Temperature and humidity monitoring for regulated environments has two parts: continuous monitoring that records conditions in real time, and a mapping study that proves the whole space stays within limits. For GMP, GDP cold chain, cleanrooms and stability storage, it is not enough to measure at one point — you must demonstrate, with calibrated instruments and documented evidence, that every part of the controlled space stays within specification.

Monitoring vs mapping — they are not the same

  • Monitoring is ongoing: fixed sensors and data loggers record temperature and humidity continuously, with alarms if a limit is breached.
  • Mapping is a study: many calibrated loggers are placed throughout a space (a cold room, warehouse, chamber or truck) over a defined period to find the hottest, coldest and most humid points — the worst cases that monitoring must then watch.

You map to find the risk; you monitor to control it. Auditors expect both, with the monitoring sensors located at the worst-case points the mapping identified.

What a mapping study involves

  • Placement: calibrated loggers distributed across the space — corners, near doors, by heat sources, at different heights.
  • Duration: long enough to capture normal operation, including door openings, defrost cycles and load changes (often several days).
  • Conditions: empty and/or loaded, and ideally across the seasons or worst-case ambient.
  • Report: the data, the hot/cold spots, the pass/fail against limits, and the recommended monitoring sensor locations.

Calibration is non-negotiable

Every sensor and logger used for monitoring or mapping must be calibrated and traceable — an uncalibrated logger proves nothing in an audit. The sensors should be calibrated before and ideally after the study, so you can show they were accurate throughout. This is where an ISO/IEC 17025 accredited calibration of the loggers matters.

Humidity matters too

Many products are sensitive to humidity as well as temperature — capsules, powders, electronics and certain biologics. Cleanrooms and stability chambers usually have humidity limits. Use instruments that measure both, and remember humidity sensors drift and need regular calibration.

Putting it together

A defensible programme combines: calibrated loggers and transmitters, a documented mapping study to find the worst cases, continuous monitoring with alarms at those points, and a calibration schedule for every sensor. Unitest Instruments supplies Rotronic humidity and temperature instruments and data loggers, calibrates them at our accredited lab, and can carry out temperature mapping studies as a service.