Piotr Kosiński

Thermal Properties of Raw Hemp Fiber as a Loose-Fill Insulation Material

ABSTRACT The article presents the possibilities of using hemp fiber as a loose-fill insulation material. The article presents the results of research concerning raw hemp fiber obtained from the Polish crop of industrial hemp of Białobrzeskie variety. The analysis involved evaluation of thermal conductivity in function of bulk density and air permeability, the properties important for insulation materials. The results of laboratory investigation were used to create the numerical simulation models of heat transfer in the frame wall partitions filled with hemp fibers. The study showed that with the increase of bulk density, the thermal conductivity and air permeability of material decrease. The obtained lambda values are comparable with the characteristic values for conventional thermal insulation materials. The results of heat transfer and temperature distribution reveal that hemp fibers characterize with strongly air permeance, what affects on the need for additional barriers against air filtration.

An Impact of Air Permeability on Heat Transfer through Partitions Insulated with Loose Fiber Materials

The paper presents the problem of windwashing in partitions including air permeable thermal insulations. There are technical solutions, which deliberately accept the filtration of air in the insulating layer, guided by the necessity of possible drying of building materials. Some scientific papers even suggest that the air infiltration decrease the heat losses through ventilation. In result there occur heat losses in building heat balance which are underestimated and therefore difficult to take into account during calculations. Heat changes on the inner surface of the building partition occur with a delay to the initiation of the wind. However, even the short-term local wind speed loads on thermal insulations result in temperature decreasing and therefore possible condensation on the inner surface of the building partition. The article presents laboratory measurements of air permeability of loose mineral wool and laboratory investigation of the impact of air filtration on heat transfer in lightweight partitions filled with loose thermal insulation.

Moisture and wetting properties of thermal insulation materials based on hemp fiber, cellulose and mineral wool in a loose state

ABSTRACT 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.