Temperature is a scalar physical quantity, one of the principal parameters determining the state of a thermodynamic system. It corresponds to the average kinetic energy of the motion and vibration of particles in the system. One of the popular methods of temperature recording is the measurement of electromagnetic (infrared, thermal) radiation parameters emitted by a body of a temperature above the absolute zero (0 K or -273.15°C). The measurement is defined as thermography and it is used to produce images of the distribution of temperatures on the surface of an object (objects) with the use of an infrared radiation detector. The main advantage of this type of measurement is its non-invasive nature. Due to the use of a thermographic camera, it is possible to detect most construction defects without interfering in the structure of a building partition. Thermography allows the measurement of temperature in the spaces that are not easily accessible or those where traditional methods are impossible to employ. Thermography is used in a variety of research specialisations. The article presents the results of research relying on the use of thermogram analysis in the estimation of thermal insulation of chosen external building partitions. Much attention was given to façade elements of the buildings. The following structures were subjects of the research: a single-family detached building (with a thermal insulation only on the first storey; laid in 2008), a two-family semi-detached building (with one of the apartments having external thermal insulation laid in 2008); and a wooden single-family building from the beginning of the 20th century (made of logs). The research was conducted according to the PN-EN 13187:1998 norm, with the use of a thermographic camera FLIR ThermaCAM e300. Thermograms were developed in ThermaCAMTM QuickRaport 1.1 program with regard to various emissivity factors of the analysed surfaces. The main aims of the research were to estimate the differences in thermal insulation of the analysed building partitions that depend on thermal modernization being done or not, and to detect the areas where thermal bridges, in majority stemming from construction defects, can be found.As the research proves, thermographic camera is a very useful tool for the estimation of thermal insulation of building partitions. Out of all analysed objects, the walls of the wooden building that had not undergone thermal modernization proved to be best thermally insulated. A partition in a wooden building insulates as much heat as a brick partition insulated with a 10 cm layer of foam polystyrene (ca. 21°C). Differences in temperatures of the external surfaces between the partitions with additional insulation and those not insulated amounted to over 4°C. The analysis of photographs and thermograms revealed multiple thermal bridges.