You know it’s long past time to consider adding a smart thermostat to your home’s repertoire–or upgrading the one you already have. Installing one will have an outsize impact not only how comfortable you are in your home, but also on your household budget. Heating and cooling your home accounts for nearly half of the average home’s utility bills, according to the U.S. Department of Energy.
A programmable thermostat can help reduce those costs by turning your HVAC system on when you anticipate being home, and off when you don’t think you’ll need indoor climate control. A smart thermostat goes far beyond relying on a simple schedule. It will enable you to create more sophisticated schedules for every day of the week, and give you complete control over your HVAC system, even when you’re away from home. We continually test and evaluate smart thermostats and can help you find the right one for your home.
Updated April 29 to add a link to our GE Lighting Cync Smart Thermostat review. This HVAC controller has several strong features to recommend it, and is one of the least expensive thermostats on the market to support add-on room sensors ($30 each). This enables the thermostat to average the temperature readings from all its sensors to set a target temperature that will eliminate hot and cold spots in your home. What it doesn’t have is AI that can learn your usage patterns to program itself.
Best smart thermostat
Nest usually gets all the attention—and the company deserves credit for shaking up a once sleepy market—but Ecobee’s latest smart thermostat is the best you can buy today. The new model builds on the model that preceded it, which was itself very well executed. Many other smart thermostats rely on measuring a home’s temperature in just one spot: Where the thermostat is located. Trouble is, that spot is usually in a hallway or somewhere else that you never spend any time in. Ecobee lets you place multi-purpose sensors in various rooms in your home, so that the rooms you’re in are the ones that the thermostat instructs your HVAC system to heat or cool to keep you comfortable.
Don’t count Nest out of the thermostat game. The Google division has worked harder than anyone to build out a comprehensive smart home ecosystem with its own products—the Nest Cam security camera series and the Nest Protect smoke and carbon-monoxide detectors—as well as a wide array of third-party products: Everything from ceiling fans to lighting controls and even smart appliances. The recent addition of the Nest Temperature Sensor makes this device even smarter.
So why does it garner runner-up status here? Nest counts on your buying other Nest products to help determine when you’re home and away, for starters. And anyone investing—or planning to invest—in Apple’s up-and-coming HomeKit ecosystem should steer clear of Nest products.
Best budget smart thermostat
Amazon wins this category with the least expensive, most sophisticated smart thermostat in its price range, and that goes double for households that revolve around Amazon’s Alexa, since it’s not compatible with Google Assistant or Apple HomeKit. But it supports a broad array of HVAC systems and it will learn your comings and goings over time to save energy by not heating and cooling an empty home.
It’s hard to beat the Nest team when it comes to attractive industrial design, and the Nest Thermostat is an elegant device if you don’t need to support more sophisticated HVAC systems or you don’t care that it doesn’t support remote sensors that can eliminate hot and cold spots in your home.
Best smart thermostat for high-voltage heaters
These types of thermostats are designed for baseboard, radiant, fan-forced convector, and similar types of heaters, as opposed to the more common central HVAC systems. As such, there are far fewer choices in this category. So far, the Mysa Smart Thermostat is our top pick, due to its elegant industrial design and its broad support for other smart home devices, including Amazon Alexa, Google Assistant, and Apple HomeKit.
Best controller for a stand-alone air conditioner
If you don’t have a central HVAC system, or if your supplement one with one or more stand-alone air conditioners, the Sensibo Air will make those units smarter and more efficient. It’s expensive, but very much worth the cash.
The Cielo Breez Plus doesn’t have the slick discrete room sensor that comes with the Sensibo Air, but it will still greatly improve the performance of your stand-alone air conditioner, and it’s less expensive than its more sophisticated competitor.
C-wire requirement Most smart thermostats require more electrical power than a set of batteries can provide. Fortunately, they don’t require so much power than they need to be plugged into the wall. They rely instead on low-voltage power provided by your HVAC system. Many smart thermostats require the presence of a dedicated C (common) wire for this purpose, while others can siphon electricity from another source, typically the R (power) wire. But the latter practice is known to cause problems with some HVAC systems, including permanent damage. If you pull out your existing thermostat to install a smart model and find no C wire connected to it, look inside the wall to see if there’s one that hasn’t been connected. If there’s no C wire, our advice is to have one installed. Some smart thermostats comes with power adapter kits that can be installed if you don’t have a C wire and don’t want to pay to have one installed.
Ease of installation A thermostat shouldn’t be difficult to install, even if you’re only moderately handy. The manufacturer should provide comprehensive, yet easy-to-understand instructions with plenty of photographs or illustrations to guide you through the process. The thermostat itself should be clearly indicate which wires go where, and most companies provide labels that you can attach to the wires coming out of the wall as you disconnect and remove your old model. The wires themselves should be color coded, but a good practice is to photograph your old thermostat for reference before you take it down.
Geofencing This feature uses the thermostat’s app and your smartphone’s GPS chip to establish a perimeter around your home. When you leave the perimeter, you presumably no longer need to heat and cool your home, or you can at least have the thermostat adjust the temperature so that it’s not running unnecessarily. When you cross the perimeter again as you come home, your HVAC system can kick into action so your house is comfortable when you walk in the door.
High-voltage heater support Most smart thermostats are designed to work with central HVAC systems. If your home is heated by high-voltage heaters (baseboard, radiant, and fan-forced convector, for example), you’ll need a thermostat that’s specifically designed to work with that type of heater.
Remote Access Remote access enables you to control your thermostat from afar, so that you can check in and adjust the temperature from wherever you have a connection to the internet.
Sensors Geofencing is great—provided everyone who lives in the home has a smartphone. Motion and proximity sensors offer an alternative means of determining if your home is occupied and therefor in need of climate control. The original Nest thermostat was often criticized for relying too much on its motion sensor. If no one walked past it often enough, it would decide that the house was empty and it would stop heating or cooling. Some smart thermostats can also tap into door and window sensors as well as the motion sensors for your home security system. And proximity sensors on the thermostat itself can trigger a thermostat’s display to turn on when you walk past it, making the screens a handy feature in their own right, even if for no other reason than providing a nighttime pathway light.
Smart-home system integration Every smart thermostat comes with an app so you can control it with your smartphone or tablet, but the best models can also be integrated with other smart-home devices and broader smart-home systems. This can range from being able to adjust the temperature with a voice command via an Amazon Echo or Google Home digital assistant, to linking to your smoke detector so that your fan automatically turns off when fire is detected, preventing smoke from being circulated throughout your home. Other options to consider include IFTTT and Stringify support, Apple HomeKit compatibility, smart-vent connectivity, and tie-ins with home security systems.
System complexity Each of the thermostats we tested support multi-stage heating, ventilation, and air conditioning (HVAC) systems, as well as heat pump systems. If your home is divided into zones that are heated and cooled independently of each other, you’ll probably need one thermostat for each zone. A single app should be able to control multiple zones.
User interface Long gone are the days when a thermostat’s user interface consisted of numbers on a dial. The more sophisticated a device becomes, the more difficult it can be to learn to use. The last thing you want to be doing is staring at inscrutable hieroglyphics on the wall when all you really want is to be warmer or cooler. A smart thermostat should convey important information at a glance and should easily adapt to your specific needs.
How we test smart thermostats
We install thermostats in a single-family home with a conventional HVAC system and use each one for a week or more to determine how effective it is at maintaining a comfortable environment. The home’s existing thermostat was wired with G, R, W, and Y wires. There was also a C wire in the wall that was connected to the furnace, but that had not been previously used.
While there is no regulated standard for color-coding HVAC wires, industry practice has the G wire connecting the thermostat to the fan. This wire is typically green. The R wire, typically red, is for power. Some systems have separate power wires for heating and cooling and are labeled RH and RC respectively. The typically white W wire is for auxiliary heat; i.e., a second source of heat. The Y wire, which is typically yellow, connects the thermostat to your air conditioner. Finally, the C or “common” wire is used to carry power and is typically blue (think cerulean if you need a mnemonic).
Our smart thermostat reviews