Investigating the vertical thermal of urban building facades using one-year IoT sensor data

Abstract

With global warming and the intensification of urban heat island effects, vertical monitoring of urban thermal environments becomes crucial. It helps reveal temperature distribution at different building heights, supports better architectural design, and improves residential comfort. Based on IoT technology, this study developed an ultra-low-power air temperature sensor (AT-IoT) and conducted year-round air temperature monitoring in 2023 at a university campus in Guangzhou. Twenty monitoring points were installed at different vertical heights on building facades with four different orientations. The results showed: 1) Significant temperature differences existed between floors. During the daytime, upper floors were about 0.75 °C warmer than lower ones, particularly in summer due to solar radiation. In winter and spring, vertical temperature differences were more pronounced, up to 1 °C; 2) Building orientation also shaped temperature patterns. Sunlit facades showed higher values, while north-facing upper floors experienced unusual warming, likely due to stagnant air zones and reflected heat; 3) Cluster analysis showed that upper-floor temperatures were relatively stable. In contrast, lower floors were more affected by ground radiation, wind speed, and vegetation. These findings enhance the understanding of facade-scale vertical temperature variations and offer scientific guidance for improving energy efficiency, optimizing energy use, and reducing heat risks.