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If you’re searching for the “Best Energy Star Smart Thermostat – Top Picks & Guide,” the most useful answer is to start with your HVAC system and wiring, not a universal winner. The Google Nest Learning Thermostat (4th gen) and ecobee Smart Thermostat Premium are two documented ENERGY STAR-certified examples, but their power requirements and smart-home integrations differ. Check your system with the manufacturer’s compatibility tool before choosing.
What ENERGY STAR certification tells you
ENERGY STAR’s connected-thermostat criteria apply to both the thermostat in the home and the service that supports it. Among other requirements, a certified product must support basic thermostat operation if the provider’s service is unavailable, provide feedback about the energy consequences of settings, show information about HVAC energy use, support scheduling, and be capable of participating in utility programs intended to help prevent brownouts and blackouts while allowing residents to override requests. The criteria also include temperature-accuracy and standby-power limits and require field savings analysis using customer-home data. ENERGY STAR’s smart thermostat criteria
The criteria specify annual HVAC runtime-reduction thresholds for a product family: heating must meet 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%. These are certification criteria based on defined measures, not a promise that a particular household will reduce runtime or utility bills by those amounts.
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Two certified models to consider
These models are examples supported by the available manufacturer and ENERGY STAR information, not a complete list of certified thermostats or a comparative test ranking. Use the ENERGY STAR Product Finder to check the current certified roster.
#1 Best Overall
- Save up to 23% every year on heating and cooling costs, adjusts to your set schedule to save energy when you’re gone and optimize comfort when you’re home. Compared to a hold of 72
- Compatible with 85% of systems, check your system’s compatibility with our online ecobee Compatibility Checker on the ecobee support page
- Change your temperature by easily tapping the color touchscreen or using the ecobee app. Plus, free software upgrades ensure you get the best out of your Smart Thermostat Essential, for years to come
- Automatically adjusts to your set schedule to save energy when you’re gone and optimize comfort when you’re home. Keep track of your energy consumption when you're on the go on the ecobee app
- Easy DIY install. No C Wire, no problem. Get the ecobee Power Extender Kit (PEK) for homes without a C-Wire and keep your walls looking nice with our trim kit – both sold separately
| Model | Supported features | Power and compatibility point |
|---|---|---|
| Google Nest Learning Thermostat (4th gen) | Google lists the model as ENERGY STAR certified and documents multi-stage heating and cooling, heat-pump support, and Matter and Google Home control. Google specifications | Google says power sharing is intended to work without a C-wire in most homes, but limited cases need a C-wire or Nest Power Connector. Check the system with Google’s compatibility checker. Google compatibility information |
| ecobee Smart Thermostat Premium | The ENERGY STAR Product Finder identifies Smart Thermostat Premium, service model EB-STATE6*, as certified. ecobee lists Apple HomeKit, Amazon Alexa, Google Assistant, and SmartThings integrations. ENERGY STAR product listing ecobee product information | ecobee specifies a dedicated 24VAC supply through a C-wire for Premium. Confirm compatibility with your equipment and wiring before purchase. ecobee compatibility checker |
How to choose the right thermostat for your home
1. Confirm HVAC compatibility
Identify your heating and cooling equipment, the number of stages it uses, and whether you have a heat pump or accessory controls. Then enter the system details in the manufacturer’s checker. Google says Nest thermostats are designed for most 24 V systems, but the checker—not the general statement—should guide your decision for a specific setup. Google compatibility information
2. Check the wiring and power requirements
Look for a C-wire and compare your wiring with the exact model’s requirements. ENERGY STAR notes that many, but not all, smart thermostats use C-wire power, and some installations may need an adapter. Nest’s power-sharing approach works without a C-wire in most homes, with limited exceptions; ecobee specifies a C-wire for Smart Thermostat Premium. Do not assume that a power accessory intended for one model will work with another. ENERGY STAR smart thermostat guidance Google compatibility information ecobee compatibility checker
Rank #2
- 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.
3. Choose the features you will actually use
Compare remote app control, scheduling or learning, occupancy sensing, HVAC energy-use feedback, and utility demand-response support. ENERGY STAR describes these as common smart-thermostat or certification-related features; the details and implementation vary by model. ENERGY STAR’s smart thermostat criteria ENERGY STAR smart thermostat guidance
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4. Match the thermostat to your smart-home setup
If you already use a preferred voice assistant or automation platform, verify support before buying. Google documents Matter and Google Home support for the 4th-gen Learning Thermostat; ecobee lists Apple HomeKit, Amazon Alexa, Google Assistant, and SmartThings for Premium. Check the manufacturers’ product information for the current details of integrations. Google specifications ecobee product information
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
5. Compare local total cost and incentives
Prices and utility incentives depend on model, location, retailer, and program terms, so there is no reliable universal price or rebate figure here. Check current listings and the ENERGY STAR Product Finder for local price and possible utility-rebate information. Google also notes that provider rebates or rewards may apply to its certified model; confirm eligibility and terms with the relevant provider. ENERGY STAR Product Finder Google product information
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Will an ENERGY STAR smart thermostat work with your HVAC system?
Certification alone does not confirm compatibility with a particular home. A thermostat may be certified yet still be unsuitable for your equipment or wiring. Check the system type, stages, heat-pump or accessory controls, and power requirements in the specific model’s compatibility checker before ordering. If the checker indicates a wiring or power issue, follow that manufacturer’s guidance rather than assuming a generic adapter will solve it.
Quick Recap
Best Value
- High use of the scheduling feature of the T5 thermostat saved customers between 8 and 16% on heating and cooling bills. Dollar savings range based on nationwide average annual single-family detached home's heat and cooling bills; actual savings varies based on consumption.
- Save Energy and Get Rewarded. Check with your energy provider about available energy savings rebates to save on your purchase. Plus, eligible customers can enroll in their local Utility's "DEMAND RESPONSE PROGRAM" which can reward you for allowing the utility to slightly adjust your AC or furnace temperature settings when there is high energy demand.
- 7-Day Flexible Scheduling or Location Based Temperature Control. It’s your choice. 7-day scheduling programs your thermostat. Geofence technology helps make you comfortable by using your smartphone’s location to know when you’re away and when you return.
- Auto Home and Away Mode. Enjoy ideal temperatures at home, then save when away.
- ENERGY STAR certified. Help save energy, track your heating and cooling with monthly energy reports and get personalized tips on reducing energy use.
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
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.
