Investigating the impact of a large river and its surrounding contextual conditions on pedestrians' summer thermal perceptions in a Cfa-climate city.

Thermal comfort studies are usually employed to find subjective thermal responses [indicated by neutral temperature (NT), i.e. the temperature with no thermal stress] of residents from a region towards thermal environments. According to the recently published works in the literature, NTs are affected by many factors, such as geographical location and microenvironments. To elucidate the origins of these effects, the impact of microenvironment elements around a water surface on pedestrians' thermal perceptions was systematically investigated in this work. The Fujiang River (FJR) in Mianyang City was taken as the sample site. The municipal meteorology station is located next to the site by around 2.5 km. By performing meteorology measurements combining questionnaires, it was found that the riverside NT (indicated by physiologically equivalent temperature, PET) of Mianyang in the summer of 2023 was 21.4 °C. The relationship between the distance from the water (DFW) and NT was quadratic linear. The same phenomenon took place by using either PET or Universal Thermal Climate Index (UTCI) indexes. Meanwhile, the meteorological contexts also affected NTs, including relative humidity (RH) and air velocity (Va). Regarding RH, the NPET increased from 15.2 °C (RH = 50%) to 26.9 °C (RH = 90%). In contrast, the NPET dropped from 23.0 to - 50.6 °C when the Va increased from 0.2 to 2.5 m/s, respectively. From our analysis, it was demonstrated that human thermal responses are significantly affected by both the microenvironmental and meteorological backgrounds around the water surface. Our work provides valuable insights for the proper use of water surfaces in urban design for adjusting thermal comfort.

A study of the thermal comfort in urban mountain parks and its physical influencing factors.

Urban thermal comforts are increasingly holding people's attention due to global warming and urban heat islands. Urban parks can absorb sunlight radiation, which reduces air temperature, improving urban microclimates. Various factors in the park are confirmed to be effective in heat mitigation. However, there are few studies on thermal comfort in urban mountain parks, and mountain areas might cause peculiar climatic conditions owing to their particular landforms. To fill this gap in the research, this study explored thermal comfort in mountain parks and the environmental factors that would affect thermal comfort. A field measurement in the summertime (July & August) of 2018, it was found that trees, the river, and the area of parks could adjust the thermal comforts of mountain parks. Their effects varied throughout the day, and the impacts of trees were most pronounced at noon and late afternoon, while the influence of rivers and park areas was most pronounced at noon. Increasing the leaf area index by 1 point could result in decreases in physiological equivalent temperature, land surface temperature, and solar radiation level by 3.90 °C, 2.69 °C, and 270.10 W/m2, respectively. The findings have practical implications for future urban mountain park design works.

Indoor thermal responses and their influential factors-- impacts of local climate and contextual environment: A literature review.

Indoor thermal comfort/perception (ITC) would be affected by contextual factors. The present article reviewed findings (thermal responses represented by neutral temperature, NT) of ITC studies published in recent decades. There were two types of contextual factors: climate (latitude, altitude, and distance from the sea) and building characteristics (building type, and ventilation mode). Through associating NTs with their contextual factors, it was found that people's thermal responses were significantly affected by climatic factors, especially latitude in summers. Increasing latitude by 10° resulted in NT decrease of around 1 °C. Others- e.g., building characteristics- were influential to some degrees. Effects of ventilation mode (natural ventilated, NV; air-conditioned, AC) varied for the seasons. Generally, people in NV buildings had higher summer NTs, such as 26.1 °C in NV and 25.3 °C in AC in Changsha. The results demonstrated significant human adaptations to climatic and microenvironmental influences. The design and construction of future residences could be more fine-tuned with the building insolation and heating/cooling technology to fit the thermal preferences of local residents for the best internal temperature settings. This study's findings may potentially serve as a foundation for future ITC research.