Thermal Imaging

Thermal imaging is also called infrared (IR) imaging or thermography.  Thermal imaging is photography (either on film or digitially) that captures the image based upon wavelengths of light that have a lower frequency than normal, visual light.  Light is brought into a lens whcih focuses an image on film or with digitial photography, on a photsensitive sensor.  Thermal imaging does the same thing, but using only light in the infrared specturm.

Thermal imaging can differentiate very small differences in temperature. Such sensitivity can even see where some water spilled and where a hand rested when wiping the water up.  Thermal imaging has many different applications. Infrared light is regularly measured by Home Inspetors with the use of an IR thermometer to measure termperatures.  Usually this is done to measure actual termperature, such as in an oven.

Thermal imaging can also be used in this way, but it is mostly used to measure the difference in the temperatures in different areas and to display these differences visually rather than as just a termperature number.  When different areas of a picture are viewed, most of the information is derived from the differences in the termperature of the various parts of the image.  This measurement is called the Delta T or Temperature difference.

Emittance is a major determining factor in thermal imaging. It is a measure of how much heat a material will radiate as a material cools down.  Materials that have a high emissivity will absorb the heat that falls on them and re-radiate (emit) it in the IR specturm.  Low emissivity materials would include metal or shiny objects.  High emissivity materals would include asbestos, concrete, stone, water and black or dull objects. 

The emissivity of the materials being imaged must be taken into account when interpreting the image.  If an actual temperature reading of the object is needed, the camera must know the emissivity of the substance being measured. See the Thermal Images tab.

Uses for thermal imaging include but are not limited to the following:

• Detecting diferences in thermal density
• Water infilitration
• Excessive moisture in materials
• Stud/joist/beam/rafter placement and structure
• Differences in temperature
• Insulation insufficiency/unevenness
• "Hot" electrical panels, breakers, swithches and wire connections
• Heating/cooling duct placement/insulation
• Pipe location
• Pest infestation
• Energy audit for locating cold and/or heat loss in a home.