Presence sensor FAQs from hotel and commercial buyers

A presence sensor is a device that detects whether a person is in a room, even when the person is sitting still or asleep. Unlike a motion sensor (PIR), which only reacts to large movement, a presence sensor uses mmWave radar to sense micro-motion such as breathing and chest movement — so it never falsely reports an occupied room as vacant. Read our [in-depth guide](/blog/presence-detection-sensor-ultimate-guide/) for the full mechanism.

A mmWave presence sensor emits 24 GHz radio waves and reads the reflections to detect human micro-motion — chest movement, gestures, and even breathing. The sensor processes the signal in real time to report occupied or vacant room status, with adjustable sensitivity and detection range up to 2.5 meters. See our [technical guide](/blog/mmwave-radar-presence-detection-guide/) for the full signal-processing breakdown.

PIR sensors only trigger on large motion and miss stationary occupants — they often report a sleeping guest or a person reading as vacant. mmWave presence sensors detect micro-motion including breathing, so they report true occupancy. For hotel rooms, smart offices, and bathrooms where a stationary person matters, mmWave is the right choice. Our [detailed comparison](/blog/mmwave-vs-pir-presence-detector/) covers the seven criteria buyers evaluate.

Common use cases include hotel room occupancy (energy saving, housekeeping status, do-not-disturb logic), smart offices (lighting and HVAC tied to real presence), bathrooms (auto light and fan), meeting rooms, and any space where knowing true occupancy matters more than detecting motion. See our [hotel occupancy solution](/solutions/hotel-room-occupancy-sensor/) for a hospitality roll-out example.

Zigbee and Matter are best for low-power mesh networks in hotels and large offices (no hub rewiring, battery-friendly). Wi-Fi is simpler for residential or small deployments where you already have strong Wi-Fi coverage. Our ceiling presence sensor ships in all three protocols so you can match your existing gateway without replacing infrastructure. Start with the [Zigbee model](/products/ceiling-presence-sensor-zigbee/) for the most common hotel deployment.

We are the OEM/ODM manufacturer — every presence sensor is designed and built in-house at our Shenzhen facility. You buy direct from the factory, with full support for custom firmware, branding, and packaging for hotel or commercial rollouts. See [our hotel solution](/solutions/hotel-room-occupancy-sensor/) for a real-world deployment, or contact us for sampling (3-5 days) and mass production (7-10 days).