If Google records that data (say, to be able to provide you with a handy chart of your energy use and some ways to improve it), the potential I am more worried about is the fact that the data exists makes it possible to subpoena.
The government holds deadly force. Private enterprise is going to do some horrifying things with your data, but barring a cyperpunk dystopia, it lacks the capability to end your life.
And yes, while it doesn't matter what they can and cannot do with your data now (unless you're a criminal not much, obviously), if the government ever becomes excessively authoritarian and dictatorial, keep in mind they can retroactively go through all the data they ever gathered on you and find something to string you up with.
Burglars could look at the database and say "Oh hey, look, no one's home right now."
This is just another excuse to throw feces at Google, and HN commenters just don't miss any possible opportunity to do that.
google data breach in last 30 days: http://money.cnn.com/2013/12/04/technology/security/password...
inside job at home security company in last year: http://www.wbng.com/news/state/198129651.html
Except that's impossible to actually implement, or manage, and makes your life so much harder for questionable benefit.
(disclaimer: I work for Google, have no special knowledge of the incident in question)
Don't see how the acquisition changed the value of that data. Do you really think Nest has better data security than Google?
But if you have access to someone's live power usage, you probably have a good idea of their schedule. On top of that, your phone makes a much better tracker than your thermostat.
What about the auto-away feature?
Your phone makes a much better tracker for such things.
I haven't invested the time into setting up a proper home automation rig yet, but it is on my to-do list.