Subzero project: Thermal insulation measurement of cold protective clothing using thermal manikins - Physiological tests

Wearer trials with human subjects were included in the Subzero project in order to validate the manikins' data against practice. Physiological tests of the project were aimed to study hu-man subjects at thermal comfort or being slightly warm in cold: 0, -10, -25 and wind-chill temperature –50 ºC. Wind-chill temperature –50 was achieved by combination of 2 tempera-tures and wind velocities: -40 ºC and 3 m/s, and -23 ºC and 10 m/s.
Moderate activity to keep subjects at thermal comfort without sweating was chosen according to IREQ-neutral (ISO/CD 11079, 2001). High activity was decided to be 50 W/m2 higher than during moderate activity in order to generate considerably more sweat. Walking speeds for moderate activity were 3.5 (0 and -10 °C) and 3.8 (-25 °C), and for high activity 4.9 (0 and -10 °C) and 5.0 km/h (-25 °C). At wind-chill temperature of -50 the walking speed was the same for both wind speeds: 5.0 km/h with 0.5° inclination. Tests involved walking on a treadmill for 90 minutes. Clothing systems without and with water vapour barrier were tested.
Wearer trials with human test subjects were carried out at 4 test institutes (study partners 2 (P2), 4 (P4), 5 (P5) and 6 (P6)). P2 and P4 carried out tests at 0 and -10 °C corresponding to ensembles A and B, P5 at -25 °C and -50 wind-chill temperature corresponding to ensembles C and D, and P6 at -10 and -25 °C. 8 young healthy men served as test subjects at each insti-tute. In total 256 single tests were performed.
The subjects reached steady state in all clothing systems and stayed at comfort. Conditions with low sweat accumulation can be used to validate manikin measurements. Consideration of ensemble weight distribution, additional energy costs due to thicker clothing and wind veloc-ity and direction could increase prediction accuracy. Manikin tests lead to realistic results that can be used in practice.