Energy auditors and insulation contractors have been using infrared cameras to diagnose home-performance problems for over 30 years. Without opening up your walls or ceilings for inspection, a trained specialist can use one of these cameras to locate insulation voids, air leaks, moisture intrusion, thermal bypasses, and thermal bridges. It’s even possible to use an infrared camera to locate leaks in hydronic tubing embedded in a slab.
These tools are known by a variety of names, including infrared (IR) cameras, thermographic scanners, and thermal imaging devices. An image produced by such a camera is called a thermogram, and a trained user of the device is called a thermographer.
Although many people assume that infrared cameras measure surface temperatures, that’s not really how the tools work. An IR camera actually measures the intensity of infrared radiation (radiant energy) being emitted by the surface it is aimed at.
The history of infrared cameras
Academic researchers began using infrared cameras to diagnose thermal envelope defects in the late 1970s, using cameras that cost more than $25,000 each. The cameras were cumbersome devices that were cooled by liquid nitrogen.
As new models of IR cameras were developed, prices began to drop. Gautam Dutt, one of the original “house doctors” at Princeton University, recalls, “For an infrared camera, we used a Magnavox unit marketed by Aga, the Aga 110. It cost about $13,000. It was expensive equipment, but it was cost-effective. The first thermal bypasses that I discovered took me weeks to discover, crawling through attics.…