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Smart HVAC systems change household energy use by giving homeowners more control over when heating and cooling runs, how it responds to occupancy, and how its operation is monitored. A smart thermostat uses little energy itself; its potential impact comes from controlling equipment that uses far more. ENERGY STAR says heating and cooling account for nearly half of the average American household’s annual energy bill—more than $900 a year—but that national context is not a savings forecast for any one home.
What makes HVAC control “smart”?
A connected thermostat can let you adjust settings remotely, create schedules, and use occupancy or geofencing features to change settings when people leave or return. Some provide feedback about HVAC operation or can participate in a utility demand-response program. The specific features depend on the thermostat, its sensors, the HVAC system, and the services you choose to enable.
That changes how a household makes control decisions: adjustments need not happen only at the wall thermostat, and routines can be automated rather than managed manually. A thermostat may also be one component of a broader home energy management system that schedules or coordinates connected devices.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsHow can smart controls affect energy use?
The thermostat’s main energy effect is indirect: schedules, occupancy responses, and other control settings can change how long the heating or cooling equipment runs. ENERGY STAR’s certification criteria evaluate runtime in field data. They require an annual heating-runtime reduction of at least 8% at the lower 95% confidence limit of the weighted national average, and at least 4% for the weighted national average of 20th percentiles. For cooling, the corresponding thresholds are at least 10% and 5%.
#1 Best Overall
- An Alexa thermostat - Amazon Smart Thermostat is an easy way to switch from a traditional thermostats for homes and help reduce energy usage.
- Create comfort zones throughout your home by connecting to select Alexa devices to automatically adjust heating and cooling based on temperature readings or presence detection.
- Save money and energy - After purchase, Amazon will send you an email with details about home thermostat rebates that may be available from energy providers in your area.
- Save energy - According to EPA estimates, ENERGY STAR certified thermostats save an average of $90 on yearly energy bills.
- Programmable thermostat and automatic control - Create your own home, away and sleep schedules, or have Alexa automatically control the temperature with Alexa+ advanced features.
These are certification thresholds for HVAC runtime, not a promise that every certified thermostat will cut every household’s bill by those amounts. Bills also depend on the home, its equipment, weather, energy rates, and how the controls are configured and used. See ENERGY STAR’s smart thermostat criteria for the methodology and current requirements.
Check compatibility before choosing a thermostat
Do not assume a thermostat will work just because a home has central heating or cooling. ENERGY STAR says most forced-air HVAC systems installed after 1975 are compatible, but that is only a rule of thumb. System type, wiring, power, and control configuration can change the answer.
Rank #2
- ENERGY STAR certified smart thermostat for home that helps you save energy and stay comfortable.Product note: You can also check your system’s compatibility before purchasing a Nest thermostat with our online Nest Compatibility Checker on the Google Nest support page.Connectivity Protocol : Wi-Fi.Connectivity Protocol : Wi-Fi
- The Nest Thermostat is designed to work without a C wire in most homes, but for some systems, including heating only, cooling only, zone controlled, and heat pump systems, you’ll need a C wire or other compatible power accessory. Lock feature: No
- Nest Thermostat turns itself down when you leave, so you don’t waste energy heating or cooling an empty home; easily program an energy efficient schedule in the Google home app on your Android or iPhone
- Remote control lets family members change the thermostat temperature from anywhere on a phone, laptop, or tablet[1]
- Savings Finder looks for more ways your thermostat can help you save, and suggests tweaks to your schedule in the app; check with your energy provider to learn more about rebates and more ways to save on a Nest thermostat
- Identify the equipment: Check whether the home uses forced air, a boiler, a heat pump, multistage or variable-speed equipment, or multiple zones. Line-voltage systems and some oil systems need particular attention.
- Check wiring and power: Confirm the thermostat terminals and whether the chosen model needs a C-wire. Some installations may use an adapter, but that is not universally required.
- Match system features: Verify support for the equipment’s stages, zoning, and control method. For high-efficiency or variable-capacity systems, ENERGY STAR advises considering a controller from the equipment manufacturer.
- Plan installation realistically: A manufacturer-matched control, additional wiring, or professional installation may be appropriate for some setups. If the system type or wiring is unclear, ask an HVAC professional to assess compatibility before buying.
- Check connectivity: The thermostat needs a reliable Wi-Fi connection. ENERGY STAR suggests considering a Wi-Fi range extender if the signal at its location is inadequate.
ENERGY STAR’s smart thermostat guidance is a useful starting point, but confirm compatibility against the thermostat maker’s requirements and the actual HVAC equipment.
Heat pumps need different settings advice
Do not automatically apply conventional-furnace advice—such as turning the temperature down whenever the home is empty—to every heat pump. ENERGY STAR recommends a steady temperature for heat pump operation and avoiding auto mode. It also advises using auto fan or a low fan speed as appropriate, cleaning filters when visibly dirty or when indicated, and getting contractor help to determine the right equipment size. The right control approach depends on the heat pump and its installation.
Rank #3
- PRIVACY PROTECTION*: Sensi won’t sell your personal information to third parties
- EASY DIY INSTALLATION: Use the built-in level and step-by-step app instructions for a quick installation. Works with HVAC equipment found in most homes. Common wire (c-wire) is not required in most applications
- SAVE ABOUT 23% ON HVAC ENERGY*: The ENERGY STAR-certified Sensi smart thermostat can help you save energy with features like flexible scheduling, remote access and usage reports
- SIMPLE CONFIGURATION: Looks and feels like a thermostat. Has buttons and fits the same space as a traditional thermostat so you don’t have to patch and paint your walls
- SMART MAINTENANCE: Sensi can help monitor the performance and efficiency of your HVAC system by delivering valuable usage reports, alerts about your equipment, and maintenance reminders like filter replacement
ENERGY STAR’s air-source heat pump guidance describes these operating recommendations.
Utility programs, privacy, and control
Some utilities offer incentives for eligible smart thermostats or invite customers to demand-response programs, where thermostat settings may be adjusted during periods of high demand. Availability, eligibility, and terms depend on the utility and location, so check current local program rules rather than assuming a rebate or enrollment option is available.
Rank #4
- EASY DIY INSTALLATION: Do it yourself fast with a built-in level and simple step-by-step instructions. Works with the HVAC equipment found in most homes
- COMMON WIRE REQUIREMENTS: Common wire(C-Wire) required for heat pump and heat/cool only systems. C-wire not required on most systems
- SAVE ABOUT 23% ON HVAC ENERGY: ENERGY STAR-certified and packed with features that help you save money, including flexible scheduling, geofencing, remote access and usage reports
- PRIVACY PROTECTION: Sensi won’t sell your personal information to third parties or leverage your thermostat activity data for targeting or advertising purposes
- CONTROL FROM ANYWHERE: The top-rated mobile app for Android and iOS devices makes it easy to control your comfort from a smartphone or tablet
ENERGY STAR says utility participation is permission-based and certified thermostats must allow users to override utility requests. Connected devices may send information to service providers, so review the thermostat provider’s privacy and data practices and the terms of any utility program. ENERGY STAR / EPA notes: “EPA understands there can be security risks associated with smart products and systems.” Its connected functionality guidance explains considerations for connected products.
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A practical order for comparing options
- Start with the HVAC system. Identify the equipment type, stages, zones, and any variable-capacity features.
- Verify wiring and compatibility. Check the thermostat’s requirements for terminals, power, and any needed adapter or manufacturer-specific controller.
- Compare useful controls. Decide whether remote adjustment, schedules, occupancy or geofencing, and additional sensors match how the household uses the home.
- Check certification and programs. Look for ENERGY STAR certification and verify current utility incentives or demand-response terms for the service address.
- Choose an installation path. Follow the manufacturer’s instructions if the system is a confirmed match; arrange professional assessment or installation when wiring or equipment compatibility is uncertain.
For a broader view of how devices can be scheduled together, see ENERGY STAR’s overview of smart home energy management systems. The U.S. Department of Energy has also described connected thermostats as a potential gateway to wider energy management, while the actual effect remains dependent on the household and equipment: Connected Thermostats Offer Gateway for Increasing Energy Savings.
Quick Recap
Best Value
- ENERGY STAR certified smart thermostat for home that helps you save energy and stay comfortable.Connectivity : Wi-Fi - 802.11b/g/n 2.4 GHz, 802.11a/n 5 GHz Wi-Fi., Wireless interconnect : Bluetooth Low Energy Please refer to the product description section below for all applicable legal disclaimers.Product note: You can also check your system’s compatibility before purchasing a Nest thermostat with our online Nest Compatibility Checker on the Google Nest support page
- The Nest Thermostat is designed to work without a C wire in most homes, but for some systems, including heating only, cooling only, zone controlled, and heat pump systems, you’ll need a C wire or other compatible power accessory
- Nest Thermostat turns itself down when you leave, so you don’t waste energy heating or cooling an empty home. Lock feature: No
- Programmable thermostat that lets you create an energy efficient schedule in the Google Home app on your Android or iPhone
- Remote control lets family members change the thermostat temperature from anywhere on a phone, laptop, or tablet[1]
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
