Share 'Does there need to be a large temp difference to see if walls have insulation'

Hi everyone,    I am new at understanding how to read an infrared camera. I want to see what a wall looks like with or without insulation. Here's my question: Does there need to be a temperture difference from the inside of the house  to the outside to see if there is insulation in the walls? What should that difference be? ie 15 degrees. Do you ask the homeowner to turn up the heat in the winter…