Environmental health in subway stations, a typical type of urban underground space, is becoming increasingly important. Ventilation is the principal measure for optimizing the complex physical environment in a subway station. This paper narratively reviews the environmental and health effects of subway ventilation and discusses the relevant engineering, environmental, and medical aspects in combination. Ventilation exerts a notable dual effect on environmental health in a subway station. On the one hand, ventilation controls temperature, humidity, and indoor air quality to ensure human comfort and health. On the other hand, ventilation also carries the potential risks of spreading air pollutants or fire smoke through the complex wind environment as well as produces continuous noise. Assessment and management of health risks associated with subway ventilation is essential to attain a healthy subway environment. This, however, requires exposure, threshold data, and thereby necessitates more research into long-term effects, and toxicity as well as epidemiological studies. Additionally, more research is needed to further examine the design and maintenance of ventilation systems. An understanding of the pathogenic mechanisms and aerodynamic characteristics of various pollutants can help formulate ventilation strategies to reduce pollutant concentrations. Moreover, current comprehensive underground space development affords a possibility for creating flexible spaces that optimize ventilation efficiency, acoustic comfort, and space perception.

The global issue of climate change has accelerated the international commitment to net-zero carbon emission development. Decarbonizing the building sector has been put on several governments’ sustainable development agendas. To provide a reference for decarbonizing the building sector, this paper summarizes the U.S. experience in zero-carbon buildings (ZCBs) from the aspects of policies, codes, and standards at the federal and local levels and those of professional societies. Based on the definition and boundaries of ZCBs, this paper introduces policies on building energy efficiency, electrification, on-site renewable energy deployment, and “buy clean”, illustrating highlights in building phases, energy systems, materials production, and fiscal incentives. The synergic efforts and coordination between federal and local levels and with professional societies are also introduced. Successful experiences in policy and standard implementation are summarized, including the systemic work of multilevel governance, clearly defined goals and stringent policies, constant upgrades of codes and standards, transparency in reporting and information sharing, and increased financial and investment opportunities. This paper provides concrete recommendations for developing zero-carbon building policies.

Achieving low carbon emissions in buildings has a critical impact on controlling global greenhouse gas (GHG) emissions. With the boom in educational buildings, especially those with reinforced concrete structures, carbon emissions from such buildings are brought to the fore. Among building carbon emissions, embodied carbon emissions are closely related to building structure and materials. This paper aims to study the embodied carbon emissions of a Chinese educational building in the design stage with a quantitative method – process-based life cycle assessment, summarizing the carbon emission characteristics of construction materials and proposing corresponding optimization methods. The results indicate that local data of emission factors is preferred for calculating the embodied carbon emissions and the number of construction materials could be obtained through design estimates; that embodied carbon emissions from material manufacturing are much higher than those from material transportation; that steel and concrete are the two most carbon-emitting materials in the reinforced concrete frame structure educational building; and that using local and reused materials are the two main low-carbon optimization measures, with carbon emission reduction contribution rates of 19.7% and 80.3%, respectively, which reused and recycled construction materials should be considered a priority in reducing the embodied carbon emissions of buildings. Graphical Abstract

The sunken courtyard has long been used in underground spaces and provides an important outdoor environment. It introduces natural elements to create a pleasant space for human activities. However, this study measured a typical sunken courtyard and found potential problems of excessive solar radiation and accumulated air pollutants in summer when at an acceptable outdoor temperature for human activities. To improve the comfort and health of a sunken courtyard, this research proposes some green retrofit designs. Firstly, compared with green wall, water and a tree, sunshade is a primary measure to improve thermal comfort. Combining sunshade, a green wall and water reduces the temperature by up to 5.6 °C in the activity zone during the hottest hour. Secondly, blocking/guiding wind walls can effectively improve the wind environment in a sunken courtyard, but only when the wind direction is close to the prevailing wind. A blocking wind wall was better at affecting velocity and uniformity, while the guiding wind wall was more efficient at discharging air pollutants. This study initially discusses the climate-adaptive design of underground spaces in terms of green, thermal comfort and natural ventilation. Designers should generally integrate above/underground and indoor/outdoor spaces using natural and artificial resources to improve comfort and health in underground spaces.

This study investigates the role of digital technologies, specifically Building Information Modelling (BIM) and City Information Modelling (CIM), in sustainable urban renewal. The study reviews the literature on urban renewal and the application of BIM and CIM technologies. The findings show that digital technologies play a crucial role in facilitating the flow and sharing of information, improving the transparency of decision-making, and enhancing public participation. The study emphasises the need for interdisciplinary collaboration and technological innovation to achieve more sustainable and liveable urban environments.

Ventilation is the basis of controlling thermal comfort and air quality in underground spaces. Natural ventilation based on spatial designs can introduce wind, light, and scenery to improve environmental health and spatial experience, and reduce health risks and energy consumption of mechanical ventilation. This paper proposes a spatial prototype that combines courtyard with wind tower, two common spatial forms connecting aboveground and underground, and can provide effective natural ventilation to underground public spaces. Computational fluid dynamics simulations and genetic optimization were conducted in the common architectural software Rhinoceros and Grasshopper. First, spatial defects are identified and optimized by analysing the simulation results. Then, geometric variables of the spatial form that obviously affect the ventilation performance were selected and automatically optimized with the target of air volume per hour. Finally, three key issues for natural ventilation of underground public spaces are discussed including human comfort, air distribution, and ventilation reliability. This paper explores the coupling between the spatial form and ventilation performance of underground public spaces, which not only alleviates the potential conflict between energy saving and environmental health, but also provides an integrated design pattern to create more open, flexible, natural and sustainable underground spaces.