What Is an Access Control System and How Does It Work?

The four parts of every access control system

• Credential: what you present — fob, card, PIN, smartphone or fingerprint
• Reader: at the door, reads the credential and passes it to the controller
• Controller: the decision-maker holding the rules — who, which door, what times — and the event log
• Lock: electric strike, maglock or motorised lock that releases on a valid read; exit is by push bar, handle or request-to-exit button so escape never needs a credential

Why businesses switch from keys

Keys fail at scale: they copy invisibly, leave with ex-staff, and 'who has one?' becomes unanswerable within a year. Access control answers it precisely — a leaver's fob dies in 30 seconds from the software, the cleaner's credential works weekday evenings only, the server room admits three named people, and the event log shows every entry with a timestamp. For multi-tenant buildings and growing teams, the management saving outweighs the hardware cost quickly.

What does a system cost?

A professional single-door system (Paxton Net2 or similar) starts from around £695 plus VAT installed. Each additional door is priced by reader type, lock hardware and cabling — typically £500–£900 per door on multi-door systems. Cloud-managed platforms add a modest subscription in exchange for browser management anywhere and automatic updates. Intercom integration, gates and lifts price individually.