mmWave presence sensors for a smart home: choosing and setting one up

A standard PIR sensor detects motion through changes in infrared radiation. That is often enough for a hallway or storage room: someone walks through, the light turns on, and it switches off after a pause. But if a person sits almost still for a while, such as at a desk, a PIR sensor may decide the room is empty.

An mmWave sensor uses radio waves and can detect very small movements, including those of a person sitting quietly. That makes it worth considering for an office, living room, or other space where lights or climate controls should stay on while someone remains there. It does not automatically map perfect room boundaries, though: placement and zone settings matter.

Some sensors use mmWave for presence and PIR for quick motion detection when someone enters. Home Assistant describes this combination for the Everything Presence One and Pro models. It can be useful when lights should turn on right away but stay on while someone reads or works at a computer.

Before buying, decide which signals your automation needs: presence only, quick motion, illuminance, or temperature. For example, the Everything Presence One combines mmWave, PIR, temperature, humidity, and illuminance sensing. That feature set may be unnecessary for a simple hallway light.

A small room may only need a sensor with configurable zones. According to Home Assistant, the certified Everything Presence Lite can be configured with four zones and track up to three people. For a larger room or ceiling installation, consider the field of view, wired power options, and the data exposed to your smart-home system.

The Everything Presence Pro combines two mmWave radars, PIR, and wired Ethernet with Power over Ethernet through one cable. This can simplify installation where Wi-Fi is unreliable or a wired setup is preferred. Check whether you have a PoE switch or injector and a suitable cable route before choosing this option.

Start with one room and observe the sensor in ordinary situations: someone enters, sits down, leaves, and when the room is empty. Configure zones to cover the area you care about, then choose a delay before the lights turn off. A delay that is too short can be annoying, while one that is too long can leave lights on after everyone has left.

Everything Smart Home devices work with Home Assistant locally through ESPHome, without requiring a cloud connection. After pairing the device, check its presence state in Home Assistant before connecting it to heating, ventilation, or other important routines. Keep manual controls available if a sensor or network temporarily stops working.