How do access control systems work?
Every system, from a single door to a whole campus, does the same three things.
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1
A person presents a credential
A card or fob held to a reader, a PIN typed on a keypad, or a finger or face presented to a biometric reader.
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2
The controller decides
The door controller checks that credential against the people allowed through that door at that time of day. Rules can differ by door, by shift and by day.
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3
The door releases, and it is logged
If the answer is yes, the lock releases for a few seconds. Either way the attempt is recorded: who, which door, when, and whether they were let in.
The rules live in software. In a business, that software is often the same system that runs clocking in, so one staff record controls both.
Types of access control systems
The main difference between systems is the credential: what a person uses to prove who they are.
Types of access control credential compared
| Credential |
How it works |
Good for |
Watch out for |
| Card or fob (RFID) |
Held to a reader a few centimetres away |
Most offices, warehouses and sites. Cheap to replace |
Cards can be lent or lost; the record shows the card, not the person |
| PIN keypad |
A code typed at the door |
Low-traffic doors, plant rooms, a second check on top of a card |
Codes get shared and written down |
| Biometric |
Fingerprint, face or palm checked against an enrolled template |
Doors where you need to know it was that person |
Biometric data has extra rules under UK GDPR; offer an alternative |
| Mobile phone credential |
The phone acts as the key |
Sites where everyone carries a work phone |
Depends on the phone and app; not something Computime offers |
For more on fingerprint and face entry, see our guide to biometric door locks.
What the hardware involves
A typical controlled door has five parts:
- A reader or keypad outside the door.
- A controller, often a small panel serving one, two or four doors, which holds the rules and the log.
- An electric lock: a magnetic lock or an electric strike in the frame.
- A way out: an exit button or handle on the inside, and a break-glass release on escape routes.
- A power supply with battery backup.
Readers and controllers come in versions for one door or several. You can see the ones we supply on our products page.
Access control for businesses: what it will not do
Access control solves real problems, but it is easy to oversell. Before you buy any system, be clear on its limits:
- It records the credential, not the person. A card lent to a colleague opens the door just the same. Biometric readers close that gap.
- It does not stop tailgating on its own. One person opening a door can let three people through. Turnstiles and speed gates deal with that; Computime connects to them but does not supply them.
- It does not make a door stronger. A weak door or frame is still weak with a good lock on it.
- It is not the same as an alarm. On Computime’s system a door forced or held open is logged, but no alert is sent. If you need alerts, that is an intruder alarm’s job.
Access control vs traditional locks
Access control compared with traditional keys and locks
|
Keys and locks |
Access control |
| Lost key or card |
Change the locks and reissue keys |
Switch the card off in seconds |
| Someone leaves |
Hope every key comes back |
Their access ends on their leave date |
| Different rules per door |
A different key per door |
Set per door, per person and per time of day |
| Knowing who went in |
No record |
Every opening logged |
| Upfront cost |
Low |
Higher: readers, controllers, locks and installation |
| Power cut |
Works |
Depends on the lock type and backup power; agreed at survey |
Where are access control systems used?
Anywhere a business needs to control who goes where:
- Offices: the front door, the server room and the stationery cupboard nobody can find the key for.
- Warehouses and logistics: stock areas, yards and gatehouses, often with barriers and turnstiles.
- Manufacturing: production areas with safety rules about who may enter.
- Schools and trusts: staff-only areas and keeping visitors to where they should be.
- Healthcare: drug rooms, records and staff areas.
What does business access control cost?
Two costs: the hardware and installation, and the software that runs it.
Hardware and installation depend on how many doors, what the doors are like and how far the cabling runs, so they are quoted per site after a survey. Be wary of a per-door price given without anyone seeing the doors.
Software is usually a yearly or monthly charge. Computime’s Access Connect module is £395 a year excl. VAT, and runs on Syncro Connect at £2 per employee per month excl. VAT, which also gives you clocking in and absence on the same staff record. It is not sold on its own.
Choosing the right access control system
- How many doors, and which ones? Start with the doors that matter: the main entrance, stock, server and plant rooms.
- Which credential? Cards for most people, biometric where you need certainty, PIN for occasional doors.
- Does it share your staff records? If the door system and your clocking system are separate, a leaver has to be removed twice. On a shared record it happens once.
- What happens in a fire? Doors on escape routes must let people out. Your installer and your fire risk assessment decide how each lock behaves.
- Who installs and who maintains it? Ask who comes out when a reader fails, and how quickly.
- Where is the data held, and for how long? Door logs are personal data, and biometric templates more so. The ICO’s guidance on biometric data is worth reading before you choose fingerprint or face.
