Early design strategy for hybrid ground source heat pump systems for a commercial building

In this study, the design strategy for hybrid ground source heat pump (GSHP) systems consisting of GSHP and air source heat pump (ASHP) is investigated with a focus on the early design stages of an air conditioning system for a commercial building. A design procedure for determining the capacity ratio of the GSHP and ASHP is presented. Then, conservative values of the design parameters for the design process are described. A case study conducted according to the introduced procedure showed that the capacity ratio of GSHP and ASHP is influenced by the magnitude of the peak load of the building and building site conditions, as well as the configuration of ground source heat exchangers. Furthermore, an effort to reduce the peak load would increase the capacity ratio of the GSHP. It was shown that the capacity ratio would be approximately set by the site conditions, which can be a dominant constraint on GSHP capacity design. Finally, in the initial design phase, a design practice with conservative design values was instituted that would help in determining the capacity ratio and the configuration of the ground source heat exchangers.