Thermal Imaging Cameras — PRN Equipment Guide

## What a thermal camera measures Thermal imaging cameras detect long-wave infrared radiation (LWIR), typically in the 8–14 µm wavelength range, emitted by objects as a function of their temperature. They produce a thermal map of a scene — a spatial display of surface temperature differences — not a photograph of light. They do not see through walls, detect magnetic fields, or directly image airflow. Importantly: thermal cameras measure **surface temperature**, not air temperature. A draught of cold air will not appear as a floating cold form unless it is cooling a surface long enough for that cooling to be visible. ## Why investigators use them Thermal cameras are useful for: - Identifying building pathology that might explain cold spots: air ingress around windows, uninsulated gaps, rising damp (evaporative cooling), blocked or poorly-sealed ducts. - Documenting temperature anomalies for comparison between investigation runs. - Mapping heat sources (electrical equipment, heating pipes, body heat) to distinguish them from points of interest. The working hypothesis in some investigations is that anomalous thermal patterns may accompany certain phenomena. This is not established scientifically, but thermal cameras at minimum help you map and exclude the mundane. ## Sensor resolution and its importance Consumer thermal cameras — including smartphone attachments — frequently have low sensor resolutions (e.g., 80×60 or 160×120 pixels). These are interpolated up to display resolution, meaning much of the detail you see is mathematically generated, not measured. For rigorous work, a higher native resolution (320×240 or above) is worth the additional cost. **Temperature accuracy** is typically ±2°C or ±2% of reading for consumer devices. This means small temperature differences (1–2°C) may be within the uncertainty margin of the instrument. Note this in your documentation. ## Emissivity — the key variable investigators overlook All thermal cameras assume a surface emissivity value (often 0.95 or 0.97 by default). Emissivity is a property of a material describing how efficiently it radiates heat relative to an ideal blackbody. Shiny, reflective surfaces (metal, mirrors, glass) have low emissivity and will appear to reflect ambient thermal radiation rather than displaying their true temperature. A cold metal door handle will appear warm if the camera is warm and the handle is reflective. Document surface materials at every point of interest. A "cold apparition" that turns out to be a reflective surface or a polished brass fixture is a false positive. ## Practical guidance - Allow the camera to equilibrate to ambient temperature for at least 10–15 minutes before use — all thermal cameras drift until their internal temperature stabilises. - Run a baseline sweep first: identify all heat sources, air vents, pipes, radiators, and exterior-facing walls before the investigation period begins. - Capture still images and label them with timestamp and room reference. - Avoid breathing or holding the camera near surfaces you are attempting to read — body heat radiates significantly.