Do Smart Thermostats Save Money? What the Data Shows

Do smart thermostats save money? Field studies say yes, often 10 to 15% of heating and cooling. What learning thermostats learn, and ecobee vs Nest.

Published October 11, 2026

The short answer

Yes, smart thermostats usually save money, though less than the boxes promise. ENERGY STAR certifies a model only after a year of field data from hundreds of homes shows at least 8% less heating run time and 10% less cooling run time (ENERGY STAR criteria). An independent utility study in Indiana measured about 13% heating gas savings in homes that switched from manual thermostats to a Nest (Cadmus 2015). You save the most when the thermostat sets the house back while you sleep or leave, and the least if you already did that by hand.

What does a learning thermostat actually learn?

A learning thermostat watches you adjust it and writes a schedule from the pattern. Each brand does this a little differently.

Google Nest. Older Nest Learning Thermostats (3rd gen and earlier) and the Nest Thermostat E use Auto-Schedule. Google's help pages describe a thermostat that starts learning on day one and settles on a schedule after about a week, then needs at least two similar changes before it shifts that schedule. The Nest Learning Thermostat (4th gen) replaced this with Smart Schedule, which can update your schedule automatically or send suggestions for you to accept. The plain Nest Thermostat uses a schedule you set yourself.

Nest Eco Temperatures. When a Nest senses an empty house, it switches to Eco Temperatures. It decides you've left from its own activity sensors, your other Nest devices and your phone's location (Google Nest Help). You choose the Eco range: 40 to 70°F (4 to 21°C) for heating and 76 to 90°F (24 to 32°C) for cooling. Google suggests a lower setting such as 56°F (13.5°C) for a well-insulated home that heats quickly, and something closer to 62°F (16.5°C) for a leaky home that heats slowly (Google Nest Help).

ecobee Comfort Settings. ecobee asks you to do more of the setup. A Comfort Setting holds your temperature preferences for one kind of activity, such as Home, Away or Sleep, and your schedule decides when each one runs. ecobee's free eco+ features add the learning layer:

Schedule Assistant recommends schedule changes when your routine shifts.
Smart Home & Away sets the temperature back when you leave and restores your Comfort Setting when you return.
Time of Use preheats or precools when electricity costs less.
Adjust for Humidity uses the indoor humidity reading to keep the house feeling like the number you set.

What information do smart thermostats use?

Most models combine four inputs:

Your schedule, typed in or learned from your adjustments.
Occupancy, from a motion or radar sensor, room sensors, or your phone's location.
Weather and humidity. The Nest Learning Thermostat (4th gen) offers Adaptive Comfort, which adjusts your comfort temperature for indoor humidity and the weather forecast. ecobee adjusts for indoor humidity through eco+.
Utility rates and grid demand. Nest's Rush Hour Rewards and ecobee's Community Energy Savings ease off during high-demand events, and ecobee's Time of Use preheats or precools while electricity costs less.

Do smart thermostats save money? What the studies show

Sort the evidence by who paid for it.

ENERGY STAR (the EPA). The EPA certifies smart thermostats on field data from occupied homes. Manufacturers run a year of data from hundreds of customer homes through EPA software, and the model must show at least 8% less heating run time and 10% less cooling run time (ENERGY STAR criteria).

Independent utility evaluation. NIPSCO, an Indiana gas and electric utility, installed 400 Nest thermostats and 400 standard programmable thermostats in homes that had manual thermostats, and hired the firm Cadmus to measure the results with billing data and a control group. Nest homes cut heating gas use by about 13%, and programmable homes by about 8%. Cooling savings landed close together, about 16% and 15% (Cadmus 2015). The evaluators traced the heating gap to Nest homes running about one degree cooler, and they attributed that to automatic away and schedule features.

Manufacturer studies. A 2015 Nest white paper pooled three bill studies, two independently funded (Oregon and Indiana) and one Nest analysis across 41 states. All three landed near 10 to 12% heating savings and about 15% cooling savings in homes with central air (Nest white paper 2015). ecobee advertises savings of up to 26%, calculated against holding the house at 72°F (22°C) all day (ecobee). Treat both as manufacturer claims, and expect a "save up to" figure to run higher than a typical household's result.

Why savings vary so much. A Lawrence Berkeley National Laboratory review found that nearly half of people with programmable thermostats don't use the programming features, and that homes with programmable thermostats can use more energy than manually controlled homes, depending on how people use them (Peffer 2011). Learning and occupancy features help mostly because they apply setbacks people forget to schedule. If you already turn the heat down every night and every time you leave, expect smaller gains.

Ecobee vs Nest: how they compare

| Feature | Nest Learning Thermostat (4th gen) | ecobee Smart Thermostat Premium | |---|---|---| | Schedule | Smart Schedule learns from your adjustments, automatic or as suggestions | You build Comfort Settings and a schedule; Schedule Assistant suggests changes | | Away detection | Thermostat motion sensor, other Nest devices, phone location | Built-in radar occupancy sensor, Smart Home & Away | | Room sensor | Comes with a Nest Temperature Sensor | SmartSensor in the box (temperature and occupancy) | | Humidity | Adaptive Comfort uses indoor humidity and forecast | Adjust for Humidity | | Energy prices | Rush Hour Rewards (through your utility) | Time of Use, Community Energy Savings | | Apple Home | Matter-certified | Apple HomeKit | | ENERGY STAR | Certified | Certified | | Published savings (manufacturer) | 10 to 12% heating, about 15% cooling (2015 study of earlier models) | Up to 26% vs a constant 72°F |

Pick Nest if you'd like the thermostat to write the schedule for you. Pick ecobee if you'd like to set the rules yourself and want the Premium's room sensor with occupancy detection in the box. Both work with Apple Home, which lets you add your own rules; see HomeKit thermostat automations.

What learning thermostats don't account for

A learning thermostat sets one temperature for the whole house, based on a schedule and on whether anyone is home. Newer models also correct for indoor humidity. How warm you feel depends on more than that. Sun through a west window can warm one room by late afternoon. A person who just finished a run feels warm at a setting that leaves a seated person chilly. Clothing and blankets shift comfort too. A thermostat reads the air near its sensor and follows the schedule you trained it on. That gap explains why the perfect temperature changes through the day.

Room sensors close part of the gap by measuring where people actually sit or sleep; thermostat room sensors covers how to place them. Just Right takes a different approach: it picks a temperature from weather, sun, time of day, a recent workout and your own corrections, then sets an Apple Home thermostat to match.

How to get comfort and savings from a smart thermostat

Keep real setbacks. Savings come from cooler nights and empty-house setbacks in winter and warmer ones in summer. See recommended thermostat settings for the numbers.
Turn on away detection and add every household member's phone, so the thermostat doesn't switch to Eco while someone's still home.
Pick a sensible Eco or Away temperature. Go lower in a tight house and a bit higher in a drafty one, so it recovers in reasonable time (Google Nest Help).
Add a room sensor in the bedroom or the room you use most, so the house heats to the comfort of the people in it.
Give the learning a week. Google says Auto-Schedule settles on a schedule after about a week of your adjustments, so judge it after that.
Heat pump owners: use a thermostat set up for your heat pump, because setting back a heat pump in heating mode can make it run inefficiently.

The bottom line

Smart thermostats save energy in field data: ENERGY STAR models must cut heating run time by at least 8% and cooling by at least 10%.
Independent and manufacturer studies cluster around 10 to 13% heating savings and about 15% cooling savings.
The savings come from setbacks the thermostat applies for you. If you already set back faithfully, expect less.
Comfort depends on sun, activity and clothing as well as air temperature, so pair a smart thermostat with room sensors and sensible setbacks.

Common questions

Do smart thermostats really save money?

Usually, yes. ENERGY STAR certifies a smart thermostat only after field data from hundreds of homes shows at least 8% less heating run time and 10% less cooling run time, and an independent Indiana utility study measured about 13% heating gas savings. Homes that already used a careful schedule tend to save less.

What does a learning thermostat learn?

It watches when you turn the temperature up or down and turns repeated changes into a schedule. Most models also sense when the house is empty, through a motion sensor or your phone's location, and switch to energy-saving temperatures until someone comes home.

Is ecobee or Nest better?

Both are ENERGY STAR certified and both save energy in field studies. Nest leans on learning your schedule for you, while ecobee has you build Comfort Settings and suggests changes, and the ecobee Premium ships with a room sensor that also detects occupancy.

What should my Nest Eco Temperature be?

Google gives no single number. You can pick 40 to 70°F (4 to 21°C) for heating and 76 to 90°F (24 to 32°C) for cooling. Google suggests a lower heating Eco Temperature such as 56°F (13.5°C) for a well-insulated home that heats quickly and a higher one such as 62°F (16.5°C) for a drafty home that heats slowly.

What are ecobee Comfort Settings?

A Comfort Setting holds your temperature preferences for one kind of activity, such as Home, Away or Sleep. Your ecobee schedule decides when each one runs, and Smart Home & Away can switch to your away settings when you leave.

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