Cold room temperature mapping
Walk-in cold rooms combine forced airflow, door traffic and defrost cycles — each leaves a signature in the data.
A 2–8 °C cold room is small enough to map thoroughly and busy enough to surprise you. Typical gradients run from the evaporator outlet (coldest, sometimes below 2 °C) to the door and the top shelves furthest from the airflow.
Placement
- Corners at low and high level, the geometric centre, directly in front of the evaporator, and beside the door.
- Product height, not the ceiling: sensors should sit where product actually sits.
- One sensor outside the room as an ambient reference helps explain door-related events.
What to expect in the data
Defrost cycles show as periodic rises at the evaporator sensor; door openings as short spikes near the door that recover within minutes. Neither is necessarily an excursion, but both must be assessed against the limits and durations in the protocol. Run the study for several days so that daily patterns and weekday deliveries are captured.
Frequently asked questions
- How long should a cold room mapping study run?
- Several days, long enough to include weekday deliveries, a weekend and multiple defrost cycles — commonly five to seven days.
- Where is the cold spot in a cold room usually?
- Directly in the evaporator air stream, where product can be exposed to sub-2 °C air; the hot spot is usually near the door or on the top shelf furthest from airflow.
References
- [1]WHO Technical Supplement 8 to TRS 961 Annex 9: Temperature mapping of storage areas (2015)
- [2]EU Guidelines on Good Distribution Practice of medicinal products for human use (2013/C 343/01)
General technical guidance written against the cited sources. It is not regulatory or legal advice and does not replace the applicable standard, guideline or a qualified reviewer's judgement.
Have a question on this topic?
Ask ValiTrac AI and see the evidence and calculation behind the answer.
Ask ValiTrac AIFree calculator: MKT & logger data check
Paste logger readings and get MKT per ICH Q1A(R2) alongside min, max, mean and out-of-limit runs with durations.
Open the calculatorTemperature Mapping on ValiTrac
Analyse logger data and identify data-quality issues, statistics, hot/cold spots and excursions.
Explore mappingRelated articles
How many sensors are needed for temperature mapping?
There is no single number: sensor count follows from the geometry, the risk points and the acceptance limits of the space.
Refrigerator temperature mapping
Pharmacy and laboratory refrigerators are small, but they have cold spots at the back and warm spots in the door — mapping shows which shelves are safe.