Energy performance and thermal comfort of integrated energy recovery ventilator system with air-conditioner for passive buildings

This study aims to provide a ventilation solution for energy-efficient buildings that suffer from high indoor moisture content during cooling seasons. With the decreased sensible load in highly insulated buildings, conventional energy recovery ventilators (ERVs) and air conditioners are inadequate to effectively handle the increased dehumidification load. Moisture removal through air conditioners requires cooling the air below its dew point, which makes precise control of indoor humidity difficult and reduces the level of indoor thermal comfort. Thus, an ERV system integrated with a cooling coil (ERV-CC) is proposed to enhance its latent heat effectiveness. Field measurements were conducted for the ERV and ERV-CC systems to compare their energy performances and levels of indoor thermal comfort. The results indicated that the ERV system did not satisfy the recommended range of indoor humidity even when the set-point temperature of the air conditioner decreased. However, the ERV-CC system could condition the indoor air within the comfort zone at higher energy efficiencies. In addition, the ERV-CC system was observed to benefit from the dehumidification effect through the enthalpy recovery process under a wider range of outdoor conditions. Especially, at low outdoor temperatures, the ERV-CC system dehumidified the incoming fresh air, whereas the ERV system humidified the fresh air. Overall, the optimum operating conditions for the ERV-CC system were determined to be a set-point temperature and relative humidity of 27 °C and 50%, respectively, while satisfying the thermal comfort criterion at an 8.24% predicted percentage dissatisfied index with minimum energy consumption. Furthermore, the ERV-CC system not only reduced the building load, but also improved the individual air conditioner performance.