Wireless occupancy sensor technology is the foundation for energy-efficient lighting, smarter HVAC control, and usable-space analytics. A wireless occupancy sensor detects presence without hardwiring to each fixture and can be deployed quickly across floors and rooms. Butlr differentiates with anonymous, heat-based sensing that preserves privacy while delivering reliable counts and presence signals for control and analytics.
How wireless occupancy sensors work
A wireless occupancy sensor detects human presence and reports it wirelessly to controllers, gateways, or cloud platforms. Sensing implementations vary by technology and use case.
Common sensing methods
- PIR (passive infrared): detects motion via changes in infrared radiation.
- Ultrasonic: emits sound waves and detects movement by return patterns.
- Microwave: uses Doppler radar to detect motion through frequency changes.
- Thermal / heat-based: measures relative heat signatures and motion heat patterns for presence and counting.
Wireless communications used by occupancy sensors include Zigbee, Bluetooth Low Energy (BLE), Wi‑Fi, sub‑GHz RF, and proprietary mesh protocols. Typical mounting options are ceiling- or wall-mounted; detection ranges vary by technology and mounting height.
Key detection characteristics
- Typical detection range: 10–40 feet depending on sensor type and mounting.
- Mounting: ceiling-mounted for broad coverage, wall-mounted for corridors and focused zones.
- Power: battery-powered for easy retrofit or wired for continuous operation.
Choose sensors based on accuracy need, privacy concerns, and integration requirements. Below is a concise comparison of common sensor types and protocols.
PIR (passive infrared)
- Accuracy: good for motion detection, less accurate for stationary occupants.
- False positives: low with proper placement; can miss still occupants.
- Privacy: anonymous—no imaging or audio.
- Best use: restrooms, corridors, high-traffic spaces.
Ultrasonic
- Accuracy: detects small movements; better for covered areas with low motion.
- False positives: more susceptible to vibrations and curtains.
- Privacy: anonymous.
- Best use: private offices, meeting rooms where motion may be subtle.
Microwave
- Accuracy: high sensitivity and range; can detect through some materials.
- False positives: higher if not tuned; can sense movement in adjacent spaces.
- Privacy: anonymous.
- Best use: large, open spaces where extended range helps.
Thermal / heat-based (Butlr)
- Accuracy: strong at presence detection and occupancy counting, including stationary occupants when calibrated.
- False positives: lower in many environments because pattern recognition separates human heat signatures from background.
- Privacy: high—no images, no audio, anonymous heat maps only.
- Best use: offices, meeting rooms, classrooms, space analytics where privacy and counts matter.
Protocol pros and cons
Zigbee
- Pros: low power, mesh networking, mature in lighting controls.
- Cons: requires gateway, limited bandwidth for analytics-heavy telemetry.
BLE (Bluetooth Low Energy)
- Pros: ubiquitous support, low power, easy integration with smartphones and gateways.
- Cons: range depends on environment; mesh support improving but varied.
Wi‑Fi
- Pros: high bandwidth, direct cloud access.
- Cons: higher power, may reduce battery life, requires strong network planning.
Sub‑GHz RF / proprietary mesh
- Pros: long range, very low power, robust mesh for large deployments.
- Cons: vendor lock‑in; may require specific gateways or controllers.
When comparing wireless occupancy sensors, prioritize attributes that affect detection reliability, lifecycle costs, and integration ease.
- Coverage & accuracy: square footage per sensor and detection angle.
- Presence vs motion sensing: ability to detect stationary occupants.
- Battery life vs wired power: expected years of battery operation or constant power options.
- Integration capabilities: compatibility with lighting controls, BMS, cloud APIs, and protocols used by your site.
- Installation ease: mounting hardware, wireless commissioning, and calibration tools.
- Analytics & reporting: real-time counts, dwell time, heat maps, and exportable datasets.
- Certifications and standards: electrical safety, radio certifications, energy codes (e.g., ASHRAE recommendations).
Common spec ranges to expect
- Detection coverage: 100–1,500 sq ft per sensor depending on mounting and technology.
- Detection angle: 90°–360° depending on lens and placement.
- Response time: sub-second presence detection for lighting control; seconds for analytics updates.
- Battery life: 2–10+ years depending on sampling rate and wireless protocol; wired options remove battery constraints.