The storage room that wasn't

A 15m² room on a school estate, labelled in the asset register as storage. Zero ventilation requirement. No environmental targets beyond the basics. An unmonitored back-of-house space.

The sensor told a different story.

Every weekday at 09:00, CO₂ inside the room rose sharply from a 400ppm baseline and held between 800 and 1,200ppm until 16:00. Temperature climbed on a predictable daytime curve. Both metrics dropped back to ambient overnight and at weekends.

Storage rooms don't breathe. They don't generate metabolic heat. They don't follow a school timetable.

The data signature was a classroom.

When the on-the-ground reality was checked, that's exactly what it was. Pressed for space, staff had added desks, chairs and a whiteboard, and a room labelled as a vault was being used to teach children in. Unventilated. Unmonitored. Failing BB101 every morning without anyone knowing.

The static register said one thing. The building said another. The register was wrong for years before anyone asked the building.

The pattern.

Asset registers drift. Spaces get repurposed without anyone updating the records. The compliance regime is set by the label; the risk is set by what's actually happening in the room.

Reading the data signature against the expected behaviour for a space's classified type catches that gap before an inspector does.