A fundamental question to ask when analyzing anything is, "Compared to what?" With no point of reference, facts and figures can grossly mislead you. It’s the same with infrared thermography (IR) — you need benchmarks.
Most thermographic cameras provide for various benchmarks, such as:
Ambient. What's the temperature outside that cabinet?
Background. What's the temperature inside that cabinet?
Reference. What's the temperature of the side panel surface of that cabinet?
When you later analyze images and spot temperatures, you'll be looking for the deltas between benchmarks and readings. If this is the latest in a series of trended surveys (including perhaps a baseline survey), then you can compare the deltas over time. An area or object with a rise in delta will be easy to spot graphically.