In thermal pictures, orange, yellow, and white colors mean that the area is warm, and the brighter the colors are, the hotter the area is.
On the other hand, dark blue and purple colors mean that the area is cold, and the darker the colors are, the colder the area is.
Using your thermal camera outside your home
Whilst using your camera outside your home, you want to see the cold blue colors. This would mean that your heating is being kept inside your house and you’re not wasting your energy use on heating the sky.
If you see bright yellow/white colors on your walls, roof or windows, focus on these areas when looking to improve insulation.
Using your thermal camera inside your home
Whilst using your camera inside your home, you want to see the warm yellow colors. This would mean cold air isn’t coming in and your heating isn’t escaping out.
If you see dark blue colors, focus on these areas when looking for draughts to plug and areas to have a better insulation.
Extractor fan left off vs extractor fan turned on
Pictures took by FLIR thermal Camera