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Home Inspection & Infrared Thermal Imaging

Infrared Thermal Imaging 
Infrared imaging provides important information relating to otherwise inaccessible areas of a residential building. Infrared detects extremely small but crucial differences in temperature from one area of a house to another. These temperature variations show up on the camera’s view screen as “cold” or “hot” spots, which reveal hidden problems that often cannot be detected in the course of a traditional visual inspection.

These problems may include:

• Faulty wiring, breakers and fuses
• Hidden moisture intrusion
• The moisture sources of mold
• Pipe and duct work leaks
• Roof and ceiling leaks
• Foundation cracks
• Heat/energy loss
• Structural concerns
• Missing insulation
• Ventilation problems
• Moisture associated with termite nests
• Rats, mice and other pests

Why Perform Infrared Home Inspections?
Combined with traditional home inspection techniques, the infrared inspection method reveals substantially more of the house than can be perceived by the naked eye and conventional inspection tools. Many things can't be be seen with only a flashlight.

Examples of infrared inspection applications:

 

• Water intrusion: scanning interior surfacesof a building with an infrared camera can reveal excess moisture due to plumbing leaks, roof leaks, leaks around windows, etc.  Wet areas of building materials cool when energy is transferred during the water evaporation process; therefore, a wet (“cooler”) area will stand out from the surrounding dry (“warmer”) surface.
   

• Insulation deficiencies: appreciable temperature differences, due to variations in thermal energy (heat) transfer, allow for detection of deficient or missing insulation when scanning ceiling and wall surfaces.
   

• Roofing leaks: scanning roof coverings can reveal water intrusion and accumulated moisture below the surface. Due to its thermal properties (high thermal capacity), water typically gives up heat at a much slower rate than the surrounding roof materials. The areas of accumulated moisture can therefore be detected when scanning the roof surface.  This type of roof inspection is best done in the evening or early nighttime after thermal energy imparted during the daytime is transferred or released.
   

• Electrical systems: deficiencies within the electrical system can be made visually apparent by use of an infrared camera.  For example, a deficient connection between electrical components can result in resistance which will manifest in an apparent temperature elevation when compared with similar types of connections under similar load conditions.
   

• Structural issues: differences in thermal capacity, conductivity, and other intrinsic qualities of building structural components can allow for their detection when scanning walls, floors, and ceilings with an infrared camera. Under the right conditions, missing structural components, and portions of structural components which are damaged (to the extent that their intrinsic qualities are significantly changed), can be detected.

  NOTE: Although infrared thermal imaging is a far better diagnostic tool than the naked eye, it does not guarantee 100% accuracy, unless removal or destruction of components can be achieved to validate findings. When possible, other tools are used to verify thermal images, but even with these considerations we do not claim to have x-ray vision. Conditions may change and cause the apparent temperatures revealed on thermal images to be different at any given time.

 
A little extra theory and fun excursions:
Infrared Thermography, thermal imaging, thermographic imaging, or thermal video, is a type of infrared imaging science. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000nanometers or 0.9–14 µm) and produce images of that radiation, called thermograms. Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature, therefore thermography allows one to see variations in temperature (hence the name). When viewed by thermographic camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night. As a result, thermography's extensive use can historically be ascribed to the military and security services.

The use of thermal imaging has increased dramatically with governments and airports staff using the technology to detect suspected swine flu cases during the 2009 pandemic. Other uses include, firefighters use it to see through smoke, find persons, and localize the base of a fire. With thermal imaging, power lines maintenance technicians locate overheating joints and parts, a tell-tale sign of their failure, to eliminate potential hazards. Where thermal insulation becomes faulty, building construction technicians can see thermal signatures that indicate heat leaks and to improve the efficiencies of cooling or heating air-conditioning. Thermal imaging cameras are also installed in some luxury cars to aid the driver, the first being the 2000 Cadillac DeVille. Some physiological activities, particularly responses, in human beings and other warm-blooded animals can also be monitored with thermographic imaging.^[1]

The appearance and operation of a modern thermographic camera is often similar to a camcorder. Enabling the user to see in the infrared spectrum is a function so useful that ability to record the output is often optional. A recording module is therefore not always built-in.

The CCD and CMOS sensors used for visible light cameras are sensitive only to the nonthermal part of the infrared spectrum called near-infrared (NIR), but not to the part of infrared spectrum useful for thermal imaging (mid- and long-wavelength infrared), so most thermal imaging cameras use specialized focal plane arrays (FPAs) that respond to longer wavelengths. The most common types are InSb, InGaAs, HgCdTe and QWIP FPA. The newest technologies are using low-cost and uncooled microbolometers FPA sensors. Their resolution is considerably lower than of optical cameras, mostly 160x120 or 320x240 pixels, up to 640x512 for the most expensive models. Thermographic cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted. Older bolometers or more sensitive models such as InSb require cryogenic cooling, usually by a miniature Stirling cycle refrigerator or liquid nitrogen.

(This article is provided courtesy of Wikopedia)