Holistic Sustainability Assessment of Solar Ground Source Heat Pump Systems: Integrating Life Cycle Assessment, Carbon Emissions and Emergy Analyses

In order to explore the increase in the environmental benefits of solar ground source heat pump (SGSHP) systems, this study assesses the environmental benefits of SGSHPs through a comprehensive sustainability evaluation, integrating life cycle assessment, carbon emission analysis, and emergy analysis based on a real project in Tianjin (39.13° N, 117.2° E). By comparing an SGSHP with the conventional GSHP system, improvements in sustainability performance are quantified. The analysis reveals that the SGSHP system has a full-cycle EI16 of 1.88 × 103, which is 15% higher than the GSHP value of 1.63 × 103. The SGSHP demonstrates a significant advantage in terms of carbon emissions at all stages, with an overall carbon emission of 31,671 kgCO2-eq, which is a reduction of about 9.4% compared to the 34,955 kgCO2-eq of the conventional GSHP system. The emergy conversion rate of SGSHP is 3.58 × 103, which is 16.23% higher than that of GSHP. This shows that the system with the addition of solar energy is able to convert raw energy into useful heat or cooling energy more efficiently, reducing emergy wastage and making it operate more efficiently, with emergy saving and environmental advantages. The SGSHP system has an ESI value of 1.12, indicating that it is in a developmental or intermediate stage, with significant potential for sustainable economic contributions. In contrast, the GSHP system, with an ESI value of 0.98, demonstrates that it is not sustainable over the long term. By using a comprehensive environmental assessment framework and comparative data analysis, this study aims to better understand the SGSHP system’s performance in energy use, carbon emissions, and ecological impact, providing a scientific foundation for its wider adoption.