Ventilation: Approved Document F, Volume 2 — Buildings other than dwellings

C O N L I N E V E R S I O N Appendix C: CO monitoring 2 NOTE: The guidance in this appendix is based on the Scientific Advisory Group for Emergencies (SAGE) EMG/SPI-B advisory group paper Application of CO monitoring as an approach to managing 2 ventilation to mitigate SARS-CoV-2 transmission. People exhale carbon dioxide (CO ) when they breathe out. If there is a build-up of CO in an area it can 2 2 indicate that ventilation needs to be improved. Checking levels of CO using a monitor can help to identify areas that are poorly ventilated. 2 Types of CO monitor to use 2 Many different types of CO monitor are available. The most appropriate portable devices for use in the 2 workplace are non-dispersive infrared (NDIR) CO monitors. 2 How to use a CO monitor 2 The level of CO in the air will vary within an indoor space. It is best to place CO monitors at head height 2 2 and away from windows, doors or air supply openings. Monitors that are positioned too close to people may give a misleadingly high reading due to the CO in 2 exhaled breath. Monitors should therefore be positioned at least 500mm away from room occupants. Measured levels of CO within a space can vary throughout the day due to changes in number of 2 occupants, activities being performed or ventilation rates in the space. The opening and closing of doors and windows can also have an effect. The amount of CO in the air is measured in parts per million (ppm). If measurements in an occupied space 2 seem very low (far below 400ppm) or very high (over 1500ppm), it is possible that the monitor is not in a suitable location. The monitor may need to be moved to another position within the space, to get a more accurate reading. Instantaneous or ‘snapshot’ CO readings can be misleading, so several measurements should be taken 2 throughout the day. The frequency of measurements should be sufficient to ensure that changes in the use of the room or space throughout the day are represented in the readings. Levels of CO may also vary 2 throughout the year, as outdoor temperatures, and therefore behaviour relating to opening windows and doors, change. How to get the most accurate readings a. Check that monitors are within the recommended calibration period. b. Follow the manufacturer’s instructions, including allowing the appropriate warm-up time for the device to stabilise c. Know how to use the monitor correctly, including the time needed to provide a reading. d. Take measurements at key times throughout the working day. e. Record CO readings, number of occupants, the type of ventilation in use at the time and the date. 2 These will help you use the CO records to decide if an area is poorly ventilated. 2 30 Approved Document F Volume 2, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N