Urban Heat Assessment, and Heat Risk Identification in Taiwan’s Built Environment.

The temperature in Taiwan is expected to continue to rise in the future based on the worst-case scenario of global warming (SSP5-8.5). And the average annual temperature in the middle /end of the 21^st century may rise by more than 1.8 ℃/ 3.4 ℃; and the number of days with high temperatures above 36 ℃ will increase in various places. Under the worst scenario (SSP5-8.5), in the middle/ late 21st century, the increase will be approximately 8.5 days/ 48.1 days, with the increase in urban areas being more significant than in other areas. In the future, the summer period will extend from the current approximately 130 days to 155-210 days, and the winter period will decrease from the current approximately 70 days to 0-50 days. Taiwan will face more severe conditions in the future.

Although Taiwan has gradually begun to address climate change and urban high temperature issues, there are no specific urban high temperature implementations and regulations, and there is a lack of tools and mechanisms to effectively quantify or assess urban high temperature risks. Since Taiwan does not have exclusive regulations on high temperature response, extreme high temperature has been viewed as one of the natural disasters, such as typhoons, earthquakes, droughts, etc. Which is highly dependent on the disaster prevention and response capabilities of individual local governments. The implementation process is different in different counties and cities, and the results cannot be reviewed uniformly. Moreover, there are differences between cities and counties, with different problems, geographical environments, social vulnerability, etc., making it difficult to compare the risks of high temperatures and share experiences.

The urban built environment is critical to outdoor thermal comfort and heat stress risks. Case studies of several outdoor activities of different scales show that under different environmental conditions, participants of different identities will have different thermal risks and different thermal perception/behavior patterns. After understanding the impact of outdoor thermal comfort and related differences in feelings and behaviors, we can further analyze the impact of outdoor high temperatures on the "built environment" and "social vulnerability".