The Nest thermostat collects data on a very frequent basis and the app can display it. An example follows.
The first 2 lines are expanded to show more detail. The last ones are normal detail. The leaf on the left shows efficient usage. The icons on the right show higher usage periods due to weather and when the Nest has determined that auto away can be switched on and the temperature raised.
So far I’m satisfied with the thermostats. I like both the remote control aspect as well as the availability of detailed data. I’m hoping that they will eventually be efficient enough to offset their cost.