Thermal Comfort for Urban Parks in Subtropics: Understanding Visitor’s Perceptions, Behavior and Attendance

The paper is an effort toward thermal comfort assessment for urban parks under the climatic conditions of Taiwan to help architects achieve better climatic design. Field interviews, observations, and micrometeorological measurements were conducted in this study. The WBGT was used as the thermophysiological index to investigate the effects of thermal conditions on visitor’s thermal perception and adaptive behavior in outdoor urban spaces. In this study, behavioral adaptations used by visitors as a means of achieving comfort were evaluated. Observational results showed that the overall attendance was influenced by sun and thermal conditions. There was a robust relationship between thermal sensation votes, as well as thermal acceptability, and thermal environment, in terms of WBGT. The upper and lower limits of 80% acceptability are 26°C WBGT and 20°C WBGT, respectively. 1. Introduction Ensuring acceptable thermal comfort conditions in outdoor spaces is always one of the considerations of landscape design, since thermal environmental conditions greatly affect individual moods and activities in the outdoors as well as the usage of the outdoor spaces. In densely populated cities, with the continuously growing emphasis on the importance of quality of life, the public attaches greater value to the quality of thermal comfort in outdoor urban spaces. At the same time, with the expansion of cities, the urban heat island effect is increasingly significant, and the trend of urban microclimate change is not optimistic. Hence, the architects or landscape designers must seriously consider the actions required for outdoor space design to support comfortable conditions. In recent years, the thermal comfort of outdoor spaces has become an important issue, attracting a considerable number of articles to analyze and discuss outdoor thermal comfort through field surveys, for example, Spagnolo and de Dear in Australia [1], Ahmed in Bangladesh [2], Nakano and Tanabe in Japan [3], Nikolopoulou and Lykoudis in European countries [4], Oliveira and Andrade [5] and Andrade et al. [6] in Portugal, Cheng et al. in Hong Kong [7], Kariminia et al. in Iran [8], and Lin [9], Hwang et al. [10], and Lin et al. [11] in Taiwan. Many of the research studies have generally used a thermophysiological index in outdoor thermal condition analysis. Some of the indices, for example, physiological equivalent temperature (PET), standard new effective temperature (SET*), universal thermal climate index (UTCI), and so forth, are based on comprehensive energy-balance models for the human body to