2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
were allowed to drink at will. Core temperature, heart rate and ambient conditions
(Tdb, Tpwb and Tg) were monitored continuously and recorded every 5 minutes.
The inflection point marks the transition from thermal balance to the loss of thermal
balance, where core temperature continued to rise. The chamber conditions five
minutes before this temperature increase was taken as the critical condition. One
investigator noted the critical condition, and some of the decisions were randomly
reviewed by a second investigator.
IT,stat values were determined using a heated manikin. In the current study, these
values were treated as a fixed value for all ensembles. The following is the process to
compute derived values for each trial based on trial conditions for the participant and
environment. The IT,r was computed according to ISO/FDIS 9920 (2007) as:
CFI=exp[-0.281(v - 0.15)+0.044(v - 0.15) 2 -0.492 w+0.176 w 2 ] and IT,r=CFI•IT,stat
where: air speed (v) was taken as 0.5 m s -1 and walking speed (w) was the treadmill
speed (m s -1 ) for the specific trial.
The total resultant evaporative resistance (Re,T,r) was computed from Equation 1. The
total static evaporative resistance (Re,T,stat) was computed following ISO/FDIS 9920
(2007) :
CFRe = 0.3 - 0.5 CFI + 1.2 CFI 2 and Re-T,stat = Re,T,r / CFRe
The resultant and static permeability index (im) where computed as im = IT / 16.7 Re,T.
RESULTS
The mean values (with standard deviations) for the derived clothing characteristics are
provided in Table 1.
Table 1: Clothing ensembles, total static clothing insulation, derived values (mean ±
sd) of resultant total insulation, resultant and static total evaporative resistance, and
resultant and static total vapour permeability index.
Clothing
Ensemble
138
IT,stat *
[m 2 °C W -1 ]
IT,r
[m 2 °C W -1 ]
Re,T,r †
[m 2 kPa W -1 ]
0.0134 a
Re,T,stat †
[m 2 kPa W -1 ]
0.0275 a
im,r †
[--]
0.56 a
im,stat †
[--]
0.41 a
Work 0.180 0.118
Clothes
±0.004 ±0.0034 ±0.0064 ±0.14 ±0.10
Cotton 0.196 0.128 0.0129
Coveralls
±0.001
a
0.0265
±0.0029
a
0.63 0.47
±0.0059 ±0.15 ±0.12
Tyvek® 0.190 0.124 0.0140
Coveralls
±0.001
a
0.0290
±0.0036
a
0.56
±0.0074
a
0.41
±0.13
a
±0.10
NexGen® 0.189 0.123 0.0175 0.0362 0.45 0.33
Coveralls
±0.001 ±0.0047 ±0.0098 ±0.12 ±0.09
Tychem 0.185 0.121 0.0319 0.0659 0.24 0.17
QC®
Coveralls
±0.001 ±0.0065 ±0.0133 ±0.05 ±0.04
* Fixed values from manikin trials.
† Same letter in a column indicates no statistical difference by Tukey's HSD at α =
0.05.