How do radar occupancy sensors compare with PIR motion sensors?

Density Waffle uses anonymous radar sensing to report zero, one, two or three-plus people, with real-time and historical occupancy data. Those outputs let a meeting-room program distinguish empty rooms, individual use and group use over time.

Radar and passive infrared (PIR) describe sensing technologies. Your purchasing decision also needs to specify the finished product’s output: motion, presence, people count or occupancy history. A motion signal and a room-use record answer different questions.

What does PIR measure?

PIR detects changes in infrared radiation associated with movement by a person or object whose temperature differs from its surroundings. Panasonic’s explanation describes this operating principle.

That makes PIR relevant when detecting movement is the job. It does not mean every PIR product behaves the same way during quiet desk work. Panasonic’s 2025 technical FAQ distinguishes standard and slight-motion detection and describes how target movement, temperature difference and distance affect detection.

Ask what the selected device actually reports and how its controller maintains occupied status between detections. A configured hold time may be appropriate for a control task, but it needs to be understood before interpreting that status as measured room use.

What does radar add?

Radar transmits radio signals and processes their reflections. Its sensing hardware and processing can support different tasks, including presence detection and people counting. Fine-motion performance depends on the implementation and configuration.

Texas Instruments’ motion-sensitivity tuning guide gives a useful engineering example: a major-motion configuration stops reporting detections when a person stops moving, while a minor-motion configuration continues detecting the person. That example concerns TI’s demonstration configuration; it is not a Waffle test.

The practical question is whether a particular product delivers the output your room decision requires. Some products combine technologies: Milesight VS370, for example, uses radar and PIR for human presence. A radar label alone does not establish a people-counting capability.

Presence, count and history serve different decisions

An occupied-or-empty signal can answer whether a room is in use. Distinguishing one person from a group supports a different decision: whether the room mix matches how people work. Historical records let teams examine that distinction across recurring periods.

Waffle’s zero, one, two and three-plus categories provide a concrete basis for that analysis. Three-plus groups everyone from three upward into one category. Use it to compare individual and group use; define a different measurement requirement if the decision needs exact larger headcounts. Density’s measurement explanation connects these categories to workplace decisions.

A proposed acceptance exercise for room-use measurement

Consider a team deciding whether to add phone booths or small collaboration rooms. This is a proposed buyer exercise, not an observed customer result.

Select representative rooms and agree on the room boundary, observation period and reporting interval. Ask each supplier to demonstrate three answers from the same reference record:

1. Presence: Was the room occupied during each observed interval?
2. Group use: Was it empty, used by one person, used by two, or used by three-plus?
3. History: Can the team recover those categories by room and time to compare recurring use?

Include quiet seated work, arrivals, departures and group meetings. Preserve the actual observations alongside each system’s output. Inspect any hold-time setting and record unavailable data separately from vacancy. Set acceptance rules before reviewing the results.

If individual use recurs, the team has a reason to investigate more solo spaces. If groups recur, it can investigate collaboration capacity. That is the decision value to demonstrate.

Book a demo, or email sales@density.io to evaluate Density’s count categories and occupancy history against your room decisions.

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