A smart home thermostat senses indoor conditions and controls connected heating or cooling equipment, adding connected features such as smartphone access, occupancy-responsive adjustments, energy tracking, or smart-home integration. The exact capabilities vary by model, and compatibility depends on your HVAC system and wiring.
What does a smart home thermostat do?
Like any thermostat, it monitors indoor conditions and signals attached heating or cooling equipment to maintain a target temperature. The “smart” part refers to capabilities added to basic temperature control. Depending on the model, these can include remote app control, occupancy or activity sensing, energy-use information, and communication with other devices or applications.
The U.S. Department of Energy (DOE) says smart thermostats can adjust based on occupancy or activity. That can help avoid heating or cooling an empty home, but not every model uses the same sensors or control methods.
How is it different from a programmable thermostat?
A programmable thermostat changes the temperature according to a schedule you set. A smart thermostat may add connectivity and respond to information beyond that schedule—for example, occupancy or activity—and may let you adjust settings from a smartphone or view energy information. A smart thermostat does not necessarily learn your habits, include remote sensors, or work with every smart-home platform.
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- Programmable thermostat and automatic control - Create your own home, away and sleep schedules, or have Alexa automatically control the temperature with Alexa+ advanced features.
| Capability | Programmable thermostat | Smart thermostat |
|---|---|---|
| Scheduled temperature changes | Yes; follows a set schedule. | May follow schedules, with additional features varying by model. |
| Occupancy or activity adjustment | Not identified as a typical programmable-thermostat feature in DOE’s comparison. | May adjust settings based on occupancy or activity. |
| Smartphone control | Not established by the DOE comparison as a standard feature. | May support remote control through an app. |
| Energy information or management | Not established by the DOE comparison as a standard feature. | May track or help manage energy use. |
These are category-level distinctions, not guarantees about a particular product. Check the manufacturer’s specifications for the features you need.
Can a smart thermostat save energy?
It can help reduce unnecessary heating or cooling when schedules, setbacks, or occupancy-aware adjustments better match how a home is used. But a smart thermostat does not guarantee lower bills: outcomes depend on weather, the HVAC equipment, software, the building, and occupant behavior.
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- 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
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- 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
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The DOE’s HVAC educational page says that if every home used a smart thermostat, the country would save 56 trillion BTUs of energy per year. This is a DOE hypothetical, not a measured saving for an individual household or a promise about current products. The page does not state a publication year in the retrieved material.
Estimating savings is also complicated by equipment differences. In a benchmarking project covering FY2023–FY2025, DOE discussed how newer multispeed HVAC systems make it harder to use equipment runtime alone as a measure of energy use. A device reporting runtime or energy information therefore should not be treated as proof of a particular bill reduction.
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- 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]
Will one work with your HVAC system?
Compatibility depends on the heating and cooling equipment and the home’s wiring. Heat pumps and dual-fuel systems have particular control considerations, so do not assume a thermostat supports them just because it supports a conventional heating or cooling system.
- Identify the HVAC system type, including whether it is a heat pump or dual-fuel system.
- Check the thermostat manufacturer’s compatibility guidance for that system and the home’s wiring.
- If the wiring is unclear or the system has specialized controls, consult the manufacturer’s installation guidance or an HVAC professional.
DOE provides specific training material on heat-pump and dual-fuel thermostat controls; system setup is also relevant to evaluating thermostat performance.
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- 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
What should you compare between smart thermostats?
Compare the areas that affect whether a thermostat can work in your home and provide the features you want:
- HVAC support and wiring: Confirm system compatibility before considering convenience features.
- Sensing and control: Check whether it uses occupancy or activity information, supports remote sensors, or relies mainly on schedules. Sensor availability varies.
- Apps and integrations: Verify remote access and compatibility with the smart-home devices or applications you use; integration is not universal.
- Energy reporting and utility programs: Look for the specific reporting or energy-management functions offered, and verify local program availability and terms separately.
- Installation and connectivity: Check installation requirements and which features depend on an internet connection or ongoing data exchange.
What are the privacy and connectivity trade-offs?
Remote access and energy-management integrations rely on data exchange. DOE’s connected-thermostat report identifies data access, privacy, and cybersecurity as considerations, alongside potential home-energy-management and demand-response functions. Review a product’s privacy information and connected-service requirements before enabling features that share data. Demand-response participation and utility programs depend on local availability and program terms.
Quick Recap
Sources
- DOE, Programmable Thermostats
- DOE Building Science Education, What Is a Smart Thermostat?
- DOE, Connected Thermostats (December 21, 2016)
- DOE, Connected Thermostats Report
- DOE, Smart Thermostat Field Study
- DOE, Heat Pump and Dual Fuel Thermostats
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