Whereas a blower door test can test how air tight a building is, infrared cameras are not able to give you an actual performance or score of your house, but they can show you where thermal bridges occur.

In Europe, infrared cameras are often used to locate the misapplication of materials and resulting thermal bridges. The lighter the colour the warmer the materials, the darker the colour the colder the materials. Great differentiation between colours means great temperature difference.

The first picture below shows a typical German home. Although double glazing and thermally improved window frames are used, the windows have a lower U-value than the walls, as the required U-value for the external walls is 0.24 W/(m²K) and the U-value for the windows 1.10 W/(m²K). Expectedly, the windows present in a darker colour as they let more heat escape through them than the walls. Determining if a thermal bridge is within the allowed limits requires meticulous measurements and comparison of internal and external material and air temperatures, humidity levels and following calculations of heat transfer. In this particular case, the thermal bridges occurring due to different U-values are within the allowed limits.