Smart Thermostat Buyer's Guide

Smart Thermostat Buyer's Guide

What Makes Smart Thermostats So Smart?

Smart thermostats are loaded with features that make it easy to save energy and money. They eliminate confusing programming, adapt to occupants' preferred heating and cooling schedule, and can be controlled from anywhere using a smart phone.

Smart Thermostat Features

Many smart thermostats share the following features. Learn more about the specifics of each thermostat through the content below and on the associated product pages.

• Learning Ability: Thermostats with learning ability will automatically adjust settings based on behavior and the actual performance of the heating/cooling system, resulting in increased savings over time
• Occupancy Sensing: Thermostats with occupancy sensing technology go into an energy-saving mode when no one is present, so it is no longer necessary for the thermostat to be adjusted when people leave. Occupancy sensors may be integrated with the thermostat, or separate devices able to be located elsewhere, depending on the model
• Geofencing: Geofencing uses the connected smartphones to determine when people are away, applying ]thermostat adjustments accordingly. When people are away, energy-saving mode is enabled. When people return, your thermostat returns to the desired set-point
• Remote Sensors: Remote temperature sensors allow the thermostat to determine the temperature in the rooms where the sensors are placed, not just where the thermostat is located. This helps customize comfort in every room. Sensors are generally sold separately, but some thermostats include a remote sensor
• App Alerts: When connected to a thermostat's app, people can receive helpful reminders and alerts through their phone. People can be reminded when it's time to replace the furnace/air conditioning filters or be notified when extreme temperatures are sensed, which could be an indication that the furnace is malfunctioning
• Energy Reports: Energy usage reports show you how much energy has been used, and often offers suggestions on how to use less
• ENERGY STAR® Certified: ENERGY STAR certified thermostats have been independently certified to deliver energy savings. These are often the most advanced of the Wi-Fi thermostats and include top-of-the-line features to help people manage their energy use

Learning Thermostats vs. Wi-Fi Thermostats

While all Learning Thermostats are Wi-Fi Thermostats (aka Connected Thermostats), not all Smart Thermostats are Learning Thermostats. Smart Thermostats will include the most common features, such as the ability to control from a smart phone, but more advanced Learning Thermostats will automatically apply adjustments over time based on occupants' behavior and the actual performance of the central heating/cooling equipment.

C-Wires: What is a Thermostat C-Wire?

You may have heard the term, you may have heard you may need one, but what exactly is a C-wire? C-wire stands for Common-wire, and despite its name, it is not exactly a household term (unless you are an HVAC professional). C-wires are sometimes required to ensure proper smart thermostat operation and functionality, providing the thermostat with continuous power through the wires connected to the heating/cooling equipment.

Why do some Thermostats require a C-Wire?

While conventional mechanical thermostats do not have any components requiring power, and while conventional programmable thermostats can run off replacable batteries, all smart thermostats cannot. This is because most of their cool features (Wi-Fi connectivity, self-programming, colorful touchscreen displays...) use power.  Providing continuous power to the smart thermostat through a C-Wire will ensure the smart thermostat's display, internal processor, and Wi-Fi connectivity are up and running 24/7.

How to Identify a C-Wire
You may be surprised to learn that many older homes are not equipped with C-wires. To determine if your current thermostat is using one, do the following:

1. Shut off the power to your thermostat by shutting off the circuit the HVAC system is on
2. Remove the thermostat from the wall
3. Check out the wiring. If there is a wire in the C-terminal, you are good to go
4. If you don’t see a wire in the C-terminal, you may have one hidden behind the wall that is currently not being used, so double check

Missing a C-Wire? Here's What to Do.

Missing a C-wire and your smart thermostat requires one? Not all hope is lost. There are two workarounds - use an adapter or have a C-wire installed.

Option 1: Use a C-wire Adapter*
If you don’t see a wire in the C-terminal, you may be able to use a C-wire adapter.* Made specifically for smart thermostats, a C-wire adapter will repurpose the existing wiring between the thermostat and the heating/cooling system to provide necessary power to the thermostat. Some thermostat models include an adapter, but if yours does not, they may be purchased separately.

Option 2: Install a C-wire*
Altrnatively, a dedicated C-wire can be installed. This is typically a simple and straightforward job for a professional.

Electrical work is not for the faint of heart! If you are not completely comfortable with this process, please consult an HVAC professional for help.

*Be sure you do not have thick, black wiring connected with nuts, or wires labeled 120V or higher. This means you likely have line voltage heating, which is not compatible with most smart thermostats.

How Do Smart Thermostats Help Save?

Smart thermostats can help you lower your energy use, which saves you money and decreases your environmental impact.

According to ENERGY STAR®, a smart thermostat can reduce heating and cooling costs by about 8-20% per year (source: energystar.gov). Actual savings may vary depending on climate, personal preferences, characteristics of the building, and local energy prices, but given that for most U.S. households over half of their energy use is for heating and cooling, these savings can be significant.

How Smart Thermostats Can Improve Your Quality of Life

Whole Home Monitoring can monitor your heating and cooling needs with simple programming, keeping your home at the optimal comfort level for your family.

Comfort & Savings: Lower energy bills means more money in your wallet to spend on things you want, not the things you need.
Form AND Function: You can have both. Smart thermostats are sleek and loaded with sophisticated features.
Smaller Carbon Footprint: An increasingly important goal for every indivicual and business.

Manufacturer Resources

Our product partners offer detailed product information on their websites.

Google Nest

Honeywell Home

ecobee

Sensi

_{Disclaimer: The content presented on this page was prepared by the individual(s) listed below, and does not necessarily reflect the views of the company or companies utilizing this site.}

_{Contributors: Al Nadeau, Philip Scarbro, September 12, 2024}

_{© 2025, AM Conservation Inc., All Rights Reserved.}