Many elevators waste a lot of energy, which contributes to higher than necessary operating costs. Regenerative drive elevators can recapture some of that lost energy and return it to the building’s power grid, leading to substantial savings.
Elevators lose energy in several ways. When an elevator slows down, energy is created in the form of heat. When an elevator that is lightly loaded or empty ascends, the motor spins, but the counterweight does most of the work. When a fully loaded elevator descends, the motor spins, but gravity does most of the work. All of that lost energy can be diverted to the power grid to fuel other systems in the building.
Power that flows to an elevator’s regenerative drive motor creates a lifting torque on the shaft and sheave that lifts the cab. When the cab descends, the motor transforms mechanical power to electrical power and pumps it into the building’s electrical grid to use in other systems. When the cab ascends with a light load or descends with a heavy one, the motor generates more power than it uses.
The amount of energy that is saved depends on several factors, such as the height of the building, how often the elevators are used, and the age of the elevator and other equipment. Since elevators with regenerative drives generate less heat than traditional elevators, machine rooms have to be cooled less, which can lead to further savings.
The cost of installing a regenerative drive system also varies depending on the type of system, the condition of the existing elevators, the height of the building, and how often the elevators are used. It is important for building owners and managers to evaluate how much energy their elevators are currently using when deciding whether to make the switch to regenerative drives.