Objective results – Weight

Weight was measured during the experiment and values obtained are shown in Table 4.11 with body mass loss results in Table 4.12. The greatest nude mass loss occurred in the Warm condition for males and in the Neutral condition for females. The wet weight of clothing, measured for 5 minutes at the end of the experiment, showed that there were slight fluctuations over time. Following the Neutral condition, weight fluctuated for males and steadily increased after 4 minutes. Females showed continual fluctuation of weight throughout the measuring period in the Neutral condition.

Table 4.11 Weights at different points during the experiment (SD in brackets)

Neutral Cool Warm

M F M F M F Weight (kg) Nude Before 79.399 62.789 79.645 62.980 79.475 62.591 (13.341) (10.171) (13.181) (10.259) (13.192) (9.965) Clothed Before 81.490 64.653 81.771 64.837 81.537 64.465 (13.466) (10.099) (13.258) (10.176) (13.259) (9.918) Clothed Chamber Start 81.481 64.816 81.693 65.041 81.517 64.664 (13.313) (10.147) (13.131) (10.254) (13.116) (9.979) Clothed Chamber End 81.393 64.813 81.734 65.022 81.449 64.617 (13.339) (10.146) (13.062) (10.264) (13.064) (9.968) Clothed After (1 minute) 81.433 64.608 81.661 64.816 81.429 64.439 (13.439) (10.096) (13.196) (10.176) (13.207) (9.921) Clothed After (2 minutes) 81.426 64.605 81.669 64.823 81.434 64.429 (13.437) (10.095) (13.212) (10.178) (13.221) (9.920) Clothed After (3 minutes) 81.434 64.610 81.667 64.823 81.442 64.427 (13.437) (10.094) (13.219) (10.173) (13.218) (9.915) Clothed After (4 minutes) 81.430 64.602 81.669 64.826 81.441 64.430 (13.440) (10.092) (13.214) (10.177) (13.216) (9.915) Clothed After (5 minutes) 81.411 64.609 81.664 64.824 81.444 64.425 (13.453) (10.097) (13.211) (10.180) (13.223) (9.915) Nude After 79.316 62.716 79.577 62.917 79.356 62.527 (13.341) (10.158) (13.132) (10.211) (13.116) (9.969) In the Cool condition, there was a slight increase in the wet weight after which, a steady decline was noted. Similar to the females in the Neutral condition, males exhibited a fluctuation in wet weight during the Cool condition.

The Warm condition resulted in different effects between the genders. Males exhibited a slight increase in wet clothing weight (weight of clothing at the end of the experiment) followed by a decline. Female weights demonstrated a steady increase throughout the 5 minute weighing.

Table 4.12 Body mass loss

Neutral Cool Warm

M F M F M F

Mass Loss (nude) (kg) Nude start – Nude end

0.083 0.073 0.068 0.063 0.119 0.064 (0.074) (0.091) (0.065) (0.086) (0.090) (0.074) Dry weight of clothing (kg)

Clothed start – Nude start

2.091 1.864 2.125 1.857 2.063 1.874 (0.188) (0.186) (0.242) (0.218) (0.141) (0.206)

Wet weight of clothing (kg) Clothed end – Nude end

1 2.117 1.892 2.084 1.900 2.074 1.912 (0.147) (0.169) (0.146) (0.187) (0.180) (0.188) 2 2.110 1.890 2.092 1.907 2.079 1.902 (0.155) (0.172) (0.148) (0.178) (0.170) (0.189) 3 2.118 1.894 2.090 1.906 2.087 1.901 (0.149) (0.174) (0.156) (0.183) (0.168) (0.194) 4 2.114 1.887 2.092 1.909 2.086 1.904 (0.155) (0.175) (0.148) (0.178) (0.163) (0.194) 5 2.095 1.893 2.087 1.908 2.089 1.898 (0.173) (0.169) (0.151) (0.178) (0.166) (0.196) Sweat trapped (kg)

(Clothed end – Nude end) – (Clothed start – Nude start)

0.026 0.028 -0.042 0.043 0.011 0.038 (0.066) (0.063) (0.242) (0.087) (0.082) (0.092) Sweat evaporated (kg)

(Nude start – Nude after) – [(Clothed end – Nude end) – (Clothed start – Nude start)]

0.057 0.045 0.110 0.020 0.108 0.026

(0.037) (0.036) (0.240) (0.013) (0.094) (0.033) Both genders exhibited similar amounts of sweat trapped in clothing during the Neutral condition, however males showed a decrease (i.e. a negative amount of sweat trapped) in the Cool condition in comparison to the females who had similar levels for the Cool and Warm conditions.

Interestingly, males had similar amounts of sweat evaporated in both the Cool and Warm conditions despite the significantly different environmental conditions and both were greater than in the Neutral condition. Females also had similar evaporated sweat levels for the Cool and Warm conditions, however both were lower than in the Neutral condition. Both genders had similar sweat evaporated in the Neutral condition.

Interpretation of results

Mass losses during the experiment were similar between genders in the Neutral and Cool conditions, however there was a marked difference in the Warm condition. This condition had the greatest mass loss for males and the least for females (although females showed similar mass losses for the three conditions).

Wet weights of clothing were shown to fluctuate in different patterns both between genders and chamber conditions. It is difficult to determine whether these result in differences in sensation as no further subjective data was collected. The increase in wet weight for both genders following the Cool condition indicates some moisture build-up within the clothing and therefore a possible increase in sensation of stickiness.

4.4.6 Subjective Results – Thermal Sensation

In the initial determination of the environmental conditions to expose participants to, a metabolic rate of 58Wm-2 was used in the calculation. During the experiment it became evident that the metabolic rate was higher than this as participants frequently shifted position, moved to look at the thermal scale sheet and were actively engaged in conversation throughout. For this reason, the metabolic rate used to calculate Predicted Mean Vote (PMV) was raised to 70Wm-2, a rate equivalent to light office work. With a metabolic rate of 70Wm-2 the actual PMV for each condition should have been: Warm = +2, Neutral = +0.4, Cool = -1.1. At the time of the experiment, the thermal chamber could not regulate cooler temperatures and humidities accurately and actual conditions were slightly warmer than predicted.

Male vs. female

Thermal sensation throughout the experiment is plotted in Figure 4.48 with a scaled version just showing the end of the experiment in Figure 4.49 (OUT refers to measurements made outside the environmental chamber). Figure 4.48 shows how males and females differ during the time to steady-state with females feeling warmer in the Cool and Neutral conditions and slightly cooler in the Warm condition.

Figure 4.48 Mean Sensation scores per gender and chamber condition

Male and female Actual Mean Votes (AMVs – sensation) were compared using a Mann-Whitney U test, the outcome of which determined that there is no significant difference between genders and AMVs inside the chamber at 30 minutes and outside the chamber (see Table 4.13 for statistics, U = statistic, r = effect size, Md=median).

Figure 4.49 Mean sensation scores in chamber to outside per gender and chamber condition Table 4.13 Comparison of gender and sensation

M F U z p r Md Mean Md Mean N/In 44.0 -1.77 0.08 0.36 0.0 -0.04 0.1 0.48 N/Out 57.5 -0.97 0.33 0.20 -1 -1.21 -1.0 -1.03 C/In 54.0 -1.14 0.26 0.23 -1 -0.96 -0.8 -0.73 C/Out 65.0 -0.47 0.64 0.10 0 0.00 0.0 -0.22 W/In 62.5 -0.56 0.57 0.11 1.5 1.83 1.75 1.58 W/Out 64.0 -0.49 0.63 0.10 -1 -0.75 -1.0 -0.81

Comparison of conditions

Following the determination that there were no differences between genders, the results were combined to compare the results of each chamber condition. Figure 4.50 shows the mean sensation throughout the experiment and once again, there is a graph illustrating the sensation at 30 minutes and on exiting the chamber (Figure 4.51).

Figure 4.50 Total mean sensation scores per chamber condition

AMVs were then combined and compared using a Wilcoxon Signed Rank Test using the votes at 30 minutes and outside to determine if there were significant differences between the chamber and outside conditions. Results determined that there was a significant difference between each condition and that these conditions were significantly different from the values outside the chamber. When outside votes were compared, however, Neutral and Warm votes were not different from one another. Table 4.14 shows the statistics obtained from the Wilcoxon analysis and the associated p level and effect size (r).

Table 4.14 Comparison of AMV and conditions

z p r N/In v C/In -3.88 <0.001 0.56 N/In v W/In -3.77 <0.001 0.54 C/In v W/In -4.14 <0.001 0.60 N/Out v C/Out -4.09 <0.001 0.59 N/Out v W/Out -1.70 0.09 0.24 C/Out v W/Out -2.83 <0.001 0.41 N/In v N/Out -4.09 <0.001 0.60 C/In v C/Out -3.20 <0.001 0.46 W/In v W/Out -4.29 <0.001 0.62

Figure 4.51 shows that although the environment outside the chamber was similar on each occasion, the inside chamber conditions resulted in a different sensation with AMV following the

Cool condition resulting in the warmest sensation and the AMV following the Neutral conditions, the coolest.

Figure 4.51 Total mean sensation scores in chamber to outside per chamber condition

The chamber conditions that were warmer than those outside resulted in a reduction in sensation whereas the Cool condition showed an increase in sensation. The votes following the Warm condition are slightly higher than those following the Neutral condition indicating there may be a ‗lag‘ in sensation with participants still feeling the effects of the warm chamber at this point.

Interpretation of results

Analysis determined that there were no significant differences between male and female sensations during the experiment. This implies that the slight differences in environments observed in section 4.4.1 and 4.4.2 had little effect on sensation. It also shows that the difference in mean skin temperature also had no effect on sensation indicating that females were more able to cope with the Neutral and Cool conditions despite their lower skin temperature.

Although the three conditions inside the chamber elicited significantly different sensations, sensations outside the chamber were not significantly different from one another following the Warm and Neutral conditions, This is particularly interesting as the previous section has shown that participants also had significantly different mean skin temperatures at this point. Therefore, in transient environments, mean skin temperature is not a reliable indicator of sensation and that there are other factors that cause the change in sensation. The decrease in hand temperature, however, may cause the sensation reduction in the Neutral and Warm conditions. Sensation following the Cool condition was significantly warmer than the other two indicating that there is no lag or continuation of the cool sensation and participants immediately perceive the slightly warmer environment despite still having lower skin temperatures.

These results have shown that here is an instantaneous and significant change in sensation as a direct result of the interaction between the two environments. Sensation following the Warm condition decreased but not to the same point as that following the Neutral condition, the rate of change, however, was greater. Sensation following the Cool condition increased, reflecting the slightly warmer conditions outside in comparison to those inside the chamber.

Subjective results now need to be compared with the existing model of sensation, Predicted Mean Vote (PMV) to determine its suitability in the case of transient environments where people move from one set of conditions to another.