Optimizing Elevator Performance

Nov. 4, 2004
Destination-based systems are faster and more efficient
In most buildings, using the elevator is much like riding a bus. Want to go uptown? Wait ’til an uptown bus comes along, and then hop on. When you reach your stop, hop off. Going downtown? Same idea.That system may work fine for buses. But as a growing number of building operators are discovering, there is a far more efficient way of running elevators – especially in highly populated buildings. It’s called “destination-based” or “hall-call” dispatching, a next-generation technology designed for multi-elevator buildings. Control systems using this intelligent technology can be included in new construction, or added to existing equipment during modernizations.In practice, destination dispatching typically shortens destination times for users by 20 to 30 percent, and results in significantly less wear and tear on the equipment. It can even help building owners and facilities professionals handle more traffic without adding elevators.For passengers, using a destination- based system is more like taking a limousine than riding a bus. Instead of “Up” or “Down” buttons at your elevator banks, there are simple numeric keypads. To go to the ninth floor, for example, you simply touch “9” on the keypad. An LCD then shows you which elevator to use. When that elevator arrives, just get on, and you will automatically stop at the ninth floor – typically in much less time, with fewer stops.Why is this more efficient? Because the system uses sophisticated software algorithms to figure out the most direct and efficient way to respond to the traffic demands moment-to-moment. The system continually calculates the optimum route for each car (based on where passengers are and where they’re going). Weight sensors in the cars, for example, can estimate the number of passengers already aboard to help “decide” whether to drop off passengers before picking up new ones, and where.The key, of course, is the efficiency of the dispatching algorithms. The best algorithms have been honed and refined over a period of years, based on real-world experience in actual buildings. It is more art than science.The bottom-line benefits can be impressive. In well-designed installations, destination-based systems typically result in about half the number of floor stops as conventional systems. That translates into about 50-percent fewer decelerations, door openings and closings, and accelerations per year, which can make a substantial difference in a building owner’s or facilities professional’s maintenance requirements    and equipment life.At the same time, passengers will get to their floors in 20- to 30-percent less time, which can be especially beneficial in older buildings that are overpopulated and “under-elevatored.” Moving to a destination-based control system can allow you to support a larger tenant base with existing elevator assets.But will passengers object? When this technology was first introduced, skeptics feared that passengers would rebel, or become confused by the new way of using elevators. In reality, however, these concerns have proven unfounded. It seems tenants are happy to take a limousine rather than ride the bus – especially if it costs them the same, and gets them to their destination sooner.Sula Moudakis is director of top range traction elevators at Schindler Elevator Corp. (www.schindler.com), Morristown, NJ.

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