Article Summary:
With Time-to-Temperature, the Nest Learning Thermostat displays how long it will take for your home to reach the temperature you’ve chosen. This keeps you from being tempted to set the temperature too high (or too low) and waste energy while running your system unnecessarily.
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 it will waste energy if you don’t remember to turn it down. The longer your system is heating or cooling your home, the more energy you’re using. Just choose a comfortable target temperature and your Nest Thermostat will tell you how long it will take to get there.
Your Nest Thermostat starts learning as soon as you install it. When you change the temperature, you’ll see the estimated time it will take to reach the new target temperature. Your thermostat will learn how quickly your home warms up and cools down and improve its estimates as you continue to use it. However, your thermostat will only estimate Time-to-Temperature for temperatures that you’ve manually set on the thermostat itself or with the Nest app. Temperatures that you have put into your schedule and temperatures added by Auto-Schedule won’t have a Time-to-Temperature displayed. Once the target temperature is reached, the Time-to-Temperature will disappear, and the screen background will turn from orange (heating) or blue (cooling) to black.
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.”
The Time-to-Temperature estimate will get more accurate as your thermostat continues to learn about your home and heating or cooling system. With the latest Nest Thermostat software in 2015, we’ve improved not only how your thermostat learns about your system, how quickly your home heats and cools, and how the weather affects. In fact we’ve improved our temperature prediction by 25% for heating and 65% for cooling, so you’ll see even more accurate Time-to-Temperature estimates and improved energy savings too. For complete details, see our whitepaper.
The Nest Thermostat also dynamically adjusts to changing weather conditions as well as how fast your home is warming up or cooling. So you’ll also see a more precise estimate as the room temperature gets closer to the target temperature. It’s like a long driving trip with GPS navigation: when you start driving from San Francisco to Los Angeles, your GPS may only be able to give you a rough estimate of the time it will take to get there based on current traffic conditions and by guessing how fast you’ll cruise. Let’s say there’s some traffic, so your GPS says it’ll take almost seven hours. But maybe you get lucky, and the traffic clears up, so you can drive faster. By the time you’re on the outskirts of the city, your GPS is pretty sure that it will take between fifteen and twenty minutes to reach your destination downtown.
Why don’t I see Time-to-Temperature?
The Nest Thermostat won’t display a time 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 you have a poorly insulated home and an extreme cold front rolls in, your heating system might have to constantly cycle to keep the temperature up. In this case, the display will simply read "HEATING" without a time.
When the seasons change and you switch your Nest Learning Thermostat between heating and cooling for the first time, it will need to learn to estimate Time-to-Temperature for the new system, so you won’t see the time estimate on the thermostat screen for the first few days. However, the next time the seasons change, your thermostat will remember what it has already learned.