Best Smart Thermostats for a Smarter Home

Our latest evaluation of the best smart thermostats turned into a battle royale between the Google Nest Learning Thermostat* and the Ecobee Smart Thermostat Premium. They're virtually tied, but we have to acknowledge the impact of the Google Nest Learning Thermostat's backup battery, urgent system alerts, and early warnings.

It squeaked into first place as a result, but we highly recommend checking out the Ecobee before making a final decision—we're definitely geeking out over its built-in smoke alarm listener, air quality monitor, and voice assistants.

And if neither one floats your proverbial boat, don't worry—we evaluated 25 smart thermostats to suss out the best options. There's a smart thermostat for every budget. 

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You just have to cut the Nest thermostat some slack for the first couple of weeks while it gathers data and (gulp) studies you. Once it figures out your routine, the energy savings start rolling in.

But now that Ecobee, Honeywell, and Amazon have their own learning thermostats, the Google Nest Learning Thermostat needs a few more tricks up its sleeve to stay relevant. Fear not—it has perks a-plenty.

Yes, a smart thermostat can improve home safety—and the Google Nest Learning Thermostat does it best. For example, it shuts down the HVAC system when your Google Nest Protect smart smoke alarm and carbon monoxide detector goes off, slowing the spread of fire or toxic gases. 

The Google Nest Learning Thermostat also protects your home and your family by providing early and urgent warnings regarding your HVAC system. For example, if the system is no longer heating or cooling your home effectively, you'll get a notification. You'll also be alerted to HVAC power failures or extra-long run times. No need to wait for your home to feel uncomfortable or for the motor to burn out before you take action.

Finally, the Google Nest Learning Thermostat tells you when it detects extreme temperatures, allowing you to turn the system back on before your pipes freeze. 

The Google Nest Learning Thermostat also has light sensors to compensate for direct sunlight, so you won't have to worry about wonky readings. The Nest Learning Thermostat also has a built-in "Farsight" motion sensor and will light up the customizable display when it senses someone in the room, even if you're 10 feet away.

It works with Bluetooth, dual-band Wi-Fi, and other smart home hubs, like Alexa and SmartThings. The only major hub that Nest doesn't play nice with is Apple HomeKit, but that may change with the imminent launch of Matter smart home.

And according to Energy Star's records, the Google Nest Learning Thermostat uses just 0.06 W when in standby mode—one of the lowest measurements of all Energy Star-certified smart thermostats. And because it's Energy Star certified, the Google Nest Learning Thermostat strategically lowers energy consumption during peak hours (known as demand response), provides energy usage reports, and has been independently proven to reduce system run time. 

Learn more about the Google Nest Learning Thermostat and its slightly-less-smart-but-still-four-stars sibling, the Google Nest Thermostat, in our full Nest Thermostat review.

We also love the Ecobee Smart Thermostat Premium's exceptional smart home compatibility. It works with dual-band Wi-Fi, Bluetooth, IFTTT, and every major voice assistant.

And did we mention that Alexa and Siri are built in to the Ecobee Premium? You don't even need an Amazon Echo or Apple HomePod to reap the benefits of voice control with this smart thermostat.

Ecobee offers several other smart thermostats, each a little more affordable than the Premium. They all earned 4+ stars in our ranking system, but we chose to diversify our list of the best smart thermostats by choosing one representative thermostat from each brand.

To compare all Ecobee thermostats, head to our full Ecobee thermostat review. Or, read our in-depth review of the Ecobee Smart Thermostat Premium.

The Wyze Thermostat isn't Energy Star certified, so it may not provide the same level of savings as some of the other smart thermostats on our list. It does provide energy reports and some maintenance alerts, like filter replacement reminders. 

No C-wire is required to install the Wyze Thermostat, and it supports ACC-/ACC+ terminals for whole-home dehumidifier and ventilator integration.

Learn more in our full Wyze Thermostat review.

The T9 pairs with up to 20 remote temperature and occupancy sensors. The T9 itself doesn't have a built-in occupancy sensor, so don't skip these accessories if you want to take advantage of its learning capabilities. 

The Honeywell Home T9 has excellent smart home compatibility, working with all the major voice control hubs, plus IFTTT and Cortana. It also integrates with Ring home security systems for seamless home automation routines. 

This Honeywell Home smart thermostat works with dual-band Wi-Fi, requires a C-wire for installation, and comes with a 2-year warranty. It's also Energy Star certified and offers extreme temp warnings, filter replacement alerts, and energy usage reports.

The Emerson Sensi Touch ST75 is Energy Star certified. You'll get energy usage reports, filter replacement reminders, and other system maintenance alerts. This thermostat also displays the weather forecast and alerts you if extreme temps are on the way. 

The Emerson Sensi Touch doesn't work with remote temperature sensors, nor does it have an occupancy sensor. However, you can use geofencing to change the thermostat settings when you leave or arrive.  

In terms of smart home connectivity, the Emerson Sensi Touch pairs with Amazon Alexa, Google Assistant, Apple HomeKit, and Samsung SmartThings for voice control and home automation integration. We're bummed it doesn't pair with IFTTT, though.  

We also found that there were little to no connectivity issues with the Sensi Touch. It worked whenever we needed it.

Before you dive into buying a smart thermostat, there are some things to check out.

Make sure the smart thermostat works with your current HVAC system. Often, the sales page will list if the programmable thermostat is compatible with zoned systems, heat pumps, and cooling- or heating-only systems.

Here's a quick vocab lesson to help you through some of the alphabet soup:

• Low-voltage vs. high-voltage systems: Most smart thermostats work with low-voltage (12 to 24V) systems instead of high-voltage (120 to 240V) systems, which are also called line-voltage systems. If you already have just one thermostat to control your heating and cooling, you probably have a low-voltage system. If you have to go room-by-room to turn on individual radiators or baseboard heaters, you have a high-voltage system. Check out Mysa's in-depth comparison to learn more.
• C-wire: Also called a common wire, a c-wire provides constant power to your thermostat. If you don't have a c-wire, your thermostat gets a power boost when the HVAC system kicks on or relies entirely on battery power. Smart thermostats use way more energy than traditional thermostats, so they need constant power from a c-wire. Most smart thermostats we evaluated come with a power adapter kit, allowing you to install them without an existing c-wire.
• ACC-/ACC+: Also called accessory wires or star terminals, these are required if you have a whole-home dehumidifier or ventilation system. They're not a common feature in smart thermostats, so double-check the thermostat's terminal compatibility before you buy.

If you're still not sure what you have, look for a compatibility guide on the thermostat manufacturer's website. You'll have to remove the cover from your current thermostat and identify some wires, but don't worry—all of the guides are easy to use.

It's annoying to reset your thermostat schedules and preferences whenever the power goes out. If you experience frequent outages or tripped breakers, look for a thermostat that has a backup battery. It's a rare feature among smart thermostats but is really nice to have.

Smart thermostats play an important role in home fire safety by shutting down the HVAC system's fans when smoke is detected. According to Polina Gordonova of Lund University, this slows down the spread of smoke and fire, which can give you a little more time to escape. 

You need a smart thermostat that uses the same protocols as your smart smoke detector so that you can create an automation routine with both devices. That's why we've highlighted smart home and home security compatibility in our smart thermostat reviews.

Your thermostat's temperature sensor dictates when the furnace or air conditioner kicks on. But if your thermostat's located in a drafty or cozy area compared to the rest of the house, you could end up with some uncomfortable temperature fluctuations throughout your home. 

If that sounds familiar, look for a smart thermostat with remote temperature sensors. Scatter them throughout your home to give your thermostat more data before it fires up the AC or furnace. If those hot and cold spots persist, you might need to add dampers to your HVAC ducts. That's a job for a pro. 

One more thing to think about is how many remote temperature sensors the thermostat can support. In our experience, all smart thermostats compatible with remote sensors will support at least six. Some can manage four times as many. 

If your goal is to save energy and money with a smart thermostat, look for tech that can figure out when you're not home.

An occupancy sensor is a better option for families. The sensor is built into the thermostat itself or into its remote temperature sensors. It uses infrared technology to detect whether anyone's nearby. If no one's around, the thermostat adjusts the temperature to save energy. 

Geofencing relies on your phone's location to figure out when you've left home. It's not a good option for people who don't like to leave their phone's location services on. On the flip side, your smart thermostat can also tell when you're headed back, allowing it to switch to more comfortable temps before you walk in the door. 

Learning thermostats are rare. To date, we only know of four: the Google Nest Learning Thermostat, the Ecobee Smart Thermostat Premium, the Honeywell T9, and the Amazon Smart Thermostat. 

These thermostats don't need to be programmed. Instead, they learn your habits—like the fact that you start walking around your home at 6:30 am. Give them enough time to figure out your schedule, and they'll program Home, Away, and Sleep modes for you. The thermostat could kick on at 6 in the morning, for example, to make sure your kitchen is comfy-cozy by the time you have breakfast. 

While all learning thermostats use occupancy sensors or geofencing, not all thermostats with occupancy sensors or geofencing are learning thermostats. The difference is admittedly subtle: learning thermostats use your habits to anticipate your heating and cooling needs, whereas non-learning thermostats simply react to occupancy and geolocation data. Take care to find one that matches your expectations. 

If you intend to save energy by using a smart thermostat, we highly recommend looking for Energy Star-certified units.

Here are some of the criteria smart thermostats must meet in order to earn the Energy Star certification:

• Consume less than 3.0 W on average when in standby mode
• Provide energy usage reports to the consumer
• Use a demand response strategy to save energy during peak hours
• Reduce annual heating run time by at least 8% on average
• Reduce annual cooling run time by at least 10% on average

A new smarty-pants thermostat isn't worth its salt unless it can take some of the guesswork and stress out of HVAC maintenance. Look for one that can remind you to change the air filter, change the UV light (if applicable), and schedule seasonal maintenance. The best smart thermostats for home use also alert you when temps fall to freezing or your HVAC system runs longer than usual.

The Google Nest Learning Thermostat keeps up with your preferences so you can spend less time adjusting the temperature and have a smaller utility bill. You can easily tie the Nest to your home security system or phone so it knows when you're away and adjusts the temperature accordingly.

It's not the most affordable of thermostats, but its attractive, minimalist design and advanced features make it all the more worth it. 

• Ecobee vs. Nest
• Vivint Element Smart Thermostat Review
• How Do Smart Thermostats Work?
• How Nest Can Turn Your House into a Smart Home
• Best Smart Home Devices
• Energy Saving Tips to Make Your Home Energy Efficient Year Round