Predicting urban thermal comfort from calibrated UTCI assessment scale - A case study in Belo Horizonte city, southeastern Brazil

Abstract

Due to high thermal loads, tropical climate cities may expose users of its public open spaces to likely thermal stresses. In order to assess thermal comfort, several aspects need to be considered, such as meteorological, thermophysiological and psycho-social/cultural. The integrated effect of these variables on thermal sensations can be achieved and evaluated by using calibrated assessment scale of thermal comfort indices. The objective of the present study is to calibrate the thermal perception categories of the Universal Thermal Climate Index (UTCI) for urban spaces of Belo Horizonte/Brazil. Microclimatic parameters were measured simultaneously to the application of 1693 questionnaires to collect individual and subjective parameters. After calculating UTCI, Ordinal Logistic Regression was used to statistically treat data. The results indicate that when UTCI <19.3 °C, thermal sensation is “Cold/Cool/Slightly cool”; if 19.3 °C ≤UTCI ≥26.7 °C, people feel “Neutral” with regard to thermal conditions; when UTCI >26.7 °C, thermal sensation is “Slightly warm/Warm/Hot”. These outcomes are compared to the results of other previous studies in Brazil. The conclusion is that it is possible to predict urban thermal comfort through calibrated assessment scale of thermal indices, such as UTCI, and provide relevant information for decision-making in the development of strategies for urban planning.