The calorimetric measuring chamber (guarded hot box) is intended for measuring the thermal transmissibility of building elements and materials using the calorimetric method. The basic principle of the measuring device is to provide the appropriate controlled boundary conditions, temperatures and air movement speed to establish a one-dimensional heat flow on the object being measured, which enables the measurement of the energy flow flowing through it. The options for setting the temperature on the warm side of the target are from 15°C to 40°C, and for the air movement speed from 0.2 m/s to 1 m/s. On the cold side, the temperature can be set from -20°C to 20°C, and the air movement speed from 0.5 m/s to 10 m/s. The size of the sample for measurement is up to 2.18 x 1.98 m. With metal halide lamps, it is also possible to simulate solar radiation from 400 W to 2000 W on the chamber. The chamber is made in accordance with standards and, in addition to research work, enables standardized measurement of joinery, windows and doors, according to SIST EN ISO 12567-1 and window profiles according to SIST EN ISO 12412-2. It can also be used for measurements of other building elements and thermal insulation materials according to ISO 8990.