Geothermal heat pump (GHP) systems are more concentrated to moderate climate regions, although the potential for GHP systems in hot and humid climates is possible as past research efforts have demonstrated this using simulations and commercial case examples. This research investigates the use of residential GHP systems for the hot and humid climate found in southern Louisiana. The authors collected field performance information, including initial system cost, and electricity consumption and costs from two residential case studies in which each case included one home with a conventional heating and cooling system and one home with a GHP system. Using a comparative analysis and analysis of variance, results illustrate that initial cost of GHP system in the first case was $13,285 more and the second case was $17,588 more than the installation costs of a conventional system. Further, the GHP system payback period depends on the whether the design uses a horizontal or vertical ground loop, and the designer and contractor’s quality and experience in performing the GHP work as the first case resulted in a payback period of 70 years while the second case had a payback period of only seven years. Findings show that when an appropriate installation occurs, GHP system can save consumption and energy costs for residential homes in hot and humid climates.