Abstract

Urban greenery significantly affects thermal comfort in urban environments, mitigating heat island effects and influencing psychological responses to temperature. This study investigates the impact of greenery density on thermal perception by employing augmented reality (AR) to overlay varying levels of greenery onto a real-world university campus setting. Thermal comfort of participants in response to these virtual modifications was assessed by completing questionnaires, while concurrent measurements of the actual thermal environment were captured using a micro-weather station. Results demonstrate that both medium and high densities of greenery perceptibly reduce thermal sensation, with high-density greenery having a more pronounced effect. A thermal perception regression model, incorporating the Physiological Equivalent Temperature (PET), indicates that medium-density greenery extends the thermal comfort range by about 4°C, while high-density greenery extends it by approximately 8°C. However, perceived shade from non-green elements like parasols did not significantly enhance comfort. Additionally, the study finds that while medium-density greenery improves comfort during hot conditions, high-density greenery may decrease the sense of openness in a space and lead to a feeling of visual oppression. Thermal comfort prediction model also demonstrated that limited openness adversely affected thermal comfort voting, even in conditions where the physiological equivalent temperature remains neutral. This research underscores the importance of optimizing greenery density in urban planning to balance thermal comfort with spatial openness.