An example: An office building consisting of several floors is owned or rented by the same company, and, due to a smart working application, the number of employees actually present in the office is very small compared to the usual expected number of employees. Is it possible to place them on one floor only in order to be able to switch off the HVAC system in the other floors and save energy and money?

No. Social distancing is the main WHO recognised procedure to reduce pandemic spread. Therefore, the occupancy index reduction is the right direction to go, while concentrating all of the employees on one floor is contrary to what is needed. It is recommended that you maintain the overall occupancy on each floor. There will be a lower power requirement due to lower internal gains, and at the same time, you maintain or increase the ventilation air flow rate to improve the IAQ.