What are PIR Lights and Where They are Used?

Security of our home and property is important if we want to protect not only our family but also our belongings and valuables. Luckily we now live in a very advanced century and different technologies have been invented to help us secure ourselves and our loved ones from unwanted visitors while we are asleep or are not at home e.g. during vacation. For these purposes different alarm systems are available based on different principles some of which are more complex than others.

Nowadays alarm systems come equipped with different features, functions and sensors but this time we are going to focus of one particular type of motion sensorPassive Infrared sensor commonly known as PIR sensor which is a particular type of motion sensor that detects infrared light.

Motion sensors (also known as motion detectors) are used to detect body movements inside or outside buildings or properties. Once the sensor is tripped and it detects such movement, it sends out signal to control panel which further on triggers the alert – be it alarm device or light. This article will solely focus on PIR sensors – their operational principles, functions as well as possibilities and limitations of this technology.

What are PIR sensors?

Every sensor is triggered by different factors and PIR sensor is no exception. It detects infrared energy produced by body heat. In other words, PIR sensor measures infrared light which is emitted from objects that generate heat (such as humans and animals). With the help of crystalline material it detects the infrared radiation which is located in its field of view and can send out signals to control system which can trigger the alarm once the movement has been detected.

To be more precise, the sensor is not triggered just by the body heat itself, it would be more accurate to say that the detector rather analyses the changes in the condition measuring the differences that have occurred regarding the amount of infrared radiation in the particular area (detector’s field). So what really PIR sensor detects is the broken field of a “normal” temperature.

PIR motion sensor

PIR motion sensor

As mentioned, PIR sensors are widely used in indoor and outdoor environments, solar security lights and alarm systems and they come adjusted for different ranges (though, the usual range for a PIR sensor is 6 meters). These sensors have gained significant popularity because they are not too expensive, they are small and easy to use. They are also long-lasting compared to other types of motion sensors and security systems.

The chosen type of sensor and its quality will also play a major role in its functionality. Some PIR sensor users complain that their detectors are unequally sensitive to different distances of the detection range and are insensitive to very slow motions or the bodies that are not moving.

PIR sensor types

  • Alarm system PIR sensors. Due to their comparatively low price and great functionality, these sensors are one of the most popular types of alarm detectors widely used in households as well as small office buildings. Once the system detects heat energy, it triggers the selected alarm device. The most common types of alarms are bells and sirens that function to both warn the occupants about unwanted persons entering the building as well as to scare burglars off.
  • Motion light PIR sensors. This can also be considered as a separate type of security device but it can also function to increase the efficiency of your outdoor lighting (typically – outdoor flood lights) turning the light on only when detecting a movement within a given range. Generally, motion light PIR sensors come with adjustable PIR sensor range and illumination time. Lights with PIR sensors can be used also indoors e.g. to turn the light on when you enter your hallway. The PIR detector sends a signal to switch on lights when a person is in the room and when the room temperature returns to its average value, another signal is sent to the light controls to turn the lights off. Typically PIR sensor is separately attached to your flood light which means that you can also consider different other aspects to ensure maximum energy efficiency. Certainly think about proper bulb type which would be environmentally friendly and consume less energy. The best choice then would be LED bulbs.
    Flood light motion detector

    Flood light motion detector

  • Video motion sensors. These sensors are used to combine video cameras with advanced signal processing. Generally, recordable motion sensors start recording when they sense motion and are used to save energy and memory storage by making the captures only when someone enters the building and not the whole time.

What are PIR lights and where are they used?

As mentioned, the most popular type of motion lights are motion activated flood lights and these lights are used for safety (increased visibility during the night) and security (protection against burglars) purposes protecting homes and properties by detecting movements of living objects (bodies) detected by a built-in PIR sensor. Motion activated lights are used for illuminating rooms and areas during the night-time and evening hours. They are commonly used in different places such as:

  • Yards of private houses;
  • Front-door;
  • Hallways of office buildings;
  • Parking lots.
Security flood light with PIR detector

Security flood light with PIR detector

Nowadays, PIR motion lights come in huge variety based on different features, functions and possible adjustments. Hence you will have to do a bit of a research to sort out which type of PIR sensor motion light will meet your needs and won’t leave you disappointed (it can happen that your motion light simply do not serve the purpose if you have chosen the wrong model). Depending on the purpose you will have to consult your retailer about different parameters of your desired PIR light such as:

  • Detection range (180 degree PIR lights have become very popular in the market);
  • Detection distance;
  • Placement;
  • Lamps;
  • Pet-immune sensors (so that it does not turn the light on every time your cat or dog passes by);
  • Weather resistance;
  • Energy efficient solutions (e.g. some motion lights come equipped with solar panel which powers the light and the sensor).


Blogger, editor, developer who loves green living. Interested in photovoltaics and solar lighting. Reviewing solar products since 2013.

You may also like...

12 Responses

  1. Robert W. LaPontny says:

    Garage yard light. How do I solve the motion of the tree’s, bushes, etc tripping the light all night long ? The sensor is about 10 ‘ up and aimed to the ground as much as it can. My thinking is to have a PIR only sensor, but doesn’t seem to be offered in the market place.

  2. selemani ally says:

    what type of PIR sensor should be used in armoury room

    • Arthur says:

      It depends on what you want the PIR sensor to do. If you need it to double as your security system then go for an alarm system PIR sensors or a video motion sensors if you already have a separate alarm. Yet, if you just need lights that will light up as you walk in then motion light PIR sensors will be perfect for you.

  3. Charles says:

    What in the sensor causes the motion activated light come on only in the dark?

  4. Himanshu says:

    Dear Arthur,

    Would help me to get the information that “Why PIR sensors are important for home & domestic applications?
    & how this sensing technology are getting popular in lighting industry.


    • Arthur says:

      PIR sensors are important for home and domestic applications because they not only provide energy savings by having a light that turns on only when needed but these lights also make your home more secure. Not without reason, PIR lights are one of the main components of many home security systems.

  5. Lynn says:

    How about links where we can buy these?

Leave a Reply

Your email address will not be published. Required fields are marked *