In Ventilation Information Paper VIP 38 of March 2018, AIVC defines smart ventilation as "process to continually adjust the ventilation system in time, and optionally by location, to provide the desired Indoor Air Quality (IAQ) benefits while minimizing energy consumption, utility bills and other non-IAQ costs (such as thermal discomfort or noise)." While these objectives are clear and the benefits of smart ventilation are now obvious, the assessment of the solutions is still a matter of debate. The assessment of smart ventilation solutions faces significant challenges due to the lack of standardized metrics and the variability of indices used, which depend on priorities such as occupant health, indoor comfort, or building preservation. This study, based on literature review of IAQ indices and numerical simulations, highlights this divergence and their impact for system assessment. Several smart strategies for 3 different ventilation systems (Mechanical Heat Recovery Ventilation, MHRV, Mechanical Extract Ventilation, MEV, and Positive Input Ventilation, PIV) were simulated in a single dwelling. The number of occupants and attendance times are fixed and 1 week scenario and 1 weekend scenario are modeled for 4 weather conditions typical of each season. Concentrations of four pollutants (Humidity, CO2, VOCt and PM2.5) were analyzed using two IAQ indices from the literature. For each ventilation system, the results of the different smart strategies were compared against a reference strategy. The results show that IAQ criteria related to health, comfort and prevention of building pathologies do not always coincide.
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 mechanical ventilation system with heat recovery (MVHR). A measurement campaign conducted from September to October 2019 provided data on particle concentrations and airflow rates across various rooms, while simulations were performed using CONTAM to model air and pollutant transport considering actual supply and exhaust airflow rates, outdoor particle concentrations, and filtration efficiencies derived from in-situ measurements. Few additional simulations were carried out to assess the impact 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. In the apartment, with a surface area of approximately 100 m(2) (1076 ft(2)), an air exchange rate of around 0.6 h-(1) was maintained during the study period. The results show that filtration efficiency varied significantly over time, particularly for particles smaller than 2 mu m. Domestic activities such as cooking and window opening had a considerable 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, contributing to the optimization of residential ventilation. By integrating empirical data with simulations, including scenarios with a portable air cleaner and a simulated infected occupant, this research sheds light on factors influencing indoor air quality in urban residential environments, with implications for air quality management in similar settings.
The CCM.FF-K1.2022 comparison was organized to determine the degree of equivalence of national standards for liquid flow in the range from 0.1 μL/min to 10.0 μL/min. A Coriolis mass flow meter and a thermal flow meter were used as transfer standards. Six laboratories from three regional metrology organizations (RMOs) participated between April 2023 and December 2023; EURAMET: METAS (Switzerland), CETIAT (France), IPQ (Portugal); SIM: NIST (United States of America); APMP: CMS (Taiwan, R.O.C.), NMIJ (Japan). METAS was the pilot laboratory and performed preliminary tests of the transfer standards to quantify their repeatability and reproducibility and to assess the stability of the artifacts. The key comparison reference values (KCRVs) were determined at each flow set point following the procedure presented by M. G. Cox and the χ2 consistency check. The degree of equivalence with the KCRV was calculated for each flow and laboratory.
Indoor air quality concerns leading to research on stand-alone air cleaner (AC) implementation. This study evaluates the effectiveness of mobile stand-alone air cleaners (ACs) in reducing airborne particles in two meeting rooms: one mechanically ventilated (1.5 vol/h) and one non-ventilated. Four AC units with varying flow patterns and equipped with HEPA filters, 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 analyze various implantation configurations, assess airflow patterns, air velocity, and particle concentration over time at different locations in the breathing zone. To quantify the air cleaners' effect on particle mitigation, the C16/C0 ratio is presented, where C16 represents the particles concentration after 16 minutes of AC operation, and C0 the initial concentration. Experimental measurements of particle concentrations for different particle sizes between 0.3 and 5 mu m 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 (lower C16/C0 ratio) is achieved with increased airflow rates, particularly in the non-ventilated room due to the absence of particle influx from ventilation. Air flow rates emerge as the key parameter influencing cleaning efficiency. Furthermore, the center 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. This study provides insights for optimizing stand-alone air cleaners (ACs) 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.
In the field of general ventilation, air filters are widely used, and introduced in ventilation ductworks, or air-handling units. These filters are passed through by air flow and noise. However, their characteristics of sound attenuation and sound generation are very poorly known, used and tested. This presentation reports a study done in collaboration with French air filtering manufacturers members of CETIAT. More than thirteen 592x592 mm filters representing four different types of air filters commercially available have been tested in laboratory, to characterise the insertion loss and the noise generation. Those types of filters are mini pleated (50 & 100 mm thickness), V-bank, bags and pleated, with different materials such as glass fiber and synthetic fiber. In addition, the effect of the dust loading has been investigated the sound characteristics as well as the influence of a series installation of a prefilter and a filter. These experimental data will be helpful for acoustic studies of ventilation networks. Some results about sound absorption can be related to the characteristics of the filters, thickness or shape but also to the loading and the use in series, whereas no obvious relation can be found for sound generation.
