Thermal and moisture adsorption/desorption properties for a selection of vegetal insulation materials

Natural, or 'green' insulation materials, have become more popular for the 'ecologisation' of construction activities. The ecological aspects for such materials are being widely analysed, but experimental data about their physical properties when installed in building constructions remains lacking. In this study, pressed samples of three locally wild grown agricultural materials - rye, reed, and hemp - are analysed. Thermal conductivity measurements were carried out using the hot plate device. Comparison with widely used mineral insulation materials shows that thermal conductivity for simple pressed materials are roughly three times higher, and are comparable to plywood and cross-laminated timber insulation properties. Additional experiments regarding such materials include measurements of hygroscopic sorption properties (adsorption/desorption), determined using the dynamic gravimetric method at different temperatures and a wide, relative humidity range. The results obtained show that the difference in all studied materials appeared only at high humidity values; the rye straw and reed spikelets adsorbed more water than other materials, which is important for potential indoor air humidity assessment.