For Best Energy Star Smart Thermostat – Top Picks & Guide, the practical answer is to start with HVAC and wiring compatibility, then choose the certified model whose controls and smart-home integrations fit your household. The Google Nest Learning Thermostat (4th gen) and ecobee Smart Thermostat Premium are two documented certified examples—not a complete market ranking or universal winners. Before buying, check your equipment, power wiring, and the current ENERGY STAR Product Finder.
What ENERGY STAR certification tells you
ENERGY STAR’s connected thermostat criteria evaluate both the in-home device and the service that supports it. Requirements address basic thermostat operation without provider connectivity, feedback about the energy consequences of settings, HVAC energy-use information, scheduling, and the ability to participate in utility programs intended to help prevent brownouts and blackouts while allowing residents to override requests. The criteria also set temperature-accuracy and standby-power limits and require field-savings analysis based on customer-home data. See the ENERGY STAR smart thermostat criteria.
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The criteria specify product-family annual HVAC runtime reduction thresholds: for heating, 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 field analysis, not a promise that an individual home will use less energy by those amounts or save a particular sum on bills.
Certification also does not tell you whether a thermostat will work with your particular furnace, heat pump, wiring, or accessories. Compatibility remains a separate purchase check.
#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
Two certified models to consider
These examples have support in official product information and the ENERGY STAR listing. They are not a tested head-to-head ranking, and they do not represent every currently certified thermostat.
| Model | Documented features | Key compatibility check |
|---|---|---|
| Google Nest Learning Thermostat (4th gen) | Google identifies the model as ENERGY STAR certified. Its published specifications describe multi-stage heating and cooling, heat-pump support, Matter and Google Home control, and power sharing designed to work without a C-wire in most homes. See Google’s specifications. | Google says a C-wire or Nest Power Connector is needed in some cases. Check the system with Google’s compatibility checker; do not assume the no-C-wire design suits every installation. |
| ecobee Smart Thermostat Premium | The ENERGY STAR Product Finder lists Smart Thermostat Premium, service model EB-STATE6*, as certified. ecobee lists Apple HomeKit, Amazon Alexa, Google Assistant, and SmartThings integration. See the ENERGY STAR product listing and ecobee product page. | ecobee specifies a dedicated 24VAC supply through a C-wire for Premium. Check your system against ecobee’s compatibility information before purchase. |
Will an ENERGY STAR smart thermostat work with your HVAC system?
Only if the model supports your system and its wiring. Identify the equipment and controls before choosing a thermostat; the ENERGY STAR label alone does not establish installation compatibility.
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.
- Identify your equipment. Note whether you have a conventional furnace or boiler, central air conditioning, a heat pump, multiple heating or cooling stages, or accessory controls such as humidification. If you are unsure, check the existing thermostat wiring and equipment documentation or ask an HVAC professional.
- Use the exact model’s compatibility checker. Google says Nest thermostats are designed for most 24 V systems but directs buyers to check compatibility. Use the manufacturer’s checker for your equipment rather than relying on a general claim about smart thermostats.
- Confirm wiring and power. Check whether a C-wire is present and what the selected model requires. ENERGY STAR notes that many, but not all, smart thermostats use C-wire power; some homes may need an adapter. Nest power sharing may work without a C-wire in most homes, while some installations require a C-wire or Nest Power Connector. ecobee Premium requires a C-wire. These power options are model-specific and should not be treated as interchangeable.
- Resolve uncertainty before ordering. If the checker flags your system, wiring is unclear, or the installation involves unusual stages or accessories, confirm the required thermostat and power setup with the manufacturer or a qualified installer.
Which features and ecosystem should you compare?
Choose features that match how your household actually operates the system. ENERGY STAR describes common smart thermostat capabilities, but exact features and implementations differ among models.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →- Control and scheduling: Decide whether remote app control, programmed schedules, or learning behavior is useful to you.
- Occupancy and energy feedback: Consider whether sensing that a home is occupied and seeing HVAC-use information will help you manage settings.
- Utility programs: Check whether you want demand-response participation. Program availability and terms depend on the utility; the criteria’s capability requirement does not mean every utility offers a program in every area.
- Smart-home integration: Match the thermostat to the devices and platform you already use. Google lists Google Home and Matter support for the 4th-gen Nest Learning Thermostat; ecobee lists Apple HomeKit, Alexa, Google Assistant, and SmartThings for Premium. Verify the functions you need in the product’s current specifications.
How to check price and local incentives
There is no single dependable national price or rebate amount in the available model evidence. Retail prices and utility incentives vary by model, location, and program terms. Check the current ENERGY STAR Product Finder for certified models, local pricing, and possible utility rebates, and confirm eligibility directly with your utility before counting an incentive toward the purchase. Google also notes that provider rebates or rewards may apply to its certified thermostat; availability and conditions depend on the provider and location. See ENERGY STAR’s Product Finder and Google’s Nest Learning Thermostat 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
Compare the full installed cost, not just the thermostat’s listed price: a wiring accessory or professional installation may affect the total, but only include an accessory after confirming that the exact model and your wiring require it.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to make the choice
Start with the compatibility checker and power requirements, then narrow by controls and ecosystem. If the Google model passes your system check and its Google Home or Matter support fits your setup, it is one certified option to investigate. If ecobee’s listed integrations suit your household and you have the required C-wire or a confirmed installation plan, Premium is another. For a broader choice, search the current ENERGY STAR Product Finder rather than treating these two examples as the entire certified market.
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.
