[IanOzsvald]

I use a FLIR One on Android. I've charted internal leaks (where cold air blows in through cracks) and external (where heat escapes through eg old windows). Wait for a cold day (eg 0C), heat the house, investigate everything you can. My 1930s London house has SO many leaks, I've spent 3 years slowly fixing them. I have a talk I should give on using 12 Govee hygrometers to back-calculate moisture (absolute humidity) coherent per room, as I was charting moisture loss to trace air leaks.

[ahaucnx]

Yes we also used thermal cameras for leak detection. Quite effective.