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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Life Cycle Assessment of concrete structures using public databases : Comparison of a fictitious bridge and tunnel

Boulenger, Maxime January 2011 (has links)
Concrete structures represent a huge investment in terms of materials and energy and they lead to significant environmental impacts. Thus, there is a need to choose the most sustainable and eco-friendly alternative. From this perspective, this report aims to evaluate the environmental impacts associated with the construction of two fictitious structures: a bridge and a tunnel. To fully assess and fairly compare the environmental burdens of those two structures, the life cycle assessment (LCA) has been chosen. Prior to the case studies, the LCA process is described and a literature review related to LCAs of road structures is performed thus revealing the key facts and key figures of such studies. Based on this literature review, a simplified LCA is performed; it relies on public databases and only takes into account the construction phase. Because of data constraints, the indicators that are considered are NOx, SO2 and CO2 emissions, and the categories that are taken into account are energy consumption, global warming potential and photochemical oxidant formation. Characterization factors come from the REciPE method. Three different stages are considered and compared during this LCA study; the production of materials, the construction processes and the transportation phase. Results show that the environmental impacts of the bridge are higher than the ones of the tunnel and that the amount of concrete has a strong influence on the final results and consequently on the interpretation phase. This study also emphasizes the importance of assumptions and describes their potential influence on the final results by considering two different alternatives related to the concrete’s manufacturing. Making the concrete directly on site instead of bringing it by truck significantly decreases the environmental impacts of both structures; indeed, for the bridge structure, it leads to a diminution in CO2 emissions, global warming potential and energy consumption by more than 60%. The main constraint of this study has been the data collection for the life cycle inventory; indeed, many data were missing or coming from different public databases which result in a lack of thoroughness and precision (e.g. different geographical representativeness). Results of this study strongly depend on the various assumptions and on the data that have been collected, and technical choices, methodologies of construction or structural design mainly depend on the project’s location; consequently, results and conclusions cannot be generalized and should be handled carefully.
2

Assessing design strategies for improved life cycle environmental performance of vehicles

Poulikidou, Sofia January 2016 (has links)
Vehicle manufactures have adopted different strategies for improving the environmental performance of their fleet including lightweight design and alternative drivetrains such as EVs. Both strategies reduce energy during use but may result in a relative increase of the impact during other stages. To address this, a lifecycle approach is needed when vehicle design strategies are developed. The thesis explores the extent that such a lifecycle approach is adopted today and assesses the potential of these strategies to reduce the lifecycle impact of vehicles. Moreover it aims to contribute to method development for lifecycle considerations during product development and material selection. Current practices were explored in an empirical study with four vehicle manufacturers. The availability of tools for identifying, monitoring and assessing design strategies was explored in a literature review. The results of the empirical study showed that environmental considerations during product development often lack a lifecycle perspective. Regarding the use of tools a limited number of such tools were utilized systematically by the studied companies despite the numerous tools available in literature. The influence of new design strategies on the lifecycle environmental performance of vehicles was assessed in three case studies; two looking into lightweight design and one at EVs. Both strategies resulted in energy and GHG emissions savings though the impact during manufacturing increases due to the advanced materials used. Assumptions relating to the operating conditions of the vehicle e.g. lifetime distance or for EVs the carbon intensity of the energy mix, influence the level of this tradeoff. Despite its low share in terms of environmental impact EOL is important in the overall performance of vehicles. The thesis contributed to method development by suggesting a systematic approach for material selection. The approach combines material and environmental analysis tools thus increases the possibilities for lifecycle improvements while minimizing risk for sub-optimizations. / <p>QC 20160920</p>
3

Kundanpassad LCA för nätverkskameror / Customized LCA for Network Cameras

Hillerström, Hanna, Troborg, Ulrika January 2010 (has links)
Antalet övervakningskameror i samhället ökar, samtidigt som deras miljöpåverkan är relativt okänd. För en produkt som tidigare bara utvärderats gällande prestanda, börjar kunderna nu efterfråga en kartläggning av miljöpåverkan. Kamerans miljöpåverkan studeras ur ett livscykelperspektiv: energi- och materialtillförsel samt utsläpp och avfall som berör allt ifrån råmaterialutvinning till slutåtervinning. Projektet är genomfört på begäran av, och för, Axis Communications AB (härmed refererade till som Axis) med huvudsyfte att öka Axis kunskap om deras produkters miljöpåverkan och utveckla en metod för genomförande av förenklade livscykelanalyser på Axis produkter. Livscykelanalysen, LCA, genomförs på en nätverkskamera utvecklad av Axis Communications AB; modell AXIS Q6032-E PTZ. Samtidigt togs metoden för förenklade livscykelanalyser fram för att möjliggöra jämförelse med andra kameramodeller i företagets produktportfolio. Även en plattform har skapats för att kunna användas i produktutvecklingens tidigare skede, för att redan där göra ett aktivt miljöval. Den metod som används för bedömning av miljöpåverkan är Eco-indicator 99. Simulering och beräkningar sker i LCA-programmet SimaPro 7.1.Resultatet visar att den största miljöpåverkan kommer ifrån användningsfasen och behovet av elektricitet. För scenariot där kameran används i Europa har tillverkningen näst störst påverkan, därefter materialanvändningen och sist transporterna. Återvinningen påverkar med ett negativt värde, d.v.s. den påverkar miljön på ett positivt sätt. Det alternativa scenariot (där kameran flygs till USA och installeras där) ger en totalt större miljöpåverkan och har transporterna som andra värsta kategorin. Vid beräkningar för Europa släpper kameran ut 663 kg CO2 under sin livstid. Den utvecklade modellen överensstämmer till 0,24% med resultatet ifrån simuleringsprogrammet. Modellen kan enligt den genomförda känslighetsanalysen anses stabil / The number of surveillance cameras installed for various purposes have increased substantially in society over the past decade. The environmental impacts from network cameras are relatively unknown and their rapid increase in number calls for studying the impacts from a life cycle perspective; from raw material extraction to decommissioning. The project is performed on request by Axis Communications AB (hereby referred to as Axis) with the main purposes to increase Axis's knowledge of the environmental impact from their products and establish a method for conducting simplified life cycle assessments (LCA) on Axis products. A case study LCA is conducted on a network camera developed by Axis; model AXIS Q6032-E PTZ. Concurrently a method for conducting simplified LCAs on other Axis cameras is developed as well as a platform to be used in product development processes to enhance life cycle thinking (LCT). The Eco-indicator 99 Method is used for the environmental impact assessment and for simulations and calculations the software program SimaPro 7.1 is used.The results emphasize the life stages and their particular activities having the largest potential environmental impacts; primarily utilization and the production of electricity. For the scenario where the camera is installed in Europe the manufacturing comes as second, then raw material extraction and processing, followed by transportations. Decommissioning impacts with a negative value, i.e. impacts the environment in a positive way. The alternative scenario (where the camera is transported by air to U.S. and installed there) gives a total higher score and has the transportation category as the second highest regarding the total environmental impact. During the whole lifetime the camera emits 663 kg CO2.The results from using the developed model to conduct simplified LCAs only differ by 0.24% from the results of the case study LCA. The LCA is considered stable based on the performed sensitivity analysis.

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