Infrared thermography is a diagnostic method that uses infrared cameras to visualize and record the temperature distribution on surfaces. It can be used to detect moisture, locate insulation errors, identify heat loss areas, find cracks in infrastructure, and determine proper insulation and window fits. The document discusses common insulation materials and techniques for floors, foundations, and walls of buildings. It also notes infrared thermography has been used for 10 years to identify defects in old building insulation and recommends various retrofitting measures like insulation, window replacement, and system modernizations.