The paper presents an evaluation of the measured data of the temperatures of three window constructions made from different materials and with different glazing systems. Measurements were carried out at different points on window friezes and glazing and they underway continuously throughout the year. These windows are suitable for low-energy buildings. Window structures were placed in the pavilion type testing laboratory. The windows were installed in an outer wall of known thermal characteristics, in a room with a constant indoor climate. The windows were exposed to the real effects of external climate conditions. The article shows the results of temperature measurements and thermo-optical properties.