The role of ventilation and air distribution in controlling the spread of Covid-19
18th November 2020
With winter just around the corner, the management of ventilation inside buildings is becoming increasingly important. We’ve known for some time that there is a risk of the virus spreading via airborne transmission and now the cooler weather has arrived forcing windows and natural ventilation sources to close, it is something that workplaces need to address.
Over recent months, the role that adequate ventilation will play in reducing the spread of Covid-19 has been stressed by numerous professional bodies and government advisors. REHVA, the Federation of European Heating, Ventilation and Air Conditioning Associations, describe ventilation as the best engineering control we have for managing the infection. What’s more, in recent weeks UK government advisors have said that “ventilation should be integral to the COVID-19 risk mitigation strategy for all multi-occupational buildings.”
Why is ventilation so important?
The most common cause of transmission is through short-range droplets, most of which fall out of the airstream within a short distance, hence social distancing rules. However, long-range airborne transmission is possible and is becoming a growing concern as we start spending more time indoors. Airborne transmission takes place when droplets evaporate into the air, reducing in size and mass, which makes it possible for them to travel in air streams around rooms and buildings.
Thankfully, the risk of infection through airborne transmission is something that can be managed with adequate ventilation and air distribution, which dilutes the buildup of the virus in the air.
The effects of poor ventilation
Closed environments with minimal ventilation are the reported site of several ‘super spreading’ events which have led to a high number of secondary infections. Scientists used these events as examples to get the World Health Organisation to recognise the potential for airborne or aerosol transmission of the virus.
What’s interesting to note is that in places such as hospitals, which have an excellent ventilation rate, the risk of aerosol transmission is almost completely eliminated. Whereas, aerosol transmission in poorly ventilated spaces is thought to be widespread, as found by scientists studying the transmission of the virus.
With these findings, it is no surprise that the UK government is being advised on the importance of ventilation in suppressing the spread of the virus.
Ways to improve ventilation and mitigate risk
Increase fresh air – Increase the amount of fresh outside air in your building and the rate of air changes per hour to dilute the airborne viral load.
Minimise recirculation – where possible, recirculated air should not be used. However, in circumstances where this is not possible, the ratio of outdoor air must be increased, with additional measures for return air filtering recommended. For buildings that have a centralised ventilation system rather than single room systems, recirculation should be avoided completely to minimise the risk of spreading the virus around the building.
Extend operating times – running your mechanical ventilation systems for longer to increase air supply and exhaust ventilation is recommended. The advice is to ventilate premises 24/7, with a lower setting used during un-occupied periods, with it ramped up a couple of hours before and whilst the building is in use.
Open windows – where possible it is also recommended that openable windows are actively used to boost air exchange, with 15 minutes the suggested duration when entering a room. Opening windows is particularly useful for buildings that have no other type of ventilation.
What makes an EcoCooling system a Covid safe solution?
EcoCoolers are installed as part of a mechanical ventilation system, designed to bring fresh air into your facility and extract inside air, therefore helping to dilute virus levels.
Each EcoCooling system is specifically designed for the size and use of the building so that there is an adequate number of air exchanges per hour, so additional ventilation should not be required.
The EcoCooling controls can also help manage fresh air levels via its automatic and manual modes. For example, the system can run in manual mode with 0% recirculation for 15-minute bursts to purge the room, or in automatic mode, the supply temperature set point can be reduced to boost the quantity of fresh air. Timers can also be adjusted to allow a burst of ventilation before and after the building is occupied.
There is no doubting the vital role ventilation will play in the battle against COVID-19 and EcoCooling is proud to have a fresh air system that can help businesses manage the risk.
For the most up to date guidelines, visit the CIBSE COVID-19 guidance webpage.