Best Smart Thermostat to Save Money (Ranked by Payback)

ENERGY STAR certified models all reach similar savings, more than 8% on average. The one that saves you the most net money is the cheapest one that works with your wiring and system, because it pays back first.

At ENERGY STAR's average savings ($72 a year on $900 of heating and cooling), the thermostats in this guide pay back in about 14 months (Amazon Smart Thermostat) to 3.3 years (ecobee Premium), then keep saving.

For savings, either. Pick on ecosystem and wiring: ecobee works with HomeKit, Alexa and Google and includes a C-wire adapter; Nest is built for Google Home, and the 4th gen Learning model runs without a C-wire in most homes.

ENERGY STAR says certified smart thermostats save more than 8% of heating and cooling costs, about $50 a year for the average household. On ENERGY STAR's $900 average heating and cooling spend, 8% is $72 a year. Adding DOE's 7 to 10 F setback for 8 hours a day can raise savings to as much as 10%, or $90 on the same $900.

At $72 a year in savings: the Amazon Smart Thermostat in about 14 months, the Nest Thermostat in about 17 months, the ecobee Enhanced in about 2.5 years, the Nest Learning Thermostat (4th gen) in about 3.1 years and the ecobee Premium in about 3.3 years. Payback is price divided by yearly savings, so a home with bigger heating and cooling bills pays back proportionally faster.

The ecobee Enhanced and ecobee Premium include a Power Extender Kit, and Google says the Nest Learning Thermostat (4th gen) needs a C-wire or its Power Connector in under 1% of installs. The Amazon Smart Thermostat needs a C-wire or an adapter sold separately. To check, remove the old thermostat and look for a wire on the terminal marked C.

Yes, as long as it is set up for your heat pump and its auxiliary heat, but skip deep setbacks. DOE warns that a big setback in heating mode can make a heat pump run inefficiently and cancel the savings, so plan on ENERGY STAR's 8% average rather than the 10% setback figure. Some heat pump and dual-fuel systems need the Nest Power Connector to run the Nest Thermostat.

Not the models in this guide. They are low-voltage (24 V) thermostats for furnaces, central air and heat pumps, and the Amazon Smart Thermostat is specifically not for electric baseboard heat. Baseboard heaters run on line voltage (120 or 240 V) and need a line-voltage thermostat.

Both, depending on what heats and cools your home. With a gas furnace, the heating savings show up on the gas bill and the cooling savings on the electric bill. With a heat pump or electric furnace, both land on the electric bill. ENERGY STAR's more than 8% average applies to the combined heating and cooling cost.

Yes. It is set up and controlled through the Alexa app and Alexa devices, so it suits homes that already use Alexa. For Apple HomeKit or Google, the ecobee Enhanced works with HomeKit, Alexa and Google, and the Nest models are built for Google Home.