Air conditioning and ventilation during the coronavirus outbreak

General ventilation
All workplaces need an adequate supply of fresh air.
This can be natural ventilation, from doors, windows etc or controlled, where air is supplied and/or removed by a powered fan.
If you work in an office or shop, natural ventilation will normally be enough to control dusts and vapours from cleaning materials etc.
Sometimes planned, powered general ventilation is an integral part of a set of control measures, eg the welding of large fabrications in a workshop.

Air conditioning
The risk of air conditioning spreading coronavirus (COVID-19) in the workplace is extremely low.
You can continue using most types of air conditioning system as normal. But, if you use a centralised ventilations system that removes and circulates air to different rooms it is recommended that you turn off recirculation and use a fresh air supply.
You do not need to adjust air conditioning systems that mix some of the extracted air with fresh air and return it to the room as this increases the fresh air ventilation rate. Also, you do not need to adjust systems in individual rooms or portable units as these operate on 100% recirculation.
If you’re unsure, ask the advice of your heating ventilation and air conditioning (HVAC) engineer or adviser.

General ventilation
Employers must, by law, ensure an adequate supply of fresh air in the workplace and this has not changed.
Good ventilation can help reduce the risk of spreading coronavirus, so focus on improving general ventilation, preferably through fresh air or mechanical systems.
Where possible, consider ways to increase the supply of fresh air, for example, by opening windows and doors (unless fire doors).
Also consider if you can improve the circulation of outside air and prevent pockets of stagnant air in occupied spaces. You can do this by using ceiling fans, desk fans or opening windows, for example.
The risk of transmission through the use of ceiling and desk fans is extremely low.

SOURCE: HSE WEBSITE 22.06.2020