Motion Detector vs. Window Sensor: Pros and Cons

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Most basic home security systems include a form of motion detectors and window sensors. While both are effective in their own ways, it’s important to understand the differences and when to use each for your security needs.

In many situations, it’s best to have both motion detectors and window sensors to safeguard your home from break-ins. However, it’s important to explore your options in different areas and evaluate where they are most suitable for installation in your home.

Motion Detectors

Motion detectors use various technologies to detect motion inside your home. One of the most common technologies motion detectors use is passive infrared (PIR), which detects changes in infrared radiation in the room. A lesser used in motion detector technology is microwave detection, which sends out microwave pulses and detects the reflection of those pulses from moving objects.

At its most basic, a motion detector is designed to compare the previous status of a room to a more recent status. However, because it does this at intervals, it can sometimes miss things. It’s important to note that motion detectors are not foolproof.


  • Captures potential intruders inside of the home.

  • Wireless installation for versatile placement. 

  • Automatically alerts you if motion is detected. 


  • Historically, they have more false positives than other sensor types.

  • They are only active in intervals. 

  • Pets can trigger an alarm if not configured correctly.

Window Sensors

Window sensors, a market expected to grow to $11.75 billion in 2023, are designed to detect when a window has been opened or broken. There are two types of window sensors: contact sensors, which are sometimes used as door sensors as well, and glassbreak sensors.

Contact sensors are used to detect when any door or window is opened. They can be placed in different areas of your window, depending on where they will be the most accurate. They are the most common pieces of security equipment when it comes to staying secure.

Glassbreak sensors detect the sound of glass breaking. They can be placed near windows in multiple rooms, and there are security panels, such as the Qolsys IQ Panel 4 which have integrated glassbreak sensors built-in.

Both contact sensors and glassbreak sensors have fewer false alarms than motion detectors. They also only detect if the window is used for entry. Securing your windows is important because it prevents the intruder from ever entering your home.


  • Detect break-in entry through a window with relatively high levels of accuracy. 

  • Creates a well-secured perimeter when paired with other sensors. 

  • Triggers and audible alarm that may deter thieves from continuing to advance. 


  • Will not help if the individual did not have to open or break a window.

  • Can still have false positives if there are loud sounds in a pitch similar to breaking glass.

  • May be prone to wearing down (though slowly) with increased window movement.

Choosing Between Motion Detectors and Window Sensors

When it comes to securing your home, it’s important to consider both motion detectors and window sensors.

While motion detectors are best at detecting once an intruder has already entered, window sensors are better at detecting the actual intrusion attempt. For most people, both will be worthwhile.

Motion detectors will need to be placed in specific zones of your home to be effective. They are ideal for monitoring large areas and can detect intruders regardless of how they gained access.

When building a comprehensive security system, it’s important to use different types of sensors and detectors in different areas of your home. For instance, you might have motion detectors installed in your hallways, bedrooms, and living rooms, while your outer windows may have both contact sensors and glassbreak sensors installed.

However, it’s important to note that motion detectors can have false positives, especially if they are not calibrated appropriately for pets. If they seem to be too easily set off, this can often lead to motion detectors being ignored or not used at all. Therefore, it’s recommended to limit motion detectors to the most important areas of your home. It’s also recommended to utilize 24/7 professional monitoring to help confirm if there is an actual intrusion; this will help prevent unnecessary dispatch of emergency services.

If you have areas where there’s a lot of movement in general, such as rustling drapes or moving plants, a motion detector may not be suitable. At the same time, a window sensor shouldn’t be relied upon for all your security needs; if you leave your door unlocked, for instance, someone could simply stroll right into your home. Likewise, if someone breaks your door instead of your window, a window sensor is not going to detect that form of intrusion.

Do you want to learn more about how window sensors, glassbreak sensors, and motion detectors work together to form the perfect security system for you? Contact us today at Brinks Home™ to work with a Security Consultant who can advise you on creating a customized security solution for your home that is backed by a certified Five Diamond emergency response center.

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