Comparison between different foundation elements as an Energy Geo-Structure in a Moderate Climate

Shallow Geothermal Energy (SGE) systems, a form of Renewable Energy Systems (RES), integrate Ground Source Heat Pumps (GSHPs) for sustainable heating and cooling in buildings. These systems rely on Ground Heat Exchangers (GHEs) to facilitate thermal energy transfer between the building and the ground. Despite their higher performance and environmental benefits compared to conventional systems, GSHPs have seen limited adoption due to substantial upfront costs and extended payback periods. To address these challenges, the current study explores the application and implementation of different foundation elements to act as Energy Geo-Structures (EGs) by utilizing foundation slabs and retaining walls within underground parking spaces as GHEs.  Computational modeling was conducted using the COMSOL Multiphysics software, with a focus on a residential building in Cyprus designed to meet nearly Zero Energy Building (nZEB) standards. The heating and cooling demands were assessed using TRNSYS software and integrated into the analysis of the proposed system. Results demonstrated that not all EGs systems achieved steady thermal performance and high Coefficient of Performance (COP) values. This study underscores the potential of partial loading and of integrating these foundation elements as GHEs, positioning them as a viable and sustainable alternative for residential energy systems.