Analysis of different ventilation strategies and CO2 distribution in a naturally ventilated classroom

Muelas, Álvaro; Remacha, Pilar; Piña, Antonio Javier Barragán; Tizné, Eduardo; El-Kadmiri, Said; Ruiz, Ana Milagros Jiménez; Aranda, Diego; Ballester, Javier

doi:10.1016/j.atmosenv.2022.119176

Cited by 24 publications

(9 citation statements)

References 26 publications

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“…Consistent with established physiology and building engineering principles, our phase 1 findings show that increasing human occupancy causes an increase in carbon dioxide levels, which is reduced with window and door opening [20, 30]. Of note, carbon dioxide did not decrease significantly with a tilted open window when there were four people in the room, compared with a fully opened window.…”

Section: Discussionsupporting

confidence: 77%

Quantifying hospital environmental ventilation using carbon dioxide monitoring – a multicentre study

Wilson,

Calabria,

Warren

et al. 2023

Anaesthesia

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SummaryThe COVID‐19 pandemic has highlighted the importance of environmental ventilation in reducing airborne pathogen transmission. Carbon dioxide monitoring is recommended in the community to ensure adequate ventilation. Dynamic measurements of ventilation quantifying human exhaled waste gas accumulation are not conducted routinely in hospitals. Instead, environmental ventilation is allocated using static hourly air change rates. These vary according to the degree of perceived hazard, with the highest change rates reserved for locations where aerosol‐generating procedures are performed, where medical/anaesthetic gases are used and where a small number of high‐risk infective or immunocompromised patients may be isolated to reduce cross‐infection. We aimed to quantify the quality and distribution of ventilation in hospital by measuring carbon dioxide levels in a two‐phased prospective observational study. First, under controlled conditions, we validated our method and the relationship between human occupancy, ventilation and carbon dioxide levels using non‐dispersive infrared carbon dioxide monitors. We then assessed ventilation quality in patient‐occupied (clinical) and staff break and office (non‐clinical) areas across two hospitals in Scotland. We selected acute medical and respiratory wards in which patients with COVID‐19 are cared for routinely, as well as ICUs and operating theatres where aerosol‐generating procedures are performed routinely. Between November and December 2022, 127,680 carbon dioxide measurements were obtained across 32 areas over 8 weeks. Carbon dioxide levels breached the 800 ppm threshold for 14% of the time in non‐clinical areas vs. 7% in clinical areas (p < 0.001). In non‐clinical areas, carbon dioxide levels were > 800 ppm for 20% of the time in both ICUs and wards, vs. 1% in operating theatres (p < 0.001). In clinical areas, carbon dioxide was > 800 ppm for 16% of the time in wards, vs. 0% in ICUs and operating theatres (p < 0.001). We conclude that staff break, office and clinical areas on acute medical and respiratory wards frequently had inadequate ventilation, potentially increasing the risks of airborne pathogen transmission to staff and patients. Conversely, ventilation was consistently high in the ICU and operating theatre clinical environments. Carbon dioxide monitoring could be used to measure and guide improvements in hospital ventilation.

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Section: Discussionsupporting

confidence: 77%

Quantifying hospital environmental ventilation using carbon dioxide monitoring – a multicentre study

Wilson,

Calabria,

Warren

et al. 2023

Anaesthesia

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“…The literature recommends a sampling height of 1.50 m, but such an installation is not always possible due to the lack of proper supports or possible sensor tampering by students. The sensor can also be installed at a height of around 2.00 m, Muelas et al [11] reports that 2.20 m turns out to be a good sampling location because the measured values are closer to the average values measured in the classroom. It is recommended, whenever possible, to avoid the installation of sensors on the wall, since the real values of the variables measured in the classroom would be underestimated [11].…”

Section: Thermal and Iaq Measurementsmentioning

confidence: 98%

“…The sensor can also be installed at a height of around 2.00 m, Muelas et al [11] reports that 2.20 m turns out to be a good sampling location because the measured values are closer to the average values measured in the classroom. It is recommended, whenever possible, to avoid the installation of sensors on the wall, since the real values of the variables measured in the classroom would be underestimated [11]. Monitoring should provide a continuous data set; a sampling interval of at least 1 minute and a monitoring period of at least two weeks is recommended.…”

Section: Thermal and Iaq Measurementsmentioning

confidence: 98%

Monitoring and analysis of environmental and IAQ conditions in classrooms with controlled mechanical ventilation

Remia,

Summa,

Stazi

et al. 2023

J. Phys.: Conf. Ser.

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Following the health emergency from COVID-19, indoor air quality control has become of paramount importance, especially inside school buildings. For this reason, in 2021, the Marche region proposed and implemented an extraordinary intervention for the safe conduct of educational activities through the installation in classrooms of controlled mechanical ventilation systems aimed at air exchange. This type of system has been installed in more than 1,200 classrooms belonging to about 130 schools throughout the Marche region. This intervention made it possible to carry out a robust experimental measurement campaign on a significant number of classrooms where controlled mechanical ventilation systems were installed. Specifically, the work proposes a replicable measurement and analysis methodology for classrooms, with the aim of monitoring thermo-hygrometric and air quality conditions for environmental comfort. Thus, the research aims to implement knowledge on environmental comfort in classrooms equipped with controlled mechanical ventilation systems. The proposed measurements and analyses cover the most important environmental variables, i.e., air temperature, relative humidity, and CO2 concentration. In addition, measurements regarding system ventilation flow rates, smoke tests and evaluations of the permeability of classrooms.

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“…Numerous investigations pointed to an improvement in the pupil’s concentration in well-ventilated classrooms. 73–75…”

Section: Introductionmentioning

confidence: 99%

“…Numerous investigations pointed to an improvement in the pupil's concentration in well-ventilated classrooms. [73][74][75] This article proposes a new methodology for effectively measuring and controlling CO2 in closed and shared spaces. The methodology is based on three stages: diagnosis, correction, and controlled monitoring.…”

mentioning

confidence: 99%

Development and validation of a methodology to measure exhaled carbon dioxide (CO₂) and control indoor air renewal

Baselga

Alba

Schuhmacher

2022

Preprint

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The measurement of CO2 has positioned itself as a low-cost and straightforward technique to indirectly control indoor air quality, allowing the reduction of the concentration of potentially pathogen-loaded aerosols to which we are exposed. However, on numerous occasions, bad practice limits the technique for CO2 level interpreting and does not apply methodologies that guarantee air renewal. This work proposes a new methodology for measuring and controlling CO2 levels for indoor air in shared spaces. The proposed methodology is based on three stages: diagnosis, correction protocols, and monitoring/control/surveillance (MCS). The procedure is explained using a cultural center as an actual base case study. Additionally, the procedure was validated by implementing 40 voluntary commercial spaces in Zaragoza (Spain). Standardization of methods is suggested so that the measurement of CO2 becomes an effective strategy to control the airborne transmission of pathogens and thus prevent future Covid-19 outbreaks and novel pandemics.

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Analysis of different ventilation strategies and CO2 distribution in a naturally ventilated classroom

Cited by 24 publications

References 26 publications

Quantifying hospital environmental ventilation using carbon dioxide monitoring – a multicentre study

Quantifying hospital environmental ventilation using carbon dioxide monitoring – a multicentre study

Monitoring and analysis of environmental and IAQ conditions in classrooms with controlled mechanical ventilation

Development and validation of a methodology to measure exhaled carbon dioxide (CO₂) and control indoor air renewal

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Analysis of different ventilation strategies and CO2 distribution in a naturally ventilated classroom

Cited by 24 publications

References 26 publications

Quantifying hospital environmental ventilation using carbon dioxide monitoring – a multicentre study

Quantifying hospital environmental ventilation using carbon dioxide monitoring – a multicentre study

Monitoring and analysis of environmental and IAQ conditions in classrooms with controlled mechanical ventilation

Development and validation of a methodology to measure exhaled carbon dioxide (CO2) and control indoor air renewal

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Product

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Development and validation of a methodology to measure exhaled carbon dioxide (CO₂) and control indoor air renewal