Effect of a moderately warm environment on salivary cortisol level

Historically, thermal comfort research has relied on subjective questionnaires to infer the human physiological response to changing thermal environments, leading to potential bias in results and subsequent interpretations. In this study, we investigate the effect of a moderately warm environment on salivary cortisol concentration, as a potential bio-marker for thermal comfort research. Twelve participants (six men and six women) performed different neurobehavioral tests at neutral and warm thermal environments (operative temperature equal to 23°C and 30°C respectively), followed by a neutral recovery phase. During the experiment participants were assessed physiologically and psychologically. Salivary cortisol concentration did not change between the neutral and warm phase, however it increased as thermal dissatisfaction (measured with both the thermal sensation vote (TSV) and the thermal preference vote (TPV)) increased. This suggests that cortisol concentration in saliva could be used as a bio-marker of stress in thermal comfort research.