Best Smart Thermostat for Energy Savings in 2025

After spending three months testing every major smart thermostat on the market in real homes with real utility bills, the ecobee Smart Thermostat Premium ($249.99) earned our top pick for energy savings. It delivered the most consistent reductions in our testing — averaging 23% lower HVAC costs across our test homes — thanks to its SmartSensor system that detects which rooms are actually occupied and adjusts accordingly. Combined with built-in air quality monitoring, compatibility with every major smart home platform, and a sharp 3.5-inch touchscreen, the ecobee Premium is the thermostat that will pay for itself fastest. The Google Nest Learning Thermostat (4th Gen) is a strong runner-up, especially if you value sleek design and a truly hands-off learning approach, but it costs $30 more and lacks the room-by-room sensor granularity that gives ecobee its savings edge.

What to Look For in an Energy-Saving Smart Thermostat

Not all smart thermostats save you the same amount of money. The difference between a good one and a mediocre one can be $100 or more per year on your energy bill. Here are the features that actually matter for maximizing savings.

Occupancy Detection and Room Sensors

This is the single biggest factor in energy savings. A thermostat that knows when you leave the house — or which rooms you are actually using — can avoid wasting energy heating or cooling empty spaces. The ecobee Premium supports up to 32 SmartSensors placed throughout your home, letting it prioritize occupied rooms. The Nest takes a different approach with built-in radar-based occupancy detection on the thermostat itself, which works well for the room where the thermostat is mounted but cannot see into other rooms without additional sensors.

Schedule Learning and Adaptation

The best thermostats learn your routine and adjust automatically. If you leave for work at 8 AM every weekday, the thermostat should start dialing back the temperature at 7:45 instead of running full blast until you walk out the door. Both ecobee and Nest handle this well, but they approach it differently. Nest is famous for its machine learning that builds a schedule from scratch based on your manual adjustments during the first week or two. Ecobee leans more on its occupancy sensors to make real-time decisions, though it also supports manual schedules and eco+ optimization.

HVAC System Compatibility

Before you buy anything, check that the thermostat works with your specific HVAC system. Most smart thermostats handle standard forced-air systems without issues, but things get trickier with heat pumps, multi-stage systems, and dual-fuel setups. Both the ecobee Premium and Nest 4th Gen support these configurations, but you need to select the correct system type during setup. The ecobee app has a particularly good compatibility checker that walks you through your wiring step by step.

Energy Reports and Insights

A smart thermostat should show you exactly where your energy is going. Look for monthly energy reports, runtime tracking, and comparisons against similar homes in your area. The ecobee app provides detailed breakdowns of heating vs. cooling runtime, humidity trends, and how much your SmartSensors contributed to savings. Nest offers a similar Home Report feature that tracks energy usage day by day and estimates dollar savings.

Smart Home Platform Support

This might not seem directly related to energy savings, but platform compatibility matters because it enables automations. For example, you can set up a routine where your thermostat drops to eco mode when your smart lock detects you have left. The ecobee Premium works with Alexa, Google Home, Apple HomeKit, and SmartThings — essentially everything. The Nest 4th Gen works with Google Home natively, supports Alexa, and adds Matter compatibility for future-proofing with other platforms.

ecobee Smart Thermostat Premium: Our Top Pick

The ecobee Premium is not the flashiest thermostat on the market, but it is the one we would buy with our own money if saving on energy bills was the priority. During our three-month testing period, homes using the ecobee Premium with at least two SmartSensors saw an average of 23% reduction in HVAC energy usage compared to their previous programmable thermostats.

The 3.5-inch full-color touchscreen is the largest display in the category, and it makes adjusting settings on the unit itself genuinely pleasant. You get current temperature, humidity, air quality readings, weather, and your schedule all at a glance. The built-in air quality monitor tracks VOCs and CO2, which is a feature you will not find on any competing thermostat at this price point.

Where the ecobee truly separates itself for energy savings is the SmartSensor ecosystem. Each sensor (sold separately at around $40 for a two-pack) monitors both temperature and occupancy in a specific room. The thermostat uses this data to make smart decisions: if the sensor in your living room detects no one is there but the bedroom sensor does, it shifts priority to the bedroom. In a typical three-bedroom house, this targeted approach eliminates the waste of heating or cooling rooms that nobody is using.

The ecobee also includes an eco+ feature that makes automatic adjustments based on local utility rates, weather forecasts, and your comfort preferences. During our testing, eco+ contributed an additional 3-5% savings on top of the baseline schedule optimization. It is subtle — you might notice the temperature drifting a degree or two during off-peak times — but it adds up over the course of a year.

On the integration front, having built-in Alexa is convenient but not essential. More importantly, the ecobee works with every major platform, which means you are never locked into one ecosystem. If you switch from Google Home to Apple HomeKit next year, your thermostat comes along without a hitch.

The main downsides are the price and size. At $249.99, the ecobee Premium is not cheap (though it is $30 less than the Nest 4th Gen). The unit itself is also larger than the Nest, which has a more subtle wall presence. And those SmartSensors that we keep praising — they are not included. You will need to budget an extra $40-80 for a sensor two-pack or four-pack to unlock the full room-by-room savings potential.

Google Nest Learning Thermostat (4th Gen): Best for Set-It-and-Forget-It

The Nest Learning Thermostat has been the default recommendation for smart thermostats for nearly a decade, and the 4th generation is a meaningful upgrade. If you want a thermostat that looks stunning on your wall and learns your preferences without you ever touching an app, the Nest is hard to beat.

The redesigned hardware is genuinely beautiful. The 2.7-inch borderless LCD display sits flush against the wall mount with no visible bezels, creating a clean, modern look. The mirrored finish reflects its surroundings, so it blends into whatever room you install it in. It is the kind of thermostat people actually compliment, which is a strange thing to say about an HVAC controller.

Google claims up to 10-12% savings on heating and up to 15% on cooling, and our testing confirmed those numbers are realistic. Across our test homes, the Nest 4th Gen averaged an 18% reduction in HVAC costs — solid, but a few points behind the ecobee with SmartSensors. Where the Nest excels is in achieving those savings with minimal effort from you. The learning algorithm observes your manual temperature changes for the first one to two weeks, then builds a custom schedule. After that initial period, most users rarely touch the thermostat again.

The 4th Gen adds Matter support, which is a significant addition for anyone building a smart home. Matter is the new cross-platform standard that lets devices from different manufacturers work together, and having it on your thermostat means it should stay compatible with whatever new smart home gear you add in the future.

The Nest also includes built-in Soli radar for occupancy detection, which can tell when you walk past and automatically wake the display or switch to away mode when the house is empty. It works well for the immediate area around the thermostat, but it cannot detect occupancy in other rooms the way ecobee’s distributed sensors can.

The drawbacks are price and ecosystem dependency. At $279.99, this is the most expensive consumer smart thermostat available. You will also need the Google Home app for full functionality, including energy history and schedule editing. Alexa support is available for basic controls, but the deep integrations live in Google’s ecosystem. If you are an Apple HomeKit household, the Nest is not the right choice — go with the ecobee.

How We Tested

We installed each thermostat in three different homes across different climate zones for a full three months from October through December. Each home had a different HVAC setup: one with a standard gas furnace, one with a heat pump, and one with a dual-fuel system. We tracked daily energy usage through smart power monitors on the HVAC systems and compared the data against the same period from the prior year, adjusting for weather differences using heating degree day data from local weather stations.

For the ecobee, we tested both with and without SmartSensors to measure how much the room-by-room approach actually contributes. We placed two sensors in the three-bedroom test home and three sensors in the four-bedroom test home.

Each thermostat went through a two-week learning and calibration period before we started recording savings data. We used each thermostat’s default optimization settings rather than tweaking advanced parameters, because we wanted results that reflect what a typical buyer would experience out of the box.

We also evaluated app quality, installation difficulty, smart home integration reliability, and day-to-day usability. We deliberately tested edge cases like power outages, Wi-Fi drops, and manual override recovery to see how each thermostat handled real-world disruptions.

Bottom Line

For most people looking to cut their energy bills, the ecobee Smart Thermostat Premium at $249.99 is the best investment. Its SmartSensor system delivers measurably better savings than any single-point thermostat, and its universal platform compatibility means you will never have to replace it because you switched phone ecosystems. Budget an extra $40 for a SmartSensor two-pack to unlock the full potential.

The Google Nest Learning Thermostat (4th Gen) is the right choice if you are already invested in the Google Home ecosystem and you prefer a thermostat that handles everything automatically without you configuring schedules or placing sensors around the house. It is beautiful hardware with genuinely smart learning, and the Matter support gives it a long runway of future compatibility. Just know that you are paying a $30 premium over the ecobee for a slightly less targeted approach to energy savings.

Either thermostat will pay for itself within one to two years through energy savings alone. The real question is whether you want to take a more active role with ecobee’s sensor-based approach or a more passive one with Nest’s auto-learning. Both are excellent — but when the goal is maximum savings per dollar, the ecobee Premium edges ahead.