What is temperature mapping?

Temperature mapping in practice

Temperature mapping — also called thermal mapping — is the systematic measurement and documentation of the temperature distribution in a three-dimensional space over a defined period. Instead of measuring at a single point, you place several calibrated data loggers at predefined positions. That reveals not just the average, but the extremes: where does it get too warm or too cold?

Mapping is used for refrigerators, freezers, cold rooms, warehouses, incubators, climate chambers and other controlled storage. It is a qualification study: it provides objective evidence that a space can reliably maintain its specified storage conditions.

What are hot spots and cold spots?

A hot spot is the warmest location in the space; a cold spot the coldest. They arise because air, cooling and heat sources are never perfectly even.

Why it matters: the average can sit comfortably within range while a hot or cold spot falls just outside it. For storage between 2 and 8 °C, a cold spot drifting toward freezing can freeze products — for many vaccines and biologicals that is irreversible damage. A hot spot, in turn, can breach the upper limit. That is exactly why these extremes are the logical place for your fixed monitoring sensor: an excursion shows there first.

Why is temperature mapping important?

• Audit evidence. Guidelines such as GDP, GMP, HACCP, WHO and ISPE expect documented proof that your storage is suitable.
• Product safety. You know products stay within the safe range at every position, not just on average.
• Justified monitoring. The mapping determines where your permanent sensors sit representatively.

How does a temperature mapping study work?

1. Protocol and risk assessment. We define up front what is tested, against which criteria and with which equipment.
2. Placement. Calibrated loggers are placed and labelled at the chosen measurement points.
3. Measurement. The loggers record continuously for the agreed period.
4. Analysis and report. The curves are overlaid, hot and cold spots identified, and you receive an audit-ready report with monitoring-position advice.

How long does a temperature mapping study take?

There is no legally fixed duration. In practice, refrigerators, freezers and smaller controlled units are often mapped for 24 to 72 hours, while warehouses and large ambient areas typically run for at least 7 consecutive days. Where seasonal variation is a factor, it is wise to measure in both the warmest and coldest period. More data gives a more reliable picture; we justify the exact duration on a risk basis in the protocol.

How many measurement points do you need?

There is no fixed legal number. For a standard refrigerator or freezer, around 9 measurement points is a logical starting point; for larger spaces it depends on volume, layout, airflow, loading and risk. Read the full explanation on measurement points or calculate it directly with our calculator.

Temperature mapping and monitoring are not the same

Mapping is a one-off or periodic qualification study; monitoring is the continuous follow-up afterwards. The mapping proves your monitoring sensors sit in a representative spot. Read the difference between monitoring and mapping.

Preparing for an audit? Also read what auditors want to see in a temperature mapping.