By Christine Toledo
Energy is a major issue today in the United States. We are faced with the challenge of finding new energy solutions through conservation and alternative energy sources. The most effective solution is often through energy-efficiency technologies.
Buildings are one of the largest users of electricity. According to the Washington, D.C.-based Energy Information Administration, buildings account for 79 percent (or $214 billion) of total U.S. electricity expenditures. As of 2003, there were 4,859,000 commercial buildings alone. Most buildings consume a significant amount of electricity through the operation of vertical transportation equipment (elevators, escalators, and moving walks). This equipment generally runs all hours that the building is open for operation.
Several methods for reducing electricity consumption for vertical transportation equipment have been considered, including energy-saving technologies. In general, there are three alternatives to making escalators and moving walks more efficient:
1)Turn the power switch to "off."
There's no denying that the best way to save energy is to shut off the equipment. But, if the equipment needs to be running, then it obviously can't be shut off.
2)Install a variable frequency drive.
Variable frequency drives (VFDs) can positively impact energy consumption; however, they do not meet current U.S. code for escalator safety, and the additional sensors and equipment that are required to retrofit existing escalators can be expensive.
3)Install equipment that can control efficiency of the motor.
This equipment can leave the speed of the escalator unchanged, but can reduce power consumption when few riders are on it. A test by Reno, NV-based Nevada Power, the electric utility for Southern Nevada, on a 40HP escalator motor at a Las Vegas Strip casino showed a reduction in average power consumption of 37 percent (see graph) when using this type of product.
With energy efficiency and the curbing of greenhouse-gas emissions ranking among the highest national priorities, solutions for vertical transportation efficiency will continue to contribute to the overall effort to reduce power consumption.