Sunday, April 1, 2012

“Pimp My Elevator” Retrofit Turns Clunkers into Energy Savers

Forget about turning your car into a rolling DJ booth, the Thyssen Krupp Americas Elevator company has just launched the vertical version of the MTV hit show from a while back, “Pimp my Ride.” The company is offering a new elevator retrofit package, which transforms an old clunker into a smoother, faster, high tech ride that collects and recycles the energy it creates from friction while braking.

Coolness factor aside, building retrofits like this could play a significant role in President Obama’s Better Buildings Initiative, which kicked off last year. The initiative seeks to “mine” buildings as a significant new source of energy. According to the Department of Energy, buildings used about 40% of the energy in the U.S. economy, costing more than $400 billion a year. The Better Buildings Initiative aims to make a dent in that with a goal of 20 percent savings for commercial and industrial buildings by 2020. In a way, that’s like discovering a whole new oil patch.

Planning more efficiency into new construction is part of the solution, but much of the focus is on energy efficiency upgrades for existing buildings. Last December, the President announced a $4 billion package for energy efficiency upgrades in federal and private sector buildings.

To cite just one iconic example of the energy-mining potential in building retrofits, the Empire State Building in New York City is in the final stages of a retrofit that earned it a LEED Gold rating. The initial, $13 million phase involved upgrading thousands of windows and the steam heat system, yielding a savings of $4.4 million per year for a quick payback on the investment. In the next phase, the Otis elevator company is upgrading the building’s 68 elevators. Like ThyssenKrupp, Otis’s upgrade package also includes regenerative braking.

ThyssenKrupp’s system saves energy in two ways. The regenerative system harvests the energy from braking, of which elevators do a lot. According to ThyssenKrupp’s promotional materials, a conventional elevator machinery can lose more than 30 percent of its energy in the form of waste heat. Tricked out with a new retrofit, the loss is only about five percent. The rest gets shunted back into the building’s electrical system to reduce its demand on the grid.

Regenerative energy capture is becoming common in systems that are characterized by stop-and-go motion, whether laterally or vertically. That includes delivery vehicles, commuter rail lines, and shipping cranes.

The second part of the savings is a direct consequence of the first. In a conventional elevator system, excess heat collects in the machine room, which then requires air conditioning to keep the machinery from overheating. That doesn’t apply in a regenerative system, since most of the heat is captured and put to use elsewhere in the building.

The trick behind the system is a gearless technology based around a permanent magnet AC motor. According to the company, a gearless machine operating at less than 240 rpm can reach the same speed as a geared machine at 1,800 rpm.

For additional savings, the motor does not consume energy unless the elevator is actually in use, and the retrofit can include high efficiency LED lighting in the cab.

Only a building manager could appreciate some of the other aspects of a gearless system. It takes up less space in the machine room, eliminates oil and carbon dust, and significantly reduces noise.

As far as the passengers go, when you step into a retrofitted elevator ThyssenKrupp claims you will experience less vertical vibration, smoother stops and starts, a more precise match between the floor of the elevator and each floor of the building, and of course, a faster ride.

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