Buyer's guide
What Is a Smart
Thermostat?
A thermostat that learns your schedule, responds to your voice, and trims your heating and cooling bill — without you touching the dial.
The basics
What makes a thermostat “smart”?
A smart thermostat replaces your existing thermostat and connects to your home Wi-Fi. From there, it can be controlled via a smartphone app from anywhere — not just by walking to the wall. Most models go further: they learn your heating and cooling preferences automatically, adjust based on whether anyone is home, and integrate with voice assistants like Alexa and Google Assistant.
The underlying hardware difference is significant. A conventional thermostat has a bimetallic strip or a simple temperature sensor and a timer. A smart thermostat has a microprocessor, an occupancy sensor, Wi-Fi or Zigbee radio, a color display, and in some cases a built-in Alexa speaker (ecobee) or Farsight display that shows the time and temperature from across the room (Nest).
The most commercially mature smart thermostats are the Google Nest Learning Thermostat (now in its 4th generation) and the ecobee Smart Thermostat Premium. Both are Matter-certified, meaning they connect to Alexa, Google Home, and Apple HomeKit simultaneously with no hub required.
For homes without central HVAC — apartments with mini-split ACs, older homes with radiators — a smart IR controller like the Cielo Breez Max adds Wi-Fi and app control to any unit that accepts a standard IR remote, at around $129.
Key features
What smart thermostats actually do
Every major smart thermostat includes these four capabilities. They are what separate them from a programmable timer thermostat.
Auto-learning schedules
Learning thermostats like Nest build a schedule automatically based on the temperatures you manually set over the first 1–2 weeks. No programming required — it infers your preferred temperature at each time of day.
Remote control
Adjust temperature from anywhere via the thermostat's app. Arrive to a pre-heated home after a late flight, or turn off the heat when you forget before leaving. Both Nest and ecobee apps work on iOS and Android.
Energy reporting
Smart thermostats log every heating and cooling cycle and show detailed energy history in their app. You can see exactly how long your HVAC ran each day, which weather events drove higher usage, and which schedule changes cut your bill.
Geofencing & presence
When your phone leaves a defined radius around your home, the thermostat switches to an energy-saving away mode automatically. When you return, it starts conditioning before you arrive. No manual mode changes needed.
Connectivity
Wi-Fi, Zigbee, and Z-Wave thermostats
The protocol a smart thermostat uses determines which hub (if any) you need and how deeply it can integrate with your smart home.
Wi-Fi (Matter)
Most commonThe Nest Learning Thermostat and ecobee Premium both connect via Wi-Fi and are Matter-certified. This means they work with Alexa, Google Home, and HomeKit simultaneously — no hub lock-in. Matter thermostats connect directly to your router.
Examples:
Google Nest 4th Gen, ecobee Premium
Built-in Zigbee
ecobee-specificThe ecobee Premium includes a built-in Zigbee coordinator — a feature unique to ecobee. This lets the thermostat act as a basic Zigbee hub for ecobee's room sensors and some third-party Zigbee accessories without needing a separate hub.
Examples:
ecobee SmartSensor, select Zigbee accessories
Z-Wave
Hub requiredZ-Wave thermostats (like the Honeywell T6 Pro or Sinopé TH1124ZB) require a Z-Wave hub — SmartThings, Hubitat, Homey Pro, or Home Assistant. In exchange, they offer the most reliable connectivity, lowest latency, and deepest hub automations.
Examples:
Honeywell T6, Sinopé TH1124ZB, CT100
Zigbee
Hub requiredZigbee thermostats pair with Zigbee hubs — the Amazon Echo Hub (built-in), SmartThings, Homey Pro, Hubitat, or Home Assistant. More brands available at lower prices than Z-Wave, with similar reliability and automation depth.
Examples:
Sinopé TH1124ZB, Stelpro KI, Centralite Pearl
Hub guide
Which hub works best with a smart thermostat?
Matter thermostats work without a hub. But pairing them with these hubs unlocks cross-device automations — adjusting temperature when a door is unlocked, or setting a scene that dims lights and adjusts heat simultaneously.
FAQ
Thermostat
Questions
Ready to pick a thermostat?
See our top-rated smart thermostats and the hubs that work best with them.