential heating and cooling purposes is presented. A case study located in Florence (Italy) is discussed. First, a building energy analysis has been performed to obtain the thermal loads. Then three heat pump systems (system 1: air-to-water, 2: groundwater-to-water, 3: surface water-to-water) have been designed and compared in terms of electric energy consumption, taking into account the dynamic changing of boundary conditions of the building. Finally, a Life Cycle Assessment analysis has been conducted to evaluate the environmental impacts of the systems. To ensure a yearly heating energy request of 2 780 kWh (peak load of 5 kW) and a yearly cooling energy request of 630 kWh (peak load of 4.4 kW) the systems present a yearly electricity consumption of 1 088 kW, 770 kW and 872 kW for system 1, 2 and 3 respectively. So the groundwater-to-water solution is the most efficient in terms of energy consumption. Based on LCA evaluation, system 2 is the environmentally less impacting system, with a Climate Change factor of 0.15 kg CO2 eq/kWh against the 0.21 kg CO2 eq/kWh of system 1. In terms of single score level, system 2 and system 3 are characterised by a reduction in impacts of about 24 % compared to system 1. The dynamic energy and LCA studies clearly show that the solution based on groundwater exploitation, in this context, is a very effective way to reduce electricity consumption and environmental impacts, confirming that the large-scale implementation of groundwater heat pump systems could be a promising option for the decarbonisation of residential heating and cooling sector.