Seigen Cho

Elderly individuals in rural China are highly vulnerable to extreme weather events and temperature fluctuations due to inadequate infrastructure in the built environment and constrained economic conditions, thereby increasing their health risks. Outdoor spaces represent one of the primary daily activity settings for rural older adults. However, existing research rarely links spatiotemporal patterns of outdoor activities to evidence-based thermal environment optimization, leaving a critical knowledge gap for age-friendly and sustainable rural design. This study focuses on the spatiotemporal differentiation patterns of daily outdoor activities among elderly people aged 60 years and above in rural Xi’an, as well as the optimization of spatial variations in thermal environments. Using on-site interviews, thermal environment measurements, thermal comfort questionnaires, continuous thermal environment monitoring, and machine learning based on random forest, this study drew the following conclusions: (1) outdoor activities in winter were concentrated between 9:00–11:00 and 13:00–17:00, while in summer, they shifted to the morning and evening periods, namely 6:00–9:00 and 17:00–21:00. (2) Models for outdoor clothing adjustment, thermal sensation, and thermal acceptability among elderly residents were established. The calculated neutral temperature was 10.19 °C, with a 90% outdoor thermal acceptability range of 9.6–27.2 °C and an 80% outdoor thermal acceptability range of 6.2–30.6 °C. These findings differ from those documented in regions with distinct climate zones and geographical settings. This discrepancy stems from regional climatic features, lifestyle variations between urban and rural older adults, and differences in the thermal environment quality of elderly-oriented outdoor activity spaces. (3) In winter, the acceptable period of the Universal Thermal Climate Index (UTCI) at south-facing entrances (10:30–16:30) was significantly longer than that in the courtyard (13:30–14:00). In summer, the comfortable period in the courtyard (before 10:00 and after 20:00) was longer than that at north-facing entrances (before 09:00). A random forest model for thermal sensation was established, and the relative importance of each parameter influencing thermal sensation was analyzed. On this basis, priority improvement pathways and strategies for the thermal environment, as well as suggestions for the subjective adaptive behaviors of elderly residents, were proposed. The research results of this study can provide technical solutions for age-friendly thermal environment design in rural areas, thereby safeguarding the comfort, health, and social well-being of the elderly population in rural areas.

Solar energy is a type of renewable and sustainable energy. Enhancing the acquisition and utilization of solar radiation in urban residential areas is a crucial strategy for advancing sustainable development goals. The morphology of urban residential areas plays a vital role in determining their solar radiation acquisition (SRA) potential. Existing studies have primarily focused on exploring the correlation between the individual morphology index and SRA potential for residential areas. However, in the actual process of project design, there is a common need to simultaneously adjust multiple morphology indexes according to specific criteria. The question of “How to compare the magnitude of the impact of simultaneous changes in multiple morphology indexes on the SRA potential of a residential area” has not yet been systematically analyzed and fully answered. This study compares the sensitivity of multiple morphology indexes when changed collectively and assesses their comprehensive impact on the SRA potential of residential areas. The aim is to determine how to comprehensively control multiple morphology indexes in the early planning and design stages to maximize solar energy utilization in residential areas. It is concluded that, when considering the floor area ratio index under identical conditions, an increase in building density proves more advantageous for enhancing SRA compared to an increase in building height. In cases where the building height is less than 24 m and the floor area ratio is below 1.5, elevating the building density yields greater photovoltaic (PV) potential for the residential area. With a limited site area, the impact of building height on SRA far outweighs that of the layout. The layout does not significantly affect the annual solar radiation amount per unit of external surface area (ASU). With increasing building height, the impact of layout on heating season solar radiation amount per unit of external surface area (HSU) becomes more pronounced. A vertical staggered layout and a row layout exhibit significantly superior performance compared to a horizontal staggered layout in this regard. However, when the building height exceeds 24 m and the floor area ratio surpasses 1.5, the PV potential of the vertical staggered layout surpasses that of the row layout and horizontal staggered layout for the same building height. The influence of building height on SRA is slightly greater than that of the building orientation under similar conditions. The change in SRA potential with orientation under the same height follows a consistent pattern.

As an effective solution to achieve carbon neutrality, the development of low-energy solar houses is now in the ascendant in China. The Qinghai Tibet Plateau (QTP), which is rich in solar energy resources, is considered to be an important region for solar technologies studying. Rural houses are the main living form for residents in the QTP, early-stage design parameters play an important role in achieving low-energy consumption of rural houses. However, researches on the design method and parameters of low-energy solar rural house were relatively poor at present. This paper examined the influence of early-stage design parameters on the energy performance of low-energy solar rural houses incorporating building-integrated photovoltaic (BIPV) roof systems. A 2-storey 110 m2 rural house was studied as an archetype. Through simulation, a range of related building parameters, such as shape coefficient, window-to-wall ratio (WWR) and azimuth angle were analysed and compared. The impact of early-stage design parameters on energy consumption in winter, ventilation in summer and BIPV system annual energy yield were considered.