Electronic access control does just that — controls access to a building or area using an electric lock and by requiring individuals to present a valid credential to a reader to gain entry. Controlling entry (access) is the function of an access control system, and an important aspect of access control system design.
Access control entry requirements are all based on security requirements (preventing individuals from entering the building). However, life safety and building codes are more concerned with the ability of individual to exit the building through these locked doors. NFPA 101 (Life Safety Code) and IBC (International Building Code) cover specific requirements for building access control and exit (egress) requirements.
Egress through an access controlled door requires the door to unlock. Unlocking the door may be accomplished manually or automatically. Manual egress uses a push button next to the door or push bar located on the door. Push buttons next to the door control power to the electric lock hardware at the door to cause it to unlock. A push bar on the door may control electric lock hardware or unlock the door by a mechanical function.
Automatic egress uses a short range motion detector mounted above the door to detect individuals as they approach the door. It automatically unlocks the electric lock when the person gets close to the door, and keeps the door unlocked for a programmed amount of time.
NFPA 101 and IBC both have similar requirements for egress through an access controlled door. The codes require a sensor that unlock the door when the occupant approaches the door, and they require that the manual release device directly unlock the door. The codes also require that activation of the building fire alarm or sprinkler system automatically unlock the door upon activation.
The manual egress device is required to be labelled PUSH TO EXIT and mounted 40-48 inches above the floor within 5 feet of the door. The manual egress device must keep the door unlocked for a minimum of 30 seconds.
The codes both require that a building with access control have a fire alarm or sprinkler system. The fire alarm or sprinkler interface to the door must control the lock directly. The door must remain unlocked while the alarm condition is active and must not reset until the control panel has been reset.
The codes also permit delayed egress in some applications. Delayed egress delays the exit through the access control door for up to 15 seconds while a local alarm sounds. This allows for investigation and helps prevent unauthorized use of an access control door for exit purposes.