All new temperature-controlled storage areas must be temperature-mapped as part of a fully documented verification process. Until this has been done, it is not safe to store temperature labile products in such areas. The temperature mapping procedures should;

  • Demonstrate the air temperature profile throughout the storage area, when empty and in a normal loaded condition.
  • Define zones which should not be used for storage of temperature labile products (for example areas in close proximity to cooling coils, cold air streams or heat sources).
  • Demonstrate the time taken for temperatures to exceed the designated limits in the event of power failure.

Subsequent mapping exercises must also be carried out on a periodic basis in order to demonstrate continuing compliance.  It is recommended to have 2 mapping exercises done at the hottest and the coldest seasons during an 18 month period. The recommendation is to perform the mapping for the facility as below;

  • Mapping 1 (summer): Conducted right before or during the convergence of the equinox when the Sun is directly over the equator. Proposal to conduct this in February/March.
  • Mapping 2 (winter): Conducted right after the Sun is directly over the tropic of Cancer in the North, when it is traditionally cold along the equator. Proposal to conduct this in July/ August.

In addition mapping should be carried out whenever significant modifications are made to the store. Examples include changes in the pattern of use that may increase loading or affect air circulation, or changes to the refrigeration equipment, such as an alteration to the set point.

Finally a remapping exercise may be justified whenever an analysis of temperature and/or humidity monitoring records show unexplained variability outside normal operating limits. All mapping exercises should be fully documented in order to demonstrate compliance to management, clients and the regulatory authorities.


A temperature mapping exercise is required for any space allocated for the storage and handling of products with a specified labelled storage temperature. This includes freezer rooms, cold rooms, temperature-controlled storage areas, quarantine areas and receiving and loading bays. It may also include laboratories. The permitted temperature ranges in these areas will vary – for example: -25°C to -10°C, 2°C to 8°C, 15°C to 25°C, etc.

Temperature mapping may also need to be carried out in spaces without active temperature control. A mapping study establishes the temperature distribution within the zone being mapped and it locates hot and cold spots. The collected data provides an essential source of information to ensure that all temperature labile products are correctly stored within their labelled temperature range(s). Mapping may also be used to identify zones where remedial action needs to be taken; for example by altering existing air distribution to eliminate hot and cold spots, or by retro-fitting new air distribution equipment to reduce temperature stratification in high-bay warehouses.

Our temperature mapping exercise involves a four stage process, as follows;

  • Prepare a mapping protocol.
  • Carry out the mapping exercise.
  • Prepare a mapping report.
  • Implement the recommendations by carrying out the remedial and other actions identified in the mapping report. A follow-up mapping exercise may then be needed to verify the effectiveness of the remedial actions.


A mapping operation requires a sufficient number of Electronic Data Logging Monitors (EDLMs) to ensure that the temperature distribution in the space to be mapped is adequately characterized. In addition, suitable computer equipment and software is needed to store and analyze the data. The selected EDLMs must;

  • Be technically suitable for the specific mapping task and for the intended operating environment.
  • Provide a reliable and continuous reliable record of time-temperature data.
  • Have an appropriate temperature range so that all anticipated temperature extremes can be recorded (e.g. from -30°C to +60°C).
  • Have a user-programmable data sampling period, with time intervals ranging from one minute to 15 minutes or more and sufficient memory for the intended length of the study and the chosen recording interval.
  • Have a NIST- traceable 3-point calibration certificate with a guaranteed error of no more than ± 0.5°C at each calibration point.
  • Allow the recorded time-temperature data to be downloaded to a computer system for subsequent analysis.
  • Have data storage and analytical software that complies with applicable regulatory requirements.


A detailed and comprehensive protocol will be prepared, reviewed and approved before the mapping exercise begins. A well-designed protocol will help ensure that the mapping study is correctly carried out. With suitable adjustments or options to cover the full range of temperature regimes, a standard protocol can be used to map any storage area in the facility. The mapping protocol should contain the following sections;

  • Approval page and change control history.
  • Acronyms and glossary.
  • Description and rationale.
  • Scope.
  • Objectives.
  • Methodology.
  • Mapping report template.
  • Annexes as needed, including templates for the mapping report.

It may be helpful to use a generic floor plan or diagram to decide where each logger should be positioned.

Figure 1 shows part of a pallet racking cold room with an adjoining temperature-controlled packing area.

 Figure 2 shows a small walk-in cold room.

STEP 6 – Record EDLM and thermostat locations: Record the EDLM locations on a temperature data logger location table for ease of traceability.

STEP 7 – Label and program the EDLMs:

Label each EDLM with a unique ID, taken from the temperature data logger location table. Enter the manufacturer’s serial number on the temperature data logger location table. Recording the serial number ensures that the device can be traced to its calibration certificate. Program each device, ensuring that the recording interval is the same – typically this should be set between 5 and 15 minutes. Set the same start time for all units. This is essential; otherwise the downloaded readings from the individual devices cannot be time-correlated. Make sure that the start time setting gives you enough time to fix all the units in position before recording begins.

STEP 8 – Fix EDLMs in position:

Fix the EDLMs in position. Make sure that each one is placed exactly as shown on the temperature data logger location table and drawing. Position and fasten the devices so that they cannot be damaged or displaced during the course of routine store operations.

STEP 9 – Conduct the mapping exercise:

Typically it should be run for a minimum of seven to 14 consecutive days for warehouses and other ambient storage areas. For temperature-controlled equipment which is not critically affected by diurnal or seasonal variations in ambient temperature (e.g. freezer rooms and cold rooms), the mapping study should be run for between 24 and 72 hours, or more if justified. If the room is fitted with duplicate refrigeration units – with or without automatic changeover – it is essential to map temperatures over a period that includes the operation of both units; preferably for a similar time period. The temperature distribution in the room may vary depending upon which system is running. At the end of the study, We collect the EDLMs and double-check their serial numbers and locations against the installation notes.

 STEP 10 – Download the EDLM readings and consolidate the data for the study analysis.


The protocol should contain a template for the mapping report. This should include the sections listed below;

  • Introduction: A description of the objectives of the mapping study.

  • Summary: A summary and discussion of the results organized in the sequence set out in the mapping protocol, including a summary of deviations (if any).
  • Conclusions and recommendations: A general conclusion for all verifications and observations indicating the acceptability of the equipment for operation. Recommendations and remarks can be incorporated as well.
  • Report annexes.

The report annexes should contain the following;

  • The site survey, showing EDLM locations.
  • The raw data, presented using the appropriate test data sheet format.
  • Spreadsheet data and related temperature graphs for every EDLM used in the mapping exercise.
  • Raw results of the data analysis.
  • Key documents and notes prepared during the mapping exercise, together with any other supporting material.
  • Deviation reports, including Corrective and Preventive Actions (CAPA) forms, if required.
  • Calibration certificates for all EDLMs used.


The final outcome and purpose of a mapping exercise is the implementation of the report recommendations. A detailed discussion of implementation is outside the scope of this document, but it could include any of the following outcomes;

  • A drawing or diagram showing where temperature labile products can safely be stored in the space that has been mapped. It is possible that there may be some zoning involved. For example, products which are not affected by freezing could be allocated to parts of a cold room where the mapping study has shown some freezing risk.
  • Allocation of pallet bays to specific categories of temperature labile products on the warehouse management system in order to control where stocks are positioned.
  • Re-positioning of temperature monitoring sensors and/or environmental control sensors.
  • Adjustment of air outlets to reduce temperature stratification and/or minimize cold and hot spots.
  • Upgrading of mechanical systems to improve temperature control and performance.
  • A decision to use the space for other purposes because it is unsuitable for the storage of temperature labile products.




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