Heating and cooling account for a significant share of Europe’s energy consumption, particularly in Mediterranean regions where cooling demand continues to increase due to warmer climates and improved comfort requirements. Although ground source heat pump (GSHP) systems offer one of the most efficient renewable technologies for air conditioning and space heating, their widespread implementation has traditionally been limited by installation costs, system complexity and the environmental impact of conventional refrigerants. Developing integrated geothermal systems that are efficient, affordable and environmentally friendly was therefore a major challenge for the European research community.

The GEOCOOL project was launched under the Fifth Framework Programme (FP5) to develop a commercial-scale, fully integrated turnkey ground source heat pump system specifically designed for heating and cooling applications in Southern European coastal regions. Coordinated by the Universitat Politècnica de València (UPV), the project sought to combine the high efficiency of shallow geothermal energy with an advanced water-to-water heat pump using propane (R290) as a natural refrigerant, significantly reducing both energy consumption and environmental impact. The system was conceived as a reliable, low-maintenance and easy-to-install solution suitable for residential and small commercial buildings.

A principal objective of GEOCOOL was to achieve an overall 50–60% reduction in non-renewable energy consumption. This target was accomplished by combining the energy savings associated with geothermal heat exchange (40–50%) with additional efficiency gains obtained through the optimisation of the heat pump unit. The use of propane as the refrigerant further improved the environmental performance of the system by eliminating high global warming potential refrigerants while maintaining excellent thermodynamic efficiency. Particular emphasis was also placed on reducing installation costs, simplifying commissioning and minimising land requirements to facilitate market adoption. By integrating renewable geothermal energy with innovative heat pump technology, GEOCOOL demonstrated the technical and economic feasibility of sustainable heating and cooling systems adapted to Mediterranean climates. The project represented one of the earliest European initiatives coordinated by UPV in shallow geothermal energy and established important technological foundations for subsequent projects such as Cheap-GSHPs, GEOCOND and GEO4CIVHIC. Its outcomes contributed to advancing ground source heat pump technology while supporting Europe’s transition towards low-carbon, energy-efficient buildings.

GEOCOOL Project has received funding from the Programme for research, technological development and demonstration on «Energy, environment and sustainable development, 1998-2002» under grant agreement No. 13548.