An Analysis on Cost Reduction Potential of Vertical Bore Ground Heat Exchangers Used for Ground Source Heat Pump Systems

Abstract

The cost for installing ground heat exchangers (GHXs) used for ground source heat pump (GSHP) systems usually accounts for more than 30% of the total cost of a GSHP system and it is the biggest contributor to the cost premium of GSHPs compared with conventional HVAC systems. This study evaluates the cost reduction potential of several possible improvements in borehole heat transfer and bore field layout. A detailed cost model for GHX installation was updated and new features were added to account for various GHX designs, geological conditions, and drilling technologies. Coupled with a well-established GHX sizing program, a systematic study was conducted to assess the impacts of these improvements on the needed total drilling length and resulting cost under various geological and loading conditions. Finally, improvements with significant potential to reduce GHX installation cost are recommended.