Annotation: The strategy of this work is to develop models, methods and software for heat loss evaluation. Firstly its necessary to compare different methods of segmentation and then create optimal method. Threshold segmentation method for brightness (corresponding to a certain temperature range in advance) and wave method for combining the pixels in the connected sets were proposed. On the basis of development model and method create an application whereby the system will evaluate the heat loss of a building. The system will be based on a personal computer, THERMO program use photos from infrared camera, which help to capture the infrared images of the wall.