Door Open Sensors: Applications for Fleets

Door open sensors—sometimes called door sensors, magnetic sensors, close sensors, or entry sensors—are devices that tell a monitoring system whether a door is open or closed and play a critical role in ensuring the quality of security systems and supply chain execution. Despite their common applications in home security for smart homes, door open sensors have also been increasingly adopted for logistical applications such as trailers, shipping containers, and even reusable bulk bins for shipping parts. While the primary function of door open sensors may seem basic at first glance, the data the door sensors collect can be used in a range of applications for fleets and distribution companies. 

The number of use cases for wireless door open sensors continues to expand. For instance, an open door alert or entry sensor can signal a risk of theft by indicating the presence of an intruder in a building or vehicle, or the loss of cold air from a reefer trailer or warehouse. Door sensors can also offer operational insights, such as the amount of time trailer doors were open during loading or unloading. Similarly, insights into the opening of a van or garage door at an unscheduled location can provide the first warning of possible cargo theft. Regardless of the application, door sensors typically rely on the same design.

How do door open sensors work?

In short, door open sensors leverage magnetic sensor technology to function. The door sensors consist of two parts: a sensor and a magnet. With door sensor security systems in place, when garage doors or vehicle doors are opened, the magnet detaches from the sensor. This movement releases a metal reed switch within the door sensor, triggering the alarm system or alert. The report may trigger an audible door alarm as well as transmit the door open event to the security system’s dashboard or portal. 

Wireless door open sensors, like the Samsara DM11, use Wi-Fi to communicate to the cloud via an IoT gateway device. For a trailer or shipping container door open sensor, various short-range wireless technologies may be used to transmit through an IoT gateway to the cloud. A door open alert or door alarm can be sent by email, text, or dashboard update, according to the user’s preference. There may also be built-in storage in case connectivity is unavailable. 

Quick start guide: How do you install a door open sensor? 

Wireless door open sensor technology has made the installation process much easier for fleets and distribution centers alike. With wireless door open sensors such as the Samsara DM11, you simply place the magnet on the door and the sensor on the trailer.

It is possible to test different mounting locations on door frames or trailers by placing the sensor and magnet by hand before mounting with adhesive tape or screws. With the Samsara DM11, the door sensor will flash orange three times when the magnet enters or leaves the sensing range. To test the range before mounting, keep the magnet and sensor more than 6 inches apart and then bring them together until the LED blinks to indicate they are in range. 

Aside from being widely used for home security systems and building security, door sensors are being installed in supermarkets and refrigerated cold storage facilities to monitor cooler door activity. 

Typically, door open sensors are one element of more comprehensive smart building or smart fleet transportation solutions that may include IoT gateways, cameras, and other sensors, depending on the needs of the application. In the case of transportation monitoring, sensors for recording temperature, humidity, and acceleration are often highly valuable.

Why door open sensors matter for fleets

Door open sensors have the ability to give fleets peace of mind by: 

• Preventing cargo theft

• Protecting refrigerated loads

• Reducing energy and food waste

• Minimizing the costs associated with load loss

Protect your fleet from cargo theft with door sensors

The cost of cargo theft and the number of cargo theft incidents remain high, as outlined in the 2020 BSI & TT Club Cargo Theft Report. According to the study, the median value of a single cargo theft incident in North America was $80,000 in 2019, up from $58,500 in 2018. It was topped globally only by South America, at $100,000 per crime. Across the globe, an average of eight cargo theft incidents take place each day. In North America, 86% of cargo theft events involve trucks and trailers, and most occur in-transit and about 10% of cargo thefts happen in unsecured lots.

Fleet management technology coupled with door sensors and alarm systems is helping to decrease the risk of cargo theft. By equipping trailer units with WiFi-enabled GPS tracking gateways, dash cams, and door sensors, fleets can verify the real-time locations of their vehicles and trailers. Real-time GPS tracking is especially useful in helping motor carriers locate lost or stolen equipment, while geofencing can provide early theft warnings by creating a virtual geographic boundary that triggers a response when a stolen vehicle leaves the geofenced zone.

Along with vehicle geofencing, door open sensors play an important role in alerting fleets of potential cargo theft. With their paired IoT gateways, door open sensors communicate through the gateway’s cellular connectivity to warn the carrier that there has been an unscheduled opening of the vehicle or garage door. With this system in place, alerts can be sent to the carrier’s fleet management dashboard and the driver’s mobile app. The Samsara DM11 Door Monitor, for example, transmits door sensor data in real time, enabling admins to view data remotely and receive instant notification when doors open unexpectedly. 

Reduce energy consumption and minimize food waste with door and window sensors

Door open alerts also play an essential role in ensuring temperature control. Receiving an alert can prompt drivers to immediately check their loads and ensure that the thermostat temperature remains within the desired range. 

Similarly, door open sensor technology via door window sensors are being used by some grocery retailers to reduce energy consumption and minimize food waste. In one case, a facility was experiencing issues with employees failing to close window doors to refrigerated rooms and food cases. Even when the windows doors were pushed shut, they weren’t always sealing properly. 

Two significant problems resulted: First, the refrigeration unit had to run longer to keep food cold, wasting energy in the process. And second, window doors left open overnight led to chilled food warming up too much to be used for sale. To reduce the risk of energy and food waste, the retailer installed door open sensors to alert admins when refrigeration room doors had been left open too long.

In another case, a food and beverage distributor installed IoT door sensors to monitor their door activity in order to optimize their delivery and inventory systems. For example, a door opening for a few seconds signaled that a customer was interacting with a product, while a longer open period indicated that the cooler was being restocked. The door open sensor was combined with IoT camera technology to alert the distributor about inventory level in the reefer, allowing them to better maintain stock of popular items and reduce unnecessary deliveries.

Use door sensors to minimize the costs associated with load loss

Another key opportunity associated with door open sensors is minimizing the costs associated with load loss. With the value of  perishable goods truckloads ranging from tens to hundreds of thousands of dollars, load loss and load rejection are serious concerns for shippers and motor carriers. The value of loads is high, and they constitute almost half of fast-moving consumer goods (FMCG) shipments. Fresh food categories, including fruits, vegetables, dairy, meat, fish, and baked products, account for nearly 49% of FMCG sales revenue. 

According to a survey of American Trucking Association members, the cost of a rejected load to motor carriers can range from $300 to $80,000. Other companies report even higher losses. Mountain Eagle Trucking, for instance, said that prior to deploying Samsara’s vehicle gateways and environmental monitors to better track their reefers’ temperatures, they were vulnerable to rejected loads that could cost anywhere from $5,000 to $150,000.

Simco Logistics, one of the largest ice cream distributors in the Mid-Atlantic, used to lose around five loads each year at a cost of tens of thousands of dollars of spoiled goods. The company installed a wireless environmental monitoring system, including the Samsara EM21 wireless environmental monitor, to enable real-time monitoring of load temperature. Simco Logistics now enjoys greater peace of mind knowing its products are being maintained at optimal temperatures.

California’s Clover Sonoma dairy company is another example of how advanced technology, including door open sensors, can help prevent rejected loads. Clover uses Samsara’s DM11 door open sensors, along with cargo and temperature sensors, relayed through Samsara vehicle IoT and asset gateways. When a major grocery chain rejected a load, saying it arrived an hour late for delivery, Clover was able to prove the truck was not only on time, but 15 minutes early. The retailer then accepted the load, saving Clover thousands of dollars. 

Customer service implications of door open sensors

Door open sensors help support customer service efforts by ensuring both reliable delivery and quality products. As mentioned above, when installed on door frames, door open sensors can provide real-time alerts of any unscheduled opening of trailer doors, enabling drivers to respond immediately. Theft can result in empty shelves and lost sales, while any deterioration of product quality can increase food waste and diminish the customer experience. According to McKinsey & Company, food quality and freshness rank as the highest concerns for consumers. Their study suggests that retailers can increase overall grocery sales by up to 10% by improving their fresh food practices and policies, such as ensuring optimal temperatures.

How to evaluate a door open sensor solution

Take the following criteria into account when deciding on a door sensor solution: 

• Battery life: When choosing a door open sensor, it’s critical to consider battery life to ensure your peace of mind. Even with always-on wireless networking and data-logging, a door open sensor like the Samsara DM11 can run for more than five years on a single AA battery so that you never have to worry about battery life again. 

• Easy installation: Be sure to take into account the installation time for your new door sensor technology. By choosing a solution with easy installation, you could save your business tens of hours in lost productivity. The Samsara DM11 takes just minutes to install. 

• Durability: Make sure your door open sensor is designed to work in harsh conditions like reefer trailers. With an IP69K rating, the Samsara DM11 is waterproof, dustproof, and protected against high pressure water and steam cleaning.

When choosing a door open sensor, it’s critical to consider battery life, WiFi connectivity, storage capabilities, and product durability. 

Why Samsara’s door open sensor is right for your fleet 

Door open sensors must also perform reliably in a range of weather conditions, so look for one designed to withstand harsh operating environments. The Samsara DM11’s robust weatherproofing, along with its functionality between -40 degrees Fahrenheit to 140 degrees Fahrenheit, protects the door sensor device against splashes, spray, dust, and other environmental wear and tear.

Finally, make sure to consider the scalability of the solution. Thanks to scalable cloud infrastructure and enterprise-grade security, Samsara door sensors can quickly bring visibility to both small and large operations. While you’re at it, choose a door open sensor with built-in storage to ensure it can log data even when gateway connectivity is unavailable. 

Door open sensors don’t just deliver value for your fleet operations. When combined with other wireless technologies to provide real-time monitoring, they also deliver peace of mind. By protecting cargo loads and providing operational insights by reporting exactly when trailer doors are opening and closing, they play a crucial role in real-time fleet monitoring for operations of every shape and size.