The concepts of Safe by Design (SbD) and Safe and Sustainable by Design (SSbD) are receiving increasing attention. The definitions of both concepts include the term ‘life cycle’ in combination with... Show moreThe concepts of Safe by Design (SbD) and Safe and Sustainable by Design (SSbD) are receiving increasing attention. The definitions of both concepts include the term ‘life cycle’ in combination with the terms ‘chemical’, ‘material’ and ‘product’, but their meanings are not further elaborated and defined in scholarly publications on SbD/SSbD. Here, we address two research questions: (1) How are the terms chemical, material and product used and defined in the scholarly literature on SbD and SSbD; (2) How are life cycles defined and which are considered in the scholarly literature on SbD/SSbD? We found largely consistent, though still confusing, uses of the terms product, material and chemical and we found four types of life cycles in the reviewed papers. Using consistent definitions of the terms product, material and chemical, we reduce the four types of life cycles found to three types of distinctive life cycles: (1) the life cycle of a product; (2) the life cycle of a chemical in a specific product; (3) the life cycle of a chemical in all its product applications. We discuss the different trade-offs that each of these life cycle approaches canidentify and argue that they are complementary and should preferably all be applied in SbD/SSbD studies. Show less
Why are both A-1${\mathbf{A}}<^>{-1}$ and (I-A)-1${(\mathbf{I}-\mathbf{A})}<^>{-1}$ used in life cycle assessment (LCA) matrix computations? This is a question that, in our experience... Show moreWhy are both A-1${\mathbf{A}}<^>{-1}$ and (I-A)-1${(\mathbf{I}-\mathbf{A})}<^>{-1}$ used in life cycle assessment (LCA) matrix computations? This is a question that, in our experience of teaching LCA, students often wonder about and struggle with. A brief survey of the literature suggests that the question can also confuse experienced LCA practitioners. Here, we seek to unify the computational structures of the two LCA approaches to achieve greater clarity and consistency, especially to make them easier to teach. We first show how small but crucial differences in the set-up of the two approaches lead to the use of A$\mathbf{A}$ versus I-A$\mathbf{I}-\mathbf{A}$. Then, we discuss the options to unify the presentations in a coherent way. We do not prescribe one way or the other. A larger point we hope to stress is the importance of unification, which may have both pedagogical and methodological benefits. Show less
Introduction Many methodological papers report a comparison of methods for LCA, for instance comparing different impact assessment systems, or developing streamlined methods. A popular way to do so... Show moreIntroduction Many methodological papers report a comparison of methods for LCA, for instance comparing different impact assessment systems, or developing streamlined methods. A popular way to do so is by studying the differences of results for a number of products. We refer to such studies as quasi-empirical meta-comparisons. Review of existing approaches A scan of the literature reveals that many different methods and indicators are employed: contribution analyses, Pearson correlations, Spearman correlations, regression, significance tests, neural networks, etc. Critical discussion We critically examine the current practice and conclude that some of the widely used methods are associated with important deficits. A new approach Inspired by the critical analysis, we develop a new approach for meta-comparative LCA, based on directional statistics. We apply it to several real-world test cases, and analyze its performance vis-a-vis traditional regression-based approaches. Conclusion The method on the basis of directional statistics withstands the tests of changing the scale and unit of the training data. As such, it holds a promise for improved method comparisons. Show less
Eco-efficiency is generally defined as the ratio of an economic and an environmental variable. This interpretation is also cited in connection to its most popular implementation, known as the "BASF... Show moreEco-efficiency is generally defined as the ratio of an economic and an environmental variable. This interpretation is also cited in connection to its most popular implementation, known as the "BASF eco-efficiency portfolio analysis". There is, however, something strange about this. A ratio is easily visualized as a slope, but BASF's method is working with a distance, which can be formulated as a weighted sum, not as a ratio. Upon closer analysis, it further shows that the two variables receive equal weight. These findings are contradicting the ISO 14045 standard and the perception in mainstream literature. We discuss the relevance of this shift of viewpoint. We also discuss some of the extensions, namely, the socio-efficiency analysis and the SEEbalance. We finally investigate the recent changes that were introduced in the eco-efficiency method, including an eco-efficiency index, and conclude that these changes have been reported in an incomplete way, or in documents that are difficult to trace. Effectively, this means that the most popular way to calculate and visualize eco-efficiency is unverifiable, impeding its status as a science-based method for sustainable industry support. We end by sketching the path forward. Show less
Limited and uneven distributed water resources have become one of the main obstacles to China's sustainable development, and the "virtual water hypothesis" (VWH) is expected to help mitigate water... Show moreLimited and uneven distributed water resources have become one of the main obstacles to China's sustainable development, and the "virtual water hypothesis" (VWH) is expected to help mitigate water stress. This study discusses the virtual water transfer pattern and water resources stress in China from the VWH perspective. Economic sectors in China are divided into land-dependent sectors and non-land-dependent sectors according to their dependence on specific local land types. Furthermore, the water resources withdrawal and utilization corresponding to these sectors are divided into land-dependent water resources (LDW) and non-land-dependent water resources (NLDW). Results show that the virtual LDW flows from economically poor to relatively developed regions, while the virtual NLDW flows in the opposite direction. LDW dominates Chinese water stress (78.2%) and virtual water flow (74.5%). Furthermore, the virtual water dominated by LDW ameliorates national water stress (the population under unsustainable water stress declined by 0.21 billion) but aggravates the imbalance of water resources between North and South. The transfer of virtual NLDW alleviates this imbalance slightly. Suitable land conditions play a decisive role in LDW withdrawal, which then cannot be replenished by virtual water. However, the withdrawal and transfer of NLDW are flexible, which should be a focus. The results point out that the possibility of water-rich regions as virtual water exporters is the key to alleviating the North-South water resource imbalance in China with VWH theory. Improvement of land productivity and water efficiency can be helpful to alleviate water stress. These findings may provide new insight into China's virtual water transfer pattern from the VWH perspective. Show less
The building sector plays a key role in energy transition and carbon reduction while capturing the dynamic characteristics (e.g. materials, energy performance, and environmental impact) of building... Show moreThe building sector plays a key role in energy transition and carbon reduction while capturing the dynamic characteristics (e.g. materials, energy performance, and environmental impact) of building stock is a great challenge during the gradual process. This study presents a bottom-up dynamic building stock model that links dynamic material flow analysis with building energy modeling. The environmental impact of material and energy requirements is assessed by considering future electricity mix. The model is applied to evaluate the pathways to the climate-neutral energy supply of residential building stock in the Netherlands by 2050. Results show that space heating demand decreases by about 2/3 by 2050, while the energy for hot water increases to 92% of space heating demand. 80% of public grid electricity for appliances and lighting can be potentially substituted if rooftop photovoltaic (PV) systems are installed on 50% of renovated buildings and all the new buildings. Greenhouse gas (GHG) emissions of operational energy are reduced by approximately 60-90%, depending on the electricity mix. Annual GHG emissions from material production are not as important as those related to operational energy. Insulation materials account for a large proportion of the carbon footprint of material production. The model has a high spatial and temporal resolution and can be linked with local energy source availability (e.g. buildings or neighborhoods) to provide more accurate support for policymaking. Show less
Yang, X.; Hu, M.; Zhang, C.; Steubing, B.R.P. 2022
Building stock growth around the world drives extensive material consumption and environmental impacts. Future impacts will be dependent on the level and rate of socioeconomic development, along... Show moreBuilding stock growth around the world drives extensive material consumption and environmental impacts. Future impacts will be dependent on the level and rate of socioeconomic development, along with material use and supply strategies. Here we evaluate material-related greenhouse gas (GHG) emissions for residential and commercial buildings along with their reduction potentials in 26 global regions by 2060. For a middle-of-the-road baseline scenario, building material-related emissions see an increase of 3.5 to 4.6 Gt CO2eq yr-1 between 2020-2060. Low- and lower-middle-income regions see rapid emission increase from 750 Mt (22% globally) in 2020 and 2.4 Gt (51%) in 2060, while higher-income regions shrink in both absolute and relative terms. Implementing several material efficiency strategies together in a High Efficiency (HE) scenario could almost half the baseline emissions. Yet, even in this scenario, the building material sector would require double its current proportional share of emissions to meet a 1.5 degrees C-compatible target.Building construction causes large material-related emissions which present a serious decarbonization challenge. Here, the authors show that the building material sector could halve emissions by increasing efficiency until 2060 but even then its emissions would be twice as high as needed to meet the 1.5 degrees C target. Show less
Cucurachi, S.; Blanco Rocha, C.F.; Steubing, B.R.P.; Heijungs, R. 2021
Life cycle assessment (LCA) models and databases have increased in size, resolution, and complexity, requiring analysts to rely on an ever-increasing number of uncertain model inputs. Such... Show moreLife cycle assessment (LCA) models and databases have increased in size, resolution, and complexity, requiring analysts to rely on an ever-increasing number of uncertain model inputs. Such increased complexity calls for systematic approaches to assessing the uncertainty of the output results of LCA models and the sensitivity of LCA model outputs to the model's uncertain inputs. In this contribution, we provide a theoretical basis and present a practical software implementation that combines uncertainty analysis and moment-independent global sensitivity analysis, which can be readily applied to full-scale LCA models. We implemented our approach in the Activity-Browser open source LCA software and it is made available for use in LCA studies. We demonstrate the approach and software implementation with a case study of crystalline silicon photovoltaics. Show less
Valdivia, S.; Backes, J.G.; Traverso, M.; Sonnemann, G.; Cucurachi, S.; Guinee, J.B.; ... ; Goedkoop, M. 2021
Purpose and context This paper aims to establish principles for the increased application and use of life cycle sustainability assessment (LCSA). Sustainable development (SD) encompassing resilient... Show morePurpose and context This paper aims to establish principles for the increased application and use of life cycle sustainability assessment (LCSA). Sustainable development (SD) encompassing resilient economies and social stability of the global system is growingly important for decision-makers from business and governments. The "17 SDGs" emerge as a high-level shared blueprint for peace, abundance, and prosperity for people and the planet, and "sustainability" for supporting improvements of products and organizations. A "sustainability" interpretation-successful in aligning stakeholders' understanding-subdivides the impacts according to a triple bottom line or three pillars: economic, social, and environmental impacts. These context and urgent needs inspired the LCSA framework. This entails a sustainability assessment of products and organizations in accordance with the three pillars, while adopting a life cycle perspective. Methods The Life Cycle Initiative promotes since 2011 a pragmatic LCSA framework based on the three techniques: LCSA = environmental life cycle assessment (LCA) + life cycle costing (LCC) + social life cycle assessment (S-LCA). This is the focus of the paper, while acknowledging previous developments. Identified and reviewed literature shows challenges of addressing the three pillars in the LCSA framework implementation like considering only two pillars; not being fully aligned with ISO 14040; lacking interconnectedness among the three pillars; not having clear criteria for results' weighting nor clear results' interpretation; and not following cause-effect chains and mechanisms leading to an endpoint. Agreement building among LCSA experts and reviewing processes strengthened the consensus on this paper. Broad support and outreach are ensured by publishing this as position paper. Results For harmonizing practical LCSA applications, easing interpretation, and increasing usefulness, consensed ten LCSA principles (10P) are established: understanding the areas of protection, alignment with ISO 14040, completeness, stakeholders' and product utility considerations, materiality of system boundaries, transparency, consistency, explicit trade-offs' communication, and caution when compensating impacts. Examples were provided based on a fictional plastic water bottle Conclusions In spite of increasing needs for and interest in SD and sustainability supporting tools, LCSA is at an early application stage of application. The 10P aim to promote more and better LCSA applications by ensuring alignment with ISO 14040, completeness and clear interpretation of integrated results, among others. For consolidating its use, however, more consensus-building is needed (e.g., on value-laden ethical aspects of LCSA, interdependencies and interconnectedness among the three dimensions, and harmonization and integration of the three techniques) and technical and policy recommendations for application. Show less
Energy efficiency plays an essential role in energy conservation and emissions mitigation efforts in the building sector. This is especially important considering that the global building stock is... Show moreEnergy efficiency plays an essential role in energy conservation and emissions mitigation efforts in the building sector. This is especially important considering that the global building stock is expected to rapidly expand in the years to come. In this study, a global-scale modeling framework is developed to analyze the evolution of building energy intensity per floor area during 1971-2014, its relationship with economic development, and its future role in energy savings across 21 world regions by 2060. Results show that, for residential buildings, while most high-income and upper-middle-income regions see decreasing energy intensities and strong decoupling from economic development, the potential for further efficiency improvement is limited in the absence of significant socioeconomic and technological shifts. Lower-middle-income regions, often overlooked in analyses, will see large potential future residential energy savings from energy intensity reductions. Harnessing this potential will include, among other policies, stricter building efficiency standards in new construction. For the commercial sector, during 1971-2014, the energy intensity was reduced by 50% in high-income regions but increased by 193% and 44% in upper-middle and lower-middle-income regions, respectively. Given the large energy intensity reduction potential and rapid floor area growth, commercial buildings are increasingly important for energy saving in the future. (C) 2021 The Author(s). Published by Elsevier Ltd. Show less
Heijungs, R.; Allacker, K.; Benetto, E.; Brandao, M.; Guinee, J.B.; Schaubroeck, S.; ... ; Zamagni A. 2021
Buildings have become a major concern because of their high energy use and carbon emissions. Thus, a material-efficient prefabricated concrete element (PCE) system was developed to incorporate... Show moreBuildings have become a major concern because of their high energy use and carbon emissions. Thus, a material-efficient prefabricated concrete element (PCE) system was developed to incorporate construction and demolition waste as feedstock for residential building energy renovation by over-cladding the walls of old buildings. By conducting life cycle assessment and life cycle costing using the payback approach, this study aims to explore the life cycle performance of energy conservation, carbon mitigation, and cost reduction of the PCE system in three European member states: Spain, the Netherlands, and Sweden. The results show that the energy payback periods for Spain, the Netherlands, and Sweden were 20.45 years, 17.60 years, 19.95 years, respectively, and the carbon payback periods were 23.33 years, 16.78 years, and 8.58 years, respectively. However, the financial payback periods were less likely to be achieved within the building lifetime, revealing that only the Swedish case achieved a payback period within 100 years (83.59 years). Thus, circularity solutions were considered to shorten the PCE payback periods. Using secondary materials in PCE fabrication only slightly reduced the payback period. However, reusing the PCE considerably reduced the energy and carbon payback periods to less than 6 years and 11 years, respectively in all three cases. Regarding cost, reusing the PCE shortened the Swedish payback period to 29.30 years, while the Dutch and Spanish cases achieved investment payback at 42.97 years and 85.68 years, respectively. The results can be extrapolated to support the design of sustainable building elements for energy renovation in Europe. Show less
