The role of ventilation in making buildings safer
The World Health Organisation (WHO) suggests “the possibility of aerosol transmission” of COVID-19 in indoor spaces. So, what’s the answer? David Cook, technical product manager at Vent-Axia, discusses the essential role of ventilation in mitigating virus transmission inside and what solutions building and facilities managers can use to help keep commercial building users safe.
Virus numbers are rising and new restrictions have been introduced by the government when it comes to indoor interaction. With increasing evidence pointing to the airborne transmission of COVID-19, more time spent indoors – with others – is a concern as winter approaches.
For businesses looking ahead at how they can mitigate the risk of virus transmission in their buildings, ventilation can play a big part, along with, social distancing, masks and handwashing. Ventilation is vital since it helps reduce the potential concentration of the virus in the air. The more air supply in the space the more the viral material is diluted.
Fortunately, the Chartered Institution of Building Service Engineers (CIBSE) published the CIBSE COVID-19 Ventilation Guidance in April giving detailed guidelines for building managers/operators to minimise the risks of airborne transmission of COVID-19. Within the guidance CIBSE’s overarching advice is to increase the air supply and exhaust ventilation, supplying as much outside air as is reasonably possible to dilute and remove the virus as much as possible.
More detailed advice includes: extending the operation times of supply and extract mechanical ventilation systems; starting ventilation at nominal speed at least two hours before the building usage time and switching to lower speed two hours after the building usage time; in demand-controlled ventilation systems lowering the CO2 setpoint to 400ppm to maintain operation; and to keep ventilation on 24/7 with lower ventilation rates when people are absent.
So, to comply with the guidance and create a safer indoor environment, there are a range of options for building and facilities managers to improve ventilation and indoor air quality. The first step is to evaluate current systems and where possible increase airflow from existing systems to meet the necessary air changes an hour this will be above the 10l/s of airflow set out in Building Regulations Part F. The number of air changes will vary depending on the application. It is also important to switch ventilation to full fresh air mode where possible rather than recirculating air and adding fresh air where there is only air conditioning.
If extract fans are installed, they should be checked whether they are in working order. If not, they should be repaired or replaced. Spare parts are available so existing extract or ventilation systems can be fixed. Where managers are keen to add extra airflow easily and quickly rather than upgrading a whole building system, commercial extract fans can be added. For example, Vent-Axia’s T-Series offers high performance ventilation with low running costs, through a simple wall or window mounted system that can be set up to either supply or extract.
Alternatively, if a current ventilation system needs upgrading, demand ventilation is a good solution. Demand Energy Recovery Ventilation (D-ERV) systems have sophisticated controls and sensors that can be used to easily adapt the system to the new COVID-19 requirements, providing ventilation appropriate to occupant needs. The sensors hand-in-hand with the demand ventilation are very helpful in the fight against COVID-19 since a CO2 sensor acts an easy-to-measure proxy to ensure there are sufficient air changes an hour to dilute the virus in the air, without over ventilating when not required. Meanwhile, when it comes to specification, any new system being installed should allow added capacity for airflow to meet potential future pandemics.
For instance, Vent-Axia’s Sentinel Totus² D-ERV offers an effective solution to ensure good ventilation, with a range of sensors, such as CO2 and PIR occupancy detection which are employed to determine the room’s air quality, adjusting the ventilation requirements automatically and managing the system’s ventilation rates accordingly.
With ventilation repeatedly cited and advocated by research, industry bodies and Government as a way to mitigate transmission of COVID-19 indoors, now is the time for building and facilities and managers to ensure there is enough airflow to dilute the virus in the air and improve indoor air quality. Evaluating current ventilation is therefore vital and then increasing airflow as much as possible to dilute the virus and so mitigate transmission to help keep employees safe.
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