Presence Detection in Home Assistant: What Actually Works

Why Is Presence Detection in Home Assistant So Hard?

Presence detection sounds simple: either someone is home or they are not. In practice, it is one of the messiest parts of any smart home because different automations need different kinds of presence. A geofence tells you whether someone is roughly within 100 to 300 metres of home. That is fine for arrival automations, but useless for turning bathroom lights off. A motion sensor reacts fast, but it loses you the moment you sit still on the sofa for 10 minutes.

That is why so many Home Assistant users get frustrated. A single method almost always fails somewhere. GPS drifts. Phones go into battery-saving mode. Wi-Fi trackers hang onto a device after you have left. PIR sensors only see movement, not actual occupancy. Bluetooth can be inconsistent through walls. The trick is not finding one perfect sensor. The trick is layering multiple signals so the weaknesses cancel out.

The best presence method for home/away is phone tracking, and the best presence method for rooms is mmWave. Once you accept that split, everything becomes much easier to design.

Which Presence Detection Methods Actually Work?

The Home Assistant companion app remains the baseline method for person entities. It uses GPS, Wi-Fi SSID changes, and background location updates to determine whether you are at home, work, or away. In 2025 it is far better than the old router-ping methods, but it still is not instant. Expect 30 seconds to 5 minutes depending on phone OS, battery saver settings, and how aggressively your phone sleeps apps.

Wi-Fi presence from UniFi, ASUS, TP-Link Omada, or router integrations is useful as a second signal. If Home Assistant sees your phone associated with the home SSID, that is a strong hint you are home. It is especially useful for confirming arrival faster than GPS alone.

PIR motion sensors still have value because they are cheap — often $15 to $30 for Zigbee models from Sonoff or Aqara — but they are not true presence sensors. Great for stairways, cupboards, and utility rooms. Bad for offices, living rooms, and bathrooms where you can sit motionless.

What Is the Best Home Assistant Presence Stack?

The best Home Assistant presence setup is:

• Layer 1: Home Assistant mobile app person tracking for each person
• Layer 2: Router or Wi-Fi integration for faster on-site confirmation
• Layer 3: mmWave presence sensors in key rooms
• Layer 4: Optional door/motion fusion for tricky spaces like bathrooms

This stack covers both macro and micro presence. Your home can know that Nick is arriving, that Nick's phone connected to Wi-Fi, and that someone is specifically in the office chair right now. That is the difference between a clever demo and a genuinely useful automation system.

A strong practical example looks like this:

• When person.nick enters the home zone, pre-cool the house if outdoor temperature is above 30°C
• When phone Wi-Fi connects, unlock the smart gate notification card and disable the alarm countdown
• When office mmWave detects presence for 20 seconds, turn on the desk lamp to 70%
• When office presence is clear for 8 minutes, turn everything off

Notice the timing. Fast-on, slow-off is one of the golden rules of presence automation. Turn things on in seconds, but delay turn-off by 5 to 15 minutes depending on the room. That reduces false offs dramatically.

Why Does the Aqara FP2 Stand Out?

The Aqara FP2 costs roughly $82 to $99, which is not cheap compared with a $20 PIR sensor. But it solves the core problem PIR cannot solve: detecting a human who is present but not moving. It uses 60 GHz mmWave radar to track micro-movements like breathing and posture shifts, so it can keep a room occupied even when you are reading, working, or watching TV quietly.

It also supports zone mapping. In the Aqara app, you divide a room into virtual areas such as sofa, desk, bed, and doorway. Home Assistant can then react differently depending on where you are. That means one sensor can replace several motion detectors in a medium-sized room.

The best room presence sensor is the Aqara FP2 because it combines stationary-person detection, zone logic, and fast response in a way PIR sensors simply cannot. Its main downside is setup. Placement matters. Mount it around 1.4 to 1.8 metres high with a clear view, and spend 10 minutes tuning zones. Once dialled in, it is dramatically more reliable than traditional motion-based lighting.

What Automations Benefit Most from Good Presence Detection?

The biggest wins come from automations where false negatives are annoying. Nobody minds tapping a light switch once in a hallway. People do mind a bathroom light turning off mid-shower or a study lamp going dark during a Zoom call.

Best use cases include:

• Office lighting: mmWave keeps lights on while you work at a desk for hours
• Bathroom occupancy: door sensor + presence prevents embarrassing light cutoffs
• Bedroom climate: detect bed zone occupancy to adjust fan or AC at night
• TV scenes: sofa zone presence can trigger dim lighting and media mode
• Home/away security: person + Wi-Fi confirmation reduces false alarm arming

If you want one automation to start with, make it this: use phone presence to switch the house to Home/Away mode, then use an FP2 in the living room or office to control lights intelligently. That single combo delivers most of the value with minimal complexity.

What Mistakes Should You Avoid?

The biggest mistake is trusting one sensor for everything. The second biggest mistake is turning things off too quickly. If a room clears, wait. In a bathroom, 3 minutes is often enough. In an office, use 8 to 15 minutes. In a living room, 10 minutes is usually safer.

Another mistake is exposing raw sensors directly into complex automations without helpers. Create template binary sensors such as binary_sensor.office_occupied or an input boolean like input_boolean.someone_home that combine several conditions. Cleaner logic is easier to debug later.

Finally, do not ignore phone battery settings. On both Android and iPhone, the Home Assistant app needs background location permission and battery optimisation disabled or relaxed. Otherwise your home/away state will always feel random.

Frequently Asked Questions

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