Study On Thermal Sensation During Step-change In Non-uniform Thermal Environment

To explore thermal sensation’s changing rules in non-uniform environment during step-change, generally analyze the thermal comfort issue involved in personalized environment and ambient environment and to improve design criteria for non-uniform thermal environment and transient space, this thesis studied on thermal sensation during step-change in non-uniform thermal environment.This dissertation focused on the following issues:thermal sensation’s changing rules during step-change in non-uniform environment created by the workstation with local ventilation and the ambient environment; the influence of local thermal sensation on the overall after step-change; overall thermal sensation’s prediction; the relationship between thermal sensation and skin temperature and the physiological interpretation of thermal sensation’s change. This dissertation also studied the effect of local ventilation method on overall thermal sensation’s improvement, the mechnisim of overall thermal sensation’s integration by local body parts, the inherent correspondence between the phenomena of hysteresis and overshooting and skin temperature’s changing rate and the just noticeable skin temperature’s change on head for stimulations. Human subject test in a mockup office was adopted in this study which is a common method in thermal comfort research. In total,122tests were carried out in the controlled environment chamber in Dalian University of Technology. The body segment stimulated by local venation included head, chest, hand and foot. During the whole test, local and overall thermal sensation and skin temperatures were monitored. Statistical analyses, as partial correlation, hypothesis test were used to explore the data. The results showed that thermal sensation presented the phenomena of hysteresis and overshooting after step-change between workstation and ambient environment which had a temperature difference of less than5℃. The durations of hysteresis and overshooting and thermal sensation’s changes generated were calculated. This dissertation proposed head thermal sensation as the basic thermal sensation added with the maximal local thermal thermal sensation difference to predict overall thermal sensation after step-change into the ambient. Refered to JND theory, the just noticeable difference on face skin temperature was linearly correated with original skin temperature. The local ventilation design using recycled air was effective to cooling on the subject and would lower the thermal sensation’s change after step into the ambient environment.The findings of thermal sensation’s changing rules involved thermal comfort in personalized environment and highly connected the workstation and ambient environment as a whole to study thermal comfort issue in non-uniform environment. The overall thermal sensation’s predictive model based on head thermal sensation and sensation difference considered the effect of step-change and local ventilation and was verified well which further provided experimental envidence for the mechanism of overall thermal sensation’s integration.The results and findings of thermal sensation’s changing rules and local ventilation’s study in this paper will contribute to the environmental design for thermal comfort in non-uniform environment and step-change space in a purpose of realiing envery saving strategies in building environment.