The question nobody asks before installing an access control system: "What happens if the server fails?" In a lot of badly designed systems, the answer is "nobody gets in or out." I've seen that happen at a clinic. This guide exists so you don't learn it the hard way.
1. The technologies on the table — what each is actually worth
125 kHz Prox/RFID badges — the least secure option available. A Prox badge can be cloned in seconds with a device that costs about 30 euros online. I've refused to install Prox on sensitive sites since 2018.
MIFARE badges (13.56 MHz) — significantly more secure, with encryption available. This is our standard. A MIFARE card costs 200-400 DZD each and can store up to 4 KB of data — presence, permissions, history.
Fingerprint biometrics — high security, nothing to lose or forget. Identification takes 0.5-2 seconds, with a false-acceptance rate around 0.001% on good hardware. Limitation: incompatible with gloves, which matters in kitchens and surgical settings. Biometric data should never leave the site — local storage only, never cloud.
Facial recognition — increasingly common on high-security sites. Sub-0.5-second identification. I reserve this for sites that genuinely need that level of security — financial institutions, high-value storage facilities.
2. System architecture: centralized vs distributed
A centralized system stores every permission on a single server — easy to manage, but a single point of failure if that server goes down.
A distributed system stores permissions locally in each door controller. If the network drops, every door keeps operating on its own local rules. This is the architecture I recommend on every project.
What we deploy: ZKTeco or HikVision controllers with local memory for 50,000 cards and 100,000 events. The central server handles management and reporting — it doesn't validate every single pass.
3. Fail-safe vs fail-secure: the choice nobody discusses
This is the most consequential decision for every door, and almost nobody raises it before installation.
Fail-safe (normally locked, opens on power loss) — for emergency exits and evacuation doors. In a fire or power failure, everyone needs to get out.
Fail-secure (normally locked, stays locked on power loss) — for sensitive zones: vaults, server rooms, pharmacies. A power cut should never grant access.
On a typical clinic: the main entrance is fail-safe (evacuation must work), the pharmacy is fail-secure (security holds even during a power failure). This decision belongs in the project spec, agreed with the client — never left to the installer's discretion alone.
4. Integrating with CCTV: where the real value shows up
Access control alone tells you "who came in." Integrated with CCTV, it tells you "who came in, at what time, here's their photo." On our projects, every access event is timestamped and linked to the nearest camera's footage. An investigation that would take two hours takes five minutes.
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