With population numbers increasing and anthropogenic climate change, the amount of available fresh water is declining. This scenario can lead to an increase in the occurrence of water conflicts, especially in transboundary river basins. Prevention strategies to avert water conflicts by designing a fair, efficient, and sustainable water allocation framework are needed. Taking into account the socioeconomic and environmental differences among the riparian countries is one of the most important features an allocation scheme should have. In this article, bankruptcy and bargaining games were used to construct a new weighted water allocation model. The proposed method was applied to allocate the contested water capital of the Mekong River during the dry season. The Mekong River originates in China and flows through Myanmar, Laos, Thailand, Cambodia, and Vietnam. The results of the allocation showed that, except for China and Vietnam, all the other riparian countries get their full claim of the water demand from the river. The water allocation payoffs satisfy individual rationality, Pareto optimality, and maximization of the group utility. Therefore, the allocation outputs from the proposed scheme are self-enforceable and sustainable.

The sustainable development of socioeconomic and environmental systems are highly dependent on water capital and water utilization efficiency. Nowadays, a significant portion of the world is facing water security issues due to a combination of various factors. As a result, socioeconomic and environmental systems are threatened. China is also currently experiencing problems. Water security assessment helps to identify key determining factors for optimal water utilization, so the authors present the Driving Forces-Pressures-Carrying Capacity-State-Impacts-Responses (DPSCIR) water security assessment framework. Unlike previous methods, the proposed framework incorporates the carrying capacity of the environment, and as a result, yields assessment results that are more realistic. As a case study, the proposed framework coupled with the entropy method is applied to assess the water security status of the One Belt and One Road (B&R) region in China. In addition, the water security level of the provinces and municipalities in this region are simulated for the time period from 2017 to 2022 using the Grey Prediction Model. The results show that Responses, State, Pressures, and Carrying Capacity Subsystems greatly influence water security of the region. According to the assessment, water security of the area improved from 2011 to 2016. The results portray the following trend among the three subregions of the study area, the water security of the 21st Maritime Silk Road (One Road) area is better than Silk Road Economic Belt (One Belt) and the Strategy Support and Pivotal Gateway (SSPG) of B&R areas. Generally, from the evaluation results it can be concluded that only focusing on the subsystem of Responses cannot entirely address the water security problems within the B&R area. Therefore, to ensure sustainable water security in the region and in the country, the government needs to design water resource management mechanisms that take all the subsystems into account.

Indoor air quality and thermal conditions are important considerations when designing indoor spaces to ensure occupant health, satisfaction, and productivity. Carbon dioxide (CO₂) concentration and indoor air temperature are two measurable parameters to assess air quality and thermal conditions within a space. Occupants are progressively affected by the indoor environment as the time spent indoors prolongs. Specifically, there is an interest in carrying out investigations on the indoor environment through surveying existing Heating, Ventilation, Air Conditioning (HVAC) system operations in classrooms. Indoor air temperature and CO₂ concentration in multiple lecture halls in Toronto, Canada were monitored; observations consistently show high indoor air temperature (overheating) and high CO₂ concentration. One classroom is chosen as a representative case study for this paper. The results verify a strong correlation between the number of occupants and the increase in air temperature and CO₂ concentration. Building Energy Simulation (BES) is used to investigate the causes of discomfort in the classroom, and to identify methods for regulating the temperature and CO₂ concentration. This paper proposes retro-commissioning strategies that could be implemented in institutional buildings; specifically, the increase of outdoor airflow rate and the addition of occupancy-based pre-active HVAC system control. The proposed retrofit cases reduce the measured overheating in the classrooms by 2-3 °C (indoor temperature should be below 23 °C) and maintain CO₂ concentration under 900 ppm (the CO₂ threshold is 1000 ppm), showing promising improvements to a classroom’s thermal condition and indoor air quality.

With the rapid economic development, water pollution has become a major concern in China. Understanding the spatial variation of urban wastewater discharge and measuring the efficiency of wastewater treatment plants are prerequisites for rationally designing schemes and infrastructures to control water pollution. Based on the input and output urban wastewater treatment data of the 31 provinces of mainland China for the period 2011–2015, the spatial variation of urban water pollution and the efficiency of wastewater treatment plants were measured and mapped. The exploratory spatial data analysis (ESDA) model and super-efficiency data envelopment analysis (DEA) combined Malmquist index were used to achieve this goal. The following insight was obtained from the results. (1) The intensity of urban wastewater discharge increased, and the urban wastewater discharge showed a spatial agglomeration trend for the period 2011 to 2015. (2) The average inefficiency of wastewater treatment plants (WWTPs) for the study period was 39.2%. The plants’ efficiencies worsened from the eastern to western parts of the country. (3) The main reasons for the low efficiency were the lack of technological upgrade and scale-up. The technological upgrade rate was −4.8%, while the scale efficiency increases as a result of scaling up was −0.2%. Therefore, to improve the wastewater treatment efficiency of the country, the provinces should work together to increase capital investment and technological advancement.

Water, in most of the transboundary river basins, is a bone of contention among their riparian states. Taking this into account, this article assessed the monthly impact of upstream water withdrawal on the water security of middle stream and downstream sub-basins at a country-basin mesh spatial resolution. Roughly 2.18 billion people in 442 sub-basin areas experience water stress intensification by less than 1% throughout the year. In addition, 2.12 billion people in 336 sub-basin areas experience water stress level change, from no water stress to one of the water stress categories, for at least one month as the result of upstream withdrawal. Even though there is a clear upstream impact in many of the basins, water disputes with severe social, economic, political, and environmental consequences are nonexistent. This might be an indication that grave water disputes are the result of complex socio-economic and political interactions, not merely because of water deficits due to upstream water withdrawal. Therefore, understanding this relationship is crucial in identifying inflection points for water conflicts within transboundary river basins.

Airflow into stairwells due to stack effect is a concern affecting fire safety, energy performance, and indoor air quality. Stack effect in tall buildings can create significant pressure differentials in vertical shafts when differences in outdoor and indoor temperature exist. The pressure differentials drive air through openings or gaps in walls and floors. Vertical shafts, consisting of stairs and elevators, may transport significant volumes of air. During heating season, this results in the infiltration of cold air at lower floors and the exhaust of warm air on the upper floors. Correspondingly, it results in the spread of air and potential contaminants within the building. Stack effect driven airflow will change according to size and distribution of leakage paths. The size of leakage areas can be approximated by a cross-sectional area of an orifice that would allow equivalent flow. This leakage area is dependent on construction material, workmanship, and even operation, as openings from windows and doors equate to large orifices. A building’s composition of these leakage areas can greatly impact the effective area and airflow. The effect of openings from stairwell doors can change the Neutral Pressure Plane location (NPP), altering airflow patterns within a building. This paper investigates the influence of effective area on airflow within stairwells for multi-unit residential buildings (MURB) due to stack effect. A range of parameters reflective of industry standards are evaluated using network modeling and computational fluid dynamics (CFD). Parametric analysis is used to determine the sensitivity to which they affect airflow between building and stairwells. The effect of airflow within vertical shafts has consequences on indoor air quality (IAQ) and smoke spread, energy efficiency, and thermal comfort. The benefit of reducing leakage in buildings can be understood by comparing the quantity and patterns in airflow in and out of stairwells. Improving air tightness of the building envelope or vertical shafts can have a significant impact on airflow.