Environmental Assessment of Freight Transportation in the U.S. (11 pp)

Goal, Scope and Background This study provides a life cycle inventory of air emissions (CO2, NOx, PM10, and CO) associated with the transportation of goods by road, rail, and air in the U.S. It includes the manufacturing, use, maintenance, and end-of-life of vehicles, the construction, operation, maintenance, and end-of-life of transportation infrastructure, as well as oil exploration, fuel refining, and fuel distribution. Methods The comparison is performed using hybrid life cycle assessment (LCA), a combination of process-based LCA and economic input-output analysis-based LCA (EIO-LCA). All these components are added by means of a common functional unit of grams of air pollutant per ton-mile of freight activity. Results and Discussion Results show that the vehicle use phase is responsible for approximately 70% of total emissions of CO2 for all three modes. This confirms that tailpipe emissions underestimate total emissions of freight transportation as infrastructure, pre-combustion, as well as vehicle manufacturing and end-of-life account for a sizeable share of total emissions. Differences between tailpipe emissions and total system wide emissions can range from only 4% for road transportation's CO emissions to an almost ten-fold difference for air transportation's PM10 emissions. Conclusion Rail freight has the lowest associated air emissions, followed by road and air transportation. Depending on the pollutant, rail is 50-94% less polluting than road. Air transportation is rated the least efficient in terms of air emissions, partly due to the fact that it carries low weight cargo. It emits 35 times more CO2 than rail and 18 times more than road transportation on a ton-mile basis. It is important to consider infrastructure, vehicle manufacturing, and pre-combustion processes, whose life-cycle share is likely to increase as new tailpipe emission standards are enforced. Recommendation and Outlook Emission factors, fuel efficiency, and equipment utilization contribute the most to uncertainty in the results. Further studies are necessary to address all variables that influence these parameters, such as road grade, vehicle speed, and vehicle weight. A focus on regional variation, end-of-life processes, fuel refining processes, terminals, as well as more accurate infrastructure allocation between freight and passenger transportation would strengthen the model.     

Consequences of Future Data Center Deployment in Canada on Electricity Generation and Environmental Impacts: A 2015–2030 Prospective Study

The environmental impacts of data centers that provide information and communication technologies (ICTs) services are strongly related to electricity generation. With the increasing use of ICT, many data centers are expected to be built, causing more absolute impacts on the environment. Given that electricity distribution networks are very complex and dynamic systems, an environmental evaluation of future data centers is uncertain. This study proposes a new approach to investigate the consequences of future data center deployment in Canada and optimize this deployment based on the Energy 2020 technoeconomic model in combination with life cycle assessment methodology. The method determines specific electricity sources that will power the future Canadian data centers and computes related environmental impacts based on several indicators. In case‐study scenarios, the largest deployment of data centers leads to the smallest impact per megawatt of data centers for all of the environmental indicators. It is found that an increase in power demand by data centers would lead to a reduction in electricity exports to the United States, driving the United States to generate more electricity to meet its energy demand. Given that electricity generation in the United States is more polluting than in Canada, the deployment of data centers in Canada is indirectly linked to an increase in overall environmental impacts. However, though an optimal solution should be found to mitigate global greenhouse gas emissions, it is not clear whether the environmental burden related to U.S. electricity generation should be attributed to the Canadian data centers.     

Assessment of CO 2 Emission Reduction Strategies for the Japanese Petrochemical Industry

Abstract: This article analyzes the possibilities for reducing carbon dioxide (CO₂) emissions in the life cycle of Japanese petrochemicals, focusing primarily on the nonenergy use of fossil fuels. For this purpose a linear programming model called CHEAP (CHemical industry Environmental strategy Analysis Program) has been developed. The results show a moderate autonomous growth of emissions by 5% in the period 2000 to 2020, if it is assumed that no new technology is introduced and demand (measured in physical units) increases 1% per year, on average. However, if it is assumed that ongoing technology development succeeds, emissions in 2020 may decrease by 5% from 2000 levels (a decrease of 10% compared to the case that assumes no new technology). This is a significant contribution to emission reduction. According to this model, a further emission reduction by 10% in 2020 is possible but costly as it requires emission reduction incentives of up to 10,000 yen per ton CO₂ (approximately 100 US/ton). The use of biomass feed-stocks, waste recycling, energy recovery from waste and gas-based co-generation are the main strategies for achieving this emission reduction.     

Societal LCA Methodology and Case Study (12 pp)

Background, Aim and Scope Societal assessment is advocated as one of the three pillars in the evaluation of, and movement toward, sustainability. As is the case with the well established LCA, and the emerging LCC, societal life cycle assessment should be developed in such as way as to permit relative product comparisons, rather than absolute analyses. The development of societal life cycle assessment is in its infancy, and important concepts require clarification including the handling of the more than two hundred social indicators. Therefore, any societal life cycle assessment methodology must explain why it is midpoint- or endpoint-based as well as its reasons to be complimentary with, or included within, life cycle assessment. Materials and Methods: A geographically specific midpoint based societal life cycle assessment methodology, which employs labour hours as an intermediate variable in the calculation has been developed and evaluated against an existing LCA comparing two detergents. The methodology is based on using an existing life cycle inventory and, therefore, has identical system boundaries and functional units to LCA. The societal life cycle assessment methodology, much like LCA, passes from inventory, through characterisation factors, to provide an ultimate result. In analogy to economics and cost estimation, societal life cycle assessment combines, into its statistics, both data as well as estimates, some of which are correlated to elements of the LCI. It focuses on the work hours required to meet basic needs.A geographically specific midpoint based societal life cycle assessment methodology, which employs labour hours as an intermediate variable in the calculation has been developed and evaluated against an existing LCA comparing two detergents. The methodology is based on using an existing life cycle inventory and, therefore, has identical system boundaries and functional units to LCA. The societal life cycle assessment methodology, much like LCA, passes from inventory, through characterisation factors, to provide an ultimate result. In analogy to economics and cost estimation, societal life cycle assessment combines, into its statistics, both data as well as estimates, some of which are correlated to elements of the LCI. It focuses on the work hours required to meet basic needs. Results: The societal life cycle assessment of an appended case study indicates that Detergent 2 generates, relative Detergent 1, approximately 20% less employment in Russia, 35% less in France, and approximately five times more in Canada and South Africa, the latter derived from its higher aluminium content. There is essentially no difference in the employment in the use country (Switzerland) nor in Morocco, where some of the waste disposal was assumed to take place. Discussion: Given that housing is more affordable, in terms of shelter units per labour hour, in South Africa, compared to Europe, it is, therefore, of no surprise that Detergent 2 provides a societal benefit in terms of housing. Detergent 2 does, however, result in dematerialization, in that its environmental impact is lower (LCI). Therefore, as less resources are employed and labour required, in extraction, production and transport, the societal benefits in health care, education and necessities, a grouped variable, are lower for Detergent 2. This is despite the employment shift away from Europe and to less 'developed' regions. Conclusions: The assessment of societal impacts involves several hundred specific indicators. Therefore, aggregation is, if not impossible, at least heavily value laden and, therefore, not recommended. The impact of a societal action, derived from a product purchase or otherwise, is also highly local. Given this, societal life cycle assessment, carried through to the midpoints, and based on an existing LCI, has been developed as a methodology. The results, for an existing LCA-detergent case, illustrate that societal life cycle assessment provides a means to investigate how policy and policy makers can be linked to sustainable development. The sensitivity analyses also clarify the decisions in regards to product improvement. Recommendations and Perspectives: The goal of societal life cycle assessment is not to make decisions, but rather to point out tradeoffs to decision- or policy-makers. This case, and the methodology that it is based on, permit such a comparison. Substituting Detergent 2 for Detergent 1 reduces resource use at the expense of an increase in atmospheric and terrestrial emissions. Access to housing is improved, though at the expense of education, health care and necessities. As a recommendation, one would look at the fact that the majority of indicators are superior for Detergent 2 relative to Detergent 1and seek to improve the aqueous emissions in Detergent 2 via a change in the formulation. An energy or fossil fuel substitution at the site of production could also improve the societal benefits in terms of education and health care. While societal life cycle assessment remains in its infancy, a methodology does exist. The field can, therefore, be viewed in a similar way to LCA in the early 1990s, with a need to validate, consolidate and, ultimately, built toward a standard. The contribution is aimed at contributing to such a discussion and therefore proposes that a societal life cycle assessment be LCI-derived, geographically specific, based on mid-points, and use employment as an intermediate variable.     

A Carbon Footprint of Textile Recycling: A Case Study in Sweden

Global population growth and rising living standards are increasing apparel consumption. Consequently, consumption of resources and generation of textile waste are increasing. According to the Swedish Environmental Protection Agency, textile consumption increased by 40% between the years 2000 and 2009 in Sweden. Given that there is currently no textile recycling plant in Sweden, the aim of this article is to explore the potential environmental benefits of various textile recycling techniques and thereby direct textile waste management strategies toward more sustainable options. Three different recycling techniques for a model waste consisting of 50% cotton and 50% polyester were identified and a life cycle assessment (LCA) was made to assess the environmental performance of them. The recycling processes are: material reuse of textile waste of adequate quality; separation of cellulose from polyester using N‐methylmorpholine‐N‐oxide as a solvent; and chemical recycling of polyester. These are compared to incineration, representing conventional textile waste treatment in Sweden. The results show that incineration has the highest global warming potential and primary energy usage. The material reuse process exhibits the best performance of the studied systems, with savings of 8 tonnes of carbon dioxide equivalents (CO₂‐eq) and 164 gigajoules (GJ) of primary energy per tonne of textile waste. Sensitivity analyses showed that results are particularly sensitive to the considered yields of the processes and to the choice of replaced products. An integration of these recycling technologies for optimal usage of their different features for treatment of 1 tonne of textile waste shows that 10 tonnes CO₂‐eq and 169 GJ of primary energy could be saved.     

Fundamental Principles for CAD-based Ecological Assessments (9 pp)

Background Aims, and Scope. As products are, directly and indirectly, main sources for ecological impact, the overall enhancement of products' ecological behaviour is an important contribution to the protection of the Earth's biosphere. This is especially important in a world where the major economical system is based on a constant rise in industrial production, consumption, and disposal of products. The true ecological performance of a product can only be determined by consideration of the impact arising from the entire lifecycle, and by including all known impacts into the assessments. The state of technology provides a standardized framework for such life cycle assessments (LCA) in the ISO 14040 series (see ISO 1997), and numerous databases and software tools are available to support the conduction of LCA. To integrate ecological indicators into decisions of everyday product development, as natural as it is the case today with finite items, design, and costs, indicators based on a consideration of the product's entire life have to be generated with little effort and in short time. Methods This article describes the fundamental principles of a technology designed to integrate lifecycle information into common 3-dimensional product models, like the ones used within modern Computer Aided Design (CAD) systems. Thereby, ecological assessments can be effectively undertaken during product development, where most of the environmental lock-in of a product is defined (see Lewis et al. 2001). Overall effects of alterations in materials or other product properties can be assessed instantly, supporting on the spot decisions to reach an improved product design. Results Next to an information model that manages the product and process representation, the research on which this article is based also deals with the calculation of resulting indicators, database access to ecological indicators, a graphical user interface, and a synchronisation tool for the CAD system Pro/Engineer . The developed concepts have been implemented as a prototype software and validated in different stages. Conclusions The concepts described in this article are a foundation for tools that integrate ecological assessments into everyday product development, on the basis of 3-dimensional CAD systems. Reuse of existing CAD data, an improved understanding of the assessment structure by product developers, and an automated calculation of resulting indicators are approaches to largely enhance the efficiency of product-related ecological assessments.     

Beyond Global Warming Potential: A Comparative Application of Climate Impact Metrics for the Life Cycle Assessment of Coal and Natural Gas Based Electricity

In the ongoing debate about the climate benefits of fuel switching from coal to natural gas for power generation, the metrics used to model climate impacts may be important. In this article, we evaluate the life cycle greenhouse gas emissions of coal and natural gas used in new, advanced power plants using a broad set of available climate metrics in order to test for the robustness of results. Climate metrics included in the article are global warming potential, global temperature change potential, technology warming potential, and cumulative radiative forcing. We also used the Model for the Assessment of Greenhouse‐gas Induced Climate Change (MAGICC) climate‐change model to validate the results. We find that all climate metrics suggest a natural gas combined cycle plant offers life cycle climate benefits over 100 years compared to a pulverized coal plant, even if the life cycle methane leakage rate for natural gas reaches 5%. Over shorter time frames (i.e., 20 years), plants using natural gas with a 4% leakage rate have similar climate impacts as those using coal, but are no worse than coal. If carbon capture and sequestration becomes available for both types of power plants, natural gas still offers climate benefits over coal as long as the life cycle methane leakage rate remains below 2%. These results are consistent across climate metrics and the MAGICC model over a 100‐year time frame. Although it is not clear whether any of these metrics are better than the others, the choice of metric can inform decisions based on different societal values. For example, whereas annual temperature change reported may be a more relevant metric to evaluate the human health effects of increased heat, the cumulative temperature change may be more relevant to evaluate climate impacts, such as sea‐level rise, that will result from the cumulative warming.     

Greenhouse Gas Emissions Reduction Opportunities for Concrete Pavements

Concrete pavements are a vital part of the transportation infrastructure, comprising nearly 25% of the interstate network in the United States. With transportation authorities and industry organizations increasingly seeking out methods to reduce their carbon footprint, there is a need to identify and quantitatively evaluate the greenhouse gas (GHG) emission reduction opportunities that exist in the concrete pavement life cycle. A select few of these opportunities are explored in this article in order to represent possible reduction approaches and their associated cost‐effectiveness: reducing embodied emissions by increasing fly ash content and by avoiding overdesign; increasing albedo by using white aggregates; increasing carbonation by temporarily stockpiling recycled concrete aggregates; and reducing vehicle fuel consumption by adding an extra rehabilitation. These reduction strategies are evaluated for interstate, arterial, collector, and local road designs under urban and rural scenarios. The results indicate that significant GHG emission reductions are possible, with over half of the scenarios resulting in 10% reductions, compared to unimproved baseline designs. Given the right conditions, each scenario has the potential to reduce GHG emissions at costs comparable to the current price of carbon.     

Reducing Life Cycle Environmental Impacts of Waste Electrical and Electronic Equipment Recycling

Collection and treatment of waste from electrical and electronic equipment (WEEE) is regulated in the European Union by the WEEE Directive. Producers are responsible for take‐back and recycling of discarded equipment. Valuable materials are, however, at risk of “getting lost” in current processes. Thus, strategies to minimize losses are sought after. The material hygiene (MH) concept was introduced to address this issue. Structural features, which are important for the outcome of reuse, recovery, and recycling, were investigated in an earlier field study of discarded dishwashers. It was proposed that a prestep, manual removal of copper prior to shredding could increase the purity of recovered material fractions. This article builds on the field study and theoretical reasoning underlying the MH concept. Dishwashers are assumed to be designed for disassembly when the prestep is introduced. A limited life cycle assessment was performed to determine whether the proposed prestep may be environmentally beneficial in a life cycle perspective. Two alternatives were analyzed: Case 1: the current shredding process. Case 2: prestep removal of copper before shredding. Targeted disassembly prior to shredding may reduce the abiotic depletion and global warming potential in a life cycle perspective. The prestep results in increased copper recovery, but, more important, copper contamination of the recovered steel fractions is reduced. The results also highlight the importance of minimizing energy consumption in all process stages.     

A Systems Approach to Sustainable Technical Product Design

Many existing methods for sustainable technical product design focus on environmental efficiency while lacking a framework for a holistic, sustainable design approach that includes combined social, technical, economic, and environmental aspects in the whole product life cycle, and that provides guidance on a technical product development level. This research proposes a framework for sustainable technical product design in the case of skis. We developed a ski under the Grown brand, benchmarked according to social, environmental, economic, and technical targets, following an initial sustainability assessment, and delivered the first environmental life cycle assessment (ELCA) and the first social life cycle assessment (SLCA) of skis. The framework applies a virtual development process as a combination of ELCA to calculate the environmental footprint as carbon equivalents of all materials and processes and a technical computer‐aided design (CAD) and computer‐aided engineering (CAE) simulation and virtual optimization using parameter studies for the nearly prototype‐free development of the benchmarked skis. The feedback loops between life cycle assessment (LCA) and virtual simulation led to the elimination of highly energy intensive materials, to the pioneering use of basalt fibers in skis, to the optimization of the use of natural materials using protective coatings from natural resins, and to the optimization of the production process. From an environmental perspective, a minimum 32% reduction in carbon equivalent emissions of materials in relation to other comparably performing skis has been achieved, as well as a pioneering step forward toward transparent communication of the environmental performance by the individual, comparable, and first published ski carbon footprint per volume unit.     

Environmental Evaluation of Industry Cluster Strategies with a Life Cycle Perspective: Replacing Fossil Feedstock with Forest‐Based Feedstock and Increasing Thermal Energy Integration

Symbiotic linkages in industry clusters in the form of interconnected materials, energy and information flows, and close proximity provide unique opportunities to develop efficient environmental strategies. The purpose of our study is to examine the practical potential of applying a life cycle approach in strategy evaluations, as the environmental impact caused by industrial symbiosis systems outside the company gates has been scarcely addressed. This is done by evaluating two strategies for an industry cluster in Sweden: (1) to replace a share of the fossil feedstock used in the industry cluster with forest‐based feedstock and (2) to improve energy efficiency through thermal energy integration. The environmental impact reduction potential of the strategies is evaluated using life cycle assessment. The ratio between investment cost and reduced global warming potential is used as an indicator to evaluate the cost‐effectiveness of the strategies. Results demonstrate the importance of applying a life cycle perspective as the assessment outcome depends heavily on whether only on‐site consequences are assessed or if upstream and downstream processes are also included. 20% of the greenhouse gas emission reduction of the energy integration strategy occurs off‐site, whereas the forest strategy has the largest reduction potential off‐site, >80%.     

Life Cycle Environmental and Cost Impacts of Using an Algal Turf Scrubber to Treat Dairy Wastewater

Using algae to simultaneously treat wastewater and produce energy products has potential environmental and economic benefits. This study evaluates the life cycle energy, greenhouse gas (GHG) emissions, eutrophication potential, and cost impacts of incorporating an algal turf scrubber (ATS) into a treatment process for dairy wastewater. A life cycle inventory and cost model was developed to simulate an ATS treatment system where harvested algae would be used to generate biogas for process heat and electricity generation. Modeling results show that using an ATS significantly reduces eutrophication impacts by reducing chemical oxygen demand, nitrogen, and phosphorus in the wastewater. With low water recirculation rates through the ATS and high algae productivity, inclusion of the ATS results in net energy displacement and a reduction of GHG emissions compared to a system with no ATS. However, if high water recirculation rates are used or if algae biosolids from the digester are dried, the system results in a net increase in energy consumption and GHG emissions. The life cycle treatment cost was estimated to be $1.42 USD per cubic meter of treated wastewater. At this cost, using an ATS would only be cost effective for dairies if they received monetary credits for improved water quality on the order of $3.83 per kilogram of nitrogen and $9.57 per kilogram of phosphorus through, for example, nutrient trading programs.     

Material and Energy Flows and Environmental Impacts of the Internet in Switzerland

The Internet leads to material and energy consumption as well as various environmental impacts on both the regional and global scale. Yet, assessments of the Internet's energy consumption and resulting greenhouse gas emissions are still rare, and assessments of material flows and further environmental impacts are virtually non‐existent. This article investigates material flows, the direct energy consumption during the use phase, as well as environmental impacts linked to the service, “Internet in Switzerland.” In our model, the service, Internet in Switzerland, is divided into various Internet participant categories. All devices used to access or provide Internet services are merged in a limited number of equipment families and, as such, included in an inventory of the existing infrastructure (stock). Based on this inventory, a material flow analysis (MFA) is performed, which includes the current stock as well as flows resulting from growth and disposal. The direct energy consumption for the operation of the infrastructure is quantified. Environmental impacts are calculated with a life cycle assessment approach, using the ecoinvent database and the software, SimaPro, applying four different methods. The MFA results in a 2009 stock of 98,100 tonnes. Approximately 4,130 gigawatt hours per year, or 7% of the total Swiss electricity consumption, were used in 2009 to operate the Swiss infrastructure. The environmental impacts caused during the production and use phases vary significantly depending on the assessment method chosen. The disposal phase had mainly positive impacts as a result of material recovery.     

Assessment of Environmental Impacts of an Aging and Stagnating Water Supply Pipeline Network

Aging urban infrastructure is a common phenomenon in industrialized countries. The urban water supply pipeline network in the city of Oslo is an example. Even as it faces increasing operational, maintenance, and management challenges, it needs to better its environmental performance by reducing, for instance, the associated greenhouse gas emissions. In this article the authors examine the environmental life cycle performance of Oslo's water supply pipelines by analyzing annual resource consumption and emissions as well as life cycle assessment (LCA) impact potentials over a period of 16 years, taking into account the production/manufacture, installation, operation, maintenance, rehabilitation, and retirement of pipelines. It is seen that the water supply pipeline network of Oslo has already reached a state of saturation on a per capita basis, that is, it is not expanding any more relative to the population it serves, and the stock is now rapidly aging. This article is part of a total urban water cycle system analysis for Oslo, and analyzes more specifically the environmental impacts from the material flows in the water distribution network, examining six environmental impact categories using the SimaPro (version 7.1.8) software, Ecoinvent database, and the CML 2001 (version 2.04) methodology. The long‐term management of stocks calls for a strong focus on cost optimization, energy efficiency, and environmental friendliness. Global warming and abiotic depletion emerge as the major impact categories from the water pipeline system, and the largest contribution is from the production and installation phases and the medium‐size pipelines in the network.     

Development of an Environmental Assessment Method for Consumer Electronics by combining Top-down and Bottom-up Approaches (11 pp)

Goal, Scope and Background Ecodesign requires environmental assessment methods, which are often time consuming and cost intensive. In this paper we proposed a method that combines top-down (e.g. LCA) and bottom-up (e.g. UNEP) approaches that allows one within short period of time to generate ecodesign ideas by identifying what to improve, how much to improve, and how to improve within a short period of time. The proposed method incorporates an environmental assessment method for use in the ecodesign of consumer electronics that employs the top-down and bottom-up approaches simultaneously. Method The proposed method consists of five modules: A. a life cycle thinking for a product, B. environmental benchmarking, C. checklist method, D. ecodesign strategies, and E. environmental design information. A key life cycle stage with significant environmental impact is identified in module A. When the identified key life cycle stage is not product manufacturing, environmental benchmarking is used; however, a checklist method is applied if product manufacturing is identified as the key life cycle stage. Ecodesign strategies for consumer electronics are obtained in module D. Environmental design information is produced by linking both the top-down and bottom-up information in module E. Results and Discussion The applicability of the proposed method was evaluated using mobile phones. First, the key life cycle stage of the mobile phone was identified as the raw material acquisition stage. Next, environmental benchmarking was carried out for 10 parameters belonging to the raw material acquisition stage. Environmental target specifications for the 10 parameters were set, ranging from 14% to 60%. Finally, environmental design information for the mobile phone was determined by linking the target specifications of the environmental benchmarking parameters and the corresponding ecodesign strategies. The proposed method was also compared with the LCA and the UNEP/promising approaches, which are representative examples of the top-down approach and the bottom-up approach, respectively. Based on the results of this comparison, the proposed method was judged to be an advanced method in facilitating the generation of ecodesign ideas. Environmentally significant benchmarking parameters correspond to what to improve, target specifications to on how much to improve, and ecodesign strategies ton how to improve. It was found that the use of the proposed method minimizes the time and money expenditure by confining the identification of environmental weak points within the key life cycle stage. Conclusion and Outlook An environmental assessment method for consumer electronics in ecodesign was proposed and applied to mobile phones. The advantages of the proposed method are as follows: it is efficient and cost-effective, and it allows designers to generate ecodesign ideas more easily and effectively by simultaneously identifying the specific environmental weak points of a product and corresponding ecodesign strategies. The proposed method can be envisaged as a useful ecodesign approach when electronic companies identify the environmental aspects of their products and integrate them into product design and development process.     

Dimensionality Reduction and Visualization of the Environmental Impacts of Domestic Appliances

There is an increasing worldwide concern about the problem of dealing with the waste electrical and electronic equipment (WEEE), given the high volume of appliances that are disposed of every day. In this article, an environmental evaluation of WEEE is performed that combines life cycle assessment (LCA) methodology and multivariate statistical techniques. Because LCA handles a large number of data in its different phases, when one is trying to uncover the structure of large multidimensional data sets, multivariate statistical techniques can provide useful information. In particular, principal‐component analysis and multidimensional scaling are two important dimension‐reducing tools that have been shown to be of help in understanding this type of complex multivariate data set. In this article, we use a variable selection method that reduces the number of categories for which the environmental impacts have to be computed; this step is especially useful when the number of impact categories or the number of products or processes to benchmark increases. We provide a detailed illustration showing how we have used the proposed approach to analyze and interpret the environmental impacts of different domestic appliances.     

Construction Matters: Comparing Environmental Impacts of Building Modular and Conventional Homes in the United States

Modular construction practices are used in many countries as an alternative to conventional on‐site construction for residential homes. While modular home construction has certain advantages in terms of material and time efficiency, it requires a different infrastructure than conventional home construction, and the overall environmental trade‐offs between the two methods have been unclear. This study uses life cycle assessment to quantify the environmental impacts of constructing a typical residential home using the two methods, based on data from several modular construction companies and conventional homebuilders. The study includes impacts from material production and transport, off‐site and on‐site energy use, worker transport, and waste management. For all categories considered, the average impacts of building the home are less for modular construction than for conventional construction, although these averages obscure significant variation among the individual projects and companies.     

Multicriteria Design of Plastic Recycling Based on Quality Information and Environmental Impacts

In this study, we develop a framework for the multicriteria design of plastic recycling based on quality information and environmental impacts for the purpose of supporting collaborative decision making among consumers, municipalities, and recyclers. The subject of this article is the mechanical recycling of postconsumer polyethylene terephthalate (PET) bottles. We present a “quality conversion matrix,” which links the quality of recycled PET resin to the quality of waste PET bottles and operational conditions, described in terms of the functions of modules constituting the entire recycling process. We estimate the quality of recycled PET resin and simulate the applicability to the intended products as the primary criterion by confirming whether the estimated quality of recycled resin satisfies the quality demands of PET resin users. The amounts of carbon dioxide (CO₂) emissions and fossil resource consumption are also estimated as the secondary criteria. An approach to collaborative decision making utilizing mixed‐integer linear programming (MILP) and Monte Carlo simulation is proposed on the premise of different objectives of various stakeholders, where all the feasible optimal solutions for achieving the quality demands are obtained. The quality requirements of waste bottles, along with the CO₂ emissions and fossil resource consumption estimated for each solution, contribute to the collaborative multicriteria design of plastic recycling.     

Implications of Uncertainty and Variability in the Life Cycle Assessment of Pig Production Systems(7 pp)

Goal, Scope and Background Calculating LCA outcomes implies the use of parameters, models, choices and scenarios which introduce uncertainty, as they imperfectly account for the variability of both human and environmental systems. The analysis of the uncertainty of LCA results, and its reduction by an improved estimation of key parameters and through the improvement of the models used to convert emissions into regional impacts, such as eutrophication, are major issues for LCA. Methods In a case study of pig production systems, we propose a simple quantification of the uncertainty of LCA results (intra-system variability) and we explore the inter-system variability to produce more robust LCA outcomes. The quantification of the intra-system uncertainty takes into account the variability of the technical performance (crop yield, feed efficiency) and of emission factors (for NH3, N2O and NO3) and the influence of the functional unit (FU) (kg of pig versus hectare used). For farming systems, the inter-system variability is investigated through differentiating the production mode (conventional, quality label, organic (OA)), and the farmer practices (Good Agricultural Practice (GAP) versus Over Fertilised (OF)), while for natural systems, variability due to physical and climatic characteristics of catchments expected to modify nitrate fate is explored. Results and Conclusion For the eutrophication and climate change impact categories, the uncertainty associated with field emissions contributes more to the overall uncertainty than the uncertainty associated with emissions from livestock buildings, with crop yield and with feed efficiency. For acidification, the uncertainty of emissions from livestock buildings is the single most important contributor to the overall uncertainty. The influence of the FU on eutrophication results is very important when comparing systems with different degrees of intensification such as GAP and OA. Concerning the inter-system variability, differences in farmer practices have a larger effect on eutrophication than differences between production modes. Finally, the physical characteristics of the catchment and the climate strongly affect the results for eutrophication. In conclusion, in this case study, the main sources of uncertainty are in the estimation of emission factors, due both to the variability of environmental conditions and to lack of knowledge (emissions of N2O at the field level), but also in the model used for assessing regional impacts such as eutrophication. Recommendation and Perspective Suitable deterministic simulation models integrating the main controlling variables (environmental conditions, farmer practices, technology used) should be used to predict the emissions of a given system as well as their probabilistic distribution allowing the use of stochastic modelling. Finally, our simulations on eutrophication illustrate the necessity of integrating the fate of pollutants in models of impact assessment and highlight the important margin of improvement existing for the eutrophication impact assessment model.