One of the most innovative locks to reach the market was a device patented in 1984, the electromagnetic lock. Now used for many applications, it has the benefits of simple installation without impacting the operation of the regular door latch, handle or hinges. However, since it is bulky and overt, architects drove the industry to design the less-simple and more problematic shear lock with a floating armature plate hidden in the top channel of the door and the electromagnet concealed in the top of the door frame.
Due to a penchant for frameless glass entry lobby doors matched to frameless glass transom and frameless glass side panels, the architect has driven the shear lock design deeper into realms of maintenance headaches with the gravity shear lock. The electromagnet is buried in the floor (a "magnet" for dust, grit, stones, rain, snow, ice and salt in winter climates) and the armature floats in a shoe on the foot of the door.
The evolution of the delayed egress systems incorporating magnetic locks was the first real compromise between life safety and security. Fire/Life Safety code dictates that a door in the "path of egress" must allow free egress at all times of occupancy regardless of whether a fire alarm has been tripped - an emergency evacuation could be required for reasons other than fire.
Although a thief with a laptop or pocketbook under their arm is free to make a quick exit at any time, delayed egress can increase security and response. For example, the exit device ("crash" or "panic" bar) does not immediately unlock the egress door but starts an irrevocable countdown (15 or 30 seconds) after which the door unlocks. While 15 or 30 seconds is a very short delay, it gives ample time to sound a local horn and initiate recording of video on both sides of the door.
If there is a fire alarm, the countdown is eliminated and the door can be opened immediately. However, as noted previously, a few AHJs mistrust the "complexity" of these systems and will not permit their use.
While electric strikes were the most common controlled door locking device, the innovations to electric locksets - both mortise and cylindrical - over the last few years have increased their recent popularity. With a full range of styles and finishes to match their non-electrified siblings, integrated request-to-exit switches, and fail-safe/fail-secure interchangeability in the field, these devices are now the favorite with architects and security system designers.
One of the most important waves in recent years has been the proliferation of standalone electronic locking systems. These units integrate the locking functions and a credential reader into a single, battery-powered unit. Many provide a selection of credential reader types - keypad, proximity card, smart card, magnetic stripe and ibutton (Dallas chip) or combinations - and many models have the intelligence to store transaction data for subsequent audit via wired or wireless data transmission.
A newer innovation to this type of lock is the Schlage modular AD system by Ingersoll Rand Security Technologies (IR), with field-interchangeable credential (and credential combination) readers. These units are also field-upgradeable from standalone to wireless and to wired units as the sophistication of the access control application evolves. Although this type of hardware is expensive, total installation costs can be reduced significantly. For example, an installed wired proximity card-reading electronic lock with built-in request-to-exit and door position switch can be installed for about a third less than installing all of these components separately. Stanley's Wi-Q line of integrated wireless locks also features latch position and key override monitoring.
Cav•, an Italian line of intelligent locks under the Assa Abloy banner, uses a technology that makes use of the credential holder's body as an antenna. If only those antenna properties could be used as a biometric. However, if a lock is to unlock under fire alarm control, it must still be wired - wireless switching is not yet reliable enough for NFPA approval.
As these integrated locking systems proliferate and the pricing is further reduced, they may become the standard in offices and classrooms to eliminate mechanical keys and costly rekeying. Battery replacements must still be scheduled - although some units warn you of a low battery condition well in advance - and credentials must be administered, but this can be performed at a fraction of the cost of periodic rekeying and the products provide the higher level of security with a searchable audit trail.