Building a chair occupancy sensor using an Aqara window sensor

Disclosure: This post contains affiliate links. If you click through and make a purchase, I will earn a commission, at no additional cost to you. Read my full disclosure here.

A digital illustration of a woman sitting on a chair at a desk. Behind her is a window through which a city can be seen.

Are you spending an excessive amount of time sitting at your desk setting up new integrations for Home Assistant and writing firmware for ESP8266 nodes? Maybe it is time to build a chair occupancy sensor to track the exact amount of time you spend there. A chair occupancy sensor can help conserve energy by, for example, putting your PC into sleep mode when the chair is empty for over 30 minutes. Conversely, it can also keep the lights on while someone is sitting at the desk. At first, a chair occupancy sensor might seem like a novelty, but you will be surprised by the practical applications once you start thinking about it.

Making use of what you already have

The Home Assistant community is full of DIY enthusiasts, and member parrel is no exception. They decided to build a chair occupancy sensor using a combination of an Aqara Window/Door Sensor and a car seat pressure sensor. This project is perfect for those who love to tinker and create their own smart home solutions.

Thanks to the use of a Zigbee sensor, the chair occupancy sensor is wire-free and can run for several months on just one coin-cell battery. And the best part? You can order all the components directly from China for a total cost of only around US$10. So, if you're looking for a budget-friendly and creative way to build your own chair occupancy sensor, look no further.

Hardware you need to build the chair occupancy sensor

If you are ready to take on this DIY project, you will need a few key components. First and foremost, you will need the Aqara Door and Window Sensors and a car seat pressure sensor. To connect the reed switch to the wires from the pressure sensor, you will also need a soldering iron and some solder.

This project is a great opportunity to get creative and build a functional and useful tool for your home. With just a few key components and a bit of soldering know-how, you'll be well on your way to creating a chair occupancy sensor that works seamlessly with your Home Assistant setup.

The simplicity behind the chair occupancy sensor's functionality

The Aqara Door and Window Sensor used in this chair occupancy project utilizes a reed switch as its core electronic component, with a magnet serving as its smaller counterpart. When the magnet is near the reed switch, the contacts in the switch close and complete the circuit, indicating that the window or door it is attached to is closed. However, in the chair occupancy sensor, the magnet is no longer necessary and can be saved for other projects or even used on your refrigerator.

To bypass the reed switch, the wires from the car seat pressure sensor are attached to either end. You can even opt to remove the reed switch entirely. Instead of relying on a magnet to close the circuit, the chair occupancy sensor uses the car seat pressure sensor to do so. Simply insert the sensor into your chair and you are all set!

An isolated image of a car seat pressure sensor. Attached to the sensor are a red and black wire.

Keep in mind that soldering the wires from the car seat pressure sensor to the Aqara Door and Window Sensor is required for this project. But besides that, it's a straightforward and uncomplicated process. So, if you're ready to enhance your smart home with a functional and efficient chair occupancy sensor, get started now! If you want to skip the soldering entirely, I have created an alternative to this project that only requires a screwdriver.

Frequently asked questions

Can I hurt myself attempting this project?

While you are unlikely to shock yourself with the battery, I recommend removing it before any solder, as the heat might damage it. I expect you to be aware of the risks and dangers when soldering, and do not take any responsibility for any damages or issues that may arise from following the guide.

Does it matter to which ends I attach the red and black wire?

Just make sure one wire is attached to either end of the reed switch. Polarity doesn't matter.

A portrait photo oif Liam Alexander Colman, the author, creator, and owner of Home Assistant Guide wearing a suit.

About Liam Alexander Colman

is an experienced Home Assistant user who has been utilizing the platform for a variety of projects over an extended period. His journey began with a Raspberry Pi, which quickly grew to three Raspberry Pis and eventually a full-fledged server. Liam's current operating system of choice is Unraid, with Home Assistant comfortably running in a Docker container.
With a deep understanding of the intricacies of Home Assistant, Liam has an impressive setup, consisting of various Zigbee devices, and seamless integrations with existing products such as his Android TV box. For those interested in learning more about Liam's experience with Home Assistant, he shares his insights on how he first started using the platform and his subsequent journey.

Leave a comment

Share to...