Regenerative Drive System
A regenerative drive system recycles electricity used to power the mobilization of the elevator. As the elevator cab moves up and down, the counterweight moves in an opposite direction and weighs 40% more than the empty cab.
In an energy-saving regenerative elevator drive, the electricity used to move the cab and the counterweight is recycled into other parts of the elevator’s power (cab lighting, for example) and sometimes even directed into other functions within the building itself. “As an added bonus, the regenerative drive system also increases the efficiency of passengers’ travel times,” said Prior.
Eco-friendly options for new construction take on different forms and technologies, such as: innovative hoist machines, machine-room-less (MRL) designs, destination software, and sustainable materials. “Elevators use very little energy according to the overall amount within the building,” said Stuart Prior, Executive Vice President, Americas Product Sales and Marketing with ThyssenKrupp. No matter how little energy the elevator uses in relation to the overall electricity pull, small conservation efforts accumulate into to a vast difference in the end. “The KONE EcoDisc® hoisting machine, introduced 12 years ago, uses half as much energy as a conventional traction elevator and a third as much as a hydraulic elevator,” said Jussi Oijala, KONE senior vice president, Global Technology.
Destination Control Software
Most applicable for the skyscraper is the invention of destination control software. When introduced by Schindler Elevator Corp., the ability for passengers to travel efficiently greatly increased. Since there are multiple floors in a skyscraper, the destination control software organizes groups of passengers. For example, rather than stopping at multiple floors for various individuals, the destination dispatch system groups all passengers traveling to a specific floor in one trip.1As a group approaches the bay of elevators, each passenger enters their destination information via a company ID badge, a key code, or another similar device. Subsequently, the passengers are gathered together and assigned to elevator cabs. The convenience of this system is beneficial; increasingly, the elimination of wasted energy is a positive environmental improvement. The software drastically reduces user wait-time and increases handling capacity by up to thirty percent. Environmental benefits are abundant, as well, decreasing the amount of wasted energy expense by maximizing elevator efficiency through passenger destination selection.1
For new installations in small to medium-sized buildings, MRL elevators eliminate the usually large elevator rooms, replacing them with a compact machine tucked into the top of the elevator shaft. "With this innovation, KONE managed to create a technology which changed the whole industry. At the time, no one could have expected how successful it would become. Now, 10 years later, there are no doubts about its success," said Heikki Leppänen, executive vice president and director for new equipment at KONE. Prior describes an MRL elevator as such: “An MRL type elevator is a system that utilizes a geared or gearless hoist machine. All or some of the other major elevator components (controller, drive, isolation, etc.) with an MRL application may or may not be located in the elevator hoistway, depending on the application and local codes.”
"With its multiple advantages, the MRL concept offers a win-win situation for all parties," Leppänen continued. An MRL mechanically lifts without the need for lubricant oils. Reportedly, it also consumes only 60% of the electricity of other geared traction machines. The elimination of the elevator room reduces the building’s square footage (usually 300-500 square feet), which saves on extra building materials and, over time, utility costs. Furthermore, the gearless design provides a smoother, quieter ride for its passengers.
Since KONE introduced the MRL elevator, they have estimated how much energy has been conserved since the first MRL was installed. “Since 1998, the KONE MonoSpace® elevator family has cumulatively saved the equivalent electricity production of a typical power plant (250 MW), avoiding the consumption of 2,000,000 barrels of oil, and the CO2 emissions of 100,000 cars driving the distance of earth’s 40,074km circumference,” said Oijala. The market indeed is now full of MRL options, such as: KONE provides the MonoSpace® and the MiniSpace™; Otis provides the Gen2®; ThyssenKrupp provides synergy; Schindler provides the SMART MRL™; and Fujitec provides the Millennium II. “It is estimated that by the end of 2010, two-thirds of the world's new elevators will feature MRL technology, further proof that the MRL concept is as valuable today as it was when it was launched over a decade ago,” said Oijala.