The article presents the results of studies concerning raw hemp shives obtained from the Polish crop of industrial hemp as a loose-fill thermal insulation material. The study focuses mainly on the measurements of the pore size distribution, thermal conductivity and air permeability of material. An increase in the value of the thermal conductivity coefficient (0.049–0.052 W/(m·K)) was demonstrated with an increase in the bulk density. The porosity of the individual pieces of shives is 78.7% and the predominant number of pores is in the diameter range of 0.9–3 μm. The paper also presents an example of the use of the tested material as thermal insulation of the wooden frame wall. The heat flow analysis was performed in various wall variants (insulation thickness: 100, 200 and 300 mm and pressure difference 0, 5, 10 and 15 Pa). A clear influence of the variables on the temperature distribution was observed.

The paper presents the results of research concerning three fiber materials – hemp fiber, cellulose fiber and mineral wool as a loose-fill thermal insulation materials. It focused on the study of moisture properties and wettability of these materials. The analysis involved evaluation of moisture sorption in different relative humidity conditions and evaluation of wettability of fibers by contact angle measurement. The study showed that the sorption equilibrium has been achieved at different times, which proves the various nature and properties of the materials. Hemp fibers were less wet than cellulose fiber, but the time needed to stabilize was shorter. The largest contact angles, indicating the strongly hydrophobic properties, were shown by mineral wool. Some samples of hemp and cellulose fibers were characterized by similar contact angles providing high wetting properties.

Despite cellulose fibers for many years are in common use as thermal insulation, some of the properties of this material should be still investigated. The article presents the properties of cellulose fibers as an insulation material in a loose state. The analysis involved evaluation of thermal conductivity in the relation of bulk density and air permeability, the properties important for insulation materials. The results of own investigation were used to carry out the numerical simulation of heat transfer in the timber frame wall filled with cellulose fibers. The study showed that the thermal conductivity and air permeability of material depend strongly on bulk density. The results of heat transfer and temperature distribution proved that cellulose fibers are characterized by strongly air permeance, what affects on the need for additional barriers against air filtration.

The paper presents the results of studies concerning raw flax shives obtained from Polish crop of flax as a loose-fill thermal insulation material. The study focusses mainly on measurements of the thermal conductivity and water vapor permeability of material, but on water absorption and capillary rise as well. The shives showed satisfactory lambda values, comparable to traditional thermal insulation materials. They also showed high mass absorptivity and the ability to uptake large amounts of water by capillary action in a short time. The paper presents also an example of the use of the tested material as thermal insulation of the flat roof. The analysis of the heat flow through the flat roof with different thicknesses of flax shives insulation was carried out.