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What reasons does the Nest Energy Report consider to account for changes in my energy use

In the monthly Nest Energy Report, one section highlights reasons that your energy use has changed since last month. Here are all the reasons we look at.

The section of the Nest Energy Report that explains why your heating or cooling usage has changed highlights the main 1 to 3 reasons for that change. However, we look at a number of factors beyond those shown on the Energy Report. Together, they add up to the difference between this month’s energy use and last month.

If you’ve only had your Nest Learning Thermostat for one month or if your energy use hasn’t changed month-to-month, this section will not appear in your Energy Report.


As the weather changes, you naturally use more or less heating or cooling, even if you never touch your thermostat. With the same schedule, a Nest Thermostat that barely turns on the heat in spring can keep the heater running 12 hours a day in winter.


Changes to your Nest Thermostat schedule - whether from Auto-Schedule or from manual edits you’ve made - can cause you to use much more or less energy. In this section we consider the change that your updated schedule has made to your energy use this month vs last month. So if your schedule has remained the same - even if it’s very efficient - it won’t be highlighted as a change factor it in the Energy Report.

Manual adjustments

When you turn the temperature up or down on the Nest Thermostat, the mobile app or the Web app, we think of it as a “manual adjustment.” In the Energy Report, we compare the manual adjustments you made last month to the ones you made this month, and check how much that impacted your energy use.


We compare how much energy you saved this month with Auto-Away vs how much you saved last month.


We compare how many hours of heating/cooling you saved this month vs last month by turning Away on manually.


We look at the difference in how much Airwave saved you this month vs last month.


We compare how much energy you saved by turning the Nest Thermostat off this month vs last month.

Added a Nest Thermostat

If you added a new Nest Thermostat to your home, we get a fuller picture of your energy use. If this happens, it may look like your energy use has gone up dramatically, so we make sure to show you this icon so you know that you haven’t necessarily used more energy. We can simply see more of it.

Calendar days

Every month doesn't have the same number of days. Between January (31 days) and February (28 days), you can heat your home for the same number of hours each day, and you will still end up using less energy in February than January.

And don't be surprised if this month’s reason is quite different than last month. We’ve found that people's behavior can really vary from month to month. For example, you may make a ton of changes in your schedule the month of November, but you may not do that again till March. If that's the case, you may see a large change in schedule between November and December, but not much between December and January.