Please follow the attached link for current guidance from the Health & Safety Executive (HSE) for air conditioning and ventilation in the workplace.

https://www.hse.gov.uk/coronavirus/equipment-and-machinery/air-conditioning-and-ventilation.htm?utm_source=govdelivery&utm_medium=email&utm_campaign=coronavirus&utm_term=aircon-1&utm_content=digest-10-jul-20