Where should the sensor go?

Before installing permanent sensors, establish where measurements will tell you something meaningful. That is the purpose of mapping.

Start with the location

Before discussing sensor numbers, I ask where the measurements need to be taken. The answer should come from evidence about the space.

A sensor can be accurate, calibrated and connected, yet sit in a location that misses the conditions we need to detect. A reassuring reading tells us little about a storage zone we have never characterised.

For me, mapping is the foundation of the installation. Its findings should explain where products can be stored and which locations need permanent monitoring.

Understand the space before fixing the sensor positions

A sensor beside the door and a sensor on the upper rack may describe very different conditions. Height, airflow, loading and the building itself all affect the places where products sit. Mapping needs to make those differences visible.

The temporary sensors used for the study need a planned distribution across the space, informed by its layout and risks. The results then guide the positions of the permanent monitoring sensors. Those are two different placement decisions.

One season may leave part of the story untold

WHO’s storage-area guidance says that areas affected by seasonal temperature variation may need studies in both the warmest and coldest seasons. It also notes that two-season mapping is typically unnecessary for cold rooms and freezer rooms. The study design therefore needs a reasoned assessment of the facility and its exposure.

When the outside climate influences a warehouse, I expect the study to address summer and winter conditions. A location selected from one seasonal study needs evidence that it remains suitable throughout the year.

The calendar alone is a poor explanation for a protocol. Document the conditions the study is intended to capture, the conditions actually encountered and any limitations. The purpose is to understand the seasonal risks the facility must manage.

Humidity deserves its own assessment

WHO also identifies relative humidity mapping as relevant where humidity-sensitive products are stored. A temperature study alone does not establish the humidity conditions throughout a storage area.

In tropical and equatorial settings, humidity belongs near the beginning of the discussion. What do the products, their packaging and their specified storage conditions require us to understand?

Where it matters, include relative humidity in the study and interpret it alongside temperature. Look at the local climate and the facility’s operating conditions. Wet and dry periods may be more useful planning references than the labels summer and winter.

The scope follows the products and the documented risks. Tropical facilities differ, and humidity can matter in temperate climates too.

Make each permanent location explainable

At the end of the study, I want a clear answer for each monitoring position: what does this sensor represent, which risk is it intended to detect and what evidence supports placing it here?

A report filed away without an effect on sensor placement has missed an essential part of its purpose. The findings should inform the installation and remain available when the layout, airflow, storage practices or operating conditions change.

When I review an installation, I want to see the reasoning behind each sensor position. Show me how you decided where to measure.