Outdoor thermal comfort and adaptive behaviors in the residential public open spaces of winter cities during the marginal season.

In winter cities, outdoor seasons are highly valued due to the long cold winter. By improving the outdoor thermal environment during marginal seasons, outdoor seasons may be extended. Therefore, outdoor thermal comfort and adaptive behaviors during marginal seasons should be considered. Three representative residential public open spaces in Harbin, a typical winter city, were selected to conduct an empirical study. Meteorological measurements and rudimentary questionnaires were administered and observations were conducted to explore outdoor thermal comfort and adaptive behaviors. Three important conclusions were obtained from the survey. The result from the questionnaire surveys showed that users of public spaces generally believed that "warm" was comfortable during the spring marginal season of the winter cities. The 90% thermal acceptable physiologically equivalent temperature (PET) range, which was calculated using meteorological measurements and questionnaire results, was more than 10.2 °C for this time period in the winter cities. This threshold value was much lower than that of temperate and subtropical zones, indicating that the outdoor thermal comfort of users in the winter cities had regional characteristics. Moreover, users engaged in static vs. dynamic activities showed different sensitivities to thermal environments. The users' location selection showed a strong dependence on microclimate rather than on the activity-supported facilities; when microclimate conditions changed, users made accommodations by moving to sunny areas or performing other adaptive behaviors, and thus, space utilization changed. These findings can inform thermal comfort-oriented planning and design from the perspectives of microclimate regulations, site planning, and activities in the residential public open spaces of winter cities.