High-Resolution Maps of Material Stocks in Buildings and Infrastructures in Austria and Germany.

The dynamics of societal material stocks such as buildings and infrastructures and their spatial patterns drive surging resource use and emissions. Two main types of data are currently used to map stocks, night-time lights (NTL) from Earth-observing (EO) satellites and cadastral information. We present an alternative approach for broad-scale material stock mapping based on freely available high-resolution EO imagery and OpenStreetMap data. Maps of built-up surface area, building height, and building types were derived from optical Sentinel-2 and radar Sentinel-1 satellite data to map patterns of material stocks for Austria and Germany. Using material intensity factors, we calculated the mass of different types of buildings and infrastructures, distinguishing eight types of materials, at 10 m spatial resolution. The total mass of buildings and infrastructures in 2018 amounted to ∼5 Gt in Austria and ∼38 Gt in Germany (AT: ∼540 t/cap, DE: ∼450 t/cap). Cross-checks with independent data sources at various scales suggested that the method may yield more complete results than other data sources but could not rule out possible overestimations. The method yields thematic differentiations not possible with NTL, avoids the use of costly cadastral data, and is suitable for mapping larger areas and tracing trends over time.

A review of spatial characteristics influencing circular economy in the built environment.

Industrialization, population growth, and urbanization are all trends driving the explosive growth of the construction industry. Creating buildings to house people and operate industry, together with building infrastructure to provide public services, requires prodigious quantities of energy and materials. Most of these virgin materials are non-renewable, and resource shortages caused by the development of the built environment are becoming increasingly inevitable. The gradually evolved circular economy (CE) is considered a way to ease the depletion of resources by extending service life, increasing efficiency, and converting waste into resources. However, the circularity of construction materials shows heavy regional distinctness due to the difference in spatial contexts in the geographical sense, resulting in the same CE business models (CEBMs) not being adapted to all regions. To optimize resource loops and formulate effective CEBMs, it is essential to understand the relationship between space and CE in the built environment. This paper reviews existing publications to summarize the research trends, examine how spatial features are reflected in the circularity of materials, and identify connections between spatial and CE clues. We found that the majority of contributors in this interdisciplinary field are from countries with middle to high levels of urbanization. Further, the case analysis details the material dynamics in different spatial contexts and links space and material cycles. The results indicate that the spatial characteristics can indeed influence the circularity of materials through varying resource cycling patterns. By utilizing spatial information wisely can help design locally adapted CEBMs and maximize the value chain of construction materials.

Unraveling the Global Warming Mitigation Potential from Recycling Subway-Related Excavated Soil and Rock in China Via Life Cycle Assessment.

Many cities across China are investing in subway projects, resulting in much subway construction activity, which has experienced a surge over the past decade. The construction activities inevitably cause a dramatic quantity of subway-related excavated soil and rock (ESR). How to manage it with minimal environmental impact on our urban ecosystem remains an open question. The present study evaluates global warming potential (GWP, expressed by CO2 eq) from different ESR recycling and landfilling scenarios via a life cycle assessment (LCA) model based on primary field investigation combined with the LCA software database. The study results illustrate that recycling ESR can significantly reduce greenhouse gas emissions. In comparison with traditional construction materials, the scenarios found that a cumulative amount of 1.1 to 1.5 million tonnes (Mt) of CO2 eq emissions could have been mitigated by using ESR generated between 2010 and 2018 to produce baking-free bricks and recycled baked brick. Using cost-benefit analysis, potential economic benefits from recycled sand and baking-free bricks are found to reach US$9 million annually. The findings of this study could provide better recycling options for ESR-related stakeholders. It is important to mention that there still is much work to be done before this recycling work can be popularized in China. Integr Environ Assess Manag 2021;17:639-650. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).