Study On Evaluation Indexes Of Outdoor Thermal Comfort For Lhasa Area

With the improvement of living quality and health awareness, people are more willing to go outdoors to enjoy recreational activities, increasing the ther mal comfort of the outdoor environment to enhance the vitality and livability of the city is increasingly valued. As a new direction of development of archit ectural disciplines, the study of thermal comfort is deepening. But the research methods and evaluation indicators are not unified, making the research results existing certain geographical limitations. By summarizing the relevant research at home and abroad, it is found that there are few researches on outdoor ther mal comfort for high altitude areas. Therefore, it is necessary to carry out envi ronmental survey and questionnaire survey in Lhasa area, getting the actual dat a, and then combining the evaluation index and mathematical method to carry on the analysis.The main contents of this paper include:1) Theoretical study on human heat transfer under low pressureTheory and mathematical model of human body temperature regulation are the theoretical basis of mechanism thermal comfort evaluation index, the press ure change will break the body's original thermal balance.In this paper, the ch anges of heat transfer via convection, evaporation, radiation and respiration bet ween people and environment in low pressure condition were studied by comp aring the mathematical expressions, basing on the convective heat transfer criter ion equation, directional radiation heat source theory and Lewis theory, then, th e physical and physiological factors affecting the outdoor thermal comfort of L hasa residents were also analyzed.2) Study on correction of outdoor thermal comfort evaluation indexThe thermal comfort evaluation index comes into being for evaluating com plex thermal environment with a simple and reasonable numerical method. ButIndicators are diversified, because there are differences of application areas and research purpose. To establish the appropriate evaluation criteria as the focus of this study, it is necessary to recognize and clarify the rationality and calcula tion steps of various outdoor thermal comfort evaluation indexes. Moreover, the special conditions such as low pressure, low oxygen partial pressure and direc tional radiation source in Lhasa area make the value or algorithm of the param eter in the evaluation index, especially in the thermal equilibrium equation cha nged. Research in accordance with the relevant theory and methods to amend i t, while ensuring the entire process is operational. In the course of the study, t he heat balance equation for the residents of Lhasa was obtained.3) Micro-climate measurement, questionnaire survey and preliminary analysis of the dataField microclimate measurement and questionnaire survey provide data sup port for the study to put forward the final evaluation of appropriate thermal co mfort and thermal stress which ensures the authenticity and reliability of the re search conclusion. The study details the design of the research, Including meas uring point selection, equipment settings, questionnaire style, data processing an d so on. analysis of the existing outdoor thermal environment in Lhasa, the res idents of the thermal comfort. Make analysis of the existing outdoor thermal e nvironment and the residents' thermal comfort in Lhasa.4) mathematical analysis: correlation and regression analysis The study is based on the relevant mathematical theory and research data,index operation, thermal sensory voting, then using the analysis software SPS S to make the correlation analysis and curve regression analysis, getting the eff ect of the climatic factors on the thermal sensation of the Lhasa residents, and the function expression of the corresponding relationship between the physiolo gical temperature, the standard effective temperature and the subjective thermal sensory voting of the Lhasa residents based on the reliability and the fitting de gree , To establish the revised physiological equivalent temperature for the eval uation of outdoor thermal environment in Lhasa region of the evaluation index,and gives the heat stress correspondence table.The research collected a large amount of data and carried out strict screening,which greatly reduced the contingency of the conclusion, or could provide refer ence for the study of outdoor thermal environment in high altitude areas and p rovide relevant theoretical support for improving the thermal environment comf ort in Lhasa area.