This study aims to examine the feasibility of using environmental product declarations (EPDs) as a data source for life-cycle assessment (LCA) in two sustainable building assessment schemes–the pilot version of the European framework Level(s) and the German system DGNB (Deutsche Gesellschaft für Nachhaltiges Bauen). An EPD is a standardized and third-party certified label to communicate product-specific environmental data based on LCA. Some green building rating systems consider it a robust LCA data source and encourage its use over generic data. This work evaluates the environmental profile of the envelope of an office building in the context of level(s) and DGNB adopting EPD as a data source. The results indicate that the EPDs did not cover the mandatory scope of the schemes. Furthermore, there was a lack of EPDs appropriate to the geographical context of the case study, leading to the adoption of EPDs of products from places other than the building site and an overestimation of the environmental impacts of transportation. Moreover, the need for EPDs considering suitable and comprehensive scenarios as well as life-cycle stages beyond the product stage is highlighted. This gap, in fact, hinders the performance of a complete LCA within the analyzed building assessment schemes when relying solely on EPDs as a data source. With this paper, we wish to encourage the further development of EPDs related to the integration of more life-cycle modules and more comprehensive scenarios, considering the direction of the latest amendment of the ISO 15804 for EPDs of construction products.

The construction industry significantly contributes to global greenhouse gas emissions and consumption of raw materials, and is thus under intense pressure to become more sustainable. Despite the ever-increasing availability of sustainable solutions, they do not seem to be widely adopted. As key decision makers in the early planning stage of a construction project, end consumers strongly impact sustainable development. However, their knowledge of sustainability-related criteria and their influence on purchasing decisions within the German construction industry is not yet sufficiently well established. Therefore, this study aims to determine the effects of sustainability-related aspects on the purchasing behavior of private individuals, as end consumers in the German construction industry. A quantitative online survey involving 306 participants was utilized to determine their understanding of the term “sustainability” and how they identify and measure the sustainability of a building product. Our results indicate that consumers have a fundamental interest in sustainable building products; however, they lack a holistic view of the concept of sustainability. With the focus on environmental aspects, social and economic aspects tend to be neglected. Since private individuals rarely make purchasing decisions in the building product sector, it is the task of the entire construction industry to establish a system in which consumers can quickly and easily obtain understandable information about sustainable products. Consumers need support from experts to understand and drive sustainable development in the construction industry.

Due to climate change and current efforts to reduce emissions in the construction sector, this study evaluates and discusses the results of a comparative cradle-to-grave Life Cycle Assessment (LCA), with a main focus on Global Warming Potential for functionally equivalent carbon-reinforced concrete (CRC) and steel-reinforced concrete (SRC) façade panels for the first time. The novelty of this study is the focus on construction waste and, in particular, the worst-case application of non-recycled construction waste. The use of CRC requires a lower concrete thickness than SRC because the carbon fiber reinforcement does not corrode, in contrast to steel reinforcement. Façade panels of the same geometrical dimensions and structural performance were defined as functional units (FU). Assuming an End-of-Life (EoL) scenario of 50% landfill and 50% recycling, the Global Warming Potential (GWP, given in CO2 equivalent (CO2e)) of the CRC façade (411–496 kg CO2e) is shown to perform better than or equal to the SRC façade (492 kg CO2e). Changing the assumption of CRC to a worst-case scenario, going fully to landfill and not being recycled (single life cycle), turns the GWP results in favor of the SRC façade. Assuming a 50-year service life for the SRC façade panel and relativizing the emissions to the years, the more durable CRC façade performs much better. Finally, depending on the system boundary, the assumed EoL and lifetime, CRC can represent a lower-emission alternative to a functionally equivalent component made of SRC. The most important and “novel” result in this study, which also leads to future research opportunities, is that delicate adjustments (especially concerning EoL scenarios and expected service life) can lead to completely different recommendations for decision-makers. Only by combining the knowledge of LCA experts, structural engineers, and builders optimal decisions can be made regarding sustainable materials and building components.

Carbon-reinforced concrete (CRC) has the potential to play a pivotal role in optimizing the built environment and has therefore been experiencing a wave of research and development in the construction industry in recent years. The production of carbon fibers for CRC is energy-intensive, prompting the need to explore circular economy approaches (e.g., recycling at the End-of-Life (EoL)) to optimize the environmental performance of this material. Underdeveloped processes and a resulting lack of primary data regarding the recycling of CRC have hampered a comprehensive sustainability assessment of the novel composite building material. The novelty of this article is the detailed presentation of possible EoL scenarios for CRC and the detailed determination of the respective environmental impacts. This study aims to model EoL options within a Life Cycle Assessment (LCA), focusing on the EoL stage based on ISO 14040/44 using the GaBi ts 10.5.1.124 software and the CML2001 (2016) methodology. The practical relevance of the study lies in the early consideration of the entire life cycle of new materials, such as CRC, already in the design phase. Furthermore, the EoL can have relevant impacts on the environment, and due to an increasing significance of sustainability aspects, this LCA clarifies first approaches for the future of the construction sector in quantitative statements (e.g., CO2 emissions). All data are literature-based and are explained in detail and calculated for our case study with the functional unit of one kilogram of re-usable material (reusable and fully usable “raw” material for further use/ development) from a double wall. The impact assessment was calculated for 11 midpoint categories and related indicators, although the main focus was on Global Warming Potential (GWP). It was found that the highest-quality recycled options for CRC arise when the individual fractions (concrete matrix and carbon fibers) are first broken up, separated and then individually processed. This study focused mainly on the processing of the carbon fibers contained in CRC, for which pyrolysis and mechanical recycling have the strongest potential for industrial application. For the demolition and separation of both the concrete and the carbon fiber fractions, the conventional transport from the demolition site to the stationary processing plant proved to be the main driver of the GWP (1.4 × 10−3 kg CO2e). In the subsequent processing of the carbon fibers, pyrolysis showed a higher GWP (9.7 × 10−3 kg CO2e) than mechanical recycling (3.1 × 10−4 kg CO2e). In addition, the production of one m³ of concrete (C30/37) was compared to a primary raw material concrete fraction. Concrete can be successfully used as a substitute material for the gravel present in the C30/37 concrete. The use of recycled parts in concrete (originating from the concrete used in carbon-reinforced concrete) as a substitute for primary gravel showed a savings of 6.9 kg CO2e per m³ of primary concrete, corresponding to a reduction of 22.5%. The results show that the mechanical recycling of carbon fibers is overall the route with the lowest energy input and emissions. However, compared to pyrolysis, the recycled carbon fibers from mechanical recycling have a lower quality. Therefore, despite the higher energy input, pyrolysis is a more promising approach to close the material cycle. Furthermore, recycled aggregate concrete can reduce emissions by a quarter compared to primary concrete. Finally, this work aimed to provide a basis for further life cycle optimization in the construction sector. In subsequent studies, the EoL must be combined with the production and use stages to depict the entire life cycle, identify possible trade-offs and compare the results with conventional construction methods or materials such as steel-reinforced concrete.

This study assesses the environmental performance in the end-of-life (EoL) of double walls made of carbon-reinforced concrete (CRC) and steel-reinforced concrete (SRC). The most feasible CRC EoL scenarios are evaluated using life cycle assessment and their environmental performances are then compared to those of SRC. The results showed that mechanical recycling is the best CRC EoL scenario, with a global warming potential (GWP) of 7.0 kg CO2 eq., while the use of renewable energy can save over 50% of GWP. For SRC, the best scenario was obtained using a mobile recycling plant (GWP of 8.8 kg CO2 eq.). In general, the further life of the reinforcements is hardly comparable. Steel can be recycled nearly without losses or downcycling, while a closed cycle of carbon fibers is not yet possible. Therefore, carbon fiber properties or EoL processes need to be improved for a closed loop with an optimized environmental performance.