How to configure your smart thermostat to save the most money

It’s not as easy as wearing a puff jacket indoors, but it’s doable.

smart thermostat on a white wall
Saving money with a smart thermostat depends on a lot of factors, including the type of home you live in and your usage.Dan LeFebvre via Unsplash

The promise of smart home tech is based on convenience. Why get off the couch when you can automate your lights, TV, and other gadgets, or even turn them on with your voice? Smart thermostats go a step further, claiming they’re not only convenient, but that they’ll actually save you money in the long run. This may be true, but they aren’t magic bullets: to save money, you have to actually use them properly.

Companies like Nest claim you can save you up to 15% on cooling, and ecobee bets for an even higher 23%. But these savings highly depend on factors such as the size of your house, the type of insulating materials it was built with, your particular usage, and the kind of thermostat you're replacing. Ecobee's estimate comes from comparing smart thermostats to a straight temperature hold, while Nest's values are based off people who did at least some programming to their thermostats. (You can read Nest's white paper on smart thermostat studies here.)

There's a bit of debate on the internet as to whether these devices can actually save enough energy to make a difference in your bills, particularly when compared with programmable models. Some users report noticeable savings, while others claim smart thermostats are just fancy versions of already-available programmable models. As is often the case, the truth lies somewhere in between.

Here's the thing: programmable thermostats are a bit of a pain to use, and they only work if your schedule is extremely predictable and you stay on top of them regularly. If you're the kind of person who sets your schedule, sticks to it, and remembers to manually adjust your thermostat every time you deviate from that schedule, then you probably won't save much money with a smart thermostat. (You might save some time and brain power, though.) If you've sort of programmed your thermostat, but find it frustrating enough that you rarely futz with it, smart thermostats like the Nest, ecobee, or Honeywell T9 have a few automation features that may save you some dough.

Let it know whether you're home or not

young person going down the stairs
Heading out? With a smart thermostat you won’t have to worry about wasting money or energy.Samantha Gades via Unsplash

Most smart thermostats can detect when you’re home, so it can turn down the climate control and save energy when you’re away. Every thermostat has its own name for it, but they’re all very similar: the Nest calls it “Home/Away Assist,” while ecobee calls it “Smart Home/Away.” Typically, this setting uses a combination of the thermostat’s internal motion sensor with the GPS in your phone to detect whether you’re inside a certain perimeter—or, in other words, whether you’re home or not. For it to work properly, however, you’ll definitely want to link it to your phone and the phone of everyone living with you—otherwise, the thermostat may think that no one’s home when only you’re away.

This becomes more useful the more irregular your schedule is. For example, my wife stays home with our two young kids, so we can’t just program the thermostat to be off from 9 a.m. to 5 p.m.. But we can program it to turn off whenever she takes the kids out for the day, solely by virtue of whether her phone has left the premises. If you come and go at random times, that’s far more useful than a programmable thermostat. Heck, even if only your weekends are unpredictable, it’s a useful feature that can add up savings over time.

Use separate temperature sensors

pug puppy covered in a blanket on a bed
Sorry, buddy—maybe you’re just too small to fire up the thermostat sensor.Matthew Henry via Unsplash

Most homes don't have a consistent temperature throughout the structure. Our living room is always cooler than the office and bedrooms, which can be frustrating, since we need to account for those rooms when setting the temperature. Some thermostats, including the ecobee and Honeywell T9, support separate temperature sensors you can place around the house (the ecobee SmartThermostat comes bundled with one extra sensor, but you can buy more if you need them).

Since they also have occupancy sensors built in, they can determine whether someone is in a given room and adjust the temperature accordingly. So instead of cooling our whole house to make the hottest rooms livable at all times, the thermostat can just cool things down a little extra when I’m in the office, or when my son wants to play in his bedroom. And when we’re all in the living room, it won’t waste its energy cooling down those areas.

You can also use these sensors to heat and cool rooms on a schedule, meaning you can instruct your thermostat to cool the living room to 75 degrees Fahrenheit during the day, and the bedroom to 75 degrees Fahrenheit in the evening. However, the occupancy sensor is the more useful "smart" feature here, which is why I find Nest's temperature sensors a bit too limited. Still, it's better than a traditional programmable thermostat, so I'd recommend grabbing a couple temperature sensors for the rooms you often use if you have a larger home.

Create your own custom automation rules

modern glass building with a single window open
There’s always someone who doesn’t understand that’s either open windows or air conditioning, not both at the same time.Chris Barbalis via Unsplash

You'll find some useful automation features within the Nest, ecobee, and Honeywell apps, but they aren't the only ones you'll get with a smart thermostat. Using a service like IFTTT, you can create easy "if this, then that" rules that incorporate all kinds of other apps and services. For example, if your family tends to open the windows without regard for the thermostat (because they're monsters), you can stick a few sensors on the windows, and with the help of a smart home hub like Samsung SmartThings, set IFTTT to shut your thermostat off whenever the windows are open. That way, you won't end up accidentally cooling the whole neighborhood. (Talking from experience here.) If you have a security system that already works with IFTTT, you may not even need to buy new equipment to make this work.

You can see how this can get really powerful. If you have ceiling fans hooked up to a smart switch, you can set them to turn on at a certain temperature threshold, potentially saving you from turning the air conditioning on too early. A couple energy companies even work with IFTTT, allowing you to automatically adjust your thermostat during peak usage times when prices go up.

Monitor your energy usage over time

Smart thermostats can easily track your usage over time, providing detailed reports about your energy consumption, graphs of the temperature in your house compared to the outside weather, and so on. It’s easy to ignore these at first, but many users report the best energy savings by merely paying attention to these insights—you might realize that you’ve been running the air conditioning when it was only a couple degrees warmer outside, or that your home/away setting wasn’t working properly. Check in on these every month and you’ll get some recommendations on how you can save a couple more bucks.

Enroll in energy-saving programs

house on a green meadow with a wind turbine behind
Sure, you could install a wind turbine in your backyard, but there are certainly easier ways to save money and energy.Lukas Bieri via Pixabay

The above features are somewhat dependent on your schedule and your house. Some people may see minimal savings from using them while others may find they make a sizable difference. But no matter what your usage looks like, a smart thermostat might allow you to take advantage of energy-saving programs in your city that offer bill credits.

For example, San Diego Gas & Electric has a program that allows the company to remotely adjust your thermostat during times of particularly high air conditioning usage across the city. If you allow your house to be a bit hotter for a couple hours, you'll save money and help the city out. If you decide you just can't deal with it on a given day, you can just re-adjust the thermostat manually yourself. Here's the kicker: you'll still receive $50 cash back for each eligible smart thermostat you enroll, and another $25 if you stay enrolled until the program ends. (SDG&E says it has 20,085 customers taking part and has reduced energy consumption by 10 megawatts in a single day this year.) Obviously, the programs in your city will vary, but it's worth checking the website for your local utility provider to see what they have available.

Don't forget to take advantage of rebates

person counts 100 dollar bills
Some local programs will give you cash back when you enroll your smart thermostat. Yes, you read right—cash back.Sharon McCutcheon via Unsplash

Finally, many energy companies offer rebates on smart thermostats to encourage their customers to use them (and save energy). Here in San Diego, that rebate is currently $75. That means ecobee's more budget-focused ecobee3 Lite, which lists for $170 on Amazon, is really closer to $95 with a rebate—and if I enroll in SDG&E's Air Conditioning Saver program, it goes down even further to $45. That's a much more enticing price tag for the convenience alone, not to mention any savings I might get from the automation features.

At the end of the day, how much you save will depend entirely on your home, the type of heating, ventilation and air-conditioning system you have, as well as your habits before getting a smart thermostat. And depending on how your cooling system is set up, you may need a professional to run a common wire so it can receive power (the Nest claims it doesn't need one, but you should run one anyway). This labor could increase your initial costs, so you'll need to do a little math to see whether it's worth it for you or not.

Getting a smart thermostat isn’t guaranteed to save you money, but if you use it properly, you’ve got a pretty good shot at saving a few bucks—and it’s a heck of a lot easier to use either way. Just make sure you actually take advantage of its automation, rather than just using it as an expensive programmable thermostat.