Calibration of the Physiological Equivalent Temperature (PET) index range for outside spaces in a tropical climate city

Abstract

This study aimed to calibrate the physiological equivalent temperature (PET) index range for Cuiabá-MT, a city with a tropical climate, for which PET calibration was not previously conducted. The air temperature, relative humidity, globe temperature, wind speed, and direction were measured in three scenarios: arboreal shading (S1), artificial shading with parasol (S2), and sun exposure (S3). Questionnaires were administered to a group of 30 people to verify the preferences, perceptions, and levels of thermal comfort of respondents with data processing, using RayMan software. The values with the greatest differences were between S1 (wooded) and S3 (sun exposure). Five categories of the PET index were adapted: slightly cold, comfortable, slightly hot, hot, and very hot. The comfortable range was found to be between 23.01 and 34.64 °C. When performing the correlation of the users' responses regarding their thermal perceptions and preferences in the different scenarios, it was found that in S1, the percentage of thermal comfort was the highest and in S3, the percentage of thermal discomfort was the highest, reinforcing the significance of afforestation in thermal comfort. The findings of this study contribute to the clarification of issues related to thermal perception and comfort in open spaces in tropical climate.