How Occupancy Sensors Work: A Technical Guide for Facilities Teams

Occupancy sensors are hardware devices that detect human presence within a defined area of an office. They provide the raw data required to distinguish between a "booked" desk and an "occupied" desk. While many organizations rely on calendar data to measure office health, that data is often inaccurate due to no-shows and ghost bookings. By integrating sensors into a unified workplace operations system like WOX, facilities teams can move from assumptions to operational truth, using real-time usage to enforce check-in policies and automate resource availability.

What are the different types of occupancy sensors for offices?

Facilities teams generally choose between four primary sensor technologies. Each has specific technical trade-offs regarding accuracy, privacy, and installation complexity.

Passive Infrared (PIR) sensors

PIR sensors are the most common choice for desk-level tracking. They work by detecting changes in infrared radiation (heat signatures) within their field of view. When a person moves into the sensor’s range, the change in heat triggers an "occupied" state.

These sensors are cost-effective and consume very little power, often running for years on a single battery. However, they require a line of sight. If an employee sits perfectly still for a long period, a PIR sensor might incorrectly report the desk as vacant. To prevent this, most systems use a "dwell time" or "delay" setting, keeping the status as occupied for several minutes after the last detected movement.

Ultrasonic sensors

Ultrasonic sensors emit high-frequency sound waves that bounce off objects and return to the device. By measuring the time it takes for the sound to return, the sensor can detect movement or the presence of a new object in the room. Unlike PIR, ultrasonic waves can move around partitions and furniture, making them useful for complex room layouts or restrooms. They are highly sensitive but can sometimes be triggered by airflow from HVAC systems, leading to false positives.

Optical or AI vision sensors

Optical sensors use low-resolution cameras and onboard computer vision to count people in a space. These are typically mounted on the ceiling and are used for "area counting" in large zones like lobbies, cafeterias, or open-plan collaboration areas.

Modern optical sensors process the image locally on the device and only transmit the count (e.g., "4 people") to the cloud. This ensures privacy because no actual video or identifiable images leave the hardware. Because WOX handles any resource type, optical sensor data can be mapped to open zones to track utilization in spaces that don't have fixed seating.

Environmental or CO2 sensors

These sensors measure carbon dioxide levels to estimate occupancy. As people breathe, CO2 levels rise. While less precise for real-time desk tracking, they are effective for understanding long-term trends in meeting room usage. They are often integrated into broader building management systems (BMS) to adjust ventilation based on how many people are in a room.

How do occupancy sensors transmit data to workplace software?

A sensor is only useful if its data reaches your operational system reliably. There are three primary ways these devices communicate.

1. LoRaWAN (Long Range Wide Area Network): This is the gold standard for large-scale office deployments. It uses a low-frequency radio signal that can penetrate thick walls and floors. You only need a few gateways to cover an entire building. It is secure, private, and keeps sensor traffic off the main corporate Wi-Fi.
2. Wi-Fi: Some sensors connect directly to the office Wi-Fi. This is easy to set up for small pilots but can become a burden for IT teams to manage at scale. It also consumes more battery power than other protocols.
3. Power over Ethernet (PoE): Usually reserved for high-end optical sensors or meeting room displays. These devices are hardwired into the network. They provide the most reliable data connection and never need battery changes, but they are the most expensive to install.

Because WOX is a unified operational system, it can ingest data from multiple sensor types and protocols simultaneously. This allows a facilities team to use cheap PIR sensors for desks and high-accuracy optical sensors for the cafeteria while maintaining a single data model for the entire building.

Why do calendar-based booking systems fail without sensors?

Most workplace tools rely on "calendar truth." If a person clicks "book" in Outlook, the system assumes the desk is used. In reality, about 30% of office bookings result in no-shows.

When you rely solely on a calendar, several problems occur:

• The "Ghost Office" effect: The software shows the office is 90% full, but the floor is actually empty. People who want to come in stay home because they think there is no space.
• Inaccurate real estate decisions: If you see high booking rates, you might lease more space. If you had sensor data showing 40% of those desks were never actually sat in, you would realize you have an excess of space.
• Lack of policy enforcement: Without sensors, there is no way to know if an employee is following hybrid work policies.

WOX solves this by treating the booking as an intent and the sensor as the verification. If a sensor does not detect presence within 20 minutes of a booking start time, the system can automatically release that desk back into the available pool. This creates "operational truth"—data that is accurate enough to use for lease renewals and tax audits.

How to integrate occupancy sensors with your spatial model

For sensors to be useful, they must be mapped to specific locations. In traditional systems, this often requires hiring a vendor to update CAD files or hardcoding sensor IDs into a database.

WOX uses self-service spatial modeling. Facilities teams can upload a floor plan and drag-and-drop sensors onto specific desks or zones. Because the system is resource-agnostic, you aren't limited to desks and rooms. You can attach a sensor to a phone booth, a laboratory station, or even a parking spot.

Once mapped, the sensor data flows into the same policy engine that governs bookings. For example, you can create a rule that says: "If a desk in the Engineering zone is occupied for more than 4 hours without a booking, send a notification to the floor warden." This turns passive data into executable operational rules.

What are the privacy considerations for workplace sensors?

Privacy is the most common concern for employees when sensors are introduced. It is important to distinguish between "monitoring" and "measuring."

• Anonymization: PIR and ultrasonic sensors cannot identify individuals. They only detect "something warm" or "something moving."
• Edge Processing: For optical sensors, ensure the hardware processes images locally. The system should only receive a numerical value, not a video feed.
• Transparency: Facilities teams should be clear that sensors are used to optimize the building’s footprint and ensure desk availability, not to track individual performance or bathroom breaks.

When sensors are integrated into WOX, the focus is on the resource lifecycle. The system tracks whether "Desk A" was used, not necessarily which specific person sat there, unless they have officially checked in. This distinction helps maintain enterprise governance without creating a culture of surveillance.

How does sensor data drive office space optimization?

The ultimate goal of occupancy sensors is to provide data for better decision-making. Most facilities teams are looking for three specific metrics:

1. Peak vs. Average Utilization: A calendar might show 80% occupancy every Tuesday. Sensors might show that at 10:00 AM, the office is 95% full, but by 2:00 PM, it drops to 30%. This suggests you need more "hot-landing" spots rather than dedicated desks.
2. Popularity by Zone: You may find that desks near windows are always occupied, while desks in the center of the floor remain empty. This data allows you to change your office layout—perhaps turning the unpopular areas into lounge space or storage.
3. Booking Friction: If sensors show high usage in a zone with low bookings, it means people are "squatting" in desks without reserving them. This indicates that your booking policy is too difficult to follow or that employees need more training on the system.

Because WOX handles complex, multi-modal booking logic, you can use this data to adjust how resources are shared. If sensors prove that a "shared" team zone is only used 10% of the time, you can instantly reconfigure that zone to be "exclusive" for a different department or open it up for slot-based bookings.

What should you look for when choosing a sensor vendor?

When evaluating hardware, avoid vendors that lock you into a proprietary software platform. Your sensors should be part of your infrastructure, not a standalone silo.

Summary of the sensor-to-operations workflow

The transition from manual management to automated operations follows a specific path:

1. Deployment: Install sensors across desks, rooms, and communal areas.
2. Mapping: Use WOX to link sensor IDs to your digital floor plan.
3. Verification: Compare calendar bookings against real-time sensor triggers.
4. Enforcement: Enable auto-release policies to free up "ghosted" desks.
5. Optimization: Use the resulting audit-grade data to consolidate floors or redesign layouts.

If you are currently managing an office based on how many people say they are coming in, you are likely overpaying for real estate. The first step toward efficiency is an audit of your actual usage.

Learn more about Workplace Analytics Guide

For comprehensive guidance, see our guide on workplace analytics and utilization optimization.