This paper deals with the impact of using phase change materials (PCM) in light building constructions. It describes how these materials react during the whole year, how they impact the summer temperature stability of a room and how they react in the transition period and in the heating period. Measuring was carried out in the experimental and reference room in the attic of the Institute of Building Structures. The layout of these identical rooms enables to compare the measured values. The measuring of the indoor climate, which had been carried out during the whole year in the reference and experimental room, was analyzed. The analysis was used to create the basic methodological procedure for using PCM in light building constructions. These materials proved to be efficient in the summer time. During the heating period the power consumption was monitored in relation to the application of the phase change materials.

Microwaves are electromagnetic waves of frequencies from 300 MHz to 300 GHz, corresponding to wavelengths from 1 m to 1 mm. For industrial application is allowed more frequencies, but we are mainly interested in the frequency 2 450 MHz, a wavelength of 12,2 cm, which we use in our applications. The heating occurs so that the electric field in the water molecules orient themselves according to polarization. Microwaves are a classical electromagnetic radiation with frequency lower than the solar radiation and therefore leave no residual radiation harmful to health. Using the device is completely safe, damage to health can occur only by direct irradiation of a few cm for several minutes, either intentionally or careless handling of the machine.

Research and development at Brno University of Technology, Faculty of Civil Engineering is focused on the experimental assessment of modern timber structures. For the assessment of the influence of different timber structures on indoor environment a comparative method is used. This method is based on the measurement of indoor environment parameters in the experimental house. There are 4 test (reference) rooms, each of them having the same geometry but a different light-weight composition of envelope which are flexible at the same time.