Performance analysis of a decentralized DCV system for ventilation and energy use in Korean residential buildings

This study investigates the applicability and performance of a decentralized demand-controlled ventilation (DCV) system in airtight South Korean residential buildings. In Korea, new residential buildings must install an energy recovery ventilator (ERV) to address both energy and indoor air quality, but pose from their conventional centralized ventilation. Unlike conventional centralized ventilation systems, which supply a uniform airflow regardless of occupancy, the decentralized DCV dynamically adjusts ventilation rates based on real-time occupancy status. A field experiment in a 59 m² apartment, using identical occupancy schedules, compared a baseline system with a decentralized DCV system. The DCV system maintained lower CO₂ concentrations, reducing time above 1000 ppm by up to 79 %, while increasing average fan energy consumption by only 9.2 %. EnergyPlus simulations were then performed for three representative apartment layouts (59 m², 84 m², and 135 m²) by applying three control scenarios under an identical occupancy schedule: (1) fixed-rate ventilation at 0.5 ACH, (2) schedule based DCV, and (3) schedule- and CO₂-threshold-based DCV. Scenario 3 achieved the most favorable balance between indoor air quality (IAQ) and energy efficiency, particularly in the 135 m² unit, where annual ventilation hours were reduced by over 94 % without exceeding the CO₂ threshold of 1000 ppm. These findings validate the effectiveness of decentralized DCV systems in mitigating unbalanced ventilation distribution and reducing energy waste in Korean residential buildings. The results provide empirical and simulation-based evidence for the feasibility of decentralized ventilation strategies in achieving both IAQ enhancement and energy conservation under realistic multi-zone occupancy conditions.