Evaluating the performance of selected thermo-physiological indices on quantifying bioclimatic conditions for pedestrians in a street canyon

A large number of indices have been developed to assess human bioclimatic conditions. The indices that could be considered valid in all climate and seasons are those that are based on calculations involving the heat balance equation. The aim of the present study is to evaluate the performance of selected existing indices based on body’s energy balance, in an outdoor built environment. A field questionnaire survey was carried out simultaneously with microclimatic measurements in a street canyon located in the centre of Athens, Greece. The experiments that lasted 2 days, were performed in July while the interviews were conducted in randomly selected people passing by or visiting the measurements sites. The values produced by COMFA, PET and UTCI were compared to the actual thermal sensation that was indicated on a 7-point thermal sensation scale by the respondents. The results showed a significant relationship between predicted and actual thermal sensation. However indices’ estimates deviated from the actual thermal sensation. The maximum percentage of correct predictions was about 37% while UTCI predicted thermal sensation better than COMFA or PET.