Spring hasn't arrived in my high desert climate in central Oregon, and this lightly snowing March morning is chilly, especially in my office far away from both the thermostat and the fireplace. But I have a quick fix for this. "Hey Google, show me my thermostat," I say.  "Got it," my Nest display responds. It brings up all my Nest thermostat settings, including a large dial on the touchscreen. At a touch, I move the temperature up a couple of degrees to keep the heat lasting longer than usual. A voice command would have worked too, but I like the tactile control when my display is handy.  Finally, I take my wireless satellite sensor — it looks like a large, white pebble you'd find in a river — and perch it on a nearby shelf. My thermostat uses the sensor's readings in combination with the primary thermostat in the hall, picking up on temperatures in the spots where people actually spend time. Like me, currently shivering in front of my computer. These are only a few of the tricks in a smart thermostat's high-tech bag, and they're especially timely. CNET's energy survey from 2024 found that 78% of US adults are concerned about rising home energy costs, with almost a third of respondents relying on borrowing and payment plans to afford their energy bills. Heating bills in winter 2024 to 25 that rose by as much as double-digit rates didn't help matters. The Trump administration's tariffs are complicating matters, from broad supply chain effects to, as CNET editor Ajay Kumar relates, the targeting of Canadian electricity. That means individual consumers in the Midwest and New England could endure even more energy woes this year. "Keeping the thermostat on a hold or trying to remember when to turn it on/off or up/down only drains energy and your wallet," Adina Roth, product lead for the Nest Learning Thermostat (like the model I'm currently using), tells me. "The most amazing part of a smart thermostat is the ability to keep your home at a comfortable temperature and balance energy usage." Changes like these help me shave $20 or more off my monthly heating costs in winter, while alerting me if my energy savings suddenly dip. While it's a new model, a couple more months of this and it will have paid for itself with minimal trouble. That's a far cry from eyeballing old dials and levers on thermostats from decades past. And installation? After wiring in my share of outdoor cameras and doorbells, this thermostat presented little challenge, especially after a quick wiring pic with my phone. Renters may need to ask permission to install one, but everyone can benefit from the savings — and without AI privacy issues to boot. I'll get more into all that farther along in this article. The end result: A mild-mannered smart device from brands like Ecobee, Google Nest, Honeywell Home and Amazon has an incredible ability to address energy issues and save us all money — without overwhelming home renovation. But that's not all this sub-$300 device can do. In this article: How far home temperature control has evolved We're entering a new era of efficient home heating and cooling, influenced by algorithms and wireless sensors to create dynamic temperature controls addressing numerous headaches. The cutting edge is changing quickly, even if most folks are slow to adopt: Our research found that only 20% of US adults have used a smart thermostat to address their energy woes. One reason for slow acceptance is how new all this tech (and the buildings that can use it) is: AI-powered smart thermostats are a very recent arrival in the history of humanity's temperature control journey. Those efforts span 50,000-year mammoth bone hearths in Ukraine, the beautiful bâdgir, or windcatcher towers, developed by ancient Persians, even a servant-powered mechanical fan with 10-foot fan wheels to cool down the palace halls of the Han dynasty. But it was the commercialization of natural gas in the 1800s that birthed modern heating, while refrigeration compression arrived in the early 1900s to do the same with cool air. Thermostats swiftly became the go-to method to measure and regulate temperature control.  Those old mechanical thermostats didn't offer much outside of basic up-or-down control until the smart home upgrades of the 2010s. Now, if you have whole house climate control, one thermostat upgrade is all you need to tap into the latest home tech evolution. A dazzling, timely home centerpiece Smart thermostats sport a marked stylish streak. Curved designs and vivid touchscreens make them look nigh-otherworldly on a humble hallway wall. Those touchscreens can be customized, but my Nest Thermostat 4 is permanently set to light up with the outdoor weather when approached. Its screen shifts with mesmerizing animations like falling snow, drifting fog or evening sunlight based on what's happening outside.  Behind the pretty face, capabilities previously unknown to thermostats are at work. While it may not be AI in the way most of us think of it these days, smart thermostats have used learning algorithms for years to study house habits. Fortunately, the basic operation will still seem familiar to anyone who's set temperatures. CNETWith a touch or twist of the dial, you can choose temperature triggers immediately or schedule changes from anywhere via the app. Once you've set a weekly schedule, you can save it and then switch between set schedules as the seasons or plans shift. Some thermostats, like Nest's "Indefinite Eco" setting (which sets everything to energy-saving levels) even offer a dedicated mode for when no one will be home for a while. Ecobee has both a "Vacation" mode and an ability for the thermostat to adopt settings from other local Ecobee users. Laura Finson, the director of product management for Brinks Home, reminds me about another useful mode most thermostats offer: "By using local weather forecasts, my thermostat can automatically adjust when extremely hot or cold weather is predicted," she said. Finson, whose company specializes in smart home and home security, said, "Once the outdoor temperature returns to a normal range, the thermostat resets the target temperature."  My Nest model can do this through the Safety Temperature mode and I'm definitely turning that on this August, our hottest time of year as well as the height of wildfire season (which means windows usually stay closed). Once you have schedules set up and learn how to use the thermostat wherever you are, you'll start getting energy use reports and notifications on how much you've saved, possibly even alerts about changing home filters. Some even encourage you to compete with the community on how energy-efficient you can be, such as via Nest "Leafs."  My Nest energy report wasn't very happy about January, but at least I had data telling me to make some changes. Tyler Lacoma/CNETAs you can see, my Nest reports showed a large rise in January energy use as temperatures plunged, a pricey change considering my utility company instituted a massive price increase. By February, smarter home practices and help from my thermostat improved my home's energy consumption significantly, ending winter in a much better place financially. Without the thermostat's analysis, shifting strategies month by month like this is much harder.   With changes and a little help from my thermostat, I managed to start correcting January's energy-hungry bills. Tyler Lacoma/CNETBut what about the initial cost? Most AI-powered thermostats cost between $200 and $300. Some, like Amazon's model, offer budget options under $100. When I contacted a spokesperson from the nonprofit Energy Trust of Oregon about discounts, he explained, "Be sure to check with your local energy provider for potential discounts. Some utilities offer rebates or discounts on smart thermostats to their customers." How presence sensing and satellite sensors changed my home heating How is a thermostat "smart"? In addition to app control, two features make smart thermostats game-changing: presence sensing with learning algorithms and satellite sensors. Both of these deeply practical features require only minimal effort to use. Presence sensing uses basic motion sensors to detect when someone is moving near the thermostat or if there's general household activity. Those sensors also help shut the thermostat screen off when not in use, which saves money and helps most of these devices earn Energy Star ratings. When enabled, AI thermostats use this data to automatically modify home heating and cooling, shifting into higher gear only when the house is active. That includes when people are getting up to grab morning coffee or coming home in the evening after wrapping up a shift. No tedious tinkering with hourly schedules is needed. The second feature, bundled free with the latest smart thermostats or available separately, is the powerful but tiny satellite sensor, a wireless dongle that can sense the temperature wherever it's placed in the home. Set this sensor (usually around $40 as an add-on) in a spot where people congregate, and it will send more accurate readings than thermostats stuck in drafty entryways or stuffy halls, customizing the comfort appropriately. Each sensor has its own tricks. Ecobee's version can sense what room people are in, so if you have multiple sensors the thermostat bases its readings on the room where the most activity is, which can help save money. Nest's sensors (as well as Nest Hubs) can combine readings with the main thermostat to average out temperature needs for the house — or focus only on one sensor as needed. My Amazon Echo Dot 5, meanwhile, can serve as a smart speaker, alarm clock and satellite sensor all in one. CNETI've found lots of ways to use both learning features and satellite sensors in my own home: Using a presence sensor keeps me from wasting money on a space heater in the mornings while learning functions quickly pick up that no one (except my cat) likes to get up early on the weekends. Eventually, my learning thermostats recognized that no one is at home on Thursdays when I like to work from communal spaces, and dipped temp levels accordingly.  Likewise, if I'm having a movie night, I can move a satellite sensor to a nearby table by the TV so the house doesn't overheat, or when snuggling in bed, I can take it to the bedroom along with morning tea. Early breakfast planned? I'll make sure it's on the kitchen counter at night so the house heats up with that area in mind. There are more serious use cases, too. When temperatures dropped below 10 degrees Fahrenheit last winter, I occasionally put satellite sensors close to my home's sink pipes so the thermostat could more closely monitor them and make sure the degrees didn't drop so much they threatened to freeze pipes.  "Sensors can also be helpful if you have someone with extra needs in the home," Adina Roth, product lead for the Nest Learning Thermostat, tells me. "When my baby niece came to stay, we made sure to prioritize temperatures for her bedroom for peace of mind that the air would stay right on target." Now my home stays comfier, saves more money and adapts to whatever I'm doing. These advanced learning features also save me from all the hassling, tiny thermostat adjustments based on shifting circumstances. I keep thinking that this is finally what home thermostats were supposed to be — it just took technology a century to catch up. Small screens, large savings — no matter your home Simple energy guidelines can get anyone started with a smart thermostat: In the cold months, set it to at most 68 degrees Fahrenheit for heating when at home, and at least several degrees lower when asleep or away. In the hot months, set cooling to trigger at 75 to 78 degrees when at home, and several degrees higher when you're asleep or away. As my colleague Jon Reed, senior CNET reporter and expert in both home energy and AI, tells me, "I see the most benefit when I'm not home. When I'm home, I don't always set it at the optimal energy-saving temperature. But if I'm out of the house, it automatically adjusts by 8 degrees or more, and that shows up in the form of lower energy bills." When in doubt, adjust until you enter the thermostat's eco mode. You can switch to eco modes via app, and in Nest's case you simply turn the thermostat manually until you see its little green leaf icon appear next to the temperature dial. Thermostat learning features help automatically dial in exactly when to make these changes based on household activity. Nest's Roth described to me how fast these features work: "In my house, I love the ability to turn down the heat or A/C when no one is home ... Pairing that with one of our more recent features, Adaptive Eco, it ensures you can still get back to your ideal temperature within an hour of arriving home." The resulting energy savings often prove to be substantial.  CNETThe above guidelines save an average home money, and Energy Star research estimates that using a smart thermostat can save a further 8% (around $50) annually on heating and cooling bills. Google's own study of Nest Learning Thermostat users showed that they saved an average of 12% on heating and 15% on cooling. That works out to average savings of $131 to $145 annually, while Ecobee told me its thermostats can save up to 26%, or around $250 at the high end. Either way, give it two years and most smart thermostats pay for themselves. While high-tech thermostats are energy-saving standouts, they work even better when combined with the latest home heating and cooling tech. Smart thermostats partner well with heat pumps, for example, the latest whole home or window units that ditch outdated fuels to use advanced refrigerants (and in some cases geothermal heat) to move cooled or warmed air into a home, like an air conditioner that can work in reverse.  Modern versions of heat pumps work even in my dry climate, where winter weather drops far below freezing, and studies have found up to 95% of homes could see energy bills drop by adopting a heat pump. Energy Star has another option for saving money if you don't mind looping in your utility company. "For homes with smart thermostats connected to an electric heating and cooling system, many utilities also offer discounts or credits during what are called energy 'rush hours,'" the spokesperson explains. "Those can often be in the evenings when more people are home and especially during heat waves or cold snaps."  Programs like Ecobee's Community Energy Savings or Renew Home can take care of the details, too. Combine these two types of revolutionary temperature technology (plus extras like solar panels or multizone systems), and they represent savings that could transform how an entire country's energy grid works — no matter what kind of home you own or rent. Warming up to renters With the number of renters in the United States now around 45 million — and millions more around the globe — there's a large demographic that may not be sure whether they would benefit from a smart thermostat, or if they can legally get one.  First, the good news: Smart thermostats provide significant benefits to renters, particularly with their automatic learning capabilities. Since many renters must cover their own electricity costs, the savings benefits remain just as significant and even more so if there are lots of people coming and going from a home. The big question is if renters can take initiative and install their own smart thermostats. Some wiring and replacements are required (more on that below), which means renters usually need to get permission from the landlord or check their lease to see what kind of devices they're allowed to add. And when renters shift to a new place, they'll likely leave the thermostat behind and cede control to the owner.  CNETThis brings me to how landlords use smart thermostats. Property firms and landlords generally want to save as much money on heating and cooling as possible, and smart thermostats give them a remote way to do that... which can invite abuse of the system. That's one of the biggest reasons why states have laws about maintaining heat in rentals: In California, habitable rental rooms need to have a minimum option of 70 degrees Fahrenheit, so landlord