Applicability Evaluation Of Outdoor Thermal Comfort Indices Of College Students In Campus In Winter In Severely Cold Region

With the acceleration of urbanization,the living pressure is also increasing.It is reported that people spend more than 90 % of their time indoors,outdoor physical activities provide stress reduction,evocation of positive emotions and well-beings,and extra physiological and psychological benefits for the elderly and the children.At present,people should spend more time on outdoor activities.So outdoor activities play a key role in daily life,and the use of outdoor space mainly determined by outdoor comfort.People's subjective response to outdoor thermal environment cannot be directly interpreted by environmental influence factors(temperature,humidity,radiation and wind,etc.),thus thermal comfort indexes(PET,UTCI,SET*,PMV)were needed to evaluate impact of outdoor thermal environment on human beings.Due to influence of people's adaptation,the reactions to environment varied by climate and locations,and many related research has been carried out by researchers all of the world.Questionnaire survey was carried out in university campus in Harbin,which is a typical severely cold climate city in China,and 686 effective questionnaires were collected totally.By choosing environmental influence factors?subjective and objective evaluation indicators,we make conclusions about college students' outdoor thermal comfot feature,and applicability evaluation of outdoor thermal comfort indices in winter in severely cold region.Comparing the relationship between the thermal comfort index and the thermal senseation vote of college students with the large random sample(more than 2000 samples),college students are less sensitive to the changes of the outdoor thermal environment in the cold winter.Therefore,the age of the sample should be considered as an important factor when study outdoor thermal comfort.The evaluation method of three statistical indicators and two qualitative indicators is used to evaluate the applicability of selected thermal comfort indicators(PET,SET*,UTCI)in winter in severe cold region.It is known that Spearman value of the calculated value of PET and the actual thermal voting of college students is the largest,which is 0.829.The correct prediction percentage of the actual thermal sensation is the highest,which is 63.12%.The classification prediction percentage has the highest degree of agreement with the actual one.The predicted response category distribution has the highest degree of agreement with the actual thermal sensation voting distribution.From the performance of each evaluation index,the physiological equivalent temperature PET has the best predictive power and expressiveness for the evaluation of outdoor thermal comfort of the university campus in the cold region,and the applicability is the best,which should be the preferred index;in comparison UTCI and SET* should be evaluated as alternative indexs.During the investigation,it was also found that the air temperature Ta had the greatest influence on the outdoor thermal sensation of college students in the cold winter.The average radiant temperature Tmrt had the greatest impact on thermal comfort,and most college students thought that the outdoor thermal environment was cold and general.