Temperature and Humidity Mapping Studies

Temperature and humidity mapping is a documented qualification study that characterizes the spatial distribution of temperature — and, where relevant, relative humidity (%RH) — throughout a controlled space or storage unit under real operating conditions. Multiple calibrated, NIST-traceable data loggers are positioned at defined points across the volume, and readings are recorded continuously over a set study period, then analyzed statistically to confirm that every location stays within the acceptance criteria. A mapping study is not the same as calibrating an instrument or continuously monitoring a unit: it answers the question “is every point in this space actually within specification?” and locates the warmest and coolest positions. The deliverable is a written report — protocol, sensor-placement rationale, raw data, statistical summary, and a pass/fail determination — that becomes part of your equipment qualification package.

Sensor count is driven by the volume, geometry, and the applicable guidance, not by a single fixed number. A small chamber, refrigerator, or incubator is typically mapped with a minimum of 9 loggers — the eight corners plus the geometric center — while a large walk-in cold room or warehouse may require dozens to more than 100 loggers arranged on a three-dimensional grid. Placement deliberately targets suspected worst-case locations: next to doors and loading docks, near cooling coils and heaters, at the highest and lowest racking levels, close to HVAC supply diffusers and return air paths, and against exterior walls. Additional loggers go at the points where the working monitoring probe and the control sensor are located, so the study can show how representative those fixed sensors are. The placement and its rationale are documented in the protocol before the study begins.

An empty (or no-load) study characterizes the space itself with no product inside, capturing the worst-case air distribution the unit can produce and establishing a baseline for the equipment. A loaded study is run with product — or a validated simulated load — in place, because stored goods add thermal mass and block airflow, which changes how heat penetrates the space and where gradients form. Regulated storage qualification frequently calls for both: the empty study to qualify the equipment and the loaded study to prove that the space still holds specification under real operating conditions. Loaded studies also verify recovery after routine events such as door openings and stock rotation. The protocol defines the load pattern, and the report reports each condition separately.

A mapping study must run long enough to capture the full range of conditions the space experiences. The practical minimum is 24 hours, so that at least one complete cycle of the HVAC or refrigeration system, any automatic defrost cycles, and the full day-to-night ambient swing are recorded. Most studies run 48 to 72 hours, and large warehouses and walk-in cold rooms with high thermal mass are often mapped over 72 hours to 7 days. Within the study, deliberate challenge tests are usually added — door-open intervals and a simulated power failure with recovery — to document how quickly the space returns to specification. Where seasonal extremes matter, the study is repeated in summer and winter rather than extended in a single session.

Femto Scientific maps essentially any controlled-temperature — and, where applicable, controlled-humidity — space or unit, including: pharmaceutical and distribution warehouses; walk-in cold rooms and walk-in freezers; stability chambers qualified to ICH climatic conditions; laboratory, pharmacy, and clinical refrigerators (typically +2 to +8 °C); standard and blood-bank freezers (−20 °C and −30 °C); ultra-low −80 °C freezers and cryogenic/liquid-nitrogen storage; CO₂ and non-CO₂ incubators; controlled-temperature cleanrooms and compounding areas; and heat processes such as ovens, dry-heat sterilizers, autoclaves, and lyophilizers. If the environment has an acceptance range that a regulator or accreditor expects you to prove, it can be mapped.