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Save on utilities: just heat or cool yourself

Posting in Science

Why run the AC for the entire room when you can just cool your body? Or, for that matter, why not just keep yourself warm, instead of heating the whole building?

Wristify (pictured), a new thermoelectric bracelet out of MIT, monitors air and skin temperature, then sends tailored pulses of hot or cold waves to the wrist to help you maintain comfortable temps.

“The human body and human skin is not like a thermometer,” MIT senior Sam Shames says. “If I put something cold directly on your body at a constant temperature, the body acclimates and no longer perceives it as cold.”

Never fight over where to set the thermostat again! Wired explains:

Think of what happens when you jump in a lake. At first, it’s bracingly cold, but after a while, you get used to it. By continually introducing that sudden jolt of cold, Shames discovered, you could essentially trick the body into feeling cold. Wristify basically makes you feel like you’re continually jumping into the lake -- or submerging into a hot bath.

Fifteen prototypes later, the working version delivers temperature change at a rate of 0.4 degrees Celsius per second, and they’ve settled on roughly 5 seconds on, 10 seconds off.

Consider some of these scary statistics:

  • In 2007, 87 percent of households in the U.S. used AC -- compared to just 11 percent in Brazil and a mere 2 percent in India.
  • But by 2025, booming nations like those are projected to account for a billion new consumers worldwide, with a corresponding explosion in AC demand.
  • Keeping indoor spaces at comfortable temperatures requires huge amounts of electricity. In the U.S., it accounts for a full 16.5 percent of energy use.

The team estimates that if the device stops one building from adjusting its temperature by even just 1 degree Celsius, it will save roughly 100 kilowatt-hours per month.

A couple weeks ago, the prototype -- a crude mess of electronics strapped to a cheap, fake Rolex band -- won first place at MADMEC, MIT’s annual materials-science design competition. The group will use their $10,000 prize to continue pushing towards development.

None of the components are prohibitively expensive -- about $50 worth of off-the-shelf parts -- and the size of the current version could probably be halved.

[MIT News Office via Wired]

Image: Franklin Hobbs

— By on November 1, 2013, 11:51 AM PST

Janet Fang

Contributing Editor

Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York. Follow her on Twitter. Disclosure