How to read a mapping study

Is there a difference at all?

The first question is not where the warmest point is. It is how large the difference between the points is.

If the span between the coldest and warmest point is half a degree, the placement of the fixed sensor hardly matters. If it is three degrees, the placement means everything.

That figure appears in the report as the difference between the lowest min and the highest max across the points.

Where are the extremes?

The warmest point is typically where the fixed sensor should be placed, because that is where the product is first at risk.

At the same time, check whether the extremes are in a place where a sensor can practically be mounted. If the warmest point is in the middle of a driving aisle, the next best place must be found, and that must be justified in the report.

When did the fluctuations happen?

Raw data over time shows whether the fluctuations coincide with something. A jump every morning is rarely the cooling system, it is loading work.

If there is a rise every six hours at all points at the same time, it is typically defrosting.

That is what determines the delay on the alarm limit afterwards. Without raw data, the delay becomes a guess.

Are the acceptance criteria met?

In the report's comparison, your own acceptance criteria are set against what was measured. If all points are within, the room is documented as suitable.

If a point is outside, it is not necessarily a problem with the room. It may be a matter of moving goods away from that particular spot, or of adjusting the system.

The assessment is yours. The report provides the basis, not the conclusion.

What the report does not answer

It does not say how many fixed sensors you should have. It says where they should sit once you have decided on a number.

Nor does it say whether you should map again, and when. That follows from your own SOPs and from how much changes.