Presence Sensing: Complete Guide to Occupancy Detection Technology 2026

Presence sensing is the technology and practice of determining whether one or more human occupants are currently present within a defined space, including the case where the person is sitting motionless, lying down, or sleeping with no visible movement. Modern presence sensing systems use millimeter-wave (mmWave) radar technology at 60 GHz (57–64 GHz) with 7 GHz of bandwidth to detect the micro-Doppler signature of human breathing at 0.2–0.5 Hz from ranges of 6–8 meters, achieving a stationary-occupant true positive rate above 99% in controlled testing and above 95% in real-world deployment, with a false positive rate below 1% over a 24-hour period. Presence sensing is fundamentally different from motion detection, which uses passive infrared (PIR) sensors that can only detect moving occupants and are unable to detect a stationary person. Presence sensing is deployed in hotel rooms for housekeeping coordination and energy management, in offices for occupancy-based HVAC and lighting control, in healthcare facilities for fall detection and patient monitoring, and in residential smart homes for automated lighting and climate control.

This guide provides a comprehensive overview of presence sensing, covering the technology, the performance characteristics, the use cases, and the selection criteria for choosing the right presence sensing system for a specific application.

Presence Sensing: The Technology

The technology behind modern presence sensing is millimeter-wave (mmWave) radar.

Presence Sensing: mmWave Radar Basics

A mmWave radar presence sensing system emits a frequency-modulated continuous wave (FMCW) chirp that sweeps across a defined bandwidth (typically 7 GHz at 60 GHz) over a short period. The reflected signal from objects in the detection zone is mixed with a copy of the transmitted chirp, producing a beat signal whose frequency is proportional to the range of the target. By performing a Fast Fourier Transform (FFT) on the beat signal, the system can determine the range of every object in the detection zone with a resolution of approximately 2.1 cm.

The system then analyzes the phase of the beat signal across successive chirps to determine the velocity of the targets. A stationary person produces a beat signal with a slowly varying phase (due to the micro-motion of breathing), while a stationary chair produces a beat signal with a constant phase. By analyzing the phase variation (the micro-Doppler signature), the presence sensing system can distinguish a stationary human from a stationary object, enabling true presence detection.

Presence Sensing: Micro-Doppler and Breathing Detection

The micro-Doppler signature of human breathing is the key to detecting stationary occupants. The periodic motion of the chest wall during breathing (amplitude 5–20 mm, frequency 0.2–0.5 Hz) produces a Doppler modulation that is clearly detectable by a 60 GHz mmWave system with 7 GHz of bandwidth.

A well-designed presence sensing system uses signal processing techniques to extract the breathing signature from the radar return, distinguish it from background noise (HVAC airflow, building vibration, fan motion), and use it as a positive indicator of human presence. The result is a system that can reliably confirm the presence of a sleeping adult at 4 m with a true positive rate above 99% in controlled testing.

Presence Sensing: Why PIR Sensors Cannot Detect Stationary Occupants

A passive infrared (PIR) sensor, used for motion detection, cannot detect stationary occupants. The PIR sensor detects changes in infrared radiation across its field of view, and a stationary person does not produce a change in the radiation pattern. The PIR sensor therefore reports "no motion" within 10–30 minutes after the last movement, even if the room is occupied.

Presence Sensing: Performance Metrics

The performance of a presence sensing system is characterized by several key metrics.

Presence Sensing: Stationary-Occupant True Positive Rate

The stationary-occupant true positive rate (TPR) is the percentage of time that a stationary human occupant is correctly reported as present. For a 60 GHz presence sensing system, the TPR is above 99% in controlled testing and above 95% in real-world deployment.

Presence Sensing: False Positive Rate

The false positive rate (FPR) is the percentage of time the system reports presence when the room is actually empty. For a well-designed presence sensing system, the FPR is below 1% over a 24-hour period.

Presence Sensing: Detection Range

The detection range of a 60 GHz presence sensing system is 6–8 m for stationary occupants and 8–12 m for moving occupants when ceiling-mounted at 2.5–3.0 m.

Presence Sensing: Detection Latency

The detection latency is the time between an occupant entering the detection zone and the system reporting the change. For a presence sensing system, the latency is typically 0.5–3 seconds.

Presence Sensing: Applications

Presence sensing is deployed in a wide range of applications.

Presence Sensing: Hotel Room Deployment

Hotel rooms are the canonical application for presence sensing. A 60 GHz ceiling-mounted system can reliably detect whether a guest is in the room throughout their stay, including when they are sleeping, and feeds the occupancy data to the building management system for housekeeping coordination and the HVAC system for energy management.

Presence Sensing: Office and Conference Room Deployment

Offices use presence sensing for per-room HVAC and lighting control, conference room availability detection, and space utilization analytics.

Presence Sensing: Healthcare and Patient Room Deployment

Healthcare facilities use presence sensing for fall detection, bed-exit alerting, and occupancy-based environmental control. The privacy profile of mmWave radar (no images, non-invasive) makes it suitable for deployment in private spaces.

Presence Sensing: Residential Smart Home Deployment

Residential smart homes use presence sensing for occupancy-based lighting, HVAC control, and security monitoring. The most compelling use case for residential presence sensing is the prevention of the "light turned off while reading" problem that plagues PIR-based motion sensors.

Presence Sensing: Selection Criteria

Selecting the right presence sensing system for a specific application requires evaluating several criteria.

Presence Sensing: Technology

For indoor presence detection, 60 GHz mmWave radar is the default choice, providing reliable stationary-occupant detection with an excellent privacy profile.

Presence Sensing: Form Factor

For most applications, a ceiling-mounted sensor (70 mm diameter ceiling puck) is the right choice. For corridors and entryways, a wall-mounted sensor may be preferred.

Presence Sensing: Connectivity

The connectivity should match the existing infrastructure. For hotel deployments, Zigbee is the most common. For office deployments, WiFi or PoE with BACnet is common. For residential deployments, Matter or Zigbee is the most common.

Presence Sensing: Certifications

The presence sensing system should carry the required certifications for the target market: FCC, CE, RoHS, and any regional certifications.

Presence Sensing: Final Recommendation

Presence sensing is a mature, reliable technology that has become the default choice for occupancy detection in hotel rooms, offices, healthcare facilities, and residential smart homes. The 60 GHz mmWave radar is the default technology, providing reliable stationary-occupant detection, an excellent privacy profile, and a compact form factor.

For a procurement team or a consumer selecting a presence sensing system, the right approach is to start with a clear definition of the application requirements, then evaluate the available systems against those requirements, then select a vendor with a proven track record in the target vertical. The recommended products for most applications are the ceiling-presence-sensor-zigbee, ceiling-presence-sensor-wifi, and ceiling-presence-sensor-matter from vendors with strong product portfolios and proven deployment track records.

With the right presence sensing system, correctly installed and integrated, the system can deliver a level of occupancy awareness that is impossible to achieve with PIR-based motion sensors, and can justify the higher unit cost through improved energy efficiency, better occupant experience, and more accurate occupancy data for downstream analytics.