Smart home & connectivity

The light turns on when you enter the hallway. The heating warms up before you get home. What looks like magic is really a team of small devices talking to each other. A smart home is nothing more than a house full of sensors, rules and switches exchanging messages over radio. And as with every team, it is worth asking: who is actually talking to whom here, and about what?

Devices speak radio

For devices to talk to each other, they need a common language and a way to transmit it. Usually that is radio: you know Wi-Fi from your phone, and alongside it there are low power radio types like Zigbee or Thread, built especially for small battery powered devices. The messages themselves are short data packets, for example: motion detected, temperature 19 degrees Celsius, lamp on. Often a central unit, a so called hub, collects all messages and passes them on, like a post office for the whole house. If the radio does not reach the hub, there is a trick: Zigbee and Thread build a mesh network in which the devices in between pass the message along hop by hop until it arrives at its destination.

Sensor, rule, actuator

Almost everything in a smart home follows a single chain: a sensor measures something, a rule decides, an actuator acts. The motion detector in the hallway is the sensor. The rule says: if motion is detected and it is dark, then light on. The lamp is the actuator, the part that actually does something. Depending on the system, the rule lives in different places: sometimes in the hub at your home, sometimes on a server on the internet, in the so called cloud. Where it lives sounds like a detail, but it decides an important question later on.

What happens when the internet goes down?

Here comes the question: if the internet goes down, does your home still work? The answer depends exactly on where the rules live. If the rule runs locally on the hub, the outage hardly matters, the motion detector and the lamp talk directly over your home network. But if the rule lives in the cloud, every message first has to travel to a server somewhere in the world and back. Without internet it never arrives, and the light switch in the app stays dead. That is why smart home fans follow a rule of thumb: whatever can run locally should run locally.

Comfort versus data

A connected home is convenient, but it also watches you. The motion detector knows when you are home. The smart thermostat knows your daily rhythm, the voice assistant listens for its wake word and then sends recordings to the cloud. Each piece of information seems harmless on its own, but put together they form a precise picture of your daily life. So it pays to ask two questions about every device: which data leaves my house, and do I really need this convenience? Data thrift does not mean doing without, it means choosing consciously.