When a cell phone or credit-card bill arrives, each call or purchase is itemized, making it possible to track trends in calling or spending, which is especially helpful if you use a phone plan with limited minutes or are trying to stick to a budget. Within the next few years, household utilities could be itemized as well, allowing residents to track their usage and see which devices utilize the most electricity, water, or gas. New sensor technology that consists of a single device for each utility, which builds a picture of household activity by tracing electrical wiring, plumbing, and gas lines back to specific devices or fixtures, could make this far simpler to implement. Researchers at the University of Washington, in Seattle, developed the sensors, which plug directly into existing infrastructure in buildings, thereby eliminating the need for an elaborate set of networked sensors throughout a structure. For example, an electrical sensor plugs into a single outlet and monitors characteristic noise in electrical lines that are linked to specific devices, such as cell-phone chargers, refrigerators, DVD players, and light switches.
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More information:
http://www.technologyreview.com/computing/22947/