In California, energy companies have to switch all customers to Time of Use (TOU) rate plans by 2019. Under TOU, energy prices change throughout the day -- it won't be easy to monitor rates and adjust cooling and heating manually every hour or so. To help users stick to their budget, Nest is introducing a new feature called "Time of Savings." The service shares customers' TOU rate info with Nest, which then auto-adjusts itself to reduce energy consumption during the most expensive periods. Nest will only change the temperature by a degree or two, though, and users will have to tweak it themselves if they want to save more money.