In a large room with a cathedral ceiling that was built as an addition to the main building, Kahabka scans the interior gable end. At the gable wall-to-ceiling intersection, a small amount of discoloration appears. It's the last rafter, which is a little cooler.
After running the blower door for a few minutes, putting the building in "dynamic conditions", Kahabka looks again with the thermal imager and sees some serious degradation of the insulation due to air leaks.
These smaller black-and-white images are thermal-imager output files that Kahabka saved from this job. The first one shows a baseline image of the cathedral ceiling, which shows virtually no air leaks, although the rafters are clearly conducting heat.This doesn't mean that no air leaks exist. It's just that under the current conditions, with warm indoor air that's probably leaking out—past warm building materials as it moves to a colder outside—a temperature difference is not visible because the temperature of all the substrates and the air temperature are the same. But when he scans the ceiling with the blower door running, air leaks begin to show clearly at the intersection between the ceiling and the exposed beam.
Similarly, the baseline image of the office wall shows a little conductive heat flow along the framing. But when viewed under dynamic conditions, air flowing through the wall insulation causes a complete breakdown of the insulation's thermal integrity.
The most severe problem in the addition is the interface with the main part of the building. What looked like a well-defined thermal boundary under static conditions has totally collapsed under dynamic conditions. The thermal boundary is clearly not functioning as a pressure boundary. As the blower door continues to run, the sun is shining on this side of the house, loading the building with solar energy. After a few minutes, the thermal image shows huge amounts of heat coming through the corner. The inside wall temperature is above 80°F. So even though it doesn't show up dark (cool air) on the image, it is still an air leak.