Conference Agenda

Indoor air quality concerns drive research on air cleaner implementation. This study evaluates the effectiveness of stand-alone air cleaners (AC) in reducing airborne particles in two meeting rooms: one mechanically ventilated (1.5 vol/h) and one non-ventilated. Six AC units with varying flow patterns, equipped with HEPA filters, including four mobile and two fixed (ceiling-type), were deployed in the rooms at airflow rates of 1, 2.5, and 5 vol/h. Three-dimensional computational fluid dynamics (CFD) simulations, treating particles as a gas, were conducted to analyse various implantation configurations, assessing airflow patterns, air velocity, particle concentration over time at different locations in the breathing zone, the time required for 50% particle removal, and cleaning efficiency. Experimental measurements of particle concentrations for different size ranges (0.3-5 µm) were taken for some simulated configuration using low-cost sensors, both to validate the simulation results and to study the variation in cleaning efficiency based on particle size.

The differences between measured and calculated particle reduction values were minimal. The findings indicate that higher particle reduction is achieved with increased airflow rates, particularly in the non-ventilated room due to the absence of particle influx from ventilation. The centre of the room is identified as the optimal position for AC placement, while corners are the least effective. Using two AC units is preferable from an acoustic standpoint while achieving similar results with one unit. Ceiling-type AC units provide a more homogeneous distribution of particle concentrations. At 5 vol/h, differences in particle concentrations across the room are minimal but become more pronounced at lower airflow rates. The homogeneity of particle concentration reduction is better understood in the non-ventilated room. This study provides insights for optimizing air cleaner use in indoor environments, enhancing overall particle reduction and size-specific cleaning efficiency to improve indoor air quality in both ventilated and non-ventilated spaces.

Indoor air quality in urban environments requires effective ventilation and filtration to reduce airborne pollutants. This study examines air and particle transport in a four-room apartment in a building located in Lyon, France, equipped with a balanced ventilation system. A measurement campaign conducted from September to October 2019 provided valuable data on particle concentrations and airflow rates across various rooms, while simulations were performed using CONTAM to model air and pollutant transport.

The simulations accounted for actual supply and exhaust airflow rates, outdoor particle concentrations, and filtration efficiencies derived from in-situ measurements.

A few additional simulations were carried out to assess the effects of a portable air cleaner used in one of the rooms, the presence of a sick occupant as a source of pollutants, and the impact of window and door opening on aerosol concentrations and occupant exposure. In the apartment, with a surface area of around 100 m², an air exchange rate of around 0.6 h-¹ was maintained during the study period.

Results show that filtration efficiency varied significantly over time, especially for particles under 2 μm. Domestic activities such as cooking and window opening were found to have a substantial impact on indoor air quality. A comparative analysis of measured and simulated data revealed systematic discrepancies, prompting iterative adjustments to model parameters related to pollutant sources and deposition rates. Sensitivity tests indicated that using average filtration efficiencies over time improved the alignment between simulated and measured particle levels.

This study underscores the importance of precise modeling in understanding indoor air dynamics, offering insights into optimizing residential ventilation. By integrating empirical data with simulations—including scenarios with a portable air cleaner and a simulated infected occupant—this research provides insights into factors influencing indoor air quality in urban residential environments, with implications for air quality management in similar settings.