Solar ground energy storage coupled with heat pumps in cold climates

The use of Ground Source Heat Pump systems for heating and cooling has grown significantly during the last years. All countries have moved to promote the use of renewable energy for the reduction of primary energy use and CO2 emissions related to space heating/cooling and domestic hot water production. These systems are a promising technology able to use free heat sources and to be used also for cooling purposes. In the presented study such system is used for space heating and it uses the ground for extracting heat and injecting solar thermal energy when in excess. This work looks at the use of vertical Borehole Heat Exchangers installed in cold climate characterized by low air temperatures. In these locations, the building load profile is usually heating dominant with absent cooling necessity, especially in residential buildings where internal gains are low. When Ground Source Heat Pump systems are used for heating only, their performance decrease due to unbalanced heat transfer with the ground. Solar thermal collectors can help in this matter by allowing a better performance of these systems installed in cold zones. All the analysis have been carried out with the dynamic simulation tool TRNSYS.