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The application of eco‐design principles in the building sector is considered a promising way to mitigate its substantial environmental impacts. However, quantitative evidence for this mitigation potential is lacking. The objective of this study was to quantify the environmental performance of diverse eco‐design strategies when applied to the building sector. A macroscale model capable of simulating the future demand for housing and related material flows within the urban building stock was developed based on an existing building stock model. These material flows were used to build inventories for a consequential life cycle assessment and, in turn, to quantify the potential environmental consequences of introducing eco‐design strategies in the building sector, assessed across 16 impact categories. Model outputs have a high level of uncertainty but are still useful for decision‐making, given the model's simplicity and transparency. The main results show that impact reductions can be obtained from specific uses of wood and wooden products, for example, when used for the walls in high‐rise buildings, whereas using hempcrete for partition walls increases the impact. Although the use of adaptability or disassembly strategies can reduce impacts, this pay‐off can only be obtained after a long period of implementation. In summary, the present study provides new quantitative insights into the ability of eco‐design strategies to mitigate environmental impacts in the building sector. [ABSTRACT FROM AUTHOR]

Purpose: Demand for Environmental Product Declarations (EPDs) is already high and increasing in the construction and building sectors. The overall purpose of EPDs is comparability of product environmental performance, and they are thus developed in accordance with product category rules (PCRs): requirements and guidelines for how to make EPDs for one or more product groups. Since several organisations publish PCRs, there is a risk of creating conflicting rules leading to inconsistencies and jeopardising the objective of comparability. Methods: This study analyses the causes for inconsistency and the consequences in terms of difference in the results across the life cycle assessment (LCA) models underlying the EPDs. Taking four EPD programmes and their actors as cases, first a document analysis was conducted to identify qualitative and quantitative differences in their guidelines. Further focusing on selected quantitative differences, a series of LCA models were designed for the same triple-glazed window product by adhering to the PCRs of each operator, to highlight the differences in results that occur when performing the same assessment via different but all formally selectable operators and compliant EPDs. Results and discussion: Results show that the EPD of a specific product can return very different impact scores if one or the other guideline is followed. Results can vary more than 10% from the base scenarios, what we consider a significant variation. This is observed across all impact categories. Focusing specifically on the climate change impact, the results show that differences are due to the choice of energy mix, reference service life and other parameters. It is thus the combination of several modelling differences that leads to a overall divergence in results, rather than one single methodological choice. Conclusions: Numerous different but at the same time compliant EPDs can be obtained for the same product, highlighting a serious harmonisation issue within the EPD system. EPDs are thus not necessarily accurate, and it remains doubtful whether EPD comparability can be achieved. This weakness of the EPD system can in the worst case be exploited by producers to obtain lower results and undermines the system. Recommendations: Besides recommending using LCA for learning and process improvement rather than just for external communication and compliance, to increase harmonisation in the EPD system, we recommend limiting the number of product-specific PCRs (e.g. complementary PCRs), align default values, learn from verification, use just one background database, increase transparency and move towards one centralized operator. [ABSTRACT FROM AUTHOR]

Seaweed is increasingly considered a promising resource to produce high‐value products such as bioplastics due to potential environmental benefits such as carbon uptake and no land‐use change. However, the environmental assessment of emerging technologies for producing bioplastic from seaweed remains challenging due to the difficulties in modeling future seaweed supply and demand. Within the consequential approach to life cycle assessment, an increase in demand for seaweed is met by the marginal suppliers in the market: those that are not constrained in their capacity to increase supply in response to an increase in demand. Current methods to identify marginal suppliers are however based on quantitative information and do not consider qualitative aspects and uncertainties inherent in the study of emerging technologies. This study, therefore, proposes and tests the use of quantitative storytelling to identify marginal suppliers. The results show that there are two main groups of countries that are expected to be the marginal suppliers of brown seaweed for different reasons. Asian countries are currently the main brown seaweed suppliers and are expected to keep increasing and be marginal suppliers in the future. However, these countries have well‐established brown seaweed aquaculture and their growth is expected to be steady. On the other hand, brown seaweed suppliers in Northern Europe and North America are still emerging but are expected to grow faster in the future due to their production capacity and technological development. [ABSTRACT FROM AUTHOR]

• Consequential LCA on the emerging biorefinery, reductive catalytic fractionation (RCF). • GHG emissions as a consequence of a change in demand for RCF products. • RCF products have higher GHG emissions than their alternatives. • RCF can outperform alternatives by process retrofitting or adding a C(C)HP unit. The emerging reductive catalytic fractionation biorefinery which is currently under development aims to convert woody biomass efficiently into high-value products. Despite its potential, the environmental consequences of its implementation are not well known. Therefore, a forward-looking consequential life cycle assessment examines greenhouse gas emissions associated with its products (pulp, phenolic monomers, and oligomers) compared to alternative market options. Findings indicate that current greenhouse gas emissions exceed those of the existing alternatives, with by-products and the gaseous waste stream as major contributors. Process adaption to (i) produce higher-valued products (bleached pulps, phenols, and propylene) and (ii) incinerate gaseous waste stream for energy are proposed, potentially reducing emissions by up to 50 %, outperforming alternative options. Compared to land-based transportation, waterways can increase feedstock availability by up to 1000 km without an increase in emissions. In conclusion, the consequential approach provides valuable insights for enhancing and optimizing the environmental performance of the process. [ABSTRACT FROM AUTHOR]

Purpose: Fired bricks are an essential construction material in Thailand where the majority of fired brick kilns use rice husk as feedstock. Given the increasing demand of rice husk from other industries, alternative feedstocks are needed for future fired brick production. This life cycle assessment (LCA) study investigates the environmental burden of Thai brick production using different biomass types. Methods: Three biomass fuels for fired brick production were compared: cane leaves, rice straw, and rice husk. Both the attributional and consequential modeling approaches were applied. Separated inventories were compiled using different databases: ecoinvent v. 3 and the Thai National Life Cycle Inventory (TH-LCI). Overall, this study includes a total of nine scenarios, for which characterized results were calculated using the Stepwise method. Differences in biomass scenario, modeling approach, and database used were tested via analysis of variance using four distinct fired brick production plants as replications. Results and discussion: Overall, using cane leaves and rice straw gives lower impacts than using rice husk. The largest burden for cane leaves and rice straw scenarios comes from the burning process, while using electricity and using fertilizers for rice cultivation were the most contributors for rice husk scenario. However, different modeling approaches yield mostly significantly different results and the consequential results were lower than the attributional ones. Regarding database choice in attributional modeling approach, results were lower when using TH-LCI compared with ecoinvent. Conclusions: Using cane leaves and rice straw as fuels in fired brick production are better scenarios than using rice husk. Nevertheless, factors related to season, size, and collection effort should be considered in the large-scale use of these biomasses. For database choice, ecoinvent is currently recommended over TH-LCI despite the higher geographical representativeness of the latter. [ABSTRACT FROM AUTHOR]

Purpose: Despite a mature debate on the importance of a time-dependent account of carbon fluxes in life cycle assessments (LCA) of forestry products, static accounts of fluxes are still common. Time-explicit inventory of carbon fluxes is not available to LCA practitioners, since the most commonly used life cycle inventory (LCI) databases use a static approach. Existing forest models are typically applied to specific study fields for which the detailed input parameters required are available. This paper presents a simplified parametric model to obtain a time-explicit balanced account of the carbon fluxes in a forest for use in LCA. The model was applied to the case of spruce as an example. Methods: The model calculated endogenous and exogenous carbon fluxes in tons of carbon per hectare. It was designed to allow users to choose (a) the carbon pools to be included in the analysis (aboveground and belowground carbon pools, only aboveground carbon or only carbon in stem); (b) a linear or sigmoidal dynamic function describing biomass growth; (c) a sigmoidal, negative exponential or linear dynamic function describing independently the decomposition of aboveground and belowground biomass; and (d) the forest management features such as stand type, rotation time, thinning frequency and intensity. Results and discussion: The parametric model provides a time-dependent LCI of forest carbon fluxes per unit of product, taking into account the typically limited data available to LCA practitioners, while providing consistent and robust outcomes. The results obtained for the case study were validated with the more complex CO2FIX. The model ensures carbon balance within spatial and time delimitation defined by the user by accounting for the annual biomass degradation and production in each carbon pool. The inventory can be used in LCA studies and coupled with classic indicators (e.g. global warming potential) to accurately determine the climate impacts over time. The model is applicable globally and to any forest management practice. Conclusions: This paper proposes a simplified and flexible forest model, which facilitates the implementation in LCA of time-dependent assessments of bio-based products. [ABSTRACT FROM AUTHOR]

Abstract: Wastewater treatment has nowadays multiple functions and produces both clean effluents and sludge, which is increasingly seen as a resource rather than a waste product. Technological as well as management choices influence the performance of wastewater treatment plants (WWTPs) on the multiple functions. In this context, Life Cycle Assessment (LCA) can determine what choices provide the best environmental performance. However, the assessment is not straightforward due to the intrinsic space and time-related variability of the wastewater treatment process. These challenges were addressed in a comparative LCA of four types of WWTPs, representative of mainstream treatment options in Denmark. The four plant types differ regarding size and treatment technology: aerobic versus anaerobic, chemical vs. combined chemical and biological. Trade-offs in their environmental performance were identified considering system expansion to model the avoided impacts achievable in different end-of-life scenarios for sludge: combustion with energy production versus agricultural application. To account for the variability in quality of effluents and sludge, and to address the related uncertainties, Monte Carlo simulation and sensitivity analysis were applied. Uncertainties related to the choice of Life Cycle Impact Assessment (LCIA) method and to the use of different data sources were also discussed. The results showed that, for the climate change and fossil depletion impact categories, recycling phosphorus to agricultural soils appear as a more sustainable alternative compared to the incineration of sludge. However, the uncertainty and sensitivity analysis showed that robust conclusions could not be drawn on the eutrophication and toxicity-related impact categories. [Copyright &y& Elsevier]

Plastic pollution is an environmental emergency and finding sustainable alternatives to traditional plastics has become a pressing need. Seaweed-based bioplastic has emerged as a promising solution, as it is biodegradable and made from renewable biomass, while seaweed cultivation itself provides various environmental benefits. However, the feasibility of implementing a brown seaweed-based bioplastic supply chain in a realistic setting remains unclear, as previous research focused either on single processing steps or on virtual supply chains aggregating data from different studies. This study describes a case study for seaweed-based bioplastic within the PlastiSea research project: from seaweed cultivation to biomass processing and bioplastic and composite material development at the lab and pilot scale, thus providing insights into its feasibility. Adopting a multidisciplinary approach, the study employs multiple methods to characterize each stage in the supply chain and provides an overall life cycle assessment (LCA) as well as lessons learned throughout the process. The analysis showed potential for producing and utilizing multiple co-products from the same seaweed source, including biopolymer extracts with varying degrees of refinement for use in low-cost (bioplastic films) and high-cost (microfiber composites) applications. The use of residual biomass as a source of alginates for producing bioplastics offers a low-cost and sustainable biomass supply currently not competing with other markets. The LCA results indicate the potential for reducing the environmental impact of seaweed-based bioplastic production through upscaling and increasing process efficiency. • Results reveal bioplastic potential at a small scale, ready for upscaling. • Residual biomass from seaweed farming is a good source of alginates for bioplastics. • Biomass processing conditions direct alginate quality and thus material properties. • The properties of films are tuned through crosslinking conditions and film thickness. • The carbon footprint is lower than LDPE and it decreases when upscaling. [ABSTRACT FROM AUTHOR]

Previous research efforts have focused on developing prospective life cycle inventory databases that build upon projections from integrated assessment models but were limited to attributional system models. A novel approach is required to construct consequential LCI databases that can be applied consistently on a large scale. To this end, the heuristic approach from Bo Weidema was selected as a basis for this study. This approach has been validated with historical data and was adapted in this study to identify the marginal suppliers in a prospective context. The different steps within the approach were analyzed, and alternative techniques for each step within the heuristic method were proposed. The techniques were tested on the future electricity sector using projections from two integrated assessment models (IMAGE and REMIND). Results show the sensitivity of results on the modelling technique selected in each step. The most sensitive step is the selection of the time interval, with even small changes resulting in a noticeable difference. In addition, the results also showed a substantial difference between the projections of the two models. The relevance and goals of the alternative techniques for each step were discussed to guide users in forming the heuristic method for their study. • Development of a prospective consequential database. • Review on consequential approaches for marginal changes. • Work builds upon the commonly used heuristic approach. • Prospective approach is applied to the electricity market using IAM projections. • Results are incorporated into premise. [ABSTRACT FROM AUTHOR]