What is the Best Motion Sensor for Home Security?

Home security motion sensors vastly increase security, detecting movement that signifies a potential threat. And when they’re connected to a smart home security system, their capabilities increase—also offering conveniences that make people’s lives easier.

But with so many options on the market, how do you know which type of motion sensor best meets your needs? Let’s examine the different varieties of this technology and how they work with modern home security systems.

The main purpose of motion detection is to sense an intruder and send an alert to your home security system’s control panel, triggering an alarm and notifying you and your monitoring center. Homeowners who opt for self-monitored systems simply take action themselves after receiving an alert.

In smart security systems, the alarm can also cause all home security cameras to start recording—capturing real-time footage that the owner can review to determine the nature of the threat. Many times, these high-quality images provide the only clues that police have to identify a perpetrator.

Motion-sensing capabilities are also often embedded in other home-security-system components, such as lights or cameras. When motion is detected, for example, lights automatically flood the area or cameras start recording.

In addition, standalone motion sensors can be used to protect loved ones from dangers within the house, sending instant notifications if kids or pets enter restricted areas or elderly parents suffering from dementia try to wander outside.

There are two main types of motion sensors. Active sensors, sometimes referred to as radar-based motion detectors, are typically more sensitive. They emit energy like microwaves or ultrasonic sound vibrations that actively search their field of view for movement, much like sonar on a submarine. When interference is detected, the device can send a signal to a control panel to sound an alarm.

Active motion sensors are commonly used in applications where even small movements are important to detect, such as automatic doors at shopping malls. They can also be found in home security systems, although their heightened sensitivity can potentially lead to a greater number of false alarms. The movement of random objects such as wind-blown branches, small animals, and even large insects may trigger an alarm connected to active motion sensors installed outdoors. Pets can also pose problems inside the house, as well as something as simple as curtains blown by an air conditioning vent.

After several false alarms, frustrated users may be tempted to turn their motion sensors off—significantly weakening their home’s defense against intruders.

Passive motion sensors work a bit differently and have several advantages when used in home security systems. Most modern sensors rely on infrared technology that doesn’t require a significant energy discharge. Instead, passive infrared (PIR) sensors pick up changes in a room’s thermal environment, which is usually stable when it’s empty. Unlike active sensors, which detect any movement in a space, passive sensors scan the room or area where they are installed for infrared heat signals radiated from living beings.

Gradual increases in temperature, such as changes in weather or household temperature, won’t trigger an alarm. But the entrance of a person creates a significant rise in infrared energy that causes the alarm to sound.

Here’s exactly how it works: All objects radiate invisible infrared rays. The average human body at rest, for example, produces energy equivalent to a 100-watt lightbulb. The rays vary with the temperature of the object from which they emit, enabling passive sensors to largely distinguish between people with body heat and inanimate objects in motion.

This also makes passive sensors more pet-friendly. By ignoring body heat from animals smaller than 40 pounds, passive sensors minimize false alarms caused by scampering dogs or cats. Careful placement is essential, however: setting them near heat sources, direct sunlight, or in the path of large pets risks setting off the alarm accidentally. But when installed properly, passive sensors help users activate their home security systems with confidence.

Passive sensors offer other advantages as well. Without the need to continuously emit waves or vibrations, they use energy sparingly, enabling batteries to last as long as eight years without replacement. Passive motion sensors also usually cost less than active sensors.

Standalone motion sensors are typically installed as interior sensors—reinforcing boundary protections like door/window and glass break sensors. If an intruder manages to get inside the house without triggering a different intrusion sensor, the motion sensor stands ready to sound an alarm.

Frontpoint Security’s Z-Wave passive motion sensors offer one of the industry’s leading detection ranges, covering a 44-foot area and a 90-degree field of view. The standard range for these passive motion sensors is about 30 feet. The coverage area is shaped like a teardrop, with the skinniest part radiating down and out from the detector—it’s carefully designed to prevent intruders from escaping detection by crawling beneath its field of view.

Proper placement is key to maximizing effectiveness and reducing the risk of false alarms. Here are some important tips to consider when placing home security motion sensors:

• Place motion sensors at “choke points”—those high-traffic areas people are forced to traverse no matter where they are heading in your home, like the main hallway or the stairwell. Intruders tend to make a beeline for the master bedroom, so be sure to put a sensor near that room and any other room where you store valuables. Other prime locations could include a living room or family room with a big-screen TV, or the corner of a room with multiple entry points.
• Most burglars break in through the front door, followed by first-floor windows and the back door. When placing motion sensors, consider where intruders are most likely to enter and what path they would take, keeping your sensor’s detection ranges in mind. The garage and the basement can also be common entry points for thieves.
• Motion sensors typically work best when intruders cross their paths by walking parallel to them, instead of coming straight at them. To garner the best results, place sensors along walls that an intruder would walk alongside, like a hallway or narrow pathway leading to a room.
• Don’t point motion detectors at windows. Direct sunlight and heat that seeps through the glass can trigger devices designed to detect changes in thermal environments. Make sure that they also aren’t facing fireplaces, air vents, space heaters, or other heating and cooling sources that may fool the sensor into sounding an alarm. Placing a motion sensor inside a hot garage can also set it off.
• Motion sensors are typically situated about four or five feet above the floor so their coverage area brushes the ground. That said, some pet owners do prefer to place them higher to mitigate false alarms triggered by larger animals. When installed near the ceiling, a motion sensor’s field of view can be aimed so it ends a few feet from the floor, detecting upright people instead of bigger pets darting across the ground.
• Infrared motion sensors generally can’t see through walls or other large, hard objects like furniture. When setting up your motion sensor, it helps to imagine it like a light beaming from the wall. Anything that would create a shadow from a light in that position can also block the motion sensor’s ability to detect movement in the “shadowed” motion area.

Many modern motion sensors are wireless, enabling them to arrive preprogrammed with out-of-the-box functionality and installation that is as simple as placing them on a shelf. The most advanced types connect to a home security system through Z-Wave, a low-energy wireless communication protocol designed for home automation.

When Z-Wave technology is embedded into everyday products like motion sensors or lights, these products become “smart”—giving them the ability to talk to each other and enabling people to control them from anywhere. Z-Wave uses much less power than Wi-Fi but offers a much longer range than Bluetooth connections. The low energy use helps to enhance sensors’ battery life, while the longer range allows them to transmit data to the security system’s central hub over distances as far as 100 meters in open spaces.

Connecting with Z-Wave lets motion sensors work in tandem with other smart home devices, expanding their core home security function to include conveniences for homeowners and renters. For instance, they can prompt smart lights to dimly illuminate the path to the bathroom if you stumble out of bed in the middle of the night or save energy by automatically raising the thermostat when no one is home. Motion sensors can also be incorporated into “scenes” that are set to a timer, turned on with a smartphone, or integrated with smart hubs like Google Home or Amazon Echo.

Motion sensors are typically deactivated from communicating with an alarm when people are home so individuals can move freely throughout the house without triggering them.

Z-Wave also makes it easy for people to adjust alarm settings remotely by using a smartphone or other mobile device. Left for work and forgot that you were dog-sitting your neighbor’s 90-pound Mastiff when you turned on the alarm? No need for a frantic trip back home. You can simply whip out your smartphone and bypass the motion sensors aimed at the area where the dog is confined while leaving the rest of the system on.

Motion sensors have long been an integral part of a home’s interior defenses. But the emergence of smart technology has expanded their capabilities, enabling them to also add vast convenience to people’s lives.

Wireless passive infrared sensors stand at this intersection of convenience and function, reducing false alarms via the ability to differentiate between the heat signatures of people, smaller pets, and inanimate objects. And when they’re integrated into a smart home security system, they become part of a stronger and more intuitive defense against intruders—keeping homeowners and renters connected to their homes with the ability to control its security from anywhere.

Frontpoint keeps families safer and more connected in their everyday lives. We've been revolutionizing the home security industry for over a decade. And we're just getting started. To shop DIY home security systems, check out our Security Packages. If you have questions or would like to discuss a quote, contact us at 1-877-602-5276.