Power saving devices show you how much electricity you are wasting

Original press release was issued by MIT, written by David L. Chandler.
Daily expenses and the necessity to pay bills belong to the least popular parts of an otherwise fine day. Most of the time, the products and services that we pay for have a clear price tag. But other expenses like electric energy consumption in a given household remain somewhat hidden. It is not easy to monitor how much energy we used up over the course of the day, so once we are handed the bill, an unpleasant mood swing may occur. But soon, there may be a much clearer way of knowing, what is the exact power output.
Researchers at MIT, led by Professor of Electrical Engineering Steven Leeb and recent graduates David Lawrence MEng ’16 and John Donnal PhD ’16, have put forth their findings in their paper ‘Current and Voltage Reconstruction From Non-Contact Field Measurements‘ regarding power saving devices and software. These devices allow to monitor precisely how much power is being used by every appliance and lighting fixture with pinpoint accuracy and low cost. The key advantage is, that the system requires no complex installation: No wires need to be disconnected as it’s designed to be self-calibrating. Authors have addressed perhaps the most significant issue which are privacy concerns — all of the detailed information stays right inside the user’s own home.

Source: MIT

With the potential to save energy, greenhouse emissions, safety improvements and easy installation by the users themselves to boot, researchers believe that once the system is fully developed, it should cost $25 to $30 per home. But how does it work? Authors addressed 3 key problems.
First was the ability to monitor changes in voltage and current without cutting the main incoming power line to a home or business or plugging every appliance into a special monitoring device. The MIT team solved the problem by using an array of five sensors, each slightly offset from the others, and a calibration system that tracks the readings from each sensor and figures out which one is positioned to give the strongest signal.
The next issue to overcome was to identify “signatures” of specific appliances. The team had to analyze the reams of data flowing in from the high-speed sensors and find out which bits correspond to current and voltage. Since every device has distinctive characteristics as to exactly how fast and how much the voltage varies, the team was able to develop a catalog of such signatures, to identify each kind of electrical load.
Last thing to figure out was how to extract the useful information and display it in a way that would make it easy for people to make decisions about energy investments. They developed an interface that allows users to “zoom in” on specific time segments, revealing enough data to tell when a refrigerator turns on or off, or goes into its defrost cycle, or how often a water heater is switching on and off during the day.
Various testing of the system has already showcased its huge potential to save energy and improve safety. One test installation at a military base revealed that large tents were being heated all day even though they were unoccupied for most of the daytime hours — a significant waste of money and fuel. Another installation found an anomalous voltage pattern, exposing some copper plumbing pipes carrying a potentially dangerous live voltage. Once it goes commercial, it could ease the lives of majority of households, now knowing exactly, how much money (and how much electricity) “zips” through.