Impact of site-specific morphology on outdoor thermal perception: A case-study in a subtropical location

Abstract

The paper addresses to what extent site-related factors affect the perceptual assessment of microclimate by users of outdoor spaces. Testing of this hypothesis was based on data normalization approaches in order to align thermal sensation data gathered during field surveys at monitoring points with differing urban morphologies, thereby looking at differences found between predicted and observed thermal responses. Outdoor thermal comfort surveys took place during 2009 over different seasons in pedestrian areas of downtown Curitiba (25.5°S, 49°W, 910m amsl), a subtropical location in Brazil. Monitoring points were defined in respect of urban geometry attributes. For the measurements, a pair of HOBO Onset weather stations was used. The outdoor index Universal Thermal Climate Index and the derived Dynamic Thermal Sensation were used for comparisons to subjective thermal sensation and thermal preference data collected from 1685 respondents over 14 campaigns. Results showed visible differences in linear regression lines between sites with different Sky View Factor, which were later confirmed by ANOVA tests. Relative differences in binned data in terms of prediction errors were found to be nonlinear between groups, which points to the need for further investigations. Results thus suggest that a given point's overall appearance affects the way people thermally perceive it.