Low-energy operators are often used when the door will be opened manually by some users and automatically by others. The doors are subject to limitations on opening speed and force to limit the generation of kinetic energy and the potential for injury, and they must be operated by a "Knowing Act." Because of these limits, most doors with low-energy operators are not required to have safety sensors, control mats or guide rails.

Many installations will be retrofitted, which means that there is some form of actuator already present. Most automatic door operators will work with most door-operator actuators. Normally all that is required is a dry, momentary contact to the door control input.

As stated in the 2007 edition of ANSI/BHMA A156.19, the requirement is that power-assist and low-energy power-operated doors are required to be activated by a "Knowing Act." This means that a person consciously intends to activate the door operator. The most common methods for doing so are push button actuators and "touchless" or touch-only switches mounted on the wall or jamb. Other popular methods include card readers, keyswitches, and keypads.

The standard also recommends mounting locations for a Knowing Act switch. The switch is to be mounted within one to five feet of the door, but not more than twelve feet. It is to be accessible from the swing side when the door is open, and not in a location where the user would be in the path of the moving door. It should be mounted at a minimum height of 34 inches and a maximum height of 48 inches above the floor, and should be mounted so the user can see the door when activating the switch.

In addition to what is included in the ANSI/BHMA standard, the 2010 ADA and ICC A117.1 include requirements pertaining to the actuators for automatic doors. Clear floor space for a wheelchair must be provided adjacent to the actuator, beyond the arc of the door swing. The mounting height can vary, depending on the reach range associated with the switch location. However, the range recommended by the ANSI/BHMA standard is acceptable for most applications. Actuators must not require tight grasping, pinching or twisting of the wrist to operate, and the operating force is limited to 22.2 N (5 lb) maximum.

The minimum size for pushplates is 102 mm (4 in.) in diameter or 102 mm square, and the minimum operable portion for vertical actuation bars is 51 mm (2 in.) wide. Both types of actuators must display the International Symbol of Accessibility.

The most popular type of push button actuator is the surface-mount type. It is typically comprised of a back box or mounting box and a pushplate containing the actual switch. These are available in hardwired or radio frequency versions. The pushplates are designed to fit single or double-gang boxes for flush-mount applications. These pushplates are also designed to attach to bollards for standalone installations, such as exterior sidewalks. Most button manufacturers provide a number of sizes and shapes, such as square, round and rectangular, typically in 4" and 6" sizes

The 2010 California Building Code requires two pushplate actuators at each actuator location: one mounted between seven and eight inches from the floor to the centerline, and the other mounted between 30 and 44 inches above the floor. Vertical actuation bars may be used in lieu of two separate actuators, with the bottom of the bar at five inches maximum above the floor, and the top at 35 inches minimum above the floor. Actuators must be in a conspicuous location, with a level and clear ground space outside of the door swing. The minimum size for pushplates is four inches, and the minimum operable portion for vertical actuation bars is two inches wide. Both types of actuators must display the International Symbol of Accessibility.

The use of motion sensors to activate a handicap door is not allowed under ANSI156.19. Once a motion sensor is added to the system the doorway must be treated as a Full Energy opening and comply with ANSI 156.10. This code requires more stringent safety requirements and will add significant cost and labor to the doorway.

Detex offers a line of low-energy automatic operators, as well as automatic operator accessories. These products are ideal in high-use, high-abuse, low-energy applications, and are economical. They work with existing access control, locking and computer signal devices. The heavy-duty construction reduces service calls and they are easy to maintain.