With the rapid development of low-carbon buildings and energy-saving technologies, phase change materials (PCM) have been extensively applied in building floor heating systems due to their excellent thermal energy storage and temperature control characteristics. However, traditional encased PCM radiant floor heating systems (RFHS) exhibit drawbacks including slow thermal response, low thermal efficiency, and excessive structural layer thickness. This study proposes an innovative solution through CFD numerical simulation: replacing the conventional circular encasement with an elliptical encasement and optimizing the elliptical axis ratio to enhance the system’s thermal performance and reduce mortar layer thickness, thereby lowering construction costs. The study analyzes the thermal state of PCMs, temperature variations of the floor structure, and heat flux distribution. The results show that as the short axis (a) length of the elliptical encasement decreases, the floor’s thermal response becomes faster. When a = 1.5 times the radius of the hot water pipe, the floor achieves the optimal balance between thermal comfort and energy efficiency. Compared to the traditional design, this approach not only enhances thermal response speed and reduces energy consumption but also decreases the mortar layer thickness by 16.7%. This study provides a theoretical basis for optimizing RFHS integrated with PCMs and holds significant potential for engineering applications.

Understanding the characteristics of biogas demand in rural areas is essential for on-demand biogas production and fossil fuel offsetting. However, the spatiotemporal features of rural household energy consumption are unclear. This paper developed a rural biogas demand forecasting model (RBDM) based on the hourly loads of different energy types in rural China. The model requires only a small amount of publicly available input data. The model was verified using household energy survey data collected from five Chinese provinces and one year’s data from a village-scale biogas plant. The results showed that the predicted and measured biogas consumption and dynamic load were consistent. The relative error of village biogas consumption was 11.45%, and the dynamic load showed seasonal fluctuations. Seasonal correction factors were incorporated to improve the model’s accuracy and practicality. The accuracy of the RBDM was 19.27% higher than that of a static energy prediction model. Future research should verify the model using additional cases to guide the design of accurate biogas production and distribution systems.

With the rapid development of the national economy, increasing attention has been given to the living environment in rural areas, especially indoor thermal and wind environments. This study conducted onsite measurements and questionnaire surveys during summer in the indoor environment of five villages in northeastern Sichuan. A total of 89 traditional residences were selected to investigate their fundamental characteristics, indoor thermal environment, humidity conditions and comfort levels. The results showed that when expressed as neutral temperature and humidity, the temperature difference was 1.35°C and the humidity difference was 8.14%. Local residents exhibited higher tolerance toward the local thermal and humidity environment compared to nonlocal volunteers, who displayed greater sensitivity toward it. In addition, local residents had a thermal comfort value of 0.03 and a thermal acceptance value of 1.16, whereas nonlocal volunteers had a thermal comfort value of 1.42 and a thermal acceptance value of −0.45.

Staffs wearing mascot costumes are quite common in performances and commercial promotions, but the internal thermal environment is usually poor in summer due to the high heat resistance of clothes and low ventilation efficiency, which increase the fatigue and discomfortable level of staffs greatly. In this study, thermal sensation and fatigue of human wearing mascot costumes in summer were explored. The three physiological indicators, including oral temperature, skin temperature and weight loss percentage, were measured, while the subjective indicators including thermal sensation, moisture sensation, air movement sensation, thermal comfort and fatigue level were inquired by a survey questionnaire. The results showed that compared volunteers dressed normal cloths, the average oral and skin temperatures of volunteers wearing mascot costumes was increased by 0.15°C and 0.60°C and their weight loss percentage was increased by 20.5%. Through the 40-minute experiment, the thermal discomfort votes of two groups are 3.22 (higher than ‘very uncomfortable (+3)’) and 1.51 (between ‘a little uncomfortable (+1)’ and ‘uncomfortable (+2)’), respectively, while their fatigue votes are 13.07 and 7.02, respectively. It showed wearing mascot costumes increased thermal discomfort and fatigue greatly.

Phase-change materials (PCMs) embedded in dynamic building envelopes can convert a passive insulation layer into an active solar-heating element. However, the thermophysical properties of the PCM used in a Dynamic Rotating Latent-Energy-Storage Envelope (DRLESE) have not been systematically optimized. This study aims to determine the PCM property combination that maximizes useful indoor heat release for winter auxiliary heating. A two-dimensional transient heat-transfer model of the DRLESE, based on the enthalpy (apparent heat-capacity) method and validated against published experimental data, was used to evaluate the effect of five PCM parameters: thermal conductivity, latent heat, solidus temperature, liquidus temperature, and layer thickness. Effective indoor thermal release and inner-surface heat flux were adopted as the evaluation indices. The results show that useful heat release peaks at a thermal conductivity of 2.0 W/(m K), a solidus temperature of 26 °C, and a liquidus temperature of 29 °C. Increasing the latent heat improves performance up to about 178.5 kJ/kg, beyond which the gain is below 3%, while increasing the layer thickness is beneficial up to 30 mm, beyond which the gain is below 6%. Relative to the low-property baselines, the optimized conductivity and thickness raise the effective indoor heat release by 58.8% and 130.3%, and the average inner-surface heat flux by 55.5% and 129.7%, respectively. Overall, this study provides quantitative PCM-selection guidance specific to the rotating dynamic envelope and identifies the diminishing-returns thresholds for latent heat and layer thickness, offering a practical basis for cost-effective PCM specification in DRLESE systems.