Understanding the combined effect of the thermal environment and personal factors on occupant performance under sedentary physical activity level

Abstract

Understanding the combined effect of the thermal environment and personal factors on occupant thermal comfort and performance is crucial, given the significant seasonal changes in these factors that impact thermal comfort. This study combined these factors into a single index, using Standard Effective Temperature (SET), to examine their relationship with occupant thermal comfort, performance, mood disturbance, willingness and well-being during winter and summer. The occupants were exposed to four and twelve different thermal conditions for the winter and summer assessments, respectively. Subjective questionnaires were used to assess thermal comfort, mood disturbance, willingness, and well-being, whereas neurobehavioral tests were used to quantify the performance. The results revealed that in winter, the thermal sensation range for maximizing thermal comfort, willingness, performance, wellness and minimizing mood disturbance was ‘neutral’ to ‘slightly warm,’ while in summer, it shifts from ‘neutral’ to ‘slightly cool’. Despite these changes, the SET remained consistent in the range of 23.5 °C to 24.5 °C across seasons, ensuring the best occupant responses. This consistency suggests that within this SET range, the body’s thermoregulation and behavioural adaptations effectively sustain comfort, willingness, performance, wellness and minimum mood disturbance, regardless of seasonal variations. These outcomes can help design occupant-centric building control algorithms for HVAC systems.