It's also an excellent surveillance tool, from what I understand (and much of my understanding started with prior Hacker News discussions). Not only can you identify if people are home, but you can identify what they are doing if it involves electricity and make good guesses at more (how many people are present, have they gone to sleep, etc.). It's appears to be literally a window into the privacy of everyone's homes, as shocking as that sounds:<p><i>it is possible to identify which appliances a consumer is using and at what times of the day, because each type of appliance generates a unique electric load "signature." NIST [National Institute of Standards and Technology] wrote in 2010 that "research shows that analyzing 15-minute interval aggregate household energy consumption data can by itself pinpoint the use of most major home appliances."</i><p>The best starting place I've found is the Congressional Research Service (an excellent resource on policy issues) report, "Smart Meter Data : Privacy and Cybersecurity", which cites many more resources and is the source of the above quote.<p><a href="https://fas.org/sgp/crs/misc/R42338.pdf" rel="nofollow">https://fas.org/sgp/crs/misc/R42338.pdf</a>