Presence Sensor Fan Control

Ever wish your fan could just know when you’re in the room? This project uses a presence sensor to detect if someone is there and automatically turns the fan on or off. Unlike a typical PIR motion sensor, this one uses Doppler radar technology—meaning it can sense movement and presence without needing a direct line of sight. It’s so sensitive, it can even detect you while you’re sleeping.

Not only does it add comfort, but it also saves electricity by shutting the fan off when the room is empty. My wife called it “the laziest automation so far”… until she realized it was actually saving energy (and me from forgetting to turn the fan off).

📐 Project Diagram

Notes:

• Warning be prepared to spend a lot of time honing this between the sensor placement and the app settings.
• The diagram Google home is connected to a smart plug.
• The Zigbee hub is a device paired into Google Home automation (Tuya or Smart Life).
• The presence sensor detects if someone is in the room or not.
• The Zigbee hub receives the sensor signal and passes it to the Smart Life (Tuya) integration paired with Google Home.
• Google Home processes the signal and triggers the smart plug on or off.
• The fan turns on or off depending on the smart plug state.
• You have to set up the automation in Google Home / Smart Life.
• The sensitivity of the presence sensor may need adjustment for optimal performance.
• Set the sensor to detect timeout (Lack of movement) after a certain period.
• The plug/fan also works using Google Assistant voice commands.

🧰 Parts List

• Presence sensor (e.g., cogae Tuya ZigBee MmWave Human Presence Sensor).
• Smart Life app (Android) — Tuya works similarly.
• Zigbee hub compatible with Google Home (mine is an “M6 Matter & Zigbee Hub”).
• Everyday Fan.
• Smart plug (e.g., Kasa Smart Plug Mini by TP-Link).
• Google Home / Nest speaker or display.

💡 Code

No code required. Set up the automation in Google Home / Smart Life.

🔍 How It Works

When the presence sensor detects someone in the room, it sends a signal to the Zigbee hub, which relays the state to your Smart Life ↔ Google Home setup. Google Home then toggles the smart plug controlling the fan, giving you instant comfort without lifting a finger.

So if I walk into the room and the fan is running, I know the sensor has detected me. When I leave, it shuts off automatically to save energy.

I use it in my bedroom and it works like a charm! Even knows presence when I'm sleeping.

This project is a great example of how smart home devices can work together to create a more comfortable and energy-efficient living space.