How much can a smart thermostat save?

Published utility and manufacturer studies generally land in the high single digits to low teens as a percentage of heating and cooling spend, and only when setbacks are actually used. If you already set back manually every day, the saving is small — the value is automation.

Most learning thermostats want one for steady power. Many kits include an adapter, but check your existing wiring before buying. If your system has no common wire and no adapter option, a plain programmable thermostat is the safer purchase.

Is a ceiling fan cheaper than air conditioning?

Per hour, dramatically — a DC ceiling fan is typically tens of watts against hundreds or thousands for a compressor. A fan cools people, not rooms, so it works as a way to raise the thermostat setpoint, not as a replacement for cooling.

Are utility rebates available?

Often, but they vary by utility and change yearly. Search your utility's website for a thermostat rebate before you buy; we cannot verify what is available at your address.

Buying guide

Best smart thermostat for saving energy

Heating and cooling is usually the biggest line on a US energy bill, so this is the upgrade with the most room to move.

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A smart thermostat does not save energy by existing. It saves energy because it runs setbacks — a few degrees back while you sleep or while the house is empty — every single day, without anyone remembering to do it.

That is why our picks are judged on how reliably they automate setbacks and how clearly they report runtime, not on how many colours the screen shows. We also include two fans, because in cooling season a fan lets you hold the thermostat higher for a fraction of the wattage.

Last updated 2026-09-15. Savings ranges are estimates based on typical US usage and electricity rates. Your actual result depends on your habits, local rate and how much the device is used — nothing here is a guaranteed saving.

How we chose

Does it automate setbacks without daily fiddling?
Does it report runtime so you can see what changed?
Is installation realistic for a normal home (C-wire, fan-rated box)?
Is the price sane relative to the heating and cooling it controls?

We don't publish invented test data or guaranteed dollar savings. Where numbers appear, the arithmetic is shown so you can run it on your own bill.

Run your own numbers in the calculator

Questions people ask

How much can a smart thermostat save?: Published utility and manufacturer studies generally land in the high single digits to low teens as a percentage of heating and cooling spend, and only when setbacks are actually used. If you already set back manually every day, the saving is small — the value is automation.
Do I need a C-wire?: Most learning thermostats want one for steady power. Many kits include an adapter, but check your existing wiring before buying. If your system has no common wire and no adapter option, a plain programmable thermostat is the safer purchase.
Is a ceiling fan cheaper than air conditioning?: Per hour, dramatically — a DC ceiling fan is typically tens of watts against hundreds or thousands for a compressor. A fan cools people, not rooms, so it works as a way to raise the thermostat setpoint, not as a replacement for cooling.
Are utility rebates available?: Often, but they vary by utility and change yearly. Search your utility's website for a thermostat rebate before you buy; we cannot verify what is available at your address.

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