Use Time to Temperature to help you save energy. Cranking the heat up to 90ºF/32ºC won’t make your home heat up any faster, but could waste energy if you don’t remember to turn it down. The longer you are heating or cooling your home, the more energy you’re using. Just choose a comfortable target temperature and Nest will tell you how long it will take to get there.

When you first install Nest, the words “heating” or “cooling” will be displayed when you change the temperature. After Nest has had a week or so to learn, it will instead display an estimate of the time it will take to heat or cool your home to the selected target temperature.

Nest will only estimate Time to Temperature for manually set temperatures, not scheduled temperatures. Once the target temperature is reached, the Time to Temperature display will disappear.

The Nest Learning Thermostat estimates Time to Temperature in increments of five minutes. If it’s less than ten minutes until the temperature you’ve selected is reached, the display will read, “less than ten minutes.” If it’s more than two hours, Nest will read “in 2+ HR.”

Nest’s Time to Temperature estimate will get more accurate as Nest continues to learn and as the current temperature gets closer to the target temperature. It’s like a long driving trip with a GPS Navigation Assistant: when you start driving from San Francisco to LA, you might not be sure how many minutes it will take to get there—you just know it will take anywhere from five to eight hours, depending on whether you get lucky with traffic on the freeway. By the time you’re on the outskirts of LA, your GPS is pretty sure that it will take between fifteen and twenty minutes to reach your destination.

This is also why Nest won’t display an estimate if continuous heating or cooling is needed to maintain the temperature that you have selected or if the temperature fluctuates unexpectedly. For example, if an extreme heat wave means your AC can barely keep the temperature down even when it’s constantly cycling, the display will simply read, “COOLING.”

When the seasons change and you switch your Nest Learning Thermostat between heating and cooling for the first time, Nest will need to learn to estimate Time to Temperature for a new system. Next time there’s a change of seasons, Nest will remember what it has already learned.