Design Implications of Ground Properties and Operating Conditions for Geothermal Cooling in Hot-Humid and Arid regions: A Case Study of Bahrain

This study assesses the feasibility of geothermal cooling for residential buildings in hot-humid and arid regions, using Bahrain as a representative case. Unlike studies relying on commercial software, this evaluation utilizes a fundamental analytical approach based on ASHRAE guidelines to explicitly demonstrate how individual parameters influence system sizing. Vertical borehole ground-coupled heat pump systems were modeled using local climatic data and subsurface thermal properties. A comprehensive sensitivity analysis was performed to isolate the impact of ground thermal conductivity, diffusivity, borehole spacing, system operating duration, and circulating water temperature on the required heat exchanger length. The analysis identifies ground thermal conductivity and circulating water temperature as the primary drivers for minimizing system footprint, yielding borehole length reductions of up to 46%. The study also quantifies the competing long-term effects on the ground heat exchanger: localized thermal buildup expands the required heat exchanger length by 39% over time, whereas natural groundwater flow provides a stabilizing 36% reduction. Techno-economic analysis indicates that despite elevated capital expenditure driven by drilling cost, geothermal cooling can substantially reduce power consumption and greenhouse gas emissions, while mitigating local ambient temperatures by rejecting heat into the ground. The findings provide a transparent, physics-based design framework that demonstrates the technical viability of geothermal cooling in high-ambient-temperature regions, provided that long-term ground thermal saturation is managed.