Here's a running list of the smart thermostats we've reviewed to date, regularly updated as we review new products.
While they have different designs and rely on different smart features, they have one thing in common: voice control.
Read on to find out more about the smart thermostats available today.
Ecobee's Ecobee3 Lite works with a ton of smart home platforms: Amazon Alexa, Apple HomeKit, Samsung SmartThings, Wink and IFTTT.
The Lite model may look like the original Ecobee3, but it doesn't come with a remote sensor for tracking your home and away status.
The Ecobee SmartThermostat with Voice Control works with Apple HomeKit, Samsung SmartThings, Wink and IFTTT -- and even has a built-in Alexa speaker.
It also comes with a remote temperature sensor so you can track the temperature in other rooms.
The Emerson Sensi Wi-Fi Programmable Thermostat doesn't have algorithmic learning or standalone presence sensors.
It does, however, work with Alexa, Apple HomeKit, Google Assistant and Wink.
Like the Emerson Sensi thermostat, the Sensi Touch supports Amazon Alexa, Apple HomeKit, Google Assistant and Wink. It also has a touchscreen display and offers geofencing and humidity monitoring.
The Nest Learning Thermostat uses algorithms to adapt to your daily routine.
Its built-in sensors help detect whether you're home or away and will adjust the temperature automatically.
It also works with Alexa devices and the Google Home speakers.
The Nest Thermostat is the latest smart thermostat from Google, but this model only costs $130.
It's available in four colors: sand (white), snow (rose gold), fog (light greenish/blueish-gray) and charcoal (dark gray). Trim kits to cover old paint or holes from previous installations are sold separately for $15.
This thermostat works with Alexa and Google Assistant.
The Nest Thermostat E is Google's entry-level smart thermostat. The E has (almost) all of the same features as the Nest Learning Thermostat, but has less expensive hardware components to keep the price down.
The Honeywell Lyric Smart Thermostat can talk with Siri through HomeKit or with Alexa via the Amazon Echo, Echo Dot and Tap speakers.
It also has geofencing capabilities tied to your phone's location. When you leave home, the Lyric should automatically adjust to a more energy-efficient temperature. And when you return, it should autoadjust back to a more comfortable setting.
Honeywell's Lyric T5 works with HomeKit and Alexa devices, so you have a couple of different ways to adjust this thermostat with your voice.
It also has geofencing capabilities. Simply set a home and away radius and let the Lyric T5 adjust the heat and air conditioning for you.
iDevices' smart thermostat doesn't have as much connected tech as some of its competitors, but it does work with HomeKit for Siri voice control.
Johnson Controls' $319 GLAS Smart Thermostat has a built-in Microsoft Cortana speaker. Ask Cortana to "change the temperature to 68 degrees" or to "switch from home to away mode." The GLAS also works with Alexa and Google Assistant if you have a compatible smart speaker at home.
This thermostat has a see-through OLED touchscreen display and gives you air quality reports.
The Lux Geo Thermostat has geofencing capabilities for automatic home and away modes.
You can also set a recurring heating and cooling schedule in the related Lux app.
The thermostat's flexible design can be mounted either vertically or horizontally.
The Kono Smart Thermostat by Lux costs $153. It looks neat and works with a variety of smart home platforms, but the dial is difficult to use.
The Resideo Honeywell Home T9 Smart Thermostat costs $200. It comes with a remote temperature, humidity and proximity sensor, as well as geofencing capabilities and support for Alexa and Google Assistant voice commands.
You can buy the T9 as a standalone device (without the remote sensor) for $170 and the sensors, which Resideo calls Smart Room Sensors, for $40 each.