The 30-Second Review

The best smart thermostat will monitor your home's activity level and adjust temperatures accordingly, heating and cooling more efficiently than a traditional thermostat. After interviewing HVAC experts and evaluating 23,000 customer reviews for models that were easy to install, we landed on two smart thermostats that enable efficient energy consumption with minimal effort.

Our Top Pick

Regardless of the type of heating or cooling system your home uses, the ecobee comes with an adapter that grants near-universal compatibility. The thermostat also has a more sophisticated method of tracking your activity than most models, ensuring comfortable temperatures when you're home and energy savings when you're not. ($250)

Runner-Up

The Nest uses smart technology that's on par with the ecobee. But, depending on your home, installation must sometimes be completed by an electrician. The trade-off? It's got a gorgeous Apple aesthetic that no other finalist could match. ($250)

The Best Smart Thermostat

All thermostats — smart or not — will heat and cool your home. The goal of smart thermostats is to automate this process, making it less hands-on for you and more efficient for your home. As a perk, many smart thermostats are also compatible with smart home systems and Amazon Alexa, allowing them to do things like check the weather or the evening news.

The largest difference between devices is the type of smart technology they employ to keep your home comfortable.

Our pick for best smart thermostat is the ecobee4 ($250). The ecobee gets its “smart” capabilities from two types of tech. First, it has multiple motion sensors: one inside the thermostat and one stand-alone sensor that can be placed in another room, like the bedroom. This lets the ecobee adjust temperatures in response to activity level. The ecobee also tracks the location of your smartphone. If you’re home sick despite normally scheduled hours, it will be able to tell and avoid turning the temperature down to “vacant house” settings. Other smart thermostats, like Honeywell's offerings and the lesser-known LUX/GEO, rely on tech that we found less reliable. The ecobee is compatible with the majority of home heating and cooling systems, making do-it-yourself installation more straightforward than it is for runner-up Nest.

As the first smart thermostat on the market, the Nest Learning Thermostat ($250) gets a lot of attention. Its minimalist appearance will appeal to people who like Apple’s aesthetic, and compared to the plastic ecobee4, the Learning Thermostat's matte metal finish gives it the feel of a luxury watch for your home. The major downside is installation, which can become tricky depending on your home’s heating and cooling system. If your house doesn't have a C-wire, you may need to purchase additional equipment or have your thermostat professionally installed. We explain these options below, but be prepared to call in an electrician if necessary. Unlike the ecobee, the Nest will grow continually “smarter" by analyzing behavior patterns and responding with greater nuance over time, but this requires you to invest time upfront teaching it your preferred settings. Like the ecobee, the Nest also relies on phone tracking to monitor when you're home.

Before You Buy, Check for Compatibility: “C” Marks the Spot

There’s one downside to buying a smart thermostat that we want to address upfront. No matter which model you choose, you’ll have to install it. And some houses make this process more difficult than others.

Home heating, ventilation, and air conditioning (HVAC) systems run using a series of wires — typically four — that control things like A/C and fan use. But a lucky 40 percent of homes have a fifth wire known as a common wire (or C wire) that can be used to provide a continuous flow of power to devices like smart thermostats, which need to be constantly “on” in order to function.

The good news: If you have a C wire, you should be able to install any smart thermostat on the market in just a few minutes. To find out if you have one, look at the wiring diagram on the access cover of your HVAC system, or remove your current thermostat from its baseplate and check for a terminal labeled with the letter “C.” This wire may be in use already, or it may simply be tucked to the side.

If your home doesn’t have a C wire (the majority of homes do not), you’ve still got three options:

  • Have a C wire professionally installed — This option tends to run between $100-$150 and can be done in under an hour by any electrician. It’s the most fail-safe option, and, as a bonus, it might also extend your thermostat’s warranty. (We look at warranties in more depth below.)
  • Purchase a power extender kit (PEK) — Power extender kits take the four existing wires commonly found in HVAC systems and adapt them to add a fifth wire that you can use as your C wire. Power extender kits generally cost around $30.
  • Power stealing — Some smart thermostats can be rigged to take the necessary electricity directly from your home’s four existing wires, without an adaptor. But this unregulated “power stealing” can cause long-term problems. Especially during times of the year that HVAC systems are used heavily (winter, summer) power stealing can cause temperature fluctuations that leave your house boiling hot or below freezing. CNET also reports that power stealing can cause HVAC systems to short circuit.

Our top pick, the ecobee4, comes with a power extender kit that makes it compatible with virtually all systems. (It can also be hooked up to a C wire, if you’ve got one.) Runner-up Nest works best with a C wire, but provides instructions for power stealing — although we don’t recommend this option.

Our Picks for the Best Smart Thermostat

Our Top Pick

Ecobee4A user-friendly device that’s compatible with most HVAC systems.

Price: $250

Smart home compatibility: Amazon Echo, Apple HomeKit, IFTTT, Samsung SmartThings, Wink

The ecobee4 prioritizes functionality over appearance, but with near-universal HVAC compatibility, built-in Alexa, and remote sensors, we don't mind picking plastic over the Nest's matte metal.

Of all our finalists, the ecobee4 is the most hassle-free right out of the box. Like most smart thermostats, it requires a continuous flow of power to function; unlike most, the ecobee4 comes with a power extender kit (PEK), which means it’s compatible even if you don’t have a C-wire, saving you both the cost of installing a new one and the risks inherent to power stealing. Only two other devices — LUX/GEO and Schneider Electric WiserAir — included power extender kits. While third-party PEKs can be purchased for homes that don't have C-wires, we prefer not needing to buy a $30 adapter to use a smart thermostat we've already paid for.

PEK Kit for Smart Thermostat

The ecobee's PEK kit makes it more easily compatible with home HVAC systems.

The installation process is also straightforward, thanks to easy-to-follow instructions for removing your old thermostat and wiring in your new one (including two separate guides for those with or without C-wires), and quick access to customer support that one user described as providing “more competent support for any product that I’ve ever asked about.” Once installed, the ecobee4 features four customizable modes (Home, Away, Sleep, and Vacation) that can be programmed and adjusted via your mobile app.

Ecobee-Manual-for-Smart-Thermostat

The ecobee's instructions are clearly laid out, aiding in a simple installation process.

As homes become increasingly reliant on smart technology, the ability to control multiple smart devices from one app will become more important. “Smart thermostats are becoming the hub of the connected home,” Craig Marin, Director of HVAC Product Lines for Sears Home Services, told us. And with Amazon Alexa built in, the ecobee4 takes a convincing step in that direction. Alexa endows the thermostat with voice capabilities for nearly everything, from adjusting the temperature to checking the news (although some Alexa features like messaging are still missing, with no news as to whether they'll be added). Similar to many of its competitors, ecobee is also compatible with a wide range of smart home systems — Apple HomeKit, IFTTT, Samsung SmartThings, and Wink — making it easy to add the ecobee4 to your system if you already own other integrated devices.

Data privacy is a growing concern.Some consumers worry about what happens to all the data that smart home devices collect, worrying manufacturers will use it for their own gains. We look at a few ways to keep your data as private as possible below.

Like the majority of our finalists, the ecobee4 uses geofencing to automate home energy savings: When you’re away, the device knows to bring down your home’s temperature, raising it again by the time you return. But to further improve accuracy — or if you just don’t like the idea of having your phone tracked — the ecobee4 can also use any of its motion sensors to gauge whether you’re home. And these motion sensors are a little more unique.

Room Sensor for Smart Thermostat

The ecobee's standalone sensors help it monitor more than one room.

For most thermostats, motion sensor readings are limited to the room in which the thermostat is placed: The living room can be at a comfortable heat while you’re stuck piling on extra blankets in the bedroom. But the ecobee uses multiple sensors in multiple rooms to detect motion and temperature patterns and ensure that the areas you’re actually in are set to the temperatures you prefer. Having multiple sensors also guarantees that the temperature won’t drop just because you haven’t walked in front of the thermostat in a while. The ecobee4 comes with one remote sensor included, and additional sensors can be purchased. (A pack of two will run you $79 — as of now, ecobee doesn't sell them individually.)

The ecobee4 isn’t perfect. The device doesn’t look as sleek as the Nest Learning Thermostat and it’s bulkier than we expected — a little bigger than a hockey puck — with shiny, black-and-white plastic hardware that may stand out against the wall you mount it on. Some users have also reported instances of the ecobee4 conflicting with other Alexa-enabled devices while answering voice commands, though an Echo Spatial Perception software update in late 2017 seems to have resolved the problem. And we found these complaints minor in the face of the ecobee4's widespread HVAC compatibility, home automation, built-in Alexa, and remote sensors.

Runner-Up

Nest Learning ThermostatStylish, and a bit more high-maintenance. May need professional installation.

Price: $250

Smart home compatibility: Amazon Echo, Google Home, IFTTT, Wink

The Nest Learning Thermostat is a beautiful device that put us in mind of an iPhone — unsurprising, given that Nest’s founder previously worked as a designer for Apple. The device’s design is sleek and intuitive, and we found rotating and clicking the dial satisfying in a way that interacting with a touchscreen never will be (though some users note that turning a dial to input information, such as Wi-Fi passwords during setup, is less convenient). But beyond its aesthetic appeal, we didn't find many compelling reasons to pick Nest over ecobee.

Nest for Smart Thermostat

The $249 Learning Thermostat is compatible with Google Home, Amazon Echo, IFTTT, and Wink. Notably absent is Apple HomeKit. Nest was acquired by Google in 2014, which means it’s now an Apple competitor. Google is a technological heavyweight, so we didn’t feel overly bothered by the limitation, but if you’re Apple loyal, this may be enough to tip you in favor of the ecobee.

As the first smart thermostat on the market back in 2011, Nest has driven much of the adoption of smart home devices and frequently tops the lists for “best smart thermostat.” But it isn't without its pitfalls. Nest claims that its devices are designed to work without a C-wire, but upon further investigation we found that the company’s smart thermostats require power stealing in order to do so. To us, this seemed misleading, since other manufacturers have found viable ways — such as PEKs — to avoid using a C-wire without risking the health of your home’s entire HVAC system. If Nest is going to claim compatibility without a C-wire, we expect them to include a power extender kit in the box.

Users cited compatibility challenges as their biggest complaint, but noted that Nest’s customer support was exceedingly helpful for any non-compatibility issues that arose during or after installation.

In addition to geofencing, the Nest Learning Thermostat distinguishes itself with machine learning that enables the device to create a home heating and cooling schedule based off of your existing habits. If you like your home to be warmer when you wake up than when you go to bed, the Nest Learning Thermostat will learn from your preferences and automatically bring your morning temperature up a few degrees compared to the evening setting. While this sounds like the ideal ‘plug-in-and-forget’ scenario, Nest requires several days of guidance from you as it adjusts to your behavior. The device becomes more intelligent with more information, and those first few days are critical to instructing it in the most cost- and energy-efficient habits.

This means that, in order to optimize your savings, the first week of owning the Nest Learning Thermostat will involve doing precisely what you purchased it to avoid: manually changing your settings to the temperature you prefer and adjusting your thermostat when you don’t need it. Fortunately, home automation makes this process easy — if you forget to turn the heat down before leaving for work, you can use the app to adjust settings remotely.

After those first few days, you’ll probably forget you ever had to teach your Nest anything, and the device’s machine learning capabilities allow it to continually fine-tune its schedule. But we thought the hands-on nature of teaching the device — drawn out over the course of several days — felt a little too much like programming a conventional thermostat. And this feature still doesn't address the temperature disparities that may occur in different rooms or the need to walk in front of the Nest for it to know you're still home. Without remote sensors (or native voice capabilities) like those built into the similarly-priced ecobee4, the biggest benefit of the Nest Learning Thermostat is its appearance.

A Couple of Others to Consider

Nest Thermostat EA second Nest model that’s cheaper, with a slightly more cartoony look.

Price: $160
Smart home compatibility: Amazon Echo, Google Home, IFTTT, Wink

The Nest E looks more cartoony than the Learning Thermostat — think Nintendo rather than Sony — and is built out of white plastic and frosted glass screen, allowing the entire device to blend easily into a wall. It can still be controlled from any smart device and has all the same learning capabilities as the Nest Learning Thermostat. But to warrant its $160 price tag, the Nest E is missing a few nice-to-haves.

Nest Comparison for Smart Thermostat

We preferred the appearance of the Nest Learning Thermostat (left) to its slimmer cousin, the Nest E.

First, the Nest E is compatible with fewer HVAC systems than even the Nest Learning Thermostat. All Nest products work best with a C-wire, but the Nest E has fewer wire terminals, which means that it may additionally not work with some multi-stage HVAC systems (systems that allow for degrees of heating and cooling, rather than a simple on and off). The Nest E supports one stage of heating, one stage of cooling, and an additional stage of either heating or cooling, but unlike the Learning Thermostat, it can’t accommodate HVAC systems with three stages of heating. Additionally, the Nest E doesn’t come equipped with Farsight, Nest’s display technology that allows the Learning Thermostat to brighten as you approach it. The Nest E also has a lower pixel density on its screen, resulting in a blurrier display. If you’re sure the device is compatible and are interested only in performance and energy savings, however, the two Nest Variants are nearly identical.

Nest isn’t the only manufacturer that produces a budget version of its devices. Ecobee offers the ecobee3 Lite, a slimmed down version of the ecobee4, at a similar price point to the Nest E. But in exchange for savings, the ecobee3 Lite does away with built-in Alexa technology and a remote sensor in the box. The sensor is what sets the ecobee apart in the first place, and while you can purchase them separately as a $79 add-on, at that point we feel you’d be better off just opting for the ecobee4.

Honeywell Lyric T6Another cheap option with similar compatibility to the Nest and a thermostat design that looks traditional.

Price: $150

Smart home compatibility: Amazon Echo, Apple HomeKit, IFTTT

It’s no coincidence that all of our top picks come from ecobee and Nest. These thermostats’ broad compatibility, technological capabilities, and ease-of-use make for compelling reasons to install them in your home, even if you don’t own any other smart home devices.

If, however, you’re interested in a smart thermostat that doesn’t look quite so… smart, the Honeywell Lyric T6 Pro Wi-Fi thermostat can offer all the savings benefits of these other devices while sparing the extra trimmings.

Honeywell for Smart Thermostat

The $150 Lyric T6 is unassuming: A simple square design and solid color make it look more like a standard programmable thermostat than a smart home device. So we were pleased to find that it performed most of the same functions as our other top picks. The Honeywell Total Connect Comfort app gives you remote access to settings, while geofencing technology allows the device to implement energy-efficient settings by tracking your phone’s location.

Like Nest devices, the Lyric T6 requires a C-wire to function, limiting the ease with which it can be installed if you don’t have a compatible HVAC system. But the Lyric T6’s instruction manual lacks the easy readability of our other picks. Coupled with Honeywell’s previously mentioned customer service complaints, we feel the ecobee4 and the Nest are both easier to get up and running. If you prefer the look of a standard thermostat and don’t want something as flashy as the Nest, or even the ecobee, the Lyric T6 is great for users who just want to take advantage of cost and energy savings.

Did You Know?

You don’t need a smart thermostat to save, but it does help.

Nest estimates that their users save, on average, between 10-12 percent on heating and 15 percent on cooling per year. It’s not a lot, but it means your smart thermostat could pay for itself within a couple of years. Abigail Daken, an environmental engineer for the EPA, told us that consumers can get equivalent savings to a smart thermostat using any programmable thermostat. The difference is that smart devices “make it practical for a much broader swath of the population.”

If you aren’t proactive about adjusting your thermostat before leaving the house or going to bed, you end up spending more money and using more energy than necessary. And the truth is, most people aren't. Smart thermostats help you enact these high efficiency habits without changing your routine — and those energy savings could save you an average of $131 to $145 on your annual bill.

Smart homes will continue to get smarter — and more affordable.

The smart home market is estimated to swell to $53.45 billion by 2022, meaning that a smart thermostat might soon become just one component of a fully integrated smart home system that controls everything from HVAC to your oven. Fortunately, since all major smart thermostat models employ backwards-compatible software updates, the smart thermostat you buy today is expected to work just as well in 2022 as it does now.

But despite these projections, adoption of smart thermostats has been slower than most experts have expected. According to Daken, the primary barrier to widespread adoption is cost: while the extended lifespan of the devices helps soften the price on the tag, many consumers simply don’t see the long-term value of smart thermostats when faced with such a steep price point. To increase accessibility, some energy companies have partnered local governments to offer rebates on smart thermostats. If you’re considering a smart thermostat, check with your local energy company before purchasing to find out if your provider offers a rebate program.

Your installation method can affect your warranty.

Most of the smart thermostats we looked at come with two warranty options: a standard warranty ranging from one to three years and an extended warranty of an additional two to three years — if the device is installed by a professional contractor. Most manufacturer-approved services run between $100-$150 on top of the price of the thermostat itself. If you feel confident in your ability to install your device, the entire process can be completed in under an hour at no additional cost, barring any issues with compatibility. But if you’re concerned about your device’s longevity, opting for professional installation is a good way to ensure longer coverage.

Data collection can’t be prevented — but it can be protected.

If you install a smart thermostat, there’s no getting around the fact that the manufacturer will have access to a significant amount of data about your personal behavior patterns, like where you live, the distance of your commute, or your typical weekend routine. This has left some consumer advocacy groups concerned about privacy risks, especially in light of the poor track record many businesses have when it comes to safeguarding consumer data. Just look at 2017’s massive Equifax breach.

When we checked out the privacy policies of our top picks, we found the policies themselves pretty similar, but a large difference in the transparency with which each company laid them out. Only Nest’s products explicitly acknowledged the importance of data privacy: The installation guide for these thermostats begins with a brief privacy statement that affirms the company’s commitment to honest and transparent communication regarding data collection. While a statement alone may have little impact, we appreciated the upfront acknowledgement.

All the privacy policies we looked at emphasized that personally identifying data wouldn’t be distributed without your consent, unless the manufacturer is required to turn it over for legal reasons. In the event that your personal data is accessed without your consent, the most likely suspect won’t be the manufacturer but a third party — hackers that access your information through your home’s Wi-Fi network, for instance. And there are a few steps you can take to mitigate falling victim to this type of privacy breach:

  • Use a dedicated email address — Setting up your smart thermostat requires registration via email address. This was true of all the brands we tested. But your personal email contains a treasure trove of information that you wouldn’t want shared with the world, so it’s a good idea to set up an email address that can be used exclusively for your smart thermostat.
  • Use a dedicated Wi-Fi network — Just as using a separate email address for registering your device will reduce the chances of having your personal email hacked, using a dedicated Wi-Fi network will cut off access between the information available on each network. This can be a more involved and expensive process — you can either purchase a second router or set up a guest network on your internet service that operates separately from your local network — but if data privacy is a large concern of yours, setting up a dedicated Wi-Fi network will help prevent easy access for nefarious hackers.
  • Keep your firmware up-to-date — Smart thermostats receive regular updates from the manufacturer in order to keep them advanced and secure. By keeping your system’s firmware up to date, you can be sure that your device is taking advantage of the latest security protections offered by the manufacturer.
  • Use a VPN — VPN services secure and encrypt your connection to your home network — think of it as a private channel that allows you to access your network while preventing people from being able to view things such as your IP address and location. VPNs aren’t a catch-all security mechanism, but using one for the Wi-Fi network that your smart thermostat is connected to means another layer of security in the event that hackers attempt to access your personal information. Check out our review of the Best VPN to learn more about VPNs and our favorite providers.

The Best Smart Thermostat, Summed Up

Smart Thermostat
Best...
Ecobee 4
Overall
Nest Learning Thermostat
Runner-Up