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Brainy Buildings *

The walls have ears—and eyes—at the University of California at Berkeley

David Pescovitz -- Interior Design, 2/1/2004 12:00:00 AM

In the midst of an energy crisis, how do you know if you're wasting power at home? After an earthquake, how confident are you that it's safe to go back inside your office? If only the walls could talk.

That's precisely the idea behind the smart-building technology in development at the University of California at Berkeley's Center for Information Technology Research in the Interest of Society. These Smart Dust "motes" are coin-size wireless sensors that keep a constant vigil on temperature, light, motion, and power consumption, and Berkeley researchers are already demonstrating mote-based systems that enable buildings to self-diagnose seismic stability or keep electricity bills in check.

Invented by Berkeley professor Kristofer Pister, the motes are loaded with TinyOS, an operating system developed with Intel. They function by self-organizing into wireless networks that pass along data, bucket-brigade style, until information reaches a central computer for processing. Some motes run on tiny solar cells or batteries, however Australian National University professor Shad Roundy, formerly at Berkeley, has been developing power-scavenging technology that harnesses vibrations from the likes of heating and cooling ducts. When ambient vibrations cause a tiny cantilevered mass to bounce up and down, resultant kinetic energy is converted into enough electricity to power a sensor.

Addressing a concern central to Californians, one thrust of the Berkeley effort is seismic safety, enabling buildings to write their own bill of health after an earthquake. John-Michael Wong, a graduate student in civil and environmental engineering, explains it this way: When the engine light on your dashboard flashes, you know immediately that the car may not be safe to drive. Now imagine a building outfitted with that technology. A Web site could notify the property manager if a support column needs a checkup. Or a display screen, mounted on the front door, might warn occupants reentering after an earthquake that their entire building is on the verge of collapse.

Wong and professor Bozidar Stojadinovic are designing this kind of "dashboard" for buildings as part of a program sponsored by an earthquake-research consortium and a Japanese construction firm. Formally called aFramework for Integration and Visualization of Structural State Data, it analyzes raw numbers from wireless sensors mounted at key points and translates the calculations into easy-to-interpret graphic displays. These seismic motes—adapted by engineering professor Steven Glaser and graduate student Jan Goethals—feature accelerometers, which detect vibration, and strain gauges, which measure the bending or twisting of a beam. Within six months, the system will be put to the test on Berkeley's "shake table" earthquake simulator.

Another effort, supported by the California Energy Commission, aims to ease the state's costly electricity crisis, combining a network of tiny sensors and smart thermostats and demand-response pricing to reduce brownouts. "From June through September, we always see huge peaks in energy demands," says mechanical-engineering professor Paul Wright, who's working on the project with Ed Arens, director of Berkeley's Center for the Built Environment. "Air-conditioning can account for a 50 percent increase over baseline consumption. Wouldn't it be great if your meter received information about when it's cheapest to run your AC, and your thermostat adjusted to reflect that?"

Demand-response cooling involves motes that monitor temperatures in various parts of a house or apartment and relay data to a networked thermostat. Meanwhile, sensors coupled to electrical circuits in breaker boxes could monitor the power consumption of other appliances. As energy prices shifted hourly, they would be transmitted wirelessly from the utility company to a smart meter at the residence.

Users' only responsibility would be to program their temperature preferences on a straightforward thermostat. "Even if you're home during the day, there are ways to spread thermal-mass load to keep the house cool—without turning on the air conditioner at peak times, when energy is most expensive," Wright says. The key to such a system is of course for energy companies to institute a time-of-use pricing structure for households as well as commercial buildings. Once the client-side technology is proven, Wright believes, utilities in the Bay Area will oblige.

Mechanical-engineering professor Paul Wright is developing tiny Smart Dust "motes" to control residential energy demands, under ordinary circumstances, as well as to help firefighters navigate an interior during a blaze.

This prototype for a solar-powered mote, which senses motion and ambient light, has already been superceded by a smaller version, measuring 2 by 2.5 millimeters.