Cooling energy savings potential from economizer integrated with ground-coupled air duct system in Korean climate

This study proposes an economizer integrated with ground-coupled air duct system (EGAS) to expand the range of outdoor air (OA) conditions suitable for economizer operation and to maximize cooling energy savings under Korean climate (4A climate zone). The EGAS features an OA duct buried underground, allowing heat exchange with the relatively stable and lower-temperature soil before determining the OA intake rates of economizer. Therefore, this study aims to evaluate the cooling energy savings potential by using EGAS in the Korean climate. To achieve this, the EGAS control algorithm was developed and integrated into the Base model to conduct building energy simulations. The results showed that EGAS increased OA intake rates, extended the operating hours of economizer. Accordingly, mixed air temperatures and cooling coil loads were reduced. Specifically, the annual cumulative cooling coil loads decreased by approximately 15.9% compared to the Basecase, HVAC energy usage was reduced by about 13%. Additionally, the indoor dry-bulb temperature and relative humidity remained within the comfort range, indicating no degradation of thermal comfort. These findings suggest that using EGAS for OA intake is an effective strategy for cooling energy savings.