When a cab goes up with a light load and down with a heavy load, the system generates more power than it uses. Over time these small amounts of power generated during each elevator’s sporadic decelerations add up to noticeable savings. They use less energy than non-regenerative drives, and reducing the excess heat in the building.
Diagram depicting how the Regenerative Drive sytem works. Image: Otis Worldwide
The most energy efficient types of elevators are machine-roomless (MRL) traction elevators. Manufacturers redesigned the motors and all of the other equipment normally housed in a machine room above conventional elevators to fit into the hoistway. These space-saving improvements eliminate the need to build and supply energy to a machine room and consume significantly less energy than the larger versions previously used. They also generate less heat.
Otis offers additional energy savings in its state-of-the-art Gen2 MRL elevator. They also compacted the controller and moved it into the hoistway, eliminating the need for a separate control room. See video to learn about the redesigned systems and how they were integrated in the Gen2.
Manufacturers are now giving more attention to improving energy usage in the other systems such as cab lighting, fans, doors, brakes, and elevator controls. They use efficient LED lights in cab panels, overhead, and in floor indicators. They include door drive motors that that can enter a standby mode or efficiently recover from removal of power when not in use. These motors also support variable door-open and -close times, and their energy use is factored into the overall control strategy.
