Full-scale performance of a low-pressure loss PM2.5 air filter for building natural ventilation

Abstract

Urban buildings increasingly rely on natural ventilation (NV) to reduce cooling energy, but high outdoor PM2.5 levels often make the NV airflow unsafe. This study presents a full-scale testing of a façade-integrated, low pressure loss electrostatic precipitator (ESP) designed to filter PM2.5, without hindering the NV airflow. Two prototype “U” channel ESP filters were installed in a weather-exposed test chamber representing a four-person office. Under single-sided NV driven solely by buoyancy and wind, the filters provided 97-109 m³/h of fresh air (enough to provide the requirements of the four occupants), while removing 55-63 % of incoming PM2.5. In hybrid-mechanical cross-ventilation, fans kept the airflow rate at 300 m³/h, while the PM2.5 removal efficiency was approximately 50 %. Using these measured efficiencies with five-year hourly climate and air-quality data for Lisbon, Frankfurt, and Helsinki, use of the device was estimated to triple the fraction of number of working hours with outdoor air temperatures suitable for NV, while simultaneously ensuring that the incoming airflow met WHO PM2.5 guidelines, in warm climates, and approximately double that fraction of working hours in cold climates. These findings demonstrate a practical pathway to healthier, low-energy ventilation in polluted urban environments while outlining the remaining challenges of long-term power supply, noise attenuation, and seasonal performance.