Establishing thermal comfort baseline in a sub-tropical region through a controlled climate chamber study

Climate chamber-based studies provide a baseline for quantifying thermal comfort. They can be used to compare real-world thermal adaptation to air temperature (Ta), relative humidity (RH) and air movement (Va). Several adaptive thermal comfort studies in subtropical regional established the role of moisture and air movement is crucial in comfort regulation. However, a baseline study in controlled environments demonstrating the combined effect of multiple environmental variable has yet to be available. In this context, this study presents the results of controlled climate-chamber-based thermal comfort experiments performed with 16 acclimatized subjects. Each subject underwent 140 test conditions covering 20-40 & DEG;C Ta, 30-70% RH, and 0.25-2.0 m/s Va while performing a sedentary activity, yielding 8360 valid subjective responses. The study yielded a Tn of 29.3 & DEG;C in terms of Ta, while the comfort temperature varied from 25.7 to 32.9 & DEG;C (Ta). The effect of RH and Va on thermal sensation, comfort and preferences are established. An empirical reformulation of the Tropical Summer Index with thermal sensation and comfort votes is presented. A comparative analysis of the baseline thermal comfort limits with the adaptive comfort limits established by various field studies in the sub-tropical region is presented. Va requirements for just comfortable and acceptably warm conditions are presented for different Ta and RH set-points.