The 5 Best Smart Thermostats to Help You Save Energy

Google's original Nest is our top choice.

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Hand adjusting a Google Nest smart thermostat

Yu Sun / Getty Images

Treehugger Tested & Approved

We think the Google Nest is a solid entry-level smart thermostat, making it our Best Overall pick.

Smart thermostat are more than round dials that serve as control panels for your heating and air conditioning. They can also help you lower your energy bills and cut your carbon footprint.

Smart thermostats connect to the internet–usually via a Wi-Fi chip—or communicate with a separate hub. They can feature app-based remote control and scheduling options, weather alerts, and even advanced algorithms that learn your heating and cooling preferences and patterns. Many smart thermostats connect with voice assistants like Alexa and include geofencing options that utilize your mobile phone to determine when you’re nearby. Some even have screens that light up when you walk within proximity so there’s no more stumbling around in the dark to manually adjust the temperature setting.

Here are some of the best smart thermostats on the market, followed by tips for getting smart about choosing one for your home.

Best Overall

Google Nest Thermostat

4.8
Google Nest Thermostat

Amazon

Dimensions: 7.09 x 4.41 inches | Batteries: 2 AAA | Screen: 2.4 inch LED; 1024 x 600 pixel | Energy-Star Certified: Yes | Colors: 4

This Alexa- and Google-Assistant enabled smart thermostat is on the low-end price-wise for a Nest, but it’s not skimpy on features. It’s budget-friendly and compatible with most HVAC systems, making it an ideal choice for entry into the smart thermostat market and our top choice.

Our reviewer found the first-generation Nest smart thermostat is easy to install and use (thanks to the Google Home app). It’s also compatible with smart speakers (sold separately). You’ll need a wi-fi internet connection and a phone or tablet running iOS or android. It uses less than 1 kilowatt an hour per month of power. Some systems may need a C-wire to use Nest, including heating or cooling-only, zone-controlled, or those with a heat pump.

Compared with the "learning" thermostats, you'll need to manually set more of your preferences and schedules.

"The appearance of a little Leaf icon when you choose a more efficient temperature is a nice, if simplistic, touch—and I can see it being a motivator to turn the heat down." ~ Sami Grover, Treehugger Writer

Best Budget

Ecobee 3 Lite

Ecobee 3 Lite

Ecobee

Dimensions: 3.93 x 3.93 0.9 inches | Batteries: Lithium Metal (included) | Screen: Y3.5 inch LED; 320 x 480 pixel display | Energy-Star Certified: Yes | Colors: 1 | Batteries: No

The Ecobee 3 could save you up to 23% on your annual energy costs. This smart thermostat factors in weather patterns and your HVAC system’s performance. While it doesn’t have all the bells and whistles of some of its competitors or even other Ecobee smart thermostats, it offers good value. It’s an ideal midrange smart thermostat and works especially well in small spaces (like studios and lofts).

It integrates seamlessly with Apple HomeKit and leading smart home ecosystems such as the Google Assistant, Alexa, and Samsung SmartThings. When you combine it with the SmartSensor (sold separately), the thermostat will detect which rooms are in use and adjust the temperature accordingly.

Best Design

Lux Kono Smart Stainless Steel Thermostat with Wi-Fi Compatibility

Lux Kono Smart Stainless Steel Thermostat with Wi-Fi Compatibility

Amazon

Dimensions: 4.5 x 4.5 x 1 Inches | Batteries: No | Screen: Black and white | Colors: 8 | Energy-Star Certified: Yes | Colors: 8

If you’re in the market for a smart-looking smart thermostat, the Lux Kono Smart ticks both boxes. The standard black stainless cover offers a modern look, but multiple faceplate options are available and can easily blend in or contrast your wall color. A paintable option is also available.

Beyond style, the Kono Smart offers substance, too. It’s compatible with forced air, gas, oil, and many electric furnaces. You can control it with Alexa, Apple, and Google voice assistants and or by the Lux app for iOS and Android devices. Installation is easy and includes a power bridge when a C-Wire is not present. It also has geofencing capability.

Best Splurge

Google Nest Learning Thermostat

4.9
Nest Learning Thermostat 3rd Gen

Home Depot

Dimensions: 3.3 x 3.3 x 1.2 inches | Batteries: 1 lithium battery (included) | Screen: LED | Energy-Star Certified: Yes | Colors: 7

If you're willing to spend more, Google upped its smart thermostat game with this generation of Nest. In addition to the features of the original Nest, this one "learns" your heating and cooling preferences and patterns in about a week and creates a schedule to match. You can control it from wherever you are using the Nest app or put it under voice control using Alexa or Google Assistant.

The Google Smart Nest Learning Thermostat is compatible with 95% of 24V heating and cooling systems—including electric, gas, forced air, heat pump, radiant, oil, hot water, geothermal, and solar. It’s easy to install and beautifully designed. It comes in multiple colors and the screen doubles as a weather or time clock.

Best for Homes Without a C-Wire

Google Nest Thermostat E

Nest Thermostat E Smart Wi-Fi Programmable Thermostat

Walmart

Dimensions: 1.77 inch diameter | Batteries: 1 lithium battery (included) | Screen: 24-bit LCD; 320x320 resolution; 182 pixels | Energy-Star Certified: Yes | Colors: 1

No C-wire? That’s no problem for Google’s Nest Thermostat E. It works with 85% of heating and cooling systems and the built-in battery allows those with older homes to bypass the need for a C-wire.

While the display simply shows the temperature, this understated member of the Nest family still changes heat and cooling settings when you’re away. Treehugger's reviewer noted that it's a less flashy looking thermostat, and may blend in better with some home's decor. You can use the Nest App to change the temperature. It will reduce your energy usage saving you money, at a lower price than the Nest Learning thermostat.

Final Verdict

If you’re looking to enter the smart thermostat market on a budget but without skimping on features, then Google’s original Nest is a great option. If you live in a home without a common wire but still want to try out a smart thermostat, Google’s Nest E will bring your home and HVAC system into the future.

What to Look for in a Smart Thermostat

Smart thermostats all share a similar goal: saving you money on your energy bills. But they can do more than just control the temperature in your home. Here are some key features to consider when shopping for a smart thermostat beyond price, dimensions, and Energy-Star certification.

Power Compatibility

Check the voltage on your HVAC system and make sure that the smart thermostat option you’re buying is compatible. Most smart thermostats come in 24, 110, or 240-volt.

Voice Assistant Compatibility

If you use Google Home, Amazon, Alexa, or Apple HomeKit, choosing a smart thermostat that integrates with these smart assistants may be a smart choice.

C-Wire or No C-Wire

A common wire (C-Wire) runs from a low voltage (24v) heating system to a heating system to provide continuous power to your smart thermostat. Many newer heating and cooling systems have C-wires guaranteeing compatibility with your smart thermostat. But, if you don’t have an older HVAC system or don’t have a low voltage system, look for a smart thermostat that doesn’t require a C-wire to work or one that comes with other ways to connect.

Remote Adjustments & Alerts

Many smart thermostats allow you to use a phone app, voice assistant, device, or table to adjust the temperature while you’re away from home. Some smart thermostats let you set alerts to inform you about temperature changes that may affect other parts of your home, like freeze warnings that could cause pipes to burst.

Display

When it comes to thermostat screens, size and color might matter so you can better use features or override settings. You might also like the addition of automatic sensors that control screen brightness when you walk within range of the thermostat screen.

Geofencing

This feature coordinates with a smartphone app and allows you to set electronic boundaries that sense when you’re home, not home, or approaching your home. Some may even let you set boundaries to warm or cool individual rooms.

Frequently Asked Questions
  • How do smart thermostats help save energy?

    Smart thermostats are designed to learn your behaviors, collect data about your energy usage, and have sensors that monitor when you’re home or away. All of these features are what allow them to know when to automatically adjust your heating and cooling levels to help reduce your energy consumption.

  • Do smart thermostats require batteries?

    Since batteries provide reliable and steady power, even when the electricity goes out, many smart thermostat models do use batteries. This can be anything from AA and AAA to lithium-ion options. When choosing a smart thermostat look for one that uses a rechargeable battery or one that has a high milliamp hour (mAh) rating so it won’t need to be replaced as often. Selecting a model that also connects to a C-wire is a good option in case your batteries wear out.

  • Do you need to hire an electrician to install a smart thermostat?

    Many smart thermostat manufacturers claim that their products are easy to install on your own without the help of an electrician. Still, unless you’re familiar with electrical wiring, you may want to get help from a pro—especially if you don’t have a C-wire.

Why Trust Treehugger?

This article was written by Heidi Wachter, who has spent a decade researching and writing about ways to reduce her environmental impact.

To make our list of picks, she researched customer, third-party, and smart technology expert reviews to find the best smart thermostat options. She looked at each smart thermostat’s energy-saving features, design, and price point. Some of the smart thermostats have also been tested by Treehugger writers in their own homes.