Framework for hybrid life cycle inventory databases: a case study on the Building for Environmental and Economic Sustainability (BEES) database

Purpose

In an effort to develop a whole building Life Cycle Assessment (LCA) tool, National Institute of Standards and Technology (NIST) is transforming new bottom-up Building for Environmental and Economic Sustainability (BEES) data into a hybrid database in which the strengths of both bottom-up and top-down approaches can be combined. The objective of this paper is to describe the framework and the process under which the hybrid BEES database is being built, with an emphasis on its accounting structure. This paper can support other efforts to build hybrid Life Cycle Inventory (LCI) databases.

Methods

The BEES hybridization utilizes the most detailed supply and use tables (SUTs)??known as item-level data??focusing particularly on the construction sectors. First, the partial SUTs at the item level are constructed and connected to standard SUTs that describe the rest of the economy, which is then followed by balancing and ??redefinition.?? Second, item-level environmental data are compiled and then also balanced and redefined, which completes the compilation of the bi-resolution SUTs with environmental data. Third, the bi-resolution SUTs are integrated with the BEES data that have been converted into matrix form. Because the completely rolled out BEES technology matrix involves a significant number of products, the integration prioritizes the product groups that are potentially the most significant contributors to the LCIA results for buildings.

Results

This step-by-step procedure will enable the creation of a hybridized BEES database, combining the strengths of both the bottom-up, process-based data and the top-down, input-output data with enhanced resolution. The benefit of hybridization at the database level??as opposed to at the individual LCA study level??is that whole-building LCA users can adopt the hybrid BEES approach, with its benefit of a more complete system definition, without the training or effort that would be required to construct a hybrid system from scratch. In addition, reformulation of new BEES data into a matrix structure better facilitates the parametric LCA application that is central to NIST??s vision to develop a tool for assessing the sustainability performance of energy technologies and systems in an integrated building design context.

Conclusions

There are currently a number of initiatives being organized to implement a hybrid approach at the LCI database level. In laying out the methodological framework for efficiently transforming an existing LCI database into a hybrid database, this paper can support future development of hybrid LCI databases.     

Life cycle assessment of light-emitting diode downlight luminaire—a case study

Purpose

Light-emitting diode (LED) technology is increasingly being used for general lighting. Thus, it is timely to study the environmental impacts of LED products. No life cycle assessments (LCA) of recessed LED downlight luminaires exist in the literature, and only a few assessments of any type of LED light source (component, lamp and luminaire) are available.

Methods

The LCA of a recessed LED downlight luminaire was conducted by using the data from the luminaire manufacturer, laboratory measurements, industry experts and literature. The assessment was conducted using SimaPro LCA software. EcoInvent and European Reference Life Cycle Database were used as the databases. The LCA included a range of environmental impacts in order to obtain a broad overview. The functional unit of the LCA was one luminaire used for 50,000 h. In addition, the sensitivity of the environmental impacts to the life was studied by assessing the LED downlight luminaire of 36,000 h and 15,000 h useful life and to the used energy sources by calculating the environmental impacts using two average energy mixes: French and European.

Results and discussion

The environmental impacts of the LED luminaire were mostly dominated by the energy consumption of the use. However, manufacturing caused approximately 23 % of the environmental impacts, on average. The environmental impacts of manufacturing were mainly due to the driver, LED array and aluminium parts. The installation, transport and end of life had nearly no effect on the total life cycle impacts, except for the end of life in hazardous waste. The life cycle environmental impacts were found to be sensitive to the life of the luminaire. The change from the French to the European average energy mix in use resulted to an even clearer dominance of the use stage.

Conclusions

The case study showed that the environmental impacts of the LED downlight luminaire were dominated by the use-stage energy consumption, especially in the case of the European energy mix in use. Luminous efficacy is, thus, a relatively appropriate environmental indicator of the luminaire. As LED technology possesses generally higher luminous efficacy compared to conventional ones, the LED luminaire is considered to represent an environmentally friendly lighting technology. However, data gaps exist in the data in LED product manufacturing and its environmental impacts. The environmental impacts of different LED products need to be analysed in order to be able to precisely compare the LED technology to the conventional lighting technologies.     

Quantifying anthropogenic mobilization,flows (in product systems) and emissions of fixed nitrogen in process-based environmental life cycle assessment: rationale,methods and application to a life cycle inventory

Purpose

Anthropogenic perturbation of the nitrogen cycle is attracting increasing attention as both an environmental and societal concern. Here, we provide the rationale and propose methods for independent treatment of anthropogenic mobilization, flows (in product systems) and emissions of fixed nitrogen in process-based environmental life cycle assessment.

Methods

We propose a simple methodology for aggregating N flows in life cycle assessment (LCA), with supporting characterization factors for all nitrogen-containing compounds on the Organization for Economic Cooperation and Development High Production Volume Chemical List for which specific chemical formulae are available, as well as all nitrogen-containing flows in the International Reference Life Cycle Data System. We subsequently apply our method and characterization factors to a life cycle inventory data set representing a subset of the consumption attributable to an average EU-27 consumer and compare the results against previously published estimates for nitrogen emissions at the consumer level that were generated using alternative methods/approaches.

Results and discussion

We derive a suite of over 2,000 characterization factors for nitrogen-containing compounds. Overall, the results generated by applying our method and characterization factors to the European Commission Basket-of-Products life cycle inventory data set are consistent with those observed from studies having a similar scope but different methodological approach.

Conclusions

This outcome suggests that anthropogenic mobilization, flows (in product systems) and emissions of fixed nitrogen can, indeed, be systematically inventoried and aggregated in process-based LCA for the purpose of better understanding and managing anthropogenic impacts on the global nitrogen cycle using the methods and characterization factors we propose.     

LCA of petroleum-based lubricants: state of art and inclusion of additives

Purpose

While the application of Life Cycle Assessment (LCA) to lubricants can be considered fully operational for general purposes outside the lubricants industry, where Life Cycle Inventories (LCIs) of mineral and synthetic base oils can be used interchangeably and where additives can be excluded, this is not the case for research and development purposes within the industry. Previous LCAs of base oils are not sufficiently detailed and comprehensive for R&D purposes, and there are no LCAs of lube additives and fully formulated lubricants. The aim of this paper is to integrate and expand previous LCAs of base oils and to investigate on the contribution of lube additives to the environmental impacts of a fully formulated lubricant.

Materials and methods

This study considers three base oils (mineral, poly-alpha-olefins (PAO) and hydrocracked) and a set of lubricating additives typically used in fully formulated engine oil. The LCA model is based on both industry and literature data.

Results and discussion

Trends in the lubricants industry towards more sophisticated base oils correspond to remarkably higher environmental impacts per kilogram of product but lead to reduced impacts per kilometre. The contribution of additives to the life cycle impacts of commercial lube oil was found to be remarkably high for some impact categories (nearly 35?% for global warming).

Conclusions

As base oil is concerned, this study made the point on data availability and provided a contribution in order to integrate and expand previous LCAs of mineral base oil and PAO. On the side of additives, the main conclusion is that in modern lubricants, the contribution of additives in terms of environmental impact can be remarkably high and, therefore, they should not be excluded.     

Global guidance principles for life cycle assessment databases: development of training material and other implementation activities on the publication

Purpose

The paper introduces the publication on “Global Guidance Principles for Life Cycle Assessment Databases”; it focuses on the development of training material and other implementation activities on the publication.

Methods

The document is the output of the “Shonan Guidance Principles” workshop. The publication provides guidance principles for life cycle assessment (LCA) databases; this includes how to collect raw data, how to develop datasets, and how to manage databases. The publication also addresses questions concerning data documentation and review, coordination among databases, capacity building, and future scenarios. As a next step, the publication is used to prepare training material and other implementation activities.

Results

The publication was launched at the LCM 2011 Conference. Since then outreach activities have been organized in particular in emerging economies. Further developments with regard to the guidance principles are foreseen as part of a flagship project within phase 3 of the Life Cycle Initiative. Training material is being developed that will include how to set up databases and develop datasets. The topic has been taken up by United Nations Environment Programme (UNEP) in its Rio?+?20 Voluntary Commitments: UNEP and Society of Environmental Toxicology and Chemistry (SETAC) through the UNEP/SETAC Life Cycle Initiative commit to facilitate improved access to good quality life cycle data and databases as well as expanded use of key environmental indicators that allows the measurement and monitoring of progress towards the environmental sustainability of selected product chains.

Conclusions

The adoption of the “Global Guidance Principles” publication as a de facto global standard is expected to facilitate the work of database teams, especially, in developing countries, and the collaboration in regional networks. These efforts are supported by the development of training material and other implementation activities.     

Life cycle assessment (LCA) applied to the process industry: a review

Purpose

Life cycle assessment (LCA) methodology is a well-established analytical method to quantify environmental impacts, which has been mainly applied to products. However, recent literature would suggest that it has also the potential as an analysis and design tool for processes, and stresses that one of the biggest challenges of this decade in the field of process systems engineering (PSE) is the development of tools for environmental considerations.

Method

This article attempts to give an overview of the integration of LCA methodology in the context of industrial ecology, and focuses on the use of this methodology for environmental considerations concerning process design and optimization.

Results

The review identifies that LCA is often used as a multi-objective optimization of processes: practitioners use LCA to obtain the inventory and inject the results into the optimization model. It also shows that most of the LCA studies undertaken on process analysis consider the unit processes as black boxes and build the inventory analysis on fixed operating conditions.

Conclusions

The article highlights the interest to better assimilate PSE tools with LCA methodology, in order to produce a more detailed analysis. This will allow optimizing the influence of process operating conditions on environmental impacts and including detailed environmental results into process industry.     

Simplifying a life cycle assessment of a mobile phone

Purpose

The possibilities for full life cycle assessment (LCA) of new Information and Communication Technology (ICT) products are often limited, so simplification approaches are needed. The aim of this paper is to investigate possible simplifications in LCA of a mobile phone and to use the results to discuss the possibilities of LCA simplifications for ICT products in a broader sense. Another aim is to identify processes and data that are sensitive to different methodological choices and assumptions related to the environmental impacts of a mobile phone.

Methods

Different approaches to a reference LCA of a mobile phone was tested: (1) excluding environmental impact categories, (2) excluding life cycle stages/processes, (3) using secondary process data from generic databases, (4) using input-output data and (5) using a simple linear relationship between mass and embodied emissions.

Results and discussion

It was not possible to identify one or a few impact categories representative of all others. If several impact categories would be excluded, information would be lost. A precautionary approach of not excluding impact categories is therefore recommended since impacts from the different life cycle stages vary between impact categories. Regarding use of secondary data for an ICT product similar to that studied here, we recommend prioritising collection of primary (specific) data on energy use during production and use, key component data (primarily integrated circuits) and process-specific data regarding raw material acquisition of specific metals (e.g. gold) and air transport. If secondary data are used for important processes, the scaling is crucial. The use of input-output data can be a considerable simplification and is probably best used to avoid data gaps when more specific data are lacking.

Conclusions

Further studies are needed to provide for simplified LCAs for ICT products. In particular, the end-of-life treatment stage need to be further addressed, as it could not be investigated here for all simplifications due to data gaps.     

Life cycle assessment of desktop PCs in Macau

Purpose

With the tremendous growth in the worldwide electronic information and telecommunication industries, there continues to be an increasing awareness of the environmental impacts related to the accelerating mass production, electricity use, and waste management of electrical and electronic products (e-products). Although Macau is a small region with a total land area of about 29.5 km² and a population of 557,000 in 2011, there are two personal computers (PCs) for every household in Macau.

Methods

This paper aims to describe the application of life cycle assessment (LCA) to investigate the environmental performance of PCs in Macau. An assessment of the PC (focusing on the desktop PC) was carried out using a detailed modular LCA based on the international standards of the ISO 14040 series. The LCA was constructed using SimaPro software version 7.2 and expressed with both the Eco-indicator'99 method and the Centrum voor Milieuwetenschappen method. Life cycle inventory information was compiled by Ecoinvent 2.2 databases, combined with literature and field investigations of the actual situations.

Results and discussion

The established LCA study showed that the manufacturing and the use of such devices are of the highest environmental importance. In the manufacturing stage, the desktop contributes the most to the total environmental impacts (44.89 Pt), followed by the LCD screens (about 27.53 Pt), while the CRT screen, keyboard, and mouse are of minor importance. During the use phase, the environmental impact is due entirely to the consumption of electricity generated by coal, oil, natural gas, and hydropower. The electricity generated by coal is by far the most important, accounting for about 66 % of the total environmental impact, followed by oil and gas. Within the EoL treatment phase, using incineration, there will be little environmental impact. When adopting recycling technology in the EoL phase, apparent environmental benefits will be generated due mainly to avoiding emissions to water (arsenic ions and cadmium ions) and to air (SO₂) in the primary production phase. For the competing technologies of CRT and LCD screens, the environmental impacts are different in different phases, but the total impacts over their entire life cycle are similar.

Conclusions

Results from a life cycle assessment can be used to compare the relative environmental impacts of competing technologies; it can also help designers and managers to focus efforts toward making environmental improvements to a particular technology.     

A hybrid life cycle assessment of water treatment chemicals: an Australian experience

Purpose

Life cycle assessment (LCA) of chemicals is usually developed using a process-based approach. In this paper, we develop a tiered hybrid LCA of water treatment chemicals combining the specificity of process data with the holistic nature of input–output analysis (IOA). We compare these results with process and input–output models for the most commonly used chemicals in the Australian water industry to identify the direct and indirect environmental impacts associated with the manufacturing of these materials.

Methods

We have improved a previous Australian hybrid LCA model by updating the environmental indicators and expanding the number of included industry sectors of the economy. We also present an alternative way to estimate the expenditure vectors to the service sectors of the economy when financial data are not available. Process-based, input–output and hybrid results were calculated for caustic soda, sodium hypochlorite, ferric chloride, aluminium sulphate, fluorosilicic acid, calcium oxide and chlorine gas. The functional unit is the same for each chemical: the production of 1 tonne in the year 2008.

Results and discussion

We have provided results for seven impact categories: global warming potential; primary energy; water use; marine, freshwater and terrestrial ecotoxicity potentials and human toxicity potential. Results are compared with previous IOA and hybrid studies. A sensitivity analysis of the results to assumed wholesale prices is included. We also present insights regarding how hybrid modelling helps to overcome the limitations of using IO- or process-based modelling individually.

Conclusions and recommendations

The advantages of using hybrid modelling have been demonstrated for water treatment chemicals by expanding the boundaries of process-based modelling and also by reducing the sensitivity of IOA to fluctuations in prices of raw materials used for the production of these industrial commodities. The development of robust hybrid life cycle inventory databases is paramount if hybrid modelling is to become a standard practice in attributional LCA.     

A system boundary identification method for life cycle assessment

Purpose

Life cycle assessment (LCA) is a useful tool for quantifying the overall environmental impacts of a product, process, or service. The scientific scope and boundary definition are important to ensure the accuracy of LCA results. Defining the boundary in LCA is difficult and there are no commonly accepted scientific methods yet. The objective of this research is to present a comprehensive discussion of system boundaries in LCA and to develop an appropriate boundary delimitation method.

Methods

A product system is partitioned into the primary system and interrelated subsystems. The hierarchical relationship of flow and process is clarified by introducing flow- and process-related interventions. A system boundary curve model of the LCA is developed and the threshold rules for judging whether the system boundary satisfies the research requirement are proposed. Quantitative criteria from environmental, technical, geographical and temporal dimensions are presented to limit the boundaries of LCA. An algorithm is developed to identify an appropriate boundary by searching the process tree and evaluating the environmental impact contribution of each process while it is added into the studied system.

Results and discussion

The difference between a limited system and a theoretically complete system is presented. A case study is conducted on a color TV set to demonstrate and validate the method of boundary identification. The results showed that the overall environmental impact indicator exhibits a slow growth after a certain number of processes considered, and the gradient of the fitting curve trends to zero gradually. According to the threshold rules, a relatively accurate system boundary could be obtained.

Conclusions

It is found from this research that the system boundary curve describes the growth of life cycle impact assessment (LCIA) results as processes are added. The two threshold rules and identification methods presented can be used to identify system boundary of LCA. The case study demonstrated that the methodology presented in this paper is an effective tool for the boundary identification.     

Ecodesign of PVC packing tape using life cycle assessment

Purpose

Polymer materials play an important role in the improvement and quality of life. However, due to their persistence in the environment, polymer materials may be harmful to the ecosystems. According to the European Directive on Packaging and Packaging Waste, management of these wastes should include prevention of their generation as a priority. The main motivation for employing ecodesign of a product is to reduce both raw material consumption and waste generation through a good initial design.

Methods

In this study, life cycle assessment (LCA) was applied to the design of printed PVC plastic packing tape in order to reduce its environmental impact. LCA software GaBi4.4^® was used to determine the PVC packing tape life cycle stage with the highest environmental impacts.

Results and discussion

LCA results showed that PVC film manufacture was the stage with the highest impact. It was therefore reasonable to assume that packing tape manufactured with material other than PVC could have reduced environmental impact, and LCA was used to evaluate this hypothesis. When using Kraft paper or polypropylene plastic packing tape, the weighted impacts were reduced by 36.3 and 39.9 %, respectively.

Conclusions

PVC plastic packing tape has been redesigned with the aim of reducing waste and raw material consumption. LCA results showed that a suitable option for reducing life cycle environmental impact is to use alternative film materials. Kraft paper and polypropylene plastic packing tape were found to give lower values of almost all environmental impact indexes and normalized and weighted impacts.     

Life cycle assessment for emerging materials: case study of a garden bed constructed from lumber produced with three different copper treatments

Purpose

The objective of this research was to evaluate the appropriateness of using life cycle assessment (LCA) for new applications that incorporate emerging materials and involve site-specific scenarios. Cradle-to-grave impacts of copper-treated lumber used in a raised garden bed are assessed to identify key methodological challenges and recommendations applying LCA for such purposes as well as to improve sustainability within this application.

Methods

The functional unit is a raised garden bed measuring 6.67 board feet (bf) in volume over a period of 20 years. The garden beds are made from softwood lumber such as southern yellow pine. The two treatment options considered were alkaline copper quaternary and micronized copper quaternary. Ecoinvent 2.2 provided certain life cycle inventory (LCI) data needed for the production of each garden bed, while additional primary and secondary sources were accessed to supplement the LCI.

Results and discussion

Primary data were not available for all relevant inventory requirements, as was anticipated, but enough secondary data were gathered to conduct a screening-level LCA on these raised garden bed applications. A notable finding was that elimination of organic solvent could result in a more sustainable lumber treatment product. Conclusions are limited by data availability and key methodological challenges facing LCA and emerging materials.

Conclusions

Although important data and methodological challenges facing LCA and emerging materials exist, this LCA captured material and process changes that were important drivers of environmental impacts. LCA methods need to be amended to reflect the properties of emerging materials that determine their fate, transport, and impacts to the environment and health. It is not necessary that all recommendations come to light before LCA is applied in the context of emerging materials. Applications of such materials involve many inputs beyond emerging materials that are already properly assessed by LCA. Therefore, LCA should be used in its current state to enhance the decision-making context for the sustainable development of these applications.     

Life cycle assessment as a decision support tool for bridge procurement: environmental impact comparison among five bridge designs

Purpose

The conventional decision-making for bridges is mostly focusing on technical, economical, and safety perspectives. Nowadays, the society devotes an ever-increased effort to the construction sector regarding their environmental performance. However, considering the complexity of the environmental problems and the diverse character of bridges, the related research for bridge as a whole system is very rare. Most existing studies were only conducted for a single indicator, part of the structure components, or a specific life stage.

Methods

Life Cycle Assessment (LCA) is an internationally standardized method for quantifying the environmental impact of a product, asset, or service throughout its whole life cycle. However, in the construction sector, LCA is usually applied in the procurement of buildings, but not bridges as yet. This paper presents a comprehensive LCA framework for road bridges, complied with LCA ReCiPe (H) methodology. The framework enables identification of the key structural components and life cycle stages of bridges, followed by aggregation of the environmental impacts into monetary values. The utility of the framework is illustrated by a practical case study comparing five designs for the Karlsnäs Bridge in Sweden, which is currently under construction.

Results and discussion

This paper comprehensively analyzed 20 types of environmental indicators among five proposed bridge designs, which remedies the absence of full spectrum of environmental indicators in the current state of the art. The results show that the monetary weighting system and uncertainties in key variables such as the steel recycling rate and cement content may highly affect the LCA outcome. The materials, structural elements, and overall designs also have varying influences in different impact categories. The result can be largely affected by the system boundaries, surrounding environment, input uncertainties, considered impact indicators, and the weighting systems applied; thus, no general conclusions can be drawn without specifying such issues.

Conclusions

Robustly evaluating and ranking the environmental impact of various bridge designs is far from straightforward. This paper is an important attempt to evaluate various designs from full dimensions. The results show that the indicators and weighting systems must be clearly specified to be applicable in a transparent procurement. This paper provides vital knowledge guiding the decision maker to select the most LCA-feasible proposal and mitigate the environmental burden in the early stage.     

Integrating environmental and economic life cycle analysis in product development: a material selection case study

Purpose

Achieving sustainability by rethinking products, services and strategies is an enormous challenge currently laid upon the economic sector, in which materials selection plays a critical role. In this context, the present work describes an environmental and economic life cycle analysis of a structural product, comparing two possible material alternatives. The product chosen is a storage tank, presently manufactured in stainless steel (SST) or in a glass fibre reinforced polymer composite (CST). The overall goal of the study is to identify environmental and economic strong and weak points related to the life cycle of the two material alternatives. The consequential win–win or trade-off situations will be identified via a life cycle assessment/life cycle costing (LCA/LCC) integrated model.

Methods

The LCA/LCC integrated model used consists in applying the LCA methodology to the product system, incorporating, in parallel, its results into the LCC study, namely those of the life cycle inventory and the life cycle impact assessment.

Results and discussion

In both the SST and CST systems, the most significant life cycle phase is the raw materials production, in which the most significant environmental burdens correspond to the Fossil fuels and Respiratory inorganics categories. The LCA/LCC integrated analysis shows that the CST has globally a preferable environmental and economic profile, as its impacts are lower than those of the SST in all life cycle stages. Both the internal and external costs are lower, the former resulting mainly from the composite material being significantly less expensive than stainless steel. This therefore represents a full win–win situation. As a consequence, the study clearly indicates that using a thermoset composite material to manufacture storage tanks is environmentally and economically desirable. However, it was also evident that the environmental performance of the CST could be improved by altering its end-of-life stage.

Conclusions

The results of the present work provide enlightening insights into the synergies between the environmental and the economic performance of a structural product made with alternative materials. Furthermore, they provide conclusive evidence to support the integration of environmental and economic life cycle analysis in the product development processes of a manufacturing company or, in some cases, even in its procurement practices.     

On the boundary between economy and environment in life cycle assessment

Purpose

We investigate how the boundary between product systems and their environment has been delineated in life cycle assessment and question the usefulness and ontological relevance of a strict division between the two.

Methods

We consider flows, activities and impacts as general terms applicable to both product systems and their environment and propose that the ontologically relevant boundary is between the flows that are modelled as inputs to other activities (economic or environmental)—and the flows that—in a specific study—are regarded as final impacts, in the sense that no further feedback into the product system is considered before these impacts are applied in decision-making. Using this conceptual model, we contrast the traditional mathematical calculation of the life cycle impacts with a new, simpler computational structure where the life cycle impacts are calculated directly as part of the Leontief inverse, treating product flows and environmental flows in parallel, without the need to consider any boundary between economic and environmental activities.

Results and discussion

Our theoretical outline and the numerical example demonstrate that the distinctions and boundaries between product systems and their environment are unnecessary and in some cases obstructive from the perspective of impact assessment, and can therefore be ignored or chosen freely to reflect meaningful distinctions of specific life cycle assessment (LCA) studies. We show that our proposed computational structure is backwards compatible with the current practice of LCA modelling, while allowing inclusion of feedback loops both from the environment to the economy and internally between different impact categories in the impact assessment.

Conclusions

Our proposed computational structure for LCA facilitates consistent, explicit and transparent modelling of the feedback loops between environment and the economy and between different environmental mechanisms. The explicit and transparent modelling, combining economic and environmental information in a common computational structure, facilitates data exchange and re-use between different academic fields.

     

Application of robust optimization in matrix-based LCI for decision making under uncertainty

Purpose

When product systems are optimized to minimize environmental impacts, uncertainty in the process data may impact optimal decisions. The purpose of this article is to propose a mathematical method for life cycle assessment (LCA) optimization that protects decisions against uncertainty at the life cycle inventory (LCI) stage.

Methods

A robust optimization approach is proposed for decision making under uncertainty in the LCI stage. The proposed approach incorporates data uncertainty into an optimization problem in which the matrix-based LCI model appears as a constraint. The level of protection against data uncertainty in the technology and intervention matrices can be controlled to reflect varying degrees of conservatism.

Results and discussion

A simple numerical example on an electricity generation product system is used to illustrate the main features of this methodology. A comparison is made between a robust optimization approach, and decision making using a Monte Carlo analysis. Challenges to implement the robust optimization approach on common uncertainty distributions found in LCA and on large product systems are discussed. Supporting source code is available for download at https://github.com/renwang/Robust_Optimization_LCI_Uncertainty.

Conclusions

A robust optimization approach for matrix-based LCI is proposed. The approach incorporates data uncertainties into an optimization framework for LCI and provides a mechanism to control the level of protection against uncertainty. The tool computes optimal decisions that protects against worst-case realizations of data uncertainty. The robust optimal solution is conservative and is able to avoid the negative consequences of uncertainty in decision making.     

Eco-efficiency of disposable and reusable surgical instruments—a scissors case

Purpose

In recent years, the rising costs and infection control lead to an increasing use of disposable surgical instruments in daily hospital practices. Environmental impacts have risen as a result across the life cycle of plastic or stainless steel disposables. Compared with the conventional reusable products, different qualities and quantities of disposable scissors have to be taken into account. An eco-efficiency analysis can shed some light for the potential contribution of those products towards a sustainable development.

Methods

Disposable scissors made of either stainless steel or fibre-reinforced plastic were compared with reusable stainless steel scissors for 4,500 use cycles of surgical scissors used in Germany. A screening life cycle assessment (LCA) and a life cycle costing were performed by following ISO 14040 procedure and total cost of ownership (TCO) from a customer perspective, respectively. Subsequently, their results were used to conduct an eco-efficiency analysis.

Results and discussion

The screening LCA showed a clear ranking regarding the environmental impacts of the three types of scissors. The impacts of the disposable steel product exceeds those of the two others by 80 % (disposable plastic scissors) and 99 % (reusable steel scissors), respectively. Differences in TCO were smaller, however, revealing significant economic advantages of the reusable stainless steel product under the constraints and assumptions of this case study. Accordingly, the reusable stainless steel product was revealed as the most eco-efficient choice. It was followed by the plastic scissors which turned out to be significantly more environmentally sound than the disposable stainless steel scissors but also more cost-intensive.

Conclusions

The overall results of the study prove to be robust against variations of critical parameters for the prescribed case study. The sensitivity analyses were also conducted for LCA and TCO results. LCA results are shown to be reliable throughout all assumptions and data uncertainties. TCO results are more dependent on the choice of case study parameters whereby the price of the disposable products can severely influence the comparison of the stainless steel and the plastic scissors. The costs related to the sterilisation of the reusable product are strongly case-specific and can reduce the economic benefit of the reusable scissors to zero. Differences in environmental and economic break-even analyses underline the comparatively high share of externalised environmental costs in the case of the disposable steel product.     

A critical evaluation of Brazilian life cycle assessment studies

Purpose

A critical evaluation of the life cycle assessment (LCA) studies was performed in the main scientific bibliographic databases (online and free access) of Brazil where the LCA methodology could be considered.

Methods

This has been an exploratory study with a qualitative evaluation of quantitative LCA studies with regard to International Organization of Standardization (ISO) 14040 standards. Firstly, the selected papers were those which used the LCA methodology in case studies (quantitative LCA studies). This survey was based on previously chosen keywords which were directly and/or indirectly related to LCA in Portuguese, English, and Spanish.

Results and discussion

One hundred and twenty papers related to LCA were found, among which 21 have been effectively used the LCA methodology applied to case studies. The study has indicated agriculture and livestock as some promising areas for the use of LCA methodology in Brazil. As for the scope of LCA, it has been found that nine papers have adopted the cradle-to-grave approach, whereas 12 papers have limited the study to some life cycle stage (cradle-to-gate, gate-to-gate, or gate-to-grave). This behavior can be justified by the difficulty in obtaining data from raw material, supply chain, inputs, or about the disposal, reuse, and recycling of products/systems. The criteria set out in the ISO 14040 standard was carried out in 17 out of the 21 selected papers.

Conclusions

The LCA of Brazilian studies could be improved. For instance, when considering the requirements and guidelines of ISO standards, at the goal phase, the papers have clearly mentioned their target audience. The scope phase requires more explanation about the allocation procedures, once the process/product is not isolated, and for most processes, it may generate more than one product. As regards the Life Cycle Inventory, these studies could improve their data sources, once few papers used primary sources. According to our understanding, the best phase performed by the papers was life cycle impact assessment. Hopefully, LCA will become a known research area and will be adopted by most of the Brazilian scientific community. It is further expected that LCA might have a regular publication in scientific journals (perhaps an own journal).     

Strategy tool trial for office furniture

Purpose

A strategic product development tool combining REACH and environmental and financial factors was previously developed for a coatings company. This paper presents results from refining this tool for an office furniture company, using life cycle assessment (LCA)-based environmental information, addressing the research questions: ? Is it possible to combine information from REACH with the LCA approach to provide useful information for a furniture producer in their environmental product development process? ? Does the approach developed for substances in mixtures need to be adapted for articles? ? Is there a correlation between energy consumption and the environmental impacts analysed? ? Will product designers get the same information independent of the environmental impact category used? ?C Will the strategy tool indicate the same ranking of products for all environmental impacts? ?C Does REACH information indicate the same set of priorities as those arising from LCA environmental data alone? (Do they agree, or is there a conflict?) ? Will strategic decisions differ if different environmental indicators are in focus? The strategy tool??s purpose is to analyse company product portfolios, identifying products that need redevelopment or redesign because of issues concerning hazardous substances, or environmental performance.

Methods

The LCA data used is cradle-to-gate data from type III environmental declarations for 11 seating solutions. REACH Complexity, health hazard and environmental class indicators (based on risk phrases) are combined with financial data and LCA-based indicators. Correlations between energy consumption and environmental impact factors for these specific furniture products are investigated. Establishing any such correlations serves to simplify subsequent analysis in the product development process, by effectively reducing the number of indicators that need to be taken into consideration.

Results

Correlations between energy consumption and the environmental impacts global warming, acidification, eutrophication and heavy metals are presented. Strategy tool figures are shown for energy consumption, ozone depletion potential and photochemical oxidation potential. The results for office chairs and conference/visitor chairs are presented separately, as the two types of chairs fulfil different functions.

Conclusions

The correlation between energy consumption and certain environmental impact indicators affords a simplification of the product development process, since energy consumption can be used as a reasonable proxy for these indicators in this specific case. The results support acknowledged principles of Ecodesign. Energy and materials minimization improves environmental performance??higher recycled material content and proportion of renewable energy resources are also beneficial. Designers have to consider multiple aspects in parallel and the strategy tool is useful for this purpose; the furniture producer has gained useful product development insight. The tool is applicable for strategic choice of products for development or redesign that can be useful across many business sectors.     

Implicit prioritization in life cycle assessment: text mining and detecting metapatterns in the literature

Purpose

Life cycle assessment aims to evaluate multiple kinds of environmental impact associated with a product or process across its life cycle. Objective evaluation is a common goal, though the community recognizes that implicit valuations of diverse impacts resulting from analytical choices and choice of subject matter are present. This research evaluates whether these implicit valuations lead to detectable priority shifts in the published English language academic LCA literature over time.

Methods

A near-comprehensive investigation of the LCA literature is undertaken by applying a text mining technique known as topic modeling to over 8200 environment-related LCA journal article titles and abstracts published between 1995 and 2014.

Results and discussion

Topic modeling using MALLET software and manual validation shows that over time, the LCA literature reflects a dramatic proportional increase in attention to climate change and a corresponding decline in attention to human and ecosystem health impacts, accentuated by rapid growth of the LCA literature. This result indicates an implicit prioritization of climate over other impact categories, a field-scale trend that appears to originate mostly in the broader environmental community rather than the LCA methodological community. Reasons for proportionally increasing publication of climate-related LCA might include the relative robustness of greenhouse gas emissions as an environmental impact indicator, a correlation with funding priorities, researcher interest in supporting active policy debates, or a revealed priority on climate versus other environmental impacts in the scholarly community.

Conclusions

As LCA becomes more widespread, recognizing and addressing the fact that analyses are not objective becomes correspondingly more important. Given the emergence of implicit prioritizations in the LCA literature, such as the impact prioritization of climate identified here with the use of computational tools, this work recommends the development and use of techniques that make impact prioritization explicit and enable consistent analysis of result sensitivity to value judgments. Explicit prioritization can improve transparency while enabling more systematic investigation of the effects of value choices on how LCA results are used.