Development of a standardized method for determining the free-cooling performance of ground-source heat pumps
Ground-source heat pumps (GSHPs) offer a unique opportunity for energy-efficient cooling through freecooling— an operating mode where the system delivers cooling using only circulating pumps, without activating the compressor. This significantly reduces energy consumption compared to conventional active cooling systems such as chillers and air conditioners. The relatively constant ground temperature throughout the year enables boreholes, originally intended for space heating, to serve as a free cold source during the summer season. Despite its high efficiency, free-cooling remains underutilized and insufficiently studied, with no established methodology, until recently for predicting its performance prior to system installation. To address this gap, this paper presents a standardized method for estimating the free-cooling capacity of GSHP systems based solely on their heating performance. Through extensive simulations, the study demonstrates strong correlations between the space heating capacity of a GSHP, its geographical location in Europe and its free-cooling potential. The proposed method yields two key correlations. The first one enables estimation of free-cooling capacity for each of the three European reference climates defined in Ecodesign Regulation EU 811/2013 and for two types of emitters. The second one allows calculation of the Energy Efficiency Ratio (EER) for free-cooling mode, again specific to climate zone. This method provides a practical and scalable way to evaluate the cooling potential and efficiency of GSHPs early in the design process, promoting wider adoption of this ultra-low-energy cooling technique. It offers manufacturers, designers, and policymakers a valuable tool for advancing decarbonized, energyefficient cooling solutions across Europe.