Autor(es): Ramzy Kahhat Abedrabbo y otros
This study analyzed the environmental impacts of a single-story residential building using different exterior wall systems. The environmental impacts over the complete life cycle of the residential buildings were determined and compared using the following indicators: air pollution index, energy consumption (embodied and operational), global warming potential, resource use, solid waste emissions, and water pollution index. The exterior wall systems analyzed were concrete block, poured in-place concrete, insulated concrete, traditional 0.05 m×0.1 m by 0.4 m ( 2 in.×4 in. by 16 in.) on center wood frame, traditional 0.05 m×0.15 m by 0.6 m ( 2 in.×6 in. by 24 in.) on center wood frame, and steel stud framing. Additionally, structural insulated panels were modeled for the operational energy of the building. For each scenario, the designs were based on the minimum 𝑅 value required by the International Building Code. ATHENA, a life-cycle assessment software tool, and eQuest, an energy usage modeling software tool that calculated the operational energy of the building, were used to evaluate the environmental impacts of the building, during the construction, use, and end of life phases, for each scenario. The results show that in the preuse phase, the insulated concrete buildings produce the greatest impact on the environment followed by the concrete block, poured in-place concrete, and steel stud buildings. Traditional wood frames had the fewest environmental impacts when considering only the preuse phase. In the use phase, the insulated concrete buildings had the lowest impacts to the environment because they required less operational energy, whereas concrete block, poured in-place concrete, traditional 0.05 m×0.15 m by 0.6 m ( 2 in.×6 in. by 24 in.) on center wood frame, traditional 0.05 m×0.1 m by 0.4 m ( 2 in.×4 in. by 16 in.) on center wood frame, and steel stud framing had progressively larger environmental impacts. The end of life phase was negligible with respect to the other phases. In the complete life-cycle assessment (LCA), 50-year life span, insulated concrete exterior walls used around 700 GJ (5%) less energy than traditional wood 0.05 m×0.15 m by 0.6 m ( 2 in.×6 in. by 24 in.) on center wall systems. The results also indicate the importance of exterior wall’s thermal mass for the energy performance of a building, especially for a city located in a hot climate zone such as Phoenix, Arizona, and the importance of a holistic approach, such as LCA, to properly assess the negative environmental impact of different technologies.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y Eric Williams
This paper considers the importation of used personal computers (PCs) in Peru and domestic practices in their production, reuse, and end-of-life processing. The empirical pillars of this study are analysis of government data describing trade in used and new computers and surveys and interviews of computer sellers, refurbishers, and recyclers. The United States is the primary source of used PCs imported to Peru. Analysis of shipment value (as measured by trade statistics) shows that 87−88% of imported used computers had a price higher than the ideal recycle value of constituent materials. The official trade in end-of-life computers is thus driven by reuse as opposed to recycling. The domestic reverse supply chain of PCs is well developed with extensive collection, reuse, and recycling. Environmental problems identified include open burning of copper-bearing wires to remove insulation and landfilling of CRT glass. Distinct from informal recycling in China and India, printed circuit boards are usually not recycled domestically but exported to Europe for advanced recycling or to China for (presumably) informal recycling. It is notable that purely economic considerations lead to circuit boards being exported to Europe where environmental standards are stringent, presumably due to higher recovery of precious metals.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y otros
Product lifespan is a fundamental variable in understanding the environmental impacts associated with the life cycle of products. Existing life cycle and materials flow studies of products, almost without exception, consider lifespan to be constant over time. To determine the validity of this assumption, this study provides an empirical documentation of the long-term evolution of personal computer lifespan, using a major U.S. university as a case study. Results indicate that over the period 1985−2000, computer lifespan (purchase to “disposal”) decreased steadily from a mean of 10.7 years in 1985 to 5.5 years in 2000. The distribution of lifespan also evolved, becoming narrower over time. Overall, however, lifespan distribution was broader than normally considered in life cycle assessments or materials flow forecasts of electronic waste management for policy. We argue that these results suggest that, at least for computers, the assumption of constant lifespan is problematic and that it is important to work toward understanding the dynamics of use patterns. We modify an age-structured model of population dynamics from biology as a modeling approach to describe product life cycles. Lastly, the purchase share and generation of obsolete computers from the higher education sector is estimated using different scenarios for the dynamics of product lifespan.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y otros
The dynamics of an e-commerce market and the associated environmental impacts from a bottom-up perspective using an agent-based model is explored. A conceptual meta-theory from psychology is adopted to form the behavioral rules of artificial consumers choosing different methods of buying a book, including conventional bookstores, e-commerce, and a proposed self-pick-up option. Given the energy and emissions savings that result from a shift to e-commerce from bookstore purchase, it appears that reductions in environmental impacts are relatively probable. Additionally, our results suggest that the shift to e-commerce is mainly due to the growth of Internet users, which ties energy and emissions savings to Internet penetration. Moreover, under any scenario, the energy and emissions savings will be provided by the introduction of the proposed self-pick-up option. Our model thus provides insights into market behaviors and related environmental impacts of the growing use of e-commerce systems at the retail level, and provides a basis for the development and implementation of more sustainable policies and practices.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y otros
We attempted to design and assess an example of a sustainable networked delivery (SND) system: a hybrid business-to-consumer book delivery system. This system is intended to reduce costs, achieve significant reductions in energy consumption, and reduce environmental emissions of critical local pollutants and greenhouse gases. The energy consumption and concomitant emissions of this delivery system compared with existing alternative delivery systems were estimated. We found that regarding energy consumption, an emerging hybrid delivery system which is a sustainable networked delivery system (SND) would consume 47 and 7 times less than the traditional networked delivery system (TND) and e-commerce networked delivery system (END). Regarding concomitant emissions, in the case of CO2, the SND system produced 32 and 7 times fewer emissions than the TND and END systems. Also the SND system offer meaningful economic benefit such as the costs of delivery and packaging, to the online retailer, grocery, and consumer. Our research results show that the SND system has a lot of possibilities to save local transportation energy consumption and delivery costs, and reduce environmental emissions in delivery system.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y otros
Reverse supply chains for the reuse, recycling, and disposal of goods are globalizing. This article critically reviews the environmental, economic, and social issues associated with international reuse and recycling of personal computers. Computers and other e-waste are often exported for reuse and recycling abroad. On the environmental side, our analysis suggests that the risk of leaching of toxic materials in computers from well-managed sanitary landfills is very small. On the other hand, there is an increasing body of scientific evidence that the environmental impacts of informal recycling in developing countries are serious. On the basis of existing evidence informal recycling is the most pressing environmental issue associated with e-waste. Socially, used markets abroad improve access to information technology by making low-priced computers available. Economically, the reuse and recycling sector provides employment. Existing policies efforts to manage e-waste focus on mandating domestic recycling systems and reducing toxic content of processes. We argue that existing policy directions will mitigate but not solve the problem of the environmental impacts of informal recycling. There are many opportunities yet to be explored to develop policies and technologies for reuse/recycling systems which are environmentally safe, encourage reuse of computers, and provide jobs.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y otros
E-commerce has been developed by the high integration of transportation infrastructures and information and communication technology (ICT) in complex urban systems. The dynamics of the e-commerce market can cause different environmental impacts. This paper explores the dynamics of e-commerce market and the associated environmental impacts from a psychological perspective using an agent-based model simulation. A conceptual meta-theory from psychology is adopted to form the behavioural rules of the artificial consumers choosing different methods of buying a book, including conventional bookstores, e-commerce, and a proposed self pick-up logistic system. The introduction of the self pick-up system can be successful according to the simulation results. The advantage of lower price will attract a group of consumers. The simulation results also show that different structures of the social network have significant impacts on the dynamics of this market. The environmental impacts in terms of energy consumption and emission generation will be reduced by the introduction of the proposed self pick-up system.
Ir al enlaceAutor(es): Ramzy Kahhat Abedrabbo y otros
Quantities of end-of-life electronics (or e-waste) around the world keep growing. More than 1.36 million metric tons of e-waste were discarded, mainly in landfills, in the U.S. in 2005, and e-waste is projected to grow in the next few years. This paper explores issues relating to planning future e-waste regulation and management systems in the U.S. It begins by reviewing the existing U.S. recycling systems in the U.S. to establish the importance of developing public responses. Other countries and regions around the world have already legislated and implemented electronic takeback and recycling systems. To establish the context of existing experience, e-waste management systems in the European Union, Japan, South Korea and Taiwan are explored. The paper then discusses what specific conditions are expected to influence the acceptability and implementation in the U.S. A key consideration is the cultural imperative in the U.S. for market-driven solutions that enable competition. Given this context, a solution is proposed that is designed to ensure a proper end-of-life option while at the same time establishing a competitive market for reuse and recycling services. The solution, termed e-Market for Returned Deposit, begins with a deposit paid by consumers to sellers at the time of purchase, electronically registered and tracked via a radio-frequency identification device (RFID) placed on the product. At end-of-life, consumers consult an Internet-enabled market in which firms compete to receive the deposit by offering consumers variable degrees of return on the deposit. After collection of the computer by the selected firm, the cyberinfrastructure utilizes the RFID to transfer the deposit to the winning firm when recycled. If the firm chooses to refurbish or resell the computer in lieu of recycling, the transfer is deferred until true end-of-life processing. Finally the paper discusses the domestic and international consequences of the implementation of the proposed design.
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