Elevators and Escalators

The power needed to operate an elevator is a function of the height of the building, the number of stops, passenger capacity and load factors, and the efficiency of the hoisting mechanism. A 2,500 lb. capacity "local" elevator making 150 stops per car-mile, for example, uses about 5 kWh per car-mile. An "express" elevator making 75 stops per car mile consumes about 4 kWh per car-mile. A 4,500 lb. capacity elevator in a 12-story department store stopping at every floor uses 13 kWh per car-mile. Energy use also varies due to different types of hoisting motors and controls, and the kind of service and the amount of load offset by the counterweight. To save energy, select speeds that are as slow as possible, and keep maximum waiting time to no more than two minutes. Work with the elevator manufacturer to study traffic patterns. If you install multiple elevators, consider reducing the number in service during light traffic periods. Energy use by escalators also is tied to a variety of factors. Assuming 35 equivalent full-load operation, escalator energy consumption may vary from 1.3 kWh per hour for a 32-in-wide model operating at 90-feet-per-minute with a 14-foot vertical rise to 3.0 kWh per hour for 48-inch-wide model operating at 90-feet-per-minute with a 25-foot vertical rise. Remember that escalators consume energy whether or not they are carrying passengers. Unlike elevators, they may be used when de-energized.