Calibration of the outdoor comfort index Physiological Equivalent Temperature (PET) for Curitiba

Abstract The analysis of the relationship between thermal comfort and the climatic conditions of a given location can be an important tool for urban planning. A possible way to perform such evaluation is by means of comfort indices, such as PET (Physiological Equivalent Temperature), which is widely used in thermal studies in open-air environments, after duly calibration to local thermal preferences. This study aims to calibrate the PET index for Curitiba, a city characterized by a temperate climate (Cfb), according to three distinct procedures. Climatic and subjective data were obtained in outdoor thermal monitoring campaigns during 2009 and 2010, covering summer, autumn and winter. Calibration procedures involved three distinct methods: 1) binning method for 1 ºC discrete variations in the PET scale; 2) identifying the most prevailing thermal sensation categories in each 1 ºC PET-bin; 3) Probit analysis. Method 2 was considered less precise in defining limits for Curitiba while Probit results corresponded well with those from Method 1, by which a comfort zone for outdoor spaces was obtained.