The effect of temperature and group perception feedbacks on thermal comfort

• Revealed the effect temperature feedback and group perception feedback on thermal comfort. • Considered the impact of individual difference on feedback. • Eliminated interference of experimenter effect by lighting adjustment and questionnaire design. • Analyzed the psychological adaption mechanism by expectation theory. • Provided theoretical support for improving thermal comfort in winter. This paper aims to identify the contribution of temperature feedback and group perception feedback on the improvement of thermal comfort. A controlled thermal comfort experiment with a total of 158 subjects was conducted to figure out the impact. The results indicate that both have positive effects on occupants’ thermal comfort. Group perception feedback can improve thermal sensation by 0.23 under cooler winter conditions, while temperature feedback can improve occupants’ thermal sensation by 0.47 under warmer conditions. Thermal satisfaction increased 0.24 with temperature feedback, indicating that temperature feedback could eliminate the downward trend of satisfaction. Extreme votes in thermal sensation, defined as votes at which the deviation from the mean exceeds the standard deviation, had decreased by 69% (from 36/77 to 11/77) with group perception feedback. Expectation theory, representing occupants’ expectations of thermal environment, can effectively explain why thermal comfort was improved by feedback. The possible reason is that subjects were aware that extreme feedbacks cannot change the current environment since either air temperature or percentage of satisfied subjects meet the standard, so the subjects’ thermal expectations are lowered correspondingly. For practice, it is possible to appropriately turn down the heating set point under overheating conditions to improve energy efficiency, based on the temperature feedback. Furthermore, group perception feedback can improve the thermal comfort under conditions that are at the edge of meeting the comfort criteria in winter and minimize extreme votes as well to build a more comfortable environment.