Thanks for reply, this is for business, HMO, Temporary Accommodation, we need to know who is in the building.
No guests allowed. Idea is take photo's of allowed tenants and management. If an unknown person enters the building it should trigger an alert. The property manager would then view footage to confirm if person is unknown or false positive.
If unknown the property manager would visit property to investigate.
The property in not manned 24/7, there will be frequent visits and off site CCTV monitoring, but can't guarantee to catch every event. Technology seems the answer.