Polystyrene Waste in Panels for Thermal Retrofitting of Historical Buildings: Experimental Study

The following article presents comprehensive research results for the insulation material based on polystyrene wastes. The presented product has the form of plates to be applied for thermal insulation of external envelopes from the inside. The laboratory tests were focused on the determination of basic technical parameters for this type of materials, i.e., thermal conductivity coefficient, diffusion resistance coefficient, reaction to fire, material sorption, and strength characteristics. For the recycling material, the obtained thermal conductivity value was 0.055 [W/mK]. The diffusion resistance coefficient was 5 [-], and therefore, this component has been qualified to a group of solutions that allow for interstitial condensation in the envelope. For the developed product, in situ tests were carried out on the actual wall system in a historical building. Based on the research, temperature and humidity profiles were obtained in the selected planes of the envelope. The performance of this material in real conditions was observed in relation to the reference product, i.e., lightweight cellular concrete (commonly used as thermal insulation from the inside). For the conducted in situ research, statistical inference was applied, which included the verification of the hypothesis-recycling panels in wall systems follow a trend of changes similar to that of slabs made of lightweight cellular concrete (a group of materials that allows for interstitial condensation). The proposed method of using secondary raw materials in insulation products allows us to obtain a product with high technical parameters that do not differ in quality from new components.