Passive Infrared Sensors (PIRs)

Passive Infrared Detectors (PIRs) are essential components in commercial security systems, designed to detect motion by measuring changes in infrared (IR) light levels emitted by objects in their field of view. They play a crucial role in identifying unauthorized movement within a protected area, triggering alarms or other security responses. Understanding the types, purposes, and functions of PIRs can significantly enhance a security system’s effectiveness.

Types of Passive Infrared Detectors

  1. Standard PIRs: Detect general motion within a specific range, typically using a single sensor element. They are suited for standard applications where the detection of any movement is the primary requirement.

  2. Dual-Technology PIRs: Combine passive infrared with another form of detection technology, such as microwave or ultrasonic sensors, to reduce false alarms. They only trigger an alarm when both sensors detect motion, providing more reliable detection.

  3. Pet-Immune PIRs: Designed to ignore the motion of pets or small animals to prevent false alarms. They achieve this through specialized lens designs or processing algorithms that differentiate between human and non-human movement.

  4. Ceiling-Mount PIRs: Installed on the ceiling to provide 360-degree coverage. Ideal for protecting a room or area from above, offering a broader detection range.

  5. Outdoor PIRs: Specifically designed for external use, these PIRs are more robust and weather-resistant. They often include features to mitigate false alarms caused by environmental factors such as moving branches or small animals.

Purpose of Passive Infrared Detectors

  • Motion Detection: The primary purpose is to detect unauthorized movement within a monitored area, alerting the security system to potential intruders.

  • Security Enhancement: By integrating PIRs into a commercial security system, businesses can enhance their overall security posture, ensuring areas are monitored continuously for any signs of intrusion.

  • Automation and Control: In addition to security applications, PIRs can be used to control lighting, HVAC, and other building systems based on occupancy, contributing to energy efficiency and convenience.

Functions of Passive Infrared Detectors

  • Infrared Heat Detection: PIRs detect changes in infrared radiation levels caused by moving heat sources, such as people, in their field of view. When a significant change is detected, it triggers a signal.

  • Alarm Activation: Upon detecting motion, PIRs send a signal to the security system’s control panel, which can then activate an alarm, start recording on a connected CCTV system, or notify security personnel.

  • Zone Coverage: PIRs can be strategically placed to cover specific zones within a building, allowing for targeted monitoring and the ability to set different sensitivity levels or activation schedules per zone.

  • Integration with Other Systems: PIRs can be integrated with other security components, such as door and window sensors, glass break detectors, and CCTV cameras, to create a comprehensive security solution.

  • Energy Management: By connecting PIRs to building management systems, businesses can automate the control of lights and HVAC based on occupancy, reducing energy consumption and costs.


Passive Infrared Detectors are versatile and effective tools in commercial security systems, offering reliable motion detection to protect against unauthorized access and enhance building management. Their functionality extends beyond security, contributing to energy efficiency and operational convenience. The selection of the appropriate type of PIR sensor depends on the specific needs of the commercial space, including the environment, the presence of pets or wildlife, and the level of sensitivity required. By understanding the types, purposes, and functions of PIRs, security professionals can design and implement tailored solutions that meet the comprehensive security and operational needs of their clients.

PIR Type Use Case Scenarios

Passive Infrared Detectors (PIRs) are integral to security systems, offering tailored solutions for diverse environments. Each type serves specific scenarios best, based on its design and capabilities. Hereu2019s a look at how different PIRs fit into various use-case scenarios:

1. Standard PIRs

  • Use-Case Scenario: Small offices or retail stores with defined areas for monitoring, such as entry points or specific sections of the store.
  • Why Best: Standard PIRs provide reliable motion detection in smaller, controlled areas where the volume and type of movement are predictable. Their straightforward functionality offers an effective and cost-efficient solution for standard security needs without the complexity of managing false alarms from known movements.

2. Dual-Technology PIRs

  • Use-Case Scenario: Large warehouses or manufacturing plants where environmental conditions may vary, such as changes in temperature or the presence of machinery that could affect motion detection.
  • Why Best: Dual-technology PIRs, combining infrared with microwave or ultrasonic sensors, minimize false alarms by requiring both sensors to trigger simultaneously for an alarm condition. This dual verification is particularly effective in environments with potential for motion detection interference, ensuring only genuine threats trigger an alarm.

3. Pet-Immune PIRs

  • Use-Case Scenario: Residential complexes or homes within a commercial property where pets are present and free to move around.
  • Why Best: Pet-immune PIRs are specifically designed to disregard the movements of small animals, reducing false alarms that standard sensors might generate. This capability ensures the security system remains effective and efficient, focusing on human movement without being triggered by pets.

4. Ceiling-Mount PIRs

  • Use-Case Scenario: Open-plan office spaces or reception areas where comprehensive coverage from a central point is desired.
  • Why Best: Ceiling-mount PIRs offer 360-degree detection coverage, making them ideal for monitoring large, open areas from above. Their elevated positioning provides a broad view, ensuring no movement goes undetected within the designated space.

5. Outdoor PIRs

  • Use-Case Scenario: Perimeter security for commercial properties, including parking lots, outdoor storage areas, or around building exteriors.
  • Why Best: Outdoor PIRs are built to withstand environmental factors such as rain, wind, and temperature fluctuations while accurately detecting human movement. Their robust design and specialized features to mitigate false alarms caused by outdoor elements make them suitable for exterior security applications.

Each type of Passive Infrared Detector is engineered to meet the challenges of specific environments, optimizing security coverage while minimizing false alarms. By carefully matching the PIR type to the scenario’s unique requirements, security systems can offer precise, reliable protection tailored to the needs of each commercial space.