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Assessing the efficacy of ventilation with CO2 monitors has been identified as a key strategy for enabling a safe and COVID-Secure return to work and school.<\/p>\nAssessing the efficacy of ventilation with CO2 monitors has been identified as a key strategy for enabling a safe and COVID-Secure return to work and school.<\/p>\n
For workplaces and schools, a safe reopening during the ongoing pandemic can only be achieved with a robust risk-reduction strategy that covers all transmission routes. Since one of the primary ways that COVID-19 is spread is through the air by aerosols – airborne liquid particles that may carry infection – keeping these particles out of the nearby air by regularly introducing clean and fresh air into communal spaces (i.e. ventilating) is vital for preventing the spread of disease.<\/p>\n
So how do you ventilate spaces effectively? And how do you know if ventilation practices are even working?<\/p>\n
The UK Government’s Scientific Advisory Group for Emergencies (SAGE), along with The Chartered Institute of Building Service Engineers (CIBSE) (UK) and the Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA) (Europe), have issued\u00a0guidelines on how to improve ventilation in rooms. Their advice includes opening windows, ensuring regular breaks for occupants and increasing mechanical ventilation.<\/p>\n
All three reports also highlight\u00a0CO2 monitoring as a key tool for any effective ventilation strategy, both to help improve ventilation and to help assess its efficacy.<\/p>\n
Feeling that a room has become ‘stuffy’ or feeling drowsy after hours sat in a meeting room are sensations that are familiar to many-and they’re caused by a\u00a0build-up of CO2.<\/p>\n
Just like CO2, aerosols carrying infectious diseases that are exhaled by occupants will linger in the air without sufficient ventilation.\u00a0The longer that a room is occupied, the greater the volume of infectious aerosols that will build up, and the greater the risk of infection.<\/p>\n
It is possible to evaluate the level of ventilation available in a room just by assessing how occupants are feeling. For example, if a person perceives that a room feels ‘stuffy’, they may proceed to open a window to increase air flow rates. However, this method is ultimately reliant on guesswork, and occupants may not be able to detect simply by feeling alone when extra ventilation is needed until it is too late.<\/p>\n
Monitoring CO2 levels eliminates guesswork from ventilation assessment and enables a\u00a0systematic approach to increasing ventilation. By accurately measuring the volume of CO2 in the air,\u00a0CO2 monitors<\/a>\u00a0provide hard evidence of when extra ventilation is needed – which might be a long time before occupants feel that the room could do with some fresh air.<\/p>\n The report from SAGE identifies that\u00a0CO2 monitoring is particularly important in workplaces and schools, where it is most likely to be an effective indicator of ventilation rates.<\/p>\n In spaces that are used for extended durations by groups, i.e. offices and classrooms, CO2 measurements reflect the air quality with a greater accuracy and give a good indication of ventilation conditions.<\/p>\n By contrast, CO2 monitoring is not as effective at indicating ventilation rates in large volume or low occupancy spaces, where airflow and dispersion of occupants may vary. In these areas, however, SAGE still recommends aiming to\u00a0keep CO2 levels low (below 800ppm)\u00a0as a good rule of thumb.<\/p>\n After establishing what ventilation is available in a room,\u00a0CO2 monitors<\/a>\u00a0should be used for two purposes:<\/p>\n CO2 monitors should be placed on an inside wall, with sensors facing away from windows or grilles so that the readings are as accurate to the inside conditions as possible. It is also recommended that they are placed in visible positions c. 1.5m off of the ground so that responsible persons can easily act upon their alerts.<\/p>\n Alarms on\u00a0CO2 monitors<\/a>\u00a0can alert occupants of the immediate need to increase ventilation in a room by signalling that the CO2 concentration has exceeded acceptable levels.<\/p>\n As a visual indicator, CO2 alarms also help to\u00a0boost awareness of the importance of ventilation. The CIBSE report suggests that involving school pupils in responding to CO2 alerts can help to increase ventilation efficacy by improving awareness.<\/p>\n The reports suggest that alarms should be set to alert\u00a0when the CO2 concentration measures at or above 1000ppm. If or when an alarm is triggered, action should be taken to immediately increase air flow into the occupied space. Opening high windows is an effective strategy, especially in colder months, as it will sufficiently increase ventilation rates while not significantly lowering room temperature or causing a draught.<\/p>\n For schools with mechanical ventilation systems, the reports recommended maximising fresh air flow at all times.<\/p>\n With data loggers,\u00a0CO2 levels can be recorded over time\u00a0so that data can be viewed and analysed, and further action taken based on this evidence.<\/p>\n Data from\u00a0CO2 monitoring<\/a>\u00a0should be used to\u00a0assess whether ventilation measures are taking effect.<\/p>\n Time-stamped data from one room might show that instances of increasing natural ventilation-for example, by opening windows or doors-is effective at lowering CO2 levels. For a different room, with different dimensions and different available ventilation routes, analysis of data may reveal that there is a need to implement more significant measures to fully protect the health of occupants. Rooms which are shown to regularly record above 1500ppm should be identified and prioritised for improvements to ventilation.<\/p>\n A further advantage of monitoring with a\u00a0CO2 data logger<\/a>\u00a0is that long-term recorded data can\u00a0provide evidence of the need for significant or structural changes to be made, helping to support funding applications.<\/p>\n Robust, easy-to-use and quick to deploy, the\u00a0Tinytag CO2 data logger<\/a>\u00a0is a simple and effective solution for indoor air quality monitoring.<\/p>\n Using\u00a0a self-calibrating non-dispersive infrared sensor (NDIR), the data logger accurately measures and records carbon dioxide concentrations with outstanding long-term stability. The\u00a0TGE-0010 model measures from 0 to 2000ppm<\/a>\u00a0and is ideal for measuring indoor air quality in busy classrooms or offices. A model measuring\u00a0up to 5000ppm<\/a>\u00a0is also available for more specialised applications.<\/p>\n The data logger has an LED on its front which will\u00a0flash red when an alarm has been triggered, enabling responsive action to high CO2 levels. The data logger can be\u00a0wall-mounted\u00a0or placed on surfaces to continuously monitor CO2 concentrations wherever is required. Compact and light-weight, the logger can be situated anywhere where there is a mains supply, and can easily be transferred between different locations for versatile monitoring throughout a building.<\/p>\n Data is offloaded and viewed in user-friendly\u00a0Tinytag Explorer software<\/a>, where it can then be exported to third-party programmes in a variety of popular file formats (.xls, .xml, .csv, .txt) for further analysis and presentation.<\/p>\nHow to improve ventilation with CO2 monitoring<\/h3>\n
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\nAlarms show when extra ventilation is needed<\/h3>\n
\nTake informed action with long-term recorded data<\/h3>\n
\nThe Tinytag CO2 data logger<\/h3>\n