Long-term performance analysis of a hybrid GSHP system for a large educational building in Finland

Ground source heat pump (GSHP) system is widely used for heating or cooling in many countries. However, in cold regions, the GSHP system may face performance deterioration due to excessive underground thermal imbalance. Therefore, hybrid GSHP systems with auxiliary heat sources are proposed for overcoming this problem. This study investigated the long-term performance of a hybrid GSHP system assisted by district heating and a chiller for a large educational building in Finland. The studied building and the hybrid GSHP system were modelled in IDA ICE 4.8. Two simulation cases were designed and compared to investigate the effects of dimensioning GSHP heating capacity on the system performance and energy consumption. The result showed that by reducing the GSHP heating capacity, in the last heating season the minimum brine temperature was increased by 3.1 ℃ and the heat pump COP was increased by 5 % compared to the reference case. The total electricity consumption in the case with the reduced GSHP heating capacity was reduced by 7 %, while in contrast the entire district heating consumption was increased by 50 %.