The effectiveness of night ventilation for the thermal balance of an aquifer thermal energy storage

Aquifer thermal energy storage (ATES) is a significant source of heating/cooling systems due to its energy and cost efficient operation. To ensure environmental and energy sustainability, the use of ATES is governed by strict regulations, one of which is the requirement of maintaining a balance in the amount of heat transfer into the ground. In general, the combination of a heat pump (HP) and an air handling unit (AHU) are commonly used to achieve this thermal balance through regeneration strategies for cooling dominated loads. However, this approach increases the operational cost and energy consumption of ATES heating/cooling systems. In this paper, an alternative approach that makes use of night ventilation (NV) for regeneration is evaluated. In addition, the operational cost and energy efficiencies of the commonly used combination of an HP and AHU are compared to those associated with NV operation. The results show that using NV for the regeneration of the cold well could reduce energy consumption by 19.3 MWh/year, which amounts to a 26.4% increase in system coefficient of performance (COP).