| Written by Constance Stickler

Monitoring refrigerated container temperatures plays a critical role in ensuring the integrity of perishable goods during transportation. Before the advent of modern refrigeration technology, long-distance transport of fruit, vegetables, or meat was impossible, and significant challenges were faced. The lack of temperature monitoring and regulation capabilities often resulted in product spoilage, economic losses and compromised food safety. Learn more about the reefer temperature monitoring device.
Reefer Temperature Monitoring Device

No video selected

Select a video type in the sidebar.

The development of refrigerated containers, which emerged in response to these challenges, proved to be a revolutionary turning point in the transportation industry. With global trade growing and new products requiring controlled temperature, effective temperature monitoring is paramount.


Refrigerated transport and temperature monitoring

Storing and transporting ice or perishable goods has a long history. Ancient civilisations such as the Persians, Romans and Chinese developed various methods to harvest ice in colder regions and transport it to warmer climates. They already had a remarkable understanding of isolation and preservation techniques. Ice houses or ice pits were built in which ice was collected during the winter months and insulated with straw or sawdust. This meant it could be stored for a more extended period of time and used all year round.

In the centuries that followed, the possibility of transporting seafood, for example, remained limited to coastal, lake and river areas. In the early 19th century, ice and salt were placed beneath and between cargo, with limited success.

However, in the second half of the 19th century, a number of inventions made it possible to transport perishable goods intact over long distances.

1867 - J.B. Sutherland of Detroit received a patent for refrigerated cars that had particular ice-holding areas at each end.

1876 - The Frenchman Charles Tellier, also called the "father of cold", invented an ether-based cooling system. This made it possible to maintain a temperature of 0° Celsius in transport boxes.

1877-  Ferdinand Carré, also from France, further developed Tellier's system. Its compression cooling made it possible to ship 150 tons of frozen meat on a ship from Sydney to Great Britain within 50 days.

From 1900 on - Refrigerated ships—specially designed for transporting bananas—were sold from 1901. CO2 machines reduced and controlled the temperature on them.

1935 - Fred McKinley Jones invented the first portable air cooler for trucks - the modern form of cold chain was born.

1950s and 1960s - The golden age of refrigerated containers is dawning, a real revolution. The control of temperature and transport is getting better and better.

1970s - The reefers that have now been developed are specifically designed for transport on container ships. As is still the case today, they are connected to the ship's network on board. On land, there are specially designed sockets or plug-in power generators (reefer genset) that ensure the power supply.

Today/the future - Remote-controlled systems can monitor and control the container's parameters in real-time. In the event of deviations, immediate action can be taken. This intelligent technology is constantly being refined.

While initially no temperature measurement was possible, simple thermometers or rudimentary temperature measuring devices were later used. Of course, these instruments were not as accurate as modern reefer temperature monitoring devices. Additionally, the ability to control and regulate the temperature inside the cooler was limited compared to today's cooling technology.


Why Reefer Temperature Monitoring is So Important

When transporting perishable goods, maintaining a precise temperature is an absolute necessity. Some goods have a slightly more extensive range of permitted temperatures; others are less flexible and spoil or become inactive (for example, pharmaceuticals) if they exceed or fall below a threshold value.

Monitoring the refrigeration temperature plays a crucial role in ensuring that these goods reach their destination fresh, safe and ready for market. If carried out inadequately, the consequences can be severe; the goods may spoil, lose quality or pose a health risk to the consumer.

Companies transporting and distributing perishable goods can face significant financial setbacks, reputational damage, and even legal liabilities due to such losses. An uninterrupted cold chain and its monitoring and recording are crucial for them.

Additionally, the importance of reliable refrigeration temperature monitoring has never been more critical, given increasingly stringent food safety regulations and quality standards, as well as growing consumer awareness and demand for traceability.

And, last but not least, a maintained cold chain helps to counteract product waste—an integral step towards more sustainability.


Factors That Affect Reefer Temperature

Maintaining the optimal temperature in a refrigerated container is a complex undertaking influenced by various factors. Understanding and managing these influences are crucial for the safe and effective transport of perishable goods. The key factors are:

External Environmental Conditions

The surrounding area's temperature and humidity, as well as weather conditions, can affect the reefer's internal temperature. Extreme values can be challenging and sometimes even overwhelming for the cooling system.

Insulation Quality

The insulation materials used in the construction of the reefer are crucial to maintaining temperature. Poor insulation can lead to heat transfer or loss, causing temperature fluctuations. In addition, poorly insulated reefers use an unnecessary amount of energy, bringing us back to sustainability.

Reefer Maintenance

Regular reefer maintenance is crucial. Any mechanical problems, refrigerant leaks, or insulation deficiencies must be addressed before transportation. If defects occur during the trip, they should be remedied as quickly as possible.


Perishable goods must be packaged appropriately. On the one hand, to protect them from physical damage; on the other hand, the packaging materials must also withstand temperature fluctuations.


Before loading, the goods should undergo pre-cooling to reduce their temperature to the desired level. This minimises thermal shock and ensures the cooling system can more efficiently maintain the required temperature during transport.

Cargo And Stowage

The type and quantity of goods can also influence temperature distribution. If the reefer is overloaded or the goods are stacked improperly, air circulation can be hindered, which in turn can result in uneven cooling.

Ventilation and air circulation

Proper air circulation and ventilation are essential for even temperature distribution in the reefer. Hotspots or cold spots can arise if ventilation is insufficient or air ducts are blocked.

Performance of the cooling system

Of course, the cooling system itself also has an enormous influence on temperature control. Mechanical failures, refrigerant leaks or incorrect settings cause temperatures to deviate from target values.

Duration of transport

Longer transport times may require more robust cooling systems or additional monitoring measures to prevent temperature fluctuations over more extended periods.

Handling practices

It is generally recommended that all goods be handled carefully. In the case of temperature-sensitive goods, further damage can result from rough handling or damage to the container (e.g. door seals) if the temperature stability is no longer ensured.

Regulatory requirements

Regulatory standards and industry guidelines for temperature maintenance and control must be followed. Failure to comply could result in official penalties, product rejections or legal obligations.

Emergency Response Plan

An indispensable factor for the success of temperature-sensitive transport is the reaction of those involved in emergencies. Therefore, an emergency plan should outline procedures to deal with temperature fluctuations, equipment failures, or other unforeseen incidents during transportation. Staff must have emergency protocols and the necessary tools and resources to respond effectively to emergencies.


the Reefer Temperature Monitoring Device

A central factor is knowledge of the current circumstances. This requires temperature monitoring devices such as data loggers or wireless sensors in the refrigerated container to continuously monitor temperature conditions throughout the journey. These devices provide real-time data and alerts, enabling proactive intervention in the event of temperature deviations.

Addressing these factors effectively requires a comprehensive approach that includes adherence to best operating standards, preventive maintenance practices, and advanced temperature monitoring technologies. By proactively managing these factors, stakeholders can optimise temperature control in the refrigerated container, minimise risks, and ensure the safe and reliable transport of perishable cargo.


Technologies Used for Reefer Temperature Monitoring

So, how are the conditions within the reefer measured and monitored? There are a variety of tools and systems used to ensure the integrity of perishable goods throughout their journey.

Manual Monitoring

Let's first take a look at the traditional method of reading the data by hand. This means that one or more employees have to make their way to the reefer area, regardless of the weather, and take the information from each reefer individually; this usually happens once per shift. The values are recorded either on paper or electronically, for example, using a tablet. Certainly, with the paper solution and the tablet solution, the data may have to be transferred to a central system later.

This creates several sources of errors: once when reading the data itself and then when transferring it. And, if things get serious during an investigation, you are never entirely immune from accusations of manipulation.

In addition, in terminals with several hundred or thousand reefer parking spaces, manual reading is often complicated and time-consuming—and sometimes simply no longer possible. We should also not forget that staying in the yard involves safety risks, especially with the reefers and their high-voltage power connections.

Automated Monitoring

From simple but essential sensors to sophisticated data logging systems and innovative remote monitoring solutions, these methods and reefer temperature monitoring devices form the backbone of modern refrigeration strategies.

Automated systems provide precise monitoring and control of temperature and other conditions. Operators can remotely monitor the condition of all refrigerated containers in real-time, allowing them to respond quickly to any deviations or emergencies. This helps to prevent spoilage of goods and also to regulate energy consumption.

Data logging capabilities enable detailed tracking of temperature trends and the generation of reports for auditing, analysis, and compliance purposes.

Reefer Temperature Monitoring Devices

A whole range of devices and systems must be coordinated to ensure smooth monitoring and control of the temperature in the reefers:

  • Sensors: The most essential sensors in reefers are those for temperature and humidity.
  • Temperature sensors: These sensors are the cornerstone of refrigeration temperature monitoring systems. They measure the temperature and deliver it in real-time. Different temperature sensors, such as thermocouples, resistance temperature detectors (RTDs), and thermistors can be used depending on factors such as accuracy, sensitivity, and operating range.
  • Humidity sensors: They measure the moisture content of the air in the reefer. This is necessary to control condensation, prevent mould formation and maintain the quality of delicate perishable goods such as fruits and vegetables.
  • Data Loggers: Data loggers are devices that record temperature values at regular intervals and can store them over expanded periods of time. They work independently and have integrated memory or storage capacity for local storage of the recorded data. The loggers are connected to the sensors via cable or radio interfaces. They work independently and have integrated memory or storage capacity for local storage of the recorded data. Many of these devices are battery-operated to be used mobile and remotely.  Data loggers typically allow users to configure recording parameters such as sampling interval, recording duration, trigger conditions and alarm thresholds. Some advanced data loggers may offer programmable features or customisable logging routines to suit specific monitoring needs. Data transmission to central monitoring stations or online solutions can be carried out wirelessly using various technologies (UHF, GPS, 5G, etc.).
  • Remote Reefer Monitoring Solutions: With these solutions, all the information collected by the sensors and passed on via the data loggers comes together. Of course, they should be integrated into the terminal operating system (TOS) to enable seamless communication and data exchange between the remote monitoring system and other terminal management systems. This improves visibility, and potential problems can be addressed quickly. The integration also enables improved customer service through real-time updates. Speaking of visibility, these systems can provide much more insight than just temperature conditions. They can generate alerts and notifications via email, SMS, or mobile applications in the event of device malfunctions or other critical events. This allows for more efficient processes to be designed and implemented regarding how problems should be dealt with (learn more about reefer monitoring integration with Navis N4).



It's time to consider automated reefer monitoring, when...

  • There are simply too many reefers to monitor manually.
  • Monitoring becomes too difficult or time-consuming.
  • As safety concerns increase, or worrying near-misses or accidents occur.
  • Serious errors often occur when transferring manually collected data.
  • Freight loss rates are steadily increasing.
  • Your customers demand accurate data.
  • You have too little insight into energy efficiency.
  • You want to introduce pricing based on electricity consumption.
  • A container terminal expansion or a greenfield construction is pending.



For a long time, the transport of refrigerated goods was only possible over very short distances. Only in the second half of the 19th century did the first of the crucial inventions make the range of exotic goods that we now see possible.

Maintaining the necessary temperature is a complex matter; a variety of external factors, such as insulation quality, packaging of goods and ambient temperature, influence the cooling temperature.

Traditional manual data reading is increasingly giving way to the automated remote reefer monitoring system, especially on large terminals. The data recorded by the sensors is collected by data loggers and sent wirelessly to systems, which can display a variety of information in real-time, as well as critical warnings and alarms.

These modern systems are a vital step in keeping pace with the growth of refrigerated cargo in global trade. With their help, the integrity of the cargo and energy consumption can be monitored and controlled, both essential elements in the pursuit of ever-greater sustainability.

Energy Efficiency in Container Terminals Whitepaper

Delve deeper into one of our core topics: Reefer Monitoring