Access Control System
- 20.1 Door Contacts
- 20.2 Request-to-Exit
- 20.3 Electrified Door Hardware
- 20.4 Readers
Access control systems are a critical component in smart buildings as security has become more important. The access control system is essential for life safety and is interfaced to the fire alarm system to facilitate building egress during life safety evacuations. Access control systems must integrate with several other smart building systems (video surveillance, HVAC, lighting, and others) as well as share data with business systems, such as human resources, time, and attendance. In a smart building, one electronic access control system for nonpublic areas should be deployed. Within secured areas the access control system would provide two levels of authentication. The system should support offline operation to allow doors to function if network connectivity is lost. The access control system should be supplemented by an intrusion detection system at potential unauthorized entrances, such as windows.
The initial access control systems were more mechanical than electronic; for example, the use of the familiar pushbuttons on a door lock that required some type of combination to be unlocked. Access Control systems are used in a variety of markets and diverse applications. Some examples include:
b Card access control for building entrances and exits; b RFID for inventory and asset tracking;
b Pharmaceutical production in order to meet FDA requirements; b Tracking of inventory and containers at seaports; b Employee entrances for time card applications.
The access control system should be configured to maximize security. For example, its use of vertical transport systems (elevators) can be based on occupant identity provide selective access to floors, as well as spaces such as parking garages. Security levels should be determined by individual, floor, area, and access privileges can be changed in response to building occupancy states (i.e., time of day). An access control system can also generate anonymous occupancy statistics for building spaces and zones. Such data can be used to correlate occupancy to other building systems such as energy consumption or lighting schedules. While access cards are generally used in many systems, biometric authentication may be utilized for an additional degree of security.
One of the largest problems with access control systems can be piggybacking and tailgating. Piggybacking happens when someone with legitimate access to a building allows someone without access to the building to enter with them. Tailgating involves taking advantage of someone who legitimately has access to the building, where a trespasser enters the building with a person (or group of people) without their knowledge. One way to prevent piggybacking and tailgating is a mantrap shield that uses sensors to ensure that only one person is entering the building using one set of credentials. Mantrap shields can also be configured with separate compartments so that if more than one person is sensed passing through the first door, the second door will remain locked.
Access systems have leveraged the IT infrastructure, which eliminates the need for local AC power by using Power over Ethernet (POE). This consolidates the sytem, saves labor cost for cable installation, reduces the time to install system devices, and provides a large base of management tools and support.
The headend of the access control system uses IT infrastructure to interconnect and share information with a databases residing on other networks. The system headend and the door controllers house data regarding access credentials. Credentials consist of who gets access to what spaces during what hours or days. This data needs to be shared, and interacts with databases residing elsewhere such as Human Resources or Student Records. Those databases have now moved to open standards for databases such as ODBC, SQL, and XML to ease the integration. Data exchange rules between access control and other systems would use standard protocols and address all physical, virtual and calculated points, and operating parameters.
The access control system monitors and controls facility access via electronic access controllers utilizing card readers, keypads, and biometric devices. The system can monitor alarm points, control output devices, manage elevator control floors, and maintain an operator audit trail of operator activity along with access control and alarm activity. The system would typically focus on electronic door hardware and integrated devices, but, can also manage motorized access gates and associated devices.
Access control is designed to be activated by an authorized card receiving a signal from a reader and activate an electronic opening device (e.g., electric lock, or gate) to allow access. Should an attempt be made to enter this system with an unauthorized card, the electronic device is not activated, thus denying entry. This system is also designed to provide for an override by the operator locally or remotely to activate electronic door devices, allowing access for circumstances not normally programmed into the system.
There are codes and standards that cover the installation, performance, testing, and maintenance of access control systems. These include:
b National Fire Protection Association (NFPA) 731; b National Electrical Code (NEC) and applicable local Electrical Codes; b Underwriters Laboratories (UL); b American National Standards Institute (ANSI);
b Federal Communications Commission (FCC) including Part 15, Radio
The management and monitoring of access control subsystems uses a server with software that provides the interface with the field-installed controllers along with the ability to manage the access control database. The database consists of the records that determine access privileges, field- installed controller behavior characteristics, history transactions, and third- party interface data.
One of the key component of access control system is the access control unit (ACU), which is an intelligent peripheral control unit that provides the interface between the management and monitoring subsystem and the devices installed at the access portal for the purpose of restricting access and monitoring the portal status. The card reader or a biometric reader captures the credential information and passes it to the ACU for processing.
Many access control cards use the patented Wiegand technology. Wie- gand is the trade name for a technology used in card readers and sensors, particularly for access control applications. Wiegand devices were originally developed by HID Corporation. A Wiegand card looks like a credit card and uses a patented magnetic principle that uses specially treated wires embedded in the credential card.
The access control system monitors and controls facility access via electronic access controllers utilizing card readers and keypad devices. The system shall be capable of monitoring alarm points, controlling output devices, and managing elevator control floors. The system shall maintain an operator audit trail of operator activity and all access control and alarm activity. Each controller shall be able to manage the hardware necessary to secure one door and maintain a full database of information so that ac?cess decisions are made within seconds. Interval data shall be collected at a maximum of 15 minutes every day per year.
In the following sections we will dicuss four fundamental peripheral components in an access control system related to the doors.