According to the World Health Organisation, “ventilation is an important factor in preventing the virus that causes COVID-19 from spreading indoors”.

Guidance provided by CIBSE (Chartered Institution of Building Services Engineers) is to minimise the risks of airborne transmission of SARS-CoV2, the virus which causes Covid-19, by increasing the air change rates of spaces by supplying as much outside air as is reasonably possible.

The underlying principle is to remove airborne pathogens in the first instance and where possible dilute those that remain to reduce the chance that they can become deposited on surfaces or inhaled by room users. Increasing the ventilation rate will ‘dilute airborne contamination and reduce the risk of exposure for building users’. For multiple spaces, CIBSE recommend that the transfer of air from one room to another should be avoided unless this is the only way of providing adequately high ventilation to all occupied rooms. Whilst CIBSE advise that for single spaces, ‘partial recirculation of air within that space, such as through a local fan coil unit, is less of a concern’ due to the fact that ‘The primary objective is to maximise the air exchange rate with outside air and to minimize the risk of any pockets of stagnant air.’ Their suggestion is that local recirculation units are considered when developing strategies due to their ability to ‘enhance air disturbance and hence help reduce the risk of stagnant air’.

Further reference can be found on the UK Government website Guidance for full opening: schools under the heading ‘Estates’ which gives a further link to the ‘Health and Safety Executive’ guidance for ‘Air Conditioning and Ventilation’ See here: HSE

In addition, the Church of England, provides answers to FAQs, see section on “Fabric & Building Maintenance”: See here: Church of England.

In all cases, Biddle recommends customers carry out their own risk assessments based on their specific installation and application of the products. The above comments should not be viewed in isolation and should be read in conjunction with the latest guidance issued by authoritative sources on the matter.