leaks for you. I found areas I never imagined and sealed them. A IR
Thermal photo will only show areas with poor insulation, not air
comming in. Best would be to hire a pro to do an energy audit and both

IR photo could indirectly show air coming in if there is a temperature
difference between outside air and indoor air. When cold air rushes in
through gaps, it cools the area around the gap, which shows up as streaks in
the IR scan. You can combine blower door, IR, and smoke all in one test.

BTW, a cold draft does not necessarily have to come through a gap. If you
have a spot with weak insulation, the air becomes cold there, and creates a
convection which you may feel as a draft. This is what I feel whenever I am
near a window.