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A line up of white smart sensors on a green and yellow background.
Photo: Rozette Rago

How Sensors Make Smart Homes Smarter

If you’ve installed a couple of smart-home gadgets and found yourself thinking, “This whole thing isn’t really that smart, is it?” you may be right. Using your smartphone and an app to directly control your thermostat or turn off the lights does make life a little easier, but it’s just like using a fancy remote control. For a truly smart home, one that runs on autopilot, you need to use sensors.

Think of sensors as the eyes, ears, and even fingers of your house. They can detect the state or condition of things around your home—if a door or window is opening, if the room is hot or cold or the floor is wet or dry, or even if someone (or something) is moving around—and then alert you. Or (and this is where things get really smart) you can set your sensors to tell other smart devices how to respond.

For example, if a sensor notices that a room is too hot, it can tell your thermostat to run. Or you can have a sensor alert you if a door opens when no one is supposed to be home—and even phone the police. Or when anyone walks down the stairs after sunset, a sensor can tell the lights to turn on. The idea is that instead of you poking buttons on your phone or shouting at a speaker to get your smart home to do things, sensors can do it all for you. That’s the difference between a home with smart things and an actual smart home.

How to get started using sensors

Many sensors require the use of a smart-home hub or bridge, a device that connects wireless devices to each other and to the Internet (sensors are one of the main reasons smart-home hubs won’t die). Other sensors work directly with smart speakers or smart-home platforms such as Apple HomeKit. The variety of the hub you use determines what type of sensors can work in your home and what you can make them do. You can read our guides to using sensors with Alexa, SmartThings, and HomeKit for a deeper explanation, but the short version is: Alexa is a good, if limited, option; if you’re a smart-home veteran, hit up SmartThings; and if you are an Apple fan, HomeKit is an excellent choice. (Sorry, Googlers: For now, the Google Home system doesn’t do much with sensors.)

Wi-Fi–only sensors from the likes of Wyze, Stitch, and iHome are good for some limited scenarios—such as monitoring when doors and windows open or close—but because they can’t talk to many smart devices outside of their own ecosystems, they’re less useful. (It is possible to connect some Wi-Fi sensors to the rest of your smart home using IFTTT, but in our testing we’ve found that to be less reliable than using a dedicated hub.)

What can you use sensors for?

To keep tabs on young chicks, we used a sensor that would trigger a light and speaker if the temperature became too hot or cold. Video: Jennifer Pattison Tuohy

Sensors can directly address a problem you need to solve. For example, if you have an Airbnb rental and want to know when your guest arrives, put a contact sensor on the front door, and you’ll get a notification on your phone whenever it opens or closes (you may need to disclose the presence of the sensor to your guests). If you want to reduce your energy use, motion sensors can turn lights off when a room is empty. For someone caring for elderly parents, a motion sensor by their bed can send an alert when they get up in the morning.

Those are pretty straightforward uses—cause and effect, if you will. But you can also also put sensors to work in sophisticated ways that allow multiple smart devices to cooperate with each other. On a practical level, for example, you might install a light and temperature sensor by a large window to turn off a Lutron Caséta light switch when the sun is streaming in and to lower your smart shades so UV rays don’t damage your furniture. Or you could put a motion sensor by your front door that turns your Philips Hue lights on, adjusts your Nest thermostat, starts music playing from an Echo speaker, and preheats your smart oven when you arrive home after 6 p.m. on a weeknight. While all of this may sound like the sort of thing you’d see in a sci-fi movie, it’s actually really easy to set up in the devices’ apps.

I’ve been using sensors for a few years now, and I’ve come up with a smorgasbord of scenarios that make my home run more smoothly. A motion sensor by my bed turns on a kettle connected to a smart plug, starts playing my Alexa Flash Briefing, and turns the kitchen lights on one time if it senses motion between 5 a.m. and 7 a.m. (I have an erratic wake-up schedule.) After 8 p.m., the same sensor triggers Alexa to play a soothing playlist in my bedroom, turns the lights in the rest of the house off, locks the doors, and sets the bedroom lights to a warm level dubbed “sunset.” When I was raising baby chickens in my bathroom, a temperature sensor in their coop alerted me if they were too hot by turning a light red and then announcing over a smart speaker “Chicks are hot!” A similar sensor that communicates with my Rachio sprinkler controller now triggers sprinklers to turn on when the mercury hits 90—giving the chickens a cooling shower during their outdoor run.

If you’ve ever wished you had a spare pair of hands or an extra set of eyes to help you out around your home, consider adding smart sensors. And once you start, you’ll quickly find more and smarter uses for these tiny devices by tying your connected gadgets together and turning your remote-controlled home into a truly smart home.

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