Essential Guide

Detector Technologies Explained

There are 4 main types of presense detectors each using different technologies to detect movement. 

Passive Infrared

PIR Sensors read the average air temperature in a room so the movement of a person or other warm object will be detected. Different sensitivities are possible but all PIR are more responsive when moving across the sensor field. False triggering can be caused by small animals or change in the air flow in a room.

Microwave/High Frequency

These sensors emits high frequency electromagnetic waves, when they hit a moving object an offset echo is caused which activates output. This makes the sensors extremely accurate, however because the High Frequency waves can permeate most building materials careful installation and commissioning is required to prevent false triggering. Ideal for large spaces such as open plan office or carparks.


Similar to a microwave sensor, sounds waves are emitted by the sensor which then listen for the echo. Sound waves can fill the entire volume of a room allowing the detector to see around corners.  However they don't travel through building material reducing false trigging dramatically when compare to a microwave sensor.


Cutting edge technology which uses a camera to determine the number of people in a room based on standard body shapes and sizes. Perfect for accurate heating, air and ventilation control or for integrating into a wider management system, for example the comings and goings of people in a waiting room.

Some products use multiple technologies to ensure the most accurate and responsive detection.

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