Putting Key-Card Entry Systems on an Energy Diet

Key-card entry systems—used all over in hotels, dormitories, restricted-access office buildings, healthcare facilities, and other commercial buildings—don’t look like energy hogs at a glance. Even though the only visible electric consumption is a single LED light, the electronic access control uses 12 to 20 watts of electricity—and not only when the door is being accessed, but 24/7. Some doors, such as those in hospitals with automated openers, also use a lot of electricity when they’re being opened, but it is the standby electricity consumption with these doors that is the far more ubiquitous issue.

Most controlled-access door systems include a power supply, a request-to-exit unit that temporarily deactivates the door alarm during exit, a card reader, and an electrified mortise lock. The power supply could serve one or a few doors, with each power supply being connected to the building’s AC wiring system. The power supply steps the power to DC, and current is transmitted to the actual lock through the metal hinge. With traditional doors, lockset power is separate from monitoring functions, meaning that a typical opening could have as many as 12 wires going to it, according to Garrett Lovejoy, Assa Abloy’s product manager for IP-based access-control locks.