• Nest Learning Thermostat

  • Emerson Sensi Touch WiFi Thermostat

  • How We Tested

  • What You Should Know About Smart Thermostats

  • Other Smart Thermostats We Tested

  • More Articles You Might Enjoy

Our Favorite Smart Thermostats of 2021

  1. Best Overall

    Nest Learning Thermostat, 3rd Gen

    Pros

    • Works with Amazon Alexa and Google Assistant

    • Straightforward setup

    Cons

    • Does not support Apple HomeKit

    Skip to the full review below
  2. Best Value

    Emerson Sensi Touch WiFi Thermostat

    Pros

    • Works with Apple HomeKit, Alexa, and Google

    • Clear directions and easy setup

    • Sleek design

    Cons

    • Only basic smart features

    Skip to the full review below
Nest Learning Thermostat weather
Credit: Google

The Nest Learning Thermostat can keep track of the local weather.

Best Overall
Nest Learning Thermostat

Google's Nest Learning Thermostat is one of the biggest names in the space, partially because it was one of the first well-designed connected thermostats on the market. But now, nearly 10 years after its introduction, it's still the best smart thermostat for most people, thanks to its sleek, intuitive design and robust set of smart features.

If you've ever used an iPod, the Nest Thermostat will be familiar to you—in fact, it was designed by Tony Fadell, the designer of the original iPod hardware. Changing the temperature is as simple as rotating the thermostat's dial. You can use the app to set a traditional time-of-day schedule—far simpler than most non-smart thermostats—or let the Nest learn your daily habits and adjust the temperature automatically. This feature is great for those who don't want to put in any effort, but might be a bit too confusing for people who like to fine-tune their schedules, so you can turn it off if you wish.

Like many other smart thermostats, the Nest can save you energy by adjusting the temperature when you aren't home, as determined by your phone's location and the Nest's built-in motion sensors, and it's also compatible with the energy-saving plans and rebates offered by many utility companies. You can adjust it with your voice using Alexa or Google Home and even get reminders when it's time to change your HVAC filter. Nest offers sensors you can put in different rooms to adjust the temperature based on where you are at any given time—but their functionality is limited compared to competitors like Ecobee and Honeywell. Still, overall the Nest is so easy to use that we think it's the best overall.

Our only other gripe with the Nest—besides its heftier price tag (which, again, rebates can help with)—is its setup. The actual process is quite easy, and the Nest app will walk you through it step-by-step if you've never installed a thermostat before. But in an effort to stay simple and compatible with a wide variety of systems, the Nest uses a workaround to draw power in homes without a common wire (or C-wire). The thermostat will function normally in most cases, but can cause problems with certain HVAC systems. If your home doesn't have a C-wire, we recommend having an HVAC professional install one, or using a thermostat like the Ecobee SmartThermostat which uses a slightly more complex (but reliable) conversion kit to power itself.

Pros

  • Works with Amazon Alexa and Google Assistant

  • Straightforward setup

Cons

  • Does not support Apple HomeKit

Emerson Sensi Touch WiFi Thermostat
Credit: Sensi

The Emerson Sensi Touch WiFi Thermostat is the best smart thermostat you can buy for the money.

Best Value
Emerson Sensi Touch WiFi Thermostat

The Emerson Sensi Touch isn't a household name in the smart thermostat space (even among tech nerds like us), but it occupies a good niche: it's the most similar to a traditional thermostat in terms of ease of use. Setup is a piece of cake (as long as you have a C-wire, which is required), and the app walks you through everything you need to know. We were able to get it set up in a few minutes.

The thermostat's touch screen doesn't include too many buttons or fancy gestures, just an up and down arrow that lets you adjust the temperature. It doesn't have a motion sensor that wakes the screen up like other thermostats, but you can wake it up with a tap of your finger and tweak its sleep settings so it isn't lighting up the room at night. In our tests, the Sensi was very responsive, kicking in as soon as we adjusted the temperature, and we didn't have any problems maintaining connectivity, either over WiFi or via cellular data.

Within the app, you get some useful adjustments (like minimum and maximum temperatures), basic geofencing, and voice assistant support. The app can be a bit clunky to use at times—schedules, for example, required some unintuitive gestures to set up—but it's not frustrating to use by any means. If the Nest is intuitive for those familiar with modern technology like the iPod, the Sensi Touch is ideal for less tech-savvy folks who are used to the way traditional thermostats work—but want the ability to adjust it from afar.

Pros

  • Works with Apple HomeKit, Alexa, and Google

  • Clear directions and easy setup

  • Sleek design

Cons

  • Only basic smart features

Related content

How We Tested

The Tester

I’m Whitson Gordon, and I’m a freelance tech writer charged with testing smart home gadgets (among other things) here at Reviewed. I’ve been writing about tech professionally for over 10 years, from building computers to setting up smart homes. I served as the editor-in-chief of Lifehacker and How-To Geek before starting a freelance career writing guides for publications like the New York Times, PCMag, and Reviewed. This isn’t just my day job—it’s my calling. I’m obsessed with researching, testing, and finding the best possible gadget in a given category, so much so that my brother made it a central joke in his best man speech at my wedding.

I've been decking out my house with smart home tech for a few years, including a major revamp after buying a new house in 2019. With all-new electrical, HVAC, and a robust WiFi system, my house is primed for testing smart gadgets of all stripes—alongside my experience setting up smart home devices in my family's older, more challenging houses.

The previous round of testing was done by Julia MacDougall, Reviewed's Senior Scientist. She oversees the integrity of the labs, the methods and standards for test procedures in every category, and she also manages the huge backlog of test data stretching back over a decade.

The Tests

I'm not going to lie, testing multiple thermostats was nerve-wracking. With the threat of damaging an expensive HVAC system, it was really important that I didn't screw this up. My HVAC system is brand new thanks to a recent remodel, and includes a C-wire, so I experienced the easy version of these thermostats, but will note their compatibility with non-C-wire-equipped systems where applicable.

For each thermostat, we safely switched off the HVAC circuit breaker, installed the backplate, mounted the front of the thermostat, and configured it with the smartphone app on both an iPhone and Android phone.

Once we had successfully installed and programmed the thermostat, we let it run while we tested out the app, the thermostat's responsiveness, and voice assistant functionality. Using Amazon Echo smart speakers, a Google Home, and Siri, ,we put the thermostats through their paces.

We also tried out the extra features on each thermostat to make sure that they are actually useful. This primarily includes scheduling and geofencing, but can also include other features like room sensors.

What You Should Know About Smart Thermostats

breaker_box
Credit: Reviewed.com / Julia MacDougall

We became intimately familiar with the circuit breakers while testing smart thermostats.

If you're shopping for a smart thermostat, be sure to answer these questions before you buy anything:

  • What kind of heating and cooling system do you have? Line-level baseboard heating, window air conditioning units, and other systems might require specialized smart thermostats like the Mysa or Sensibo Sky, respectively, so make sure you know your system before you buy a thermostat designed for central air.

  • Will your current HVAC setup work with a smart thermostat? (You may want to consult a professional before continuing.)

  • Do you have a C-wire? Some thermostats will work without a C-wire, while others won't (or may require a separate conversion kit).

  • How much smart functionality do you want? Are geofencing or "learning" requirements, or do you just need basic remote access from your phone?

  • Do you use voice assistants, like Amazon Alexa, Siri, or Google Assistant? Are they compatible with the smart thermostat you're investigating?

  • Is the wall behind your current thermostat clean/neat enough to be exposed, if you replace your current model with a smaller thermostat? If not, are you willing to patch and/or paint that area?

  • Will you want to install the smart thermostat yourself, or will you want a contractor to do it? Keep in mind that contractors may favor smart thermostats not available for resale.

  • Finally—and perhaps most importantly—who will use this thermostat, and what is their level of tech-savviness? Just because you're comfortable using complex smart devices doesn't mean your spouse, roommate, or kids are, which may impact the thermostat you ultimately choose to buy.

We've addressed these concerns (and more) in our buying guide here, so be sure to read the entries thoroughly if you want to get the best smart thermostat for your family.


Other Smart Thermostats We Tested

Wyze Smart Thermostat

Wyze, the budget-focused smart home company that's been releasing great products left and right, now has a thermostat to compete with the likes of Nest. For a faction of the price of other smart thermostats, you get a quality product with a good amount of features, making it an incredible value. The app's step-by-step walkthrough makes setup easy, and it'll even help you create your first schedule and decide how much you favor comfort over energy savings—which affects how quick you want the temperature to be ready when you arrive home, how quickly it responds to temperature changes, and so on.

Like the Nest, it has a motion sensor that turns the screen on when you walk by, so you can see the current temperature of your room. The knob works very similarly to Nest's rotating wheel as well—you just turn it to adjust the temperature. If you're on Auto mode, you turn the wheel to select the Heat or Cool mode, then press inward to select that option and adjust the temperature. The button is a bit hard to press, though, with a bit more resistance than most people would expect, which can be a bit annoying. The knob also feels just a tad on the cheap side, but this isn't much of a complaint—the whole unit still feels much nicer than its price tag would suggest.

Finally, schedule creation works much like the Ecobee and similar models, where you choose presets for Home, Away, and Sleep—though Wyze doesn't allow you to create custom presets beyond those three. Then, you schedule when you want those presets to happen throughout the week. Wyze also offers a number of advanced options, like how often the fan cycles, the minimum run time, and even a temperature correction if you find the thermostat's measurements are off by one or two degrees. For such an affordable device, it has rather fine-grained controls, while still being pretty easy to use, and Wyze is promising even more advanced features in the future. At the time of launch, though, it doesn't support Google Home or Siri, which may be a deal breaker for some—so hopefully we see updates come soon to bring Wyze in line with its competition. For a budget-friendly smart thermostat that works with Google Assistant, we recommend our best value pick, the Emerson Sensi WiFi Touch Thermostat.

One final note: Wyze's smart thermostat is currently available for pre-order only and is expected to ship in February.

Pros

  • Affordable

  • Easy to install

  • Works with Amazon Alexa

Cons

  • Does not work with Google Assistant or Apple's Siri

Nest Thermostat

The Nest Thermostat is a more basic version of our No. 1 pick for smart thermostats, the Nest Learning Thermostat. It’s compatible with Google Assistant and Amazon Alexa, and it can be controlled remotely via the Google Home app. Unlike the Nest Learning Thermostat, it does not work with the Nest app and cannot learn your temperature preferences over time.

However, the new Nest Thermostat includes comparable features to the Nest Learning Thermostat like Eco Mode, Home/Away Assist, and scheduling features to help you save on energy costs, offering good value for the money. We found these settings easy to adjust within the Google Home app and enjoyed reviewing the energy reports, which offer helpful insights into when your unit is running and for how long.

The first HVAC system we tried to test the thermostat on didn’t have a C-wire, and we experienced some unpredictable behavior that Nest attributed to the lack of a C-wire. With the second system, we had a few hiccups during the setup process, but Nest customer service sent us a new thermostat right away, and once connected, the thermostat performed well at heating and cooling. Everything you need to get started is in the box, except the trim kit, which can be purchased separately.

Pros

  • Compatible with Amazon Alexa and Google Assistant

  • Google Home app is easy to use

  • Works well

Cons

  • No native integration with Apple HomeKit

  • Trim kit is additional cost

  • Doesn't work with Nest Temperature Sensors

Ecobee SmartThermostat with Voice Control

While the Nest aims to be easy and hassle-free, the Ecobee SmartThermostat is more about creating an incredibly feature-rich system. It uses a touch screen with a drag-to-adjust slider for changing the temperature, alongside a plethora of settings to tweak. In my experience, the touch slider is a bit under-sensitive, making it a tad annoying to adjust the temperature from the thermostat itself, but this is a small gripe—especially when you consider the Ecobee has Amazon Alexa microphones built-in, so you can adjust the temperature with your voice instead. Its included conversion kit is also great for systems that don't have a C-wire, though it does add some complexity to the setup process.

Ecobee's scheduling may seem confusing at first blush, but it's nice once you get the hang of it: instead of merely setting temperatures based on time of day, you set your desired "comfort settings" for different instances: like setting the AC to 76 when I'm home, 80 when I'm away, 74 when I'm sleeping, and so on. Then you schedule those comfort settings for certain times of day, or assign them to Ecobee's external room sensors. For example: we have the Ecobee switch to the "sleep" temperatures when our toddlers are napping in the afternoon, and it uses the sensors in their room to determine the temperature rather than the thermostat's sensor in the living room.

Options like this make the Ecobee extremely powerful, alongside its geofencing features, community rebates, and other eco-monitoring options. Personally, I'd rather use an Echo or Echo Dot than the microphones in the thermostat—Amazon cripples a few too many features in third-party Alexa devices—but even if those weren't included, this is the most powerful thermostat for tinkerers who want everything just so.

Pros

  • Amazon Alexa built-in

  • Can be installed without a C-wire

  • Useful features

Cons

  • Touch controls under-sentitive

Ecobee3 Lite Smart Thermostat

Ecobee's lower-cost "Lite" thermostat is very similar to its more expensive sibling: it has the same touch screen interface, the same app, and most of the same features. It's a bit slimmer, so it looks better against your wall, but doesn't come with the built-in Amazon Alexa microphones, nor does it come bundled with a room sensor. It does, however, still come with the power extender to accommodate those without a C-wire.

Whether it's worth the discount depends on your usage. Since it doesn't come with a room sensor—which is part of what makes Ecobee's thermostats great—you'll probably have to buy a 2-pack separately, which will bring you up to the same cost as the Ecobee SmartThermostat (though you'll have two sensors instead of one). If you don't plan on using the Amazon Alexa mics and prefer the slimmer profile, the Ecobee3 Lite is a great alternative.

Pros

  • Works with Apple HomeKit, Alexa, and Google

  • Simple setup process

Cons

  • No built-in Amazon Alexa

  • No extra temperature sensor

iDevices Thermostat

The iDevices thermostat is probably the closest a smart thermostat can get to looking and feeling like an analog thermostat. Instead of a touch screen, the iDevices Thermostat has four physical buttons for temperature changes in addition to the app. The temperature display is small and the rectangular white body is slim, making for an unobtrusive profile. It's also one of the least expensive thermostats we tested, coming in under $100.

Setup was easy on our iOS device, though the Android process was slightly more involved. While the app itself is pretty basic (and does not offer geofencing), we found the “Override” setting and the scheduling module to be set up nicely. The “Override” setting allowed us to manually set the temperature and then set the exact time duration we wanted for that manual override before it reverted to the preset schedule. When creating a schedule, it’s easy to precisely dial in any temperature at any time of day. The iDevices thermostat responded well to commands from both Amazon Alexa and from Siri, as well as remotely with mobile data, and we didn't experience any connectivity issues.

Pros

  • Works with Apple HomeKit, Alexa, and Google

Cons

  • Took longer to set up on Android

Honeywell Lyric Round Thermostat

Honeywell's Lyric thermostat sports a round shape similar to the Nest, though it has two touch buttons on its face as well as a rotating dial. Setup was straightforward, and the Honeywell Lyric app is initially easy to understand and to use. We liked the dial-turning method of changing the temperature, and how the motion detector on the thermostat sensed when we were nearby and lit up the display.

We weren't as keen on the scheduling part of the app, which defaults to the geofencing feature. For setting more specific weekly temperature schedules, we had to dig further into the app, and that's when it got a bit clunky and hard to operate. Overall it worked fine—changing the temperature was straightforward, and notifications for high/low temperature and humidity offer nice peace of mind. But overall it's not as well-designed as the other thermostats we tested.

Pros

  • Works with Apple HomeKit, Alexa, and Google

  • App is mostly easy to understand and to use

Cons

  • Requires a 2.4 GHz internet connection

  • Scheduling can be difficult to do

Honeywell Lyric T5 Thermostat

The Honeywell Lyric T5 thermostat is the more basic cousin of the Honeywell Lyric Round thermostat. The full touchscreen on the T5 makes it easy to change the temperature and check the settings. The Lyric T5 lacks the motion sensor of the Lyric Round thermostat, but other than that, the experience with changing the temperature, geofencing, scheduling, and vocal assistant integration is identical.

The Lyric T5 looks a bit more industrial than the Lyric Round, with a square black profile with a slightly smaller footprint than those of standard thermostats. A new version of this thermostat is now available, but we haven't tested it. The new model, the Honeywell Home T5+, is available on Amazon.

Pros

  • Works with Apple HomeKit, Alexa, and Google

  • Easy to use

Cons

  • Connectivity issues

  • Requires a 2.4 GHz connection

Honeywell T9 WiFi Smart Thermostat

Honeywell has been in the heating and cooling business for over 100 years, but their smart thermostats haven't quite gained the recognition that other companies’ have. The Honeywell T9 deserves a bit more love than it gets, thanks to its balance between features and ease of use, though it does have a few small drawbacks that keep it from being best in class.

While other thermostat apps help you check your configuration and adjust the instructions accordingly, the Honeywell app doesn't walk you through the process at all, leaving you to fend for yourself with the paper instructions. Then, connecting it to the app is a slight hassle involving Airplane Mode, but once you're in, the app is great—it'll help you set up your schedules and geofencing right off the bat, and even prompt you to look for rebates. It's easy to use, and room sensors ensure you can keep a consistent temperature in whatever room you're currently using.

Unfortunately, there is a bit of a delay when you give the thermostat a command. In my testing, adjusting the temperature on my phone or through a voice assistant seemed to register on the thermostat's screen instantly—but the actual A/C wouldn't click on for a minute or so. This didn't happen with the Nest, Sensi, or Ecobee thermostats, and it's likely to drive some users a little batty. It's a good thermostat, it just doesn't quite overtake the others we tested.

Pros

  • Works with Apple HomeKit, Alexa, and Google

  • App works with Android and iOS devices

Cons

  • Connectivity issues during setup

  • Old school setup process

Glas Smart Thermostat by Johnson Controls

Arguably the snazziest looking thermostat we tested, the Glas Smart Thermostat is undeniably futuristic, with its transparent OLED touch screen and built-in voice assistant. Unfortunately, that voice assistant is Microsoft's Cortana, which means you're either buying in fully to Microsoft's system (unlikely) or settling for something other than what your other smart speakers use. It's easy to ignore Cortana and just use your existing Amazon Echos or Google Homes, but it's a bummer that you're paying for functionality you might not even use.

Still, Glas is pretty neat, with a well-designed app that makes adjusting temperatures and setting schedules fairly easy. Unfortunately, that's where most of the big benefits end—setup was difficult thanks to some frustrating wire terminals, and there's no geofencing feature like the other thermostats we tested had. It wasn't very responsive to temperature changes from the app, either, often taking a minute or two to shut itself off when asked to. Given its steep price over its competitors, it's hard to fully recommend the Glas, unless you're willing to pay for aesthetics alone (and sacrifice features in the process).

Pros

  • Works with Amazon Alexa and Google Assistant

  • Well-designed app

Cons

  • Difficult setup

  • No geofencing features

Lux Kono Smart Thermostat

The Lux Kono is a futuristic-looking thermostat, and it offers removable faceplates in multiple colors to match your decor. But in terms of usability, it was a distant finisher among the thermostats we tested. Setup was needlessly complicated compared to its competitors, with no in-app instructions until after you get WiFi set up—which is difficult using only the thermostat's tiny LED screen and knob (as opposed to the high-res screen other thermostats provide).

The app was no better, with an absolute mess of an interface, overloaded with information and difficult to use, whether you're adjusting the current temperature or creating a schedule (which only allows you 2 or 4 "changes" per day—no more, no less—and splits heating and cooling schedules into two separate sections, even if you use Auto mode). The app looks like it used to be better, but apparently went through a redesign that was undoubtedly a step backward. Like the Honeywell and Glas thermostats, it often took minutes to respond to commands from the app (though Alexa and Google Assistant were strangely faster). Geofencing worked fine in our tests, but overall, there's little reason to use the Lux Kono over other, better-designed thermostats.

Pros

  • Works with Amazon Alexa and Google Assistant

Cons

  • Complicated setup

  • App is difficult to navigate

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Meet the testers

Julia MacDougall

Julia MacDougall

Senior Scientist

@reviewed

Julia is the Senior Scientist at Reviewed, which means that she oversees (and continually updates) the testing of products in Reviewed's core categories such as televisions, washing machines, refrigerators, and more. She also determines the testing methods and standards for Reviewed's "The Best Right Now" articles.

See all of Julia MacDougall's reviews
Whitson Gordon

Whitson Gordon

Freelance Writer

Whitson Gordon is a valued contributor to the Reviewed.com family of sites.

See all of Whitson Gordon's reviews

Checking our work.

We use standardized and scientific testing methods to scrutinize every product and provide you with objectively accurate results. If you’ve found different results in your own research, email us and we’ll compare notes. If it looks substantial, we’ll gladly re-test a product to try and reproduce these results. After all, peer reviews are a critical part of any scientific process.

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