Earth-Coupled Cooling Strategies Across Regions: A Review Toward Adaptation In Hot And Humid Climates

Abstract

Earth-coupled cooling systems harness the stable subsurface temperature maintained by the earth’s thermal inertia to reduce indoor heat loads, offering a promising passive or hybrid solution for energy-efficient thermal comfort. This study presents a comprehensive literature review of 30 selected key publications on earth-coupled cooling across diverse climates, aiming to clarify definitions, establish a systematic classification, and assess potential applications in hot and humid tropical regions such as Indonesia. The review distinguishes two primary categories based on heat exchange mechanisms: direct earth- coupled cooling, which relies on conductive contact between building structures and soil; and indirect earth-coupled cooling, which circulates air or water through buried pipes for convective and radiant cooling. Indirect systems are further classified as earth–air heat exchangers (EAHE) and earth–water heat exchangers (EWHE), with EAHEs being more prevalent due to their simpler design. Performance factors for EAHEs include pipe diameter, length, arrangement, burial depth, airflow velocity inside the tubes, and soil thermal conductivity, while integration with other passive systems (e.g., green roofs and solar chimneys) or mechanical assistance can further enhance performance. Findings show that while complex hybrid systems have been implemented in arid and temperate climates, tropical applications remain limited, often relying on basic EAHE configurations. The study highlights the importance of reassessing underutilized techniques, such as those based on thermal mass or evaporative cooling for tropical conditions. By providing a clear definition and structured classification, this research offers a foundation for future adaptation, innovation, and broader implementation of earth-coupled cooling systems in tropical climatic contexts.