Towards climate-adaptive design: Performance variations, underlying patterns, and differentiated strategies of earth-air heat exchangers across diverse climates in China

Earth-air heat exchangers are effective for achieving energy savings and decarbonization in buildings, yet their adaptation across diverse climate zones remains insufficiently understood. To address this gap, this study provides a standardized comparative analysis across ten climatically diverse cities in China using a tri-indicator framework encompassing energy output, efficiency, and carbon reduction. Delta moment-independent measure sensitivity analysis, local weighted regression and Spearman correlation analyses are integrated to reveal the patterns of system behavior. Results indicate that climatic conditions significantly impact performance. Harbin in the severe cold zone shows an annual heating output exceeding 4300 kWh, more than seven times that of Kunming in the mild zone, while achieving an average energy efficiency of 51 and a carbon dioxide reduction of 1300 kg. Sensitivity analysis reveals that the parameter importance rankings for the three indicators vary across different cities. Trend analysis uncovers complex nonlinearities, showing that while larger pipe diameters increase energy output via a larger heat exchange area, they reduce efficiency because the energy needed to move the air grows faster than the heat gained. Trade-offs exist among the three indicators, where energy output is negatively correlated with energy efficiency but exhibits a significant positive correlation with carbon reduction. The variations in optimal parameters across different regions demonstrate the need for targeted design and optimization strategies for earth-air heat exchangers under specific climatic conditions. This study provides a theoretical foundation for optimizing the regional adaptability of earth-air heat exchangers and supporting sustainable development goals across diverse climate contexts.