ecobee3 Thermostat with Sensor, Wi-Fi, 2nd Generation, Works with Alexa Works with Alexa for voice control (Alexa device sold separately). Smart, really smart - intuitively understands when to turn on your heating or cooling equipment based on your home's unique energy profile, the weather outside, and thousands of other data points to make sure you're comfortable at all times Knows you have a life - senses whether anyone's home and which rooms are occupied, delivering comfort when you're at home and saving you energy and money when you're not Lowers your energy bills - ecobee saves homeowners an average of 23%* annually, paying for itself in energy savings (*Learn more at ecobee.com/savings)