Usually yes, but less than the box suggests. ENERGY STAR says that, on average, certified smart thermostats save “approximately 8% of heating and cooling bills,” and that results vary with climate, comfort preferences, occupancy and equipment. That saving comes from running the heating and cooling less while you sleep or are out. A smart thermostat makes those setbacks easier to keep; it doesn’t make the furnace or air conditioner more efficient.
Heating and cooling are the right place to look. ENERGY STAR says “nearly half of the energy used in your home goes to heating and cooling.”
Who saves more, and who saves less
ENERGY STAR’s smart thermostat FAQ is specific about the households at each end:
- More: homes that “experience extreme changes in temperature over the course of a year.” ENERGY STAR’s heating and cooling page adds homes with high heating and cooling bills and homes that are unoccupied for much of the day.
- Less: temperate climates, where savings “are generally slightly lower,” and homes that are always occupied, which “will see less savings” regardless of climate.
- A different answer: homes with variable-capacity heat pumps or air conditioners “will generally perform best with a manufacturer-recommended thermostat regardless of whether it is ENERGY STAR certified.”
If someone is home all day and the old thermostat already follows a sensible schedule, expect little change. If the house sits at one temperature while everyone is out, there is more to gain.
Why maker claims are higher than ENERGY STAR’s
Savings figures depend on what they are compared with. The table sets the published numbers side by side; each is the source’s own claim.
| Source | Claim | Compared with |
|---|---|---|
| ENERGY STAR | About 8% of heating and cooling bills, on average | Field data from certified products, per EPA’s test method |
| 12% on heating bills and 15% on cooling, on average | Utility bills before and after installing a Nest thermostat | |
| Up to 31% on heating and cooling bills | An assumed constant 72°F baseline | |
| ecobee | Up to 26% on heating and cooling costs | A constant 72°F hold |
The 72°F figures compare a smart thermostat with a home held at one temperature all day and night. Google says plainly that its up-to-31% number “is an industry baseline for comparative purposes but may not represent the typical customer experience.” ENERGY STAR’s number comes from real installations: EPA’s method has providers analyze “a year of data from each sample home” with EPA software and compares runtime with “the installed base of all other thermostats in the United States.”
ENERGY STAR also tells utilities not to count on its national figure for any one area, given “the significant variation in heating and cooling degree days, HVAC equipment, and home characteristics from one region to the next.” The same caution applies to a single house.
The settings that do the saving
ENERGY STAR’s heating and cooling guide offers this schedule as “a starting point for setting energy-saving temperatures,” to adjust for your household:
| Period | ENERGY STAR time | Heating setpoint | Cooling setpoint |
|---|---|---|---|
| Wake | 6:00 a.m. | < 70°F | > 78°F |
| Day (away) | 8:00 a.m. | Setback at least 8°F | Setup at least 7°F |
| Evening | 6:00 p.m. | < 70°F | > 78°F |
| Sleep | 10:00 p.m. | Setback at least 8°F | Setup at least 4°F |
The same guide gives four habits that matter as much as the numbers:
- Hold long setbacks. Keep energy-saving temperatures “for long periods of time, such as during the day when no one is home and at bedtime.”
- Use hold for trips. Set a constant energy-saving temperature when away for a weekend or vacation.
- Don’t keep overriding. “Every time you do, you use more energy and may end up paying more on your energy bill.”
- Place the thermostat well. Keep it away from registers, appliances, lighting, doorways, fireplaces, windows, direct sun and drafts; interior walls are best.
Smart features automate parts of this. ENERGY STAR describes geofencing as letting a thermostat “detect when you’ve left for the day to ‘set back’ your HVAC system,” and notes that many smart thermostats learn preferences and build a schedule on their own. Google describes Nest thermostats setting an Eco temperature when sensors and your phone’s location show you’ve left, if you opt in. Whether an away mode or a timer suits your household better is covered in the geofencing versus timer comparison .
Heat pumps: deep setbacks can backfire
Heat pumps need more care. ENERGY STAR’s guide says a heat-pump home “may require a special programmable thermostat to maximize your energy savings year-round.” The reason is backup heat. Energy Trust of Oregon explains that auxiliary heat “relies on electric resistance heat strips to heat the home, using substantially more energy than the heat pump technology,” and that a lockout setting in the thermostat keeps those strips off above a chosen outdoor temperature.
ENERGY STAR’s smart thermostat criteria include a measure of “average resistance heat utilization for heat pump installations.” If you have a heat pump, get the lockout set correctly before chasing bigger setbacks; the heat-pump thermostat comparison explains how different models handle it.
Utility programs change cost, not always energy
ENERGY STAR requires certified smart thermostats to be able to work with utility demand response programs, though “there are no specific required responses.” Makers build features around them: Google’s Rush Hour Rewards lets you “earn rewards from your energy company by using less energy when others are using more,” and ecobee’s Time of Use feature “preheats or precools your home when energy is less expensive.” Shifting heating or cooling to a cheaper hour can lower the bill without lowering total kWh, so decide which result you’re after. Many ENERGY STAR partners also sponsor rebates on certified models.
How to check your own savings
Compare like with like. The EIA explains that degree days measure “how cold or warm a location is,” using a 65°F base, and that “some electric and natural gas utilities publish degree-day data on their websites and some include it on customer utility bills.” Compare a winter month after the change with a winter month before it that had similar heating degree days, rather than this January with a milder one.
Keep a note of schedule changes, overrides and who was home. The weekly trend guide covers like-for-like comparisons in more detail. If you’re choosing hardware, the best smart thermostats list compares current models on wiring and system support.
Sources
- ENERGY STAR: smart thermostat FAQ
- ENERGY STAR: smart thermostats
- ENERGY STAR: heating and cooling at home
- ENERGY STAR: Guide to Energy-Efficient Heating and Cooling (PDF)
- Google Store: Nest thermostat energy savings
- ecobee: compare smart thermostats
- ecobee: Smart Thermostat Essential (eco+ features)
- Energy Trust of Oregon: auxiliary heat lockout settings
- U.S. Energy Information Administration: degree days
Sources were checked on October 9, 2026. Savings figures are the cited source’s own; this guide does not estimate savings for any household.