Thermal resistance of sleeping bags under simulated body pressure

Sleeping bags provide thermal insulation, but compression during use reduces thickness and lowers insulation. A test bench was designed to measure the temperature difference and heat flow on samples subjected to body-pressure levels between 0.02 and 2 kPa. The setup was validated using commercial insulating materials, showing discrepancies of less than 3%. Three samples provided by an industrial partner, and two samples used in commercial sleeping bags were evaluated. All samples exhibited a non-linear decrease in thickness as pressure increased. Likewise, thermal resistance declined markedly with increasing pressure; the reduction was most pronounced in the low-pressure range (from 20 to 500 Pa) and gradually diminished at higher pressures (from 1000 to 2000 Pa) as fiber compaction progressed. Repeated-measures ANOVA found significant effects of material and pressure. Depending on the sample, the decrease in thermal resistance ranged from 65% to 84%. These findings underscore the importance of accounting for compression effects when evaluating the thermal performance of textile structures used in sleeping bags.