1. A method for displaying a colored thermal image in an infrared (IR) thermal camera to detect thermal transmission through a partition separating an outside and an inside of a construction, the method comprising: registering a first air temperature value (T A ) on the outside of the construction; registering a second air temperature value (T B ) on the inside of the construction; calculating a temperature level value (T ISO ) based on the registered first air temperature value (T A ), the registered second air temperature value (T B ), and a temperature color alarm level value (T CAL ); imaging a surface area of the partition located between the outside and the inside of the construction, to create the thermal image of a temperature distribution in at least a part of the surface area; comparing a surface area temperature in at least one image point of the thermal image to the temperature level value (T ISO ); adjusting a color of the at least one image point in dependence of the relation between the surface area temperature in the at least one image point and the temperature level value (T ISO ), to create a colored version of the thermal image; and displaying the colored version of the thermal image.