Feasibility and climate adaption of shallow geothermally driven direct ventilation

Ground heat exchangers in ground source heat pump (GSHP) systems can provide low-temperature water, which has the potential to be utilized for pre-cooling in building ventilation. In this study, a novel shallow geothermally driven direct ventilation system was established. Experimental measurements were conducted to evaluate the effectiveness of the system. In addition, a TRNSYS software dynamic numerical model was developed to assess the long-term operational characteristics. The results of the long-term experiments indicated stable shallow soil temperatures, which were significantly lower than the outdoor temperatures in summer. Even when the outdoor temperature rose to 39.0°C, the system could provide an air supply temperature of 19.5°C, maintaining an average indoor temperature of 24.9°C. Numerical simulation results demonstrated that a shallow geothermally driven direct ventilation system could achieve an 88.9% rate of satisfaction for the cooling season. The system performed efficiently in dry and cold regions, such as Xi’an, and in severely cold regions, such as Shenyang. The results showed that two buried pipes exhibited optimal operational efficiencies. Therefore, installing a ventilation cooling system with buried pipes covering an effective cooling area of 18 m² is recommended. These findings provide valuable reference data for effective promotion of shallow geothermal energy in low-energy buildings.