Abstract

With the increasing demand for leisure outdoor spaces, understanding the occupants’ thermal comfort requirement outdoors is an essential and forward-looking matter for designers to design more new attractive spaces. This paper presents the results of a long-term field comfort survey in shaded outdoor spaces, which primarily concerned with the comfort conditions of open spaces in cities. The database consists of 3,837 questionnaire guided interviews from field surveys in different study sites in a campus, in Taichung, throughout a whole year. The findings confirm a strong relationship between people’s thermal sensation votes and the operative temperature or ET* of microclimate. There is also convincing evidence for adaptive behaviors happening, with the monthly variation in thermal neutral temperature, as well as the boundaries of comfort zone. In determining a range of temperatures around the thermal neutral temperature corresponding with 90 and 80% thermal acceptability, in this study, we apply the relationship between mean thermal sensation and percentage of dissatisfied, as illustrated in the classic PPD versus PMV curve. The relationship indicates that a large group of subjects expressing mean thermal sensation vote in the interval between -0.42 and +0.42 (or -0.76 and +0.76) could expect to have 10% (or 20%) of its members expressing dissatisfaction. Applying the criteria to each monthly regression model of thermal sensation as a function of ET* produced a mean yearly comfort band of 5°C ET* for 90% acceptability and 7°C ET* for 80% acceptability, both center on the thermal neutral temperature.

Key words: Outdoor spaces, thermal comfort, long-term field survey, thermal neutral temperature, thermal comfort band.