Temperature Mapping

Is the validation study performed before taking new cooling quipment or storage space into use. This article explains many different aspects to concern when working professionally with mapping.


How to make a temperature mapping of your refrigerators and freezers?

Easily map your refrigeration equipment using this temperature mapping template.

When new equipment is being put into use or when temperature monitoring is implemented, it is important to know how the equipment is performing. All refrigeration equipment will have hot and cold zones which are important to be aware of when placing temperature sensitive goods in the cooling equipment. A temperature mapping can help you spot these.

Overall, temperature mapping should be used as a tool to give you an overview of your equipment and to prove to authorities and auditors that your equipment is working properly in those areas where critical goods are placed.

Mapping refrigeration equipment with Euprys Mapping Kit

Save time by using Eupry’s easy-to-use Mapping Kit with accredited DANAK ISO17025 calibration and 21CFR PART11 compliance.

Cooling equipment mapping is an important process in examining whether refrigeration equipment is working properly.

Practical mobile box with the number of data loggers (temperature sensors) needed.

A wireless base station and extra batteries

All data loggers are START calibrated, and an END calibration is performed

Eupry data loggers sent to clients for mapping the area and monitoring temperature

What is temperature mapping?

Mapping of refrigeration equipment is the process that is carried out to prove that the equipment meets the criteria set for the equipment and to find any hot and cold zones. In other words temperature mapping provides evidence that the equipment maintains temperatures within defined limits at all times.

Inside a refrigerator the temperature can vary from point to point. A regular consumer refrigerator in your kitchen will in many cases show that temperature in the top of the fridge is 5 degrees higher than in the bottom. This is the main reason for performing a mapping study before taking new cooling equipment into use. The mapping can sometimes tell if some areas are either too hot or cold to be used. 

After you have mapped the equipment, you will have a clear idea of ​​how the equipment meets temperature requirements, and which zones in the equipment can be used for storage and which cannot. Last but not least, it will give you a good idea of ​​where to place your temperature monitoring equipment to get the best picture of the temperature of the critical goods.

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How is a temperature mapping performed?

Temperature mapping refrigeration equipment does not have to be complicated or time consuming. The most important thing is that the scope and complexity fit the equipment and the frame in which the equipment is included. You, therefore, don’t need to overdo the temperature mapping if your processes does not require it.

The most important elements of mapping are:

  • Create a plan for the mapping
  • Check the documentation of the measuring equipment
  • Setup your measuring equipment
  • Collect data
  • Document and evaluate results

1. Create a plan

Before mapping takes place, you must specify how to map, for example by making a temperature mapping standard operating procedure (SOP):

  • How many places do you want to measure?
  • Should the equipment contain goods during the mapping?
  • What are your acceptance criteria – i.e. what are the external limits for temperatures in the equipment?
  • What kind of temperature mapping equipment will you use?

The most important thing before you start the process is to find out what your limits are so you have something to validate against, as well as how thoroughly you expect to do the mapping.

2. Check the documentation of the measuring equipment

You must check that the measurement equipment you use for mapping is calibrated and comes with a certificate showing that the equipment is calibrated within a reasonable limit and timespan. Typically, 0.5C precision and a maximum calibration interval of 1 year will be enough.

Additionally, make sure you can extract data when you have completed the mapping, e.g. by using a system where you can export reports within specific time periods.

3. Set up your measuring equipment

Typically, the mapping will take place in the areas of the refrigeration equipment where high temperature fluctuations are expected. This will usually be:

  • The front door far from the cooling element
  • Close to the compressor at the bottom
  • At the back panel where the cooling elements are located.

You can save time by assessing where the largest fluctuations will occur. You will never be able to find all extremes in the refrigeration equipment, so it is more important to choose locations that are representative.

Optimally, you have several pieces of measuring equipment, that you can install at the same time. If you have only had a few or a single piece, you can instead move it around and thus create an overview of the temperature extremes in the equipment.

Typically it will be enough to measure in a 24 hours time span. This ensures that you catch both hot times in the middle of the day as well as the normal cooling cycle that the cooling equipment goes through.

To get a good picture of how your equipment performs under normal conditions, you can fill up the equipment with goods. The mapping can also run without goods, but it will not provide a precise picture of how your equipment behaves under normal conditions. 

During the mapping, it is important not to open the doors of the equipment as this may affect the measurements.

Eupry example on conducting temperature mapping of refrigerators

An example of temperature mapping equipment placement

4. Collect data

Whether you use multiple pieces of equipment or few that you move around, data must be collected and compared. If the goal of the mapping is to provide a credible picture of how your equipment is performing, it is important that the entire measurement period is included.


Eupry are experts in temperature monitoring, validation and compliance, get in touch if you have any questions!

5. Document and evaluate results

When you’re done, it’s time to draw some conclusions based on the data.

Typically, the hottest and coldest areas will be of interest since the risk of deviations during normal use are high in these areas. If there are areas that are found to be unsuitable for temperature sensitive items, it may be a good idea to mark these with tape so the staff knows they cannot use them. At the same time note which areas are within the limits and thus can be used for storing critical goods.

Sometimes it may be apparent that the cooling equipment must be adjusted after which you have to perform a new mapping study.

The data gathered from the temperature mapping can also be used to show where it is advantageous to place temperature monitoring in normal operation. If the cooling equipment turns out to have a zone where there are large fluctuations, this location can be used for temperature monitoring as this will give an early warning if the equipment malfunctions.

It is especially advantageous to use a temperature monitoring system with an alarm function, that notifies you if the equipment fails or does not work properly. This way deviations can be captured in time which will save valuable goods.

Who performs temperature mapping?

Eupry optimizes how organizations monitor, and document temperatures. Using the Internet of Things (IoT), Eupry changes the way organizations approach compliance, quality, and efficiency. We have a wide variety of customers in several sectors. If you have any questions regarding how to secure temperature sensitive goods, you are welcome to contact us.

Cold room temperature mapping

When mapping cold rooms it is important to understand the implication loading has on the temperature of the different parts of the cold room. 

Also distribution of air, or airflow, is a large factor on the performance of the cold room. If there is no airflow, or the airflow is obstructed the risk of having areas with a lower or higher temperature is high. When air is not being circulated easily around the room, areas which are in connection to a hotter surface (wall to surrounding area for example) will tend to become non-compliant.

Illustration of Cold room temperature mapping made from Euprys Software tools. Explain about the example

Freezer temperature mapping

A lot of freezers are being used for storage of sensitive assets, and freezers tend to have some issues that larger cold rooms do not. 

Loading has a large impact on the performance of freezers, which need to be considered when temperature mapping and using freezers. As a freezer has a small thermal mass, when hot or cold goods are put into the fridge, the temperature in the areas where goods are placed will often be drastically affected as the introduced mass will have to be cooled or heated with the small capacity of a freezer. 

It is therefore important to evaluate the effect of larger loadings to a small freezer, and implement these findings into the standard operating procedures for the use of a freezer.

Placement of a freezer in the surrounding area is also important, as a freezer has to get rid of the excessive heat generated when the freezer is performing cooling cycles. A freezer, either large or small, has to generate heat which it has to dissipate easily for the freezer to perform optimally.

If the freezer is placed inside an enclosed space, the heat can not escape and thus it can not perform as expected. Also the room temperature must not be too high, which also will cause it to perform badly. This also affects how temperature mapping is performed, as the temperature mapping has to reflect normal use of the freezer.

Fridge temperature mapping

The goal of a fridge is to maintain temperatures within specified limits. 

Temperature mapping in fridges is used in order to locate hot and cold spots and understand thermal balance over the entire processing volume, or in other words to ensure that the fridge can actually maintain temperature within limits. 

It is important to understand the importance of maintaining temperatures within limits, as otherwise the stored goods will not be maintained at the specified temperatures. Having mapped fridges avoids downtime in business operations and performance interruption of equipment. 

Warehouse temperature mapping

In the case of mapping temperatures in a warehouse, the goals of the mapping are the same as if mapping smaller pieces of equipment, but the practical considerations varies. 

When mapping a warehouse, one of the important things that the mapping should investigate is possible airflow issues. Especially with larger warehouses, there can be issues with airflows which either create colder or hotter areas, either due to high flow of cold air in some areas, or the lack of airflow in other areas. A mapping should take into account possible airflow issues, and can give information on where to place sensitive assets and where not to. 

Next to air vents, doors and packing areas, etc., temperature variations can be expected, and therefore these areas are of special interest.

Another important factor is external influences. This could be from walls that are connected to areas of substantially different temperature, or outer walls that will experience great temperature difference from different seasonal changes. Because of this, a mapping is normally performed during the coldest and hottest season.

Furthermore, through proper temperature mapping, these variations can be measured, analyzed and adjusted throughout the entire system as well as different points to ensure a more efficient and effective operation of managed warehouses. 

Another point of interest is the amount of sensors used to perform the thermal mapping of a warehouse. When a larger area is being mapped, a larger amount of sensors is needed. Care should be given when choosing amount and position of sensors, as to allow for detecting variations in temperature in different areas of the warehouse. 

WHO has issued a guideline which can aid in determining the amount and positions of sensors which can be downloaded here: https://www.who.int/medicines/areas/quality_safety/quality_assurance/TS-mapping-storage-areas-final-sign-off-a.pdf

In the case of warehouses, having information of the external conditions of the building is important for successful temperature mapping or monitoring of temperature sensitive products. To ensure that all external conditions are met, particularly for pharmaceutical products, it is necessary to map warehouses. Even a few degrees of variations may affect the quality of the product. Changes in temperature location, layout, cooling equipment, air circulation, product quality, and many other factors can cause temperature fluctuations. Next to air vents, doors and packing areas, etc., temperature variations can be expected. Temperature mapping can help understand the warehouse’s temperature dynamics and ensure the most sensitive areas are controlled. Furthermore, through proper temperature mapping, these variations can be measured, analyzed and adjusted throughout the entire system as well as different points to ensure a more efficient and effective operation of managed warehouses.  

Validating storage areas with temperature mapping

Storage areas can both be a smaller rooms with medicine or very large storage buildings with robotic placement machinery. Validation and mapping could in theory follow the same protocol but in practical life care should be taken as to where to place sensors.

When storage areas are being thermally validated using a thermal mapping, airflow issues is one of the major points of interest. 

As there are often storage racks with goods stored on them, the airflow can be obstructed, and thus creating large variations in temperature and humidity. Therefore it is often required to perform mapping with and without goods on shelves, which can confirm that the storage area can still maintain temperatures or humidity levels within specifications, even though goods obstruct airflows.

3D mapping visualization

For better understanding of the temperature distribution, the gathered temperature mapping data can be visualized in 3D as shown below.

In the above example, it is clear that there is an issue at the left front of the freezer, and that the temperature in general is higher at this point. 

A 3D mapping visualization can help improve the understanding of where a potential issue is, or where it is safe or not safe to store valuable goods in a freezer.

The same approach can be used to gain insights into the temperature performance of storage areas and warehouses.

For even an even better overview of temperature distributions over time, a heatmap mapping visualization can be made from data gathered during a mapping study. 

Below is an example that has been made from data from a small storage room with a single air condition unit over the course of 24 hours. 

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From the 3D mapping visualization is can be seen that one side of the storage room is colder in cycles as the air conditioning units turns on and off, something that would be difficult to see from graphs alone.

Another use for 3D mapping visualizations is when observing events in temperature controlled environments, such as door openings or power failures. 

An example of such a use can be seen below:

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As can be seen, the colder air from an adjacent room cools from the left over time, which is now very clear from the mapping visualization. Based on these results, care can be taken as to where sensitive assets should be placed in the temperature controlled storage room.

Questions about a Temperature Mapping Study?

Typical questions that we get about temperature mapping studies

What limits should I use as an acceptable range for study  ? 

This depends on multiple factors, one being what kind of products are stored. For example for pharmaceutical companies it is crucial to maintain the temperature. Particularly for medication, with refrigerators, the temperature should be between 2° C and 8° C and with freezers it should be between -50° C and -15° C dependent on use. 

Another factor which should be accounted for is the uncertainty of the sensors or data loggers used for the mapping. The uncertainty of the measurement equipment should be taken into account by decreasing the span of acceptable temperature or humidity.

What kinds of sensors should I use ? 

The sensors for performing a mapping of any kind of equipment or facility should be chosen to the task at hand. 

Some specifications to look for are:

  • Resolution
    The resolution should normally be at least 0.05°C so that even small temperature variations can be detected.
  • Accuracy
    Dependent on the acceptable span for different mapping exercises, the required accuracy can vary from ±0.1°C to ±0.5°C for either small acceptable spans to larger spans.
    For humidity a normal acceptable accuracy is ±3%.

Furthermore it can be beneficial to look at how data is handled, both during and after mapping, as time used for gathering data can be higher than expected if wired systems are used rather than wireless systems.

The feature of concern should be measured by your sensors, e.g. humidity or temperatures. The sensors must be accurate for a temperature of ±0.1°C which is good, and the relative humidity is good at ±3%. If you use software requiring tools to collect and download data or produce report you will need to show the software has been tested and complies with (Insert qualification requirements). 

How many sensors do I need, where should I position them? 

This depends on factors such as geometric space. You must analyse the room and classify possible causes of humidity and temperature variations such as doors and windows. Include these observations in your reasoning so that reviewers of the thermal validation can understand and assess your choices. These are called the rationals, and is an important part of the mapping exercise.

What kind of calibration is needed for my sensors? 

All sensors used for a mapping exercise must be calibrated, either traceable or accredited based on quality requirements. 

Based on quality requirements, it should also be decided whether the sensors should also be calibrated after the mapping exercise. In less regulated areas, a start calibration is sufficient, while more rigorous standards of quality require an end calibration to be performed to ensure that the sensor is also accurate at the end of mapping exercises.

What is the appropriate mapping study duration?  

Your mapping study should be long enough to ensure that you have accurately captured the environmental dynamics of the area being mapped. The larger the area, the more activity is ongoing during the study, the longer the estimated time of the mapping. It is worth considering seasonal changes for these spaces, and therefore perform mapping twice in a year – once at the hottest and coldest time of the year. For all these things it is critical that a consistent justification for decisions is established and that these are documented as part of the validation procedure. The reasoning should be scientifically based, applicable to facilities and products and suitable for the intended use of the area being mapped.