Outdoor Thermal Comfort In Northern China

Outdoor spaces in cities provide citizens with places for exercise and socialize.Outdoor thermal comfort is important to a city’s livability and vitality, but currently,the design of outdoor spaces rarely considers the thermal environment and thermalcomfort. Through literature survey, it is found that very little study was conducted inNorthern China, therefore, this thesis aimed to study outdoor thermal comfort in suchregion in Tianjin through microclimatic monitoring, questionnaire survey and activityrecording.Analytic results suggest that the outdoor comfortable rate of Tianjin reached83%,the main uncomfortable situation occurred in summer. Meanwhile, in outdoorenvironment, thermal sensation was found to vary with seasons, In cold season,―slightly warm‖thermal sensation was perceived as most comfortable, just as―neutral‖in comfort season and―slightly cool‖in hot season. In addition, thepreference of weather parameters is directly linked with the value of air temperature.the higher the air temperature, the higher wind speed and lower solar radiation andrelative humidity residents desire and vice versa. For different age groups, theirphysiological and psychological difference resulted in difference in thermal comfort.Although the senior used more clothing to compensate their reduced metabolic rate,their thermal sensation was still the lowest. Because of their higher activity level,children were highest in thermal sensation. Comparison of the Actual Sensation Vote(ASV) model between Tianjin and Wuhan residents revealed that citizens in Tianjincan tolerate colder environment. Besides, the number of people in outdoor spaces wasassociated with resident’s lifestyle and outdoor thermal comfort.The data was also used to evaluate thermal comfort models such as PredictedMean Vote (PMV), Physiological Equivalent Temperature (PET) and UniversalThermal Climate Index. The study found that UTCI could well predict outdoorthermal comfort in Tianjin while PMV overestimate the thermal sensation. Besides, athermal sensation range of PET for Tianjin was identified and compared with therange of middle/western Europe and Taiwan which indicates Tianjin residents had awider―neutral‖range and could tolerate cool environment as low as11oC PET. This thesis also developed a simulation tool for calculation outdoor thermalcomfort distribution. By combining the flow field simulated by Computational FluidDynamics (CFD) and the radiation field calculated by Ecotect, the resulted outdoorthermal comfort field can help planners to design more comfortable outdoorenvironment.Our research has provided a database in cold climate in China and some newfindings about outdoor thermal comfort that can be used to better understand outdoorthermal comfort.