Comprehensive evaluation of public comfort on street roads considering the combined effects of thermal and acoustic environments

Abstract The development and high population in urban areas contribute to environmental pollution. Countermeasures have been separately implemented for each type of pollution. However, public comfort in urban areas is influenced by multiple factors. Therefore, we focused on two distinct factors that influence public comfort: thermal comfort and noise. We attempted to understand their combined effect on overall comfort and to formulate the effect using subjective measurements in real streets. Experiments were conducted in three seasons with six different noise levels in Toyohashi-Japan with ten male subjects for each season. Climatic thermal factors, such as air temperature, human factors, such as activity level, and physiological conditions such as body temperature, were considered. To evaluate the acoustic conditions, we measured the sound level for each frequency-band. Moreover, a questionnaire survey was conducted to assess thermal, acoustic, and overall perceptions. Thermal sensation and the acoustic sensation of loudness were quantified using human thermal load (HTL) and equivalent noise level (LAeq) respectively. Additionally, thermal and acoustic sensations are effective indicators of thermal and acoustic comfort, respectively. Consequently, thermal and acoustic comfort can be determined using the objective HTL and LAeq, respectively. Finally, overall comfort was obtained in terms of thermal and acoustic comfort. The overall effect of thermal–acoustic comfort on subjective comfort remains unclear; however, overall discomfort appears to be more sensitive to thermal discomfort than to acoustic discomfort in this study. The proposed methodology can be used for comprehensively evaluating environmental comfort in different scenarios, with potential applications in urban planning.