This paper is based on findings resulting from ASHRAE Research Project RP-1384.

Hybrid ground-coupled heat pump systems (HyGCHPs) couple conventional ground-coupled heat pump (GCHP) equipment with supplemental heat rejection or extraction systems. In cooling-dominated climates, the use of a supplemental heat-rejection system has been shown to significantly improve the economics of the system. However, the design and operation of HyGCHPs are more complex than GCHPs, and the interaction between the components, the building, and the ground are nonintuitive. A systematic and comprehensive optimization of HyGCHP systems is necessary in order to fully quantify and understand how they should be designed and what their true potential is. This paper describes a simulation study integrating a HyGCHP model with an optimization engine in order to identify the optimal system design (i.e., component sizes) and control strategy that minimizes the lifecycle cost (LCC) of the system for a range of different climates and building types. In addition, the sensitivity of the optimal design to various economic parameters and physical assumptions was studied. The results of the parametric study were used to develop general design guidelines that can be used to select an equipment configuration, size the equipment, and control the equipment for an optimally designed HyGCHP system.

Units: Dual