It has been established that effective fresh air ventilation plays an important role in reducing the spread of the Covid-19 virus.
On 23 October, CIBSE have released version 4 of Covid-19 Ventilation Guidance providing guidance on the set up and operation of ventilation systems.
Ventilation is a very important way of diluting any airborne pathogens and there is good evidence showing that room occupants are more at risk of catching an illness in a poorly ventilated room than in a well ventilated room.
To minimise the risks of far-field airborne aerosol transmission of SARS-CoV-2, the general advice is to increase the air supply and exhaust ventilation, supplying as much outside air as is reasonably possible. The underlying principle is to dilute and remove airborne pathogens as much as possible, exhausting them to the outside and reducing the chance that they can become deposited on surfaces or inhaled by room users. Recirculation or transfer of air from one room to another should be avoided unless this is the only way of providing adequate ventilation rates to all occupied rooms.
In naturally ventilated buildings, strategies such as intermittent airing and partial window opening to complement background ventilation should be adopted.
Ventilation should be balanced against other factors, particularly thermal comfort.
Key actions identified in the new ventilation guidance are:
- Understand your ventilation system.
- Understand where you may have poorly ventilated spaces or areas.
- Increase the ventilation rate as much as reasonably possible; this may require changes to CO2 set points (for both mechanical ventilation and automated windows).
- Avoid recirculation/transfer of air from one room to another unless this is the only way of providing a sufficient rate to all occupied rooms.
- Recirculation of air within a single room where this is complemented by an outside air supply is acceptable, as this helps to provide more outside air to occupants and can help to maintain thermal comfort.
- Where thermal (or enthalpy) wheels are installed to recover heat, then a competent engineer/technician should check the configuration and operating conditions.
KJ Tait have been advising Clients since the beginning of the pandemic on the set up and operation of their ventilation systems to minimise risk, and have been engaged to review the fresh air rates in buildings and ensure all areas are suitably ventilated.
KJ Tait Engineers have been investigating and including in their design services, the installation of technologies that limit the potential for viruses in general to spread, some examples are:
- Contactless amenities such as sensor taps, flushing and towel dispensing in WCs
- Contactless movement within lifts/access barriers via a phone app, QR code or a whole building specific app
- Air purification within lift cars including UV-C lamps
- Contactless entry/exit to buildings via automatic open final exit doors including visitors
- Apps to encourage stair usage
- Retrofitting lift finishes and buttons with a smart surface coating to restrict the build-up of microbes
- Air quality sensors
- Effective staff communication when colleagues test positive for Covid-19.
Building designs are also being influenced in recognition of the virus transmission risks and we have seen an increase in the size of reception areas, lift car sizes and corridor widths, and in certain facilities such as Health Centres, control over movements by implementing one way systems.
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