How do smart thermostats work?

Smart thermostats

Smart thermostats save you time, money and mental energy by allowing you to create heating and cooling schedules, monitor your usage, make adjustments directly from your phone and more. How does a smart thermostat work, and how can it allow you to expend less energy thinking about your heating and cooling preferences? 

Read on to learn more about the features of smart thermostats that make them a brilliant addition to your smart home network or a convenient and cost-saving standalone smart device. 

How does a smart thermostat work? 

What makes a smart thermostat smart? All smart thermostats come equipped with Wi-Fi connectivity to allow you to control your device from the companion application on your mobile device or other smart devices. Most smart thermostats also automatically adjust heating and cooling temperature settings based on schedules and algorithms set by the user’s preferences, daily routine, lifestyle and local weather conditions.

Apple Watch Series 5

Smart thermostats connect to your smart home network (such as to your Alexa/Echo Dot) or to your smartphone, laptop, tablet or Apple Watch to allow you to monitor and make adjustments to the temperature in your home. Through the smart thermostat’s companion application, the user can create schedules for heating and cooling to ensure that the air conditioning operates according to their preferences. 

Many smart thermostats also feature sensing capabilities so that the AC can be turned off automatically when no one is home. Some also feature the ability to adapt to your schedule and heat or cool your house only when you’re home, which offers a level of convenience and efficiency that traditional programmable thermostats can’t. 

For example, a smart thermostat can learn that you come home at 5 p.m. every day and adjust your HVAC to ensure your home is at a comfortable temperature when you arrive. Some smart thermostats can also automatically turn off your heat or AC when you depart each day without requiring you to remember to do so manually. 

What features do smart thermostats come with? 

Each smart thermostat company and model offers its own set of features. Here are some of the most common smart thermostat features: 

  • Has the ability to set heating and cooling schedules.
  • Has the ability to learn your schedule and detect when you are home to adjust its temperature settings accordingly. 
  • Monitor and control your device from anywhere using mobile apps on your mobile device or computer, sometimes with the ability to set email alerts.
  • Regular in-depth energy consumption reports with suggestions for reducing consumption.
  • Has the ability to integrate with your existing smart home system.

How can a smart thermostat save me money?

Some manufacturers indicate that smart thermostats can save you up to 25% on utility bills by significantly improving your HVAC’s performance and reducing energy consumption. Smart thermostats accomplish this by ensuring your heat and AC are only running how and when you want them.  

One way smart thermostats save you money is by allowing you to monitor and make adjustments to temperature settings remotely. If you were to forget to turn off your heat before leaving for work, for example, you could quickly solve this without returning home through your smart thermostat’s companion app. 

Another way a smart thermostat can save you money is through scheduled heat and cooling programs. You can set a schedule for your thermostat and choose a thermostat with learning capabilities. These features allow you to heat or cool your home only when you’re in it.

Honeywell Home WiFi Thermostat

Many smart thermostats such as the Nest Learning Thermostat or the Honeywell Home WiFi Thermostat generate regular reports on your energy usage and heating and cooling patterns. By reviewing your usage data regularly, you can make informed decisions about how you’re consuming energy. 

What do I need to consider when choosing a smart thermostat? 

Existing HVAC system

It’s essential to ensure that the smart thermostat you buy is compatible with your home’s HVAC existing system. Many popular smart thermostat models include compatibility checkers on their websites. 

Smart thermostats often require a C-wire, enabling the continuous flow of power to the thermostat. This is necessary for features like Wi-Fi connectivity and touch screens. Some thermostat ports aren’t equipped with C-wires because many older thermostats don’t require them.

ecobee3 Smarter Wi-Fi Thermostat with Remote Senso

If you don’t have a C-wire, you can hire an electrician to install one. You can also consider choosing a smart thermostat designed to work without a C-wire, such as the ecobee3 or Emerson Sensi. Alternatively, you can buy a C-wire adapter that you can install near your HVAC unit’s control board.

Compatibility with your existing smart home system 

If you already have smart home devices, be sure to select a smart thermostat that is compatible with your system. 

Google Nest Learning Thermostat

For example, if you currently use Apple HomeKit, you should select a model you can control from the platform, such as the Carrier Cor, the Hive or many others. For an IFTTT smart home system, you should consider the Google Nest Learning Thermostat

What you need to buy to go with your smart thermostat

Ecobee SmartSensor 2 Pack 

Ecobee SmartSensor 2 Pack 

These sensors work with the Ecobee Smart Thermostat (be sure to select sensors compatible with your smart thermostat). Detect motion to adjust the temperature in rooms that are in use and save energy when you’re not at home.

Where to buy: Sold by Amazon and Home Depot

Nest Thermostat Wall Plate

Nest Thermostat Wall Plate

Match your Nest Thermostat to the other design elements of your living space to create an aesthetically pleasing, cohesive setup. Wall plates come in a variety of colors including white, silver, black and bronze.

Where to buy: Sold by Amazon


Evelyn Waugh is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money.

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