Question: What do the different colours on a thermogram represent?
You must memorise this colour scale.
Hottest parts: white/yellow/red
Coldest parts: black/dark blue/purple.
Whole range: Hottest - White/yellow/red/green/purple/blue/black - Coldest.
The two brightest parts of the house are the hottest ones and seem to be the roof and windows.
Caution: Windows are not the hottest part of a house! The camera is actually recording the temperature of the room, because the infrared radiation from the room goes straight through the windows. If the curtains were closed the windows would look black. As a rough rule, whatever a material does to visible light it will also do to infrared radiation. Block or reflect etc.
Some Thermograms only come in greyscale - on those the brightest part of the image is the hottest.