Universität Stuttgart

Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1

Browse

Search Results

Now showing 1 - 10 of 30

Open Access
Environmental impact of a mono-material timber building envelope with enhanced energy performance
(2022) Bucklin, Oliver; Di Bari, Roberta; Amtsberg, Felix; Menges, Achim
Broader adoption of timber construction is a strategy for reducing negative greenhouse gas (GHG) emissions created by the construction industry. This paper proposes a novel solid timber building envelope that uses computational design and digital fabrication to improve buildings’ energy performance. Timber beams are sawn with deep slits that improve thermal insulation and are milled with various joints for airtight, structural connections. To minimize embedded energy and to simplify disposal, the envelope is assembled without adhesives or metal fasteners. The building envelope is evaluated for thermal resistance and airtightness, and fabrication is evaluated for duration and power output during sawing. Finally, a Lifecycle Assessment (LCA) is carried out. The Global Warming Potential (GWP) is compared to that of other wood envelope systems with similar thermal conductance. Compared to other timber constructions with similar building physics properties, the proposed system showed lower GWP values (-15.63 kg CO2 eq./m² construction). The development and analysis demonstrate the potential to use digitally controlled subtractive manufacturing for improving the quality of solid timber to achieve higher environmental performance in building envelopes. However, further design and fabrication optimizations may be necessary to reduce required materials and production energy.
Open Access
Sustainability assessment of fuel cell buses in public transport
(2018) Lozanovski, Aleksandar; Whitehouse, Nicole; Ko, Nathanael; Whitehouse, Simon
Hydrogen fuel cell (H2FC) buses operating in every day public transport services around Europe are assessed for their sustainability against environmental, economic and social criteria. As part of this assessment the buses are evaluated against diesel buses both in terms of sustainability and in terms of meeting real world requirements with respect to operational performance. The study concludes that H2FC buses meet operability and performance criteria and are sustainable environmentally when ‘green’ hydrogen is used. The economic sustainability of the buses, in terms of affordability, achieves parity with their fossil fuel equivalent by 2030 when the indirect costs to human health and climate change are included. Societal acceptance by those who worked with and used the buses supports the positive findings of earlier studies, although satisfactory operability and performance are shown to be essential to positive attitudes. Influential policy makers expressed positive sentiments only if ‘green’ hydrogen is used and the affordability issues can be addressed. No “show-stopper” is identified that would prevent future generations from using H2FC buses in public transport on a broad scale due to damage to the environment or to other factors that impinge on quality of life.
Open Access
Managing uncertainties in LCA dataset selection
(2019) Pfeuffer, Simon; Wehner, Daniel; Bouslama, Raed
The selection of LCA datasets requires an understanding of the available datasets in a database and awareness about the uncertainties associated with the dataset selection. Therefore, a graphical presentation technique is introduced to support the communication of information about available datasets and uncertainties.
Open Access
Life cycle assessment for early-stage process optimization of microbial biosurfactant production using kinetic models : a case study on mannosylerythritol lipids (MEL)
(2024) Bippus, Lars; Briem, Ann-Kathrin; Beck, Alexander; Zibek, Susanne; Albrecht, Stefan
Introduction: This study assesses the environmental impacts of mannosylerythritol lipids (MELs) production for process optimization using life cycle assessment (LCA). MELs are glycolipid-type microbial biosurfactants with many possible applications based on their surface-active properties. They are generally produced by fungi from the family of Ustilaginaceae via fermentation in aerated bioreactors. The aim of our work is to accompany the development of biotechnological products at an early stage to enable environmentally sustainable process optimization. Methods: This is done by identifying hotspots and potentials for improvement based on a reliable quantification of the environmental impacts. The production processes of MELs are evaluated in a cradle-to-gate approach using the Environmental Footprint (EF) 3.1 impact assessment method. The LCA model is based on upscaled experimental data for the fermentation and purification, assuming the production at a 10 m³ scale. In the case analyzed, MELs are produced from rapeseed oil and glucose, and purified by separation, solvent extraction, and chromatography. Results: The results of the LCA show that the provision of substrates is a major source of environmental impacts and accounts for 20% of the impacts on Climate Change and more than 70% in the categories Acidification and Eutrophication. Moreover, 33% of the impacts on Climate Change is caused by the energy requirements for aeration of the bioreactor, while purification accounts for 42% of the impacts respectively. For the purification, solvents are identified as the main contributors in most impact categories. Discussion: The results illustrate the potentials for process optimization to reduce the environmental impacts of substrate requirements, enhanced bioreactor aeration, and efficient solvent use in downstream processing. By a scenario analysis, considering both experimental adaptations and prospective variations of the process, the laboratory development can be supported with further findings and hence efficiently optimized towards environmental sustainability. Moreover, the presentation of kinetic LCA results over the fermentation duration shows a novel way of calculating and visualizing results that corresponds to the way of thinking of process engineers using established environmental indicators and a detailed system analysis. Altogether, this LCA study supports and demonstrates the potential for further improvements towards more environmentally friendly produced surfactants.
Open Access
A process-planning framework for sustainable manufacturing
(2021) Reiff, Colin; Buser, Matthias; Betten, Thomas; Onuseit, Volkher; Hoßfeld, Max; Wehner, Daniel; Riedel, Oliver
Process planning in manufacturing today focuses on optimizing the conflicting targets of cost, quality, and time. Due to increasing social awareness and subsequent governmental regulation, environmental impact becomes a fourth major aspect. Eventually, sustainability in manufacturing ensures future competitiveness. In this paper, a framework for the planning of sustainable manufacturing is proposed. It is based on the abstraction and generalization of manufacturing resources and part descriptions, which are matched and ranked using a multi-criteria decision analysis method. Manufacturing resources provide values for cost, quality, time and environmental impacts, which multiply with their usage within a manufacturing task for a specific part. The framework is validated with a detailed modeling of a laser machine as a resource revealing benefits and optimization potential of the underlying data model. Finally, the framework is applied to a use case of a flange part with two different manufacturing strategies, i.e., laser metal-wire deposition and conventional milling. The most influential parameters regarding the environmental impacts are the raw material input, the manufacturing energy consumption and the machine production itself. In general, the framework enabled the identification of non-predetermined manufacturing possibilities and the comprehensive comparison of production resources.
Open Access
Reliability as a key driver for a sustainable design of adaptive load-bearing structures
(2022) Efinger, Dshamil; Ostertag, Andreas; Dazer, Martin; Borschewski, David; Albrecht, Stefan; Bertsche, Bernd
The consumption of construction materials and the pollution caused by their production can be reduced by the use of reliable adaptive load-bearing structures. Adaptive load-bearing structures are able to adapt to different load cases by specifically manipulating internal stresses using actuators installed in the structure. One main aspect of quality is reliability. A verification of reliability, and thus the safety of conventional structures, was a design issue. When it comes to adaptive load-bearing structures, the material savings reduce the stiffness of the structure, whereby integrated actuators with sensors and a control take over the stiffening. This article explains why the conventional design process is not sufficient for adaptive load-bearing structures and proposes a method for demonstrating improved reliability and environmental sustainability. For this purpose, an exemplary adaptive load-bearing structure is introduced. A linear elastic model, simulating tension in the elements of the adaptive load-bearing structure, supports the analysis. By means of a representative local load-spectrum, the operating life is estimated based on Woehler curves given by the Eurocode for the critical notches. Environmental sustainability is increased by including reliability and sustainability in design. For an exemplary high-rise adaptive load-bearing structure, this increase is more than 50%.
Open Access
Holistic quality model and assessment : supporting decision-making towards sustainable construction using the design and production of graded concrete components as an example
(2022) Frost, Deniz; Gericke, Oliver; Di Bari, Roberta; Balangé, Laura; Zhang, Li; Blagojevic, Boris; Nigl, David; Haag, Phillip; Blandini, Lucio; Jünger, Hans Christian; Kropp, Cordula; Leistner, Philip; Sawodny, Oliver; Schwieger, Volker; Sobek, Werner
This paper describes a holistic quality model (HQM) and assessment to support decision-making processes in construction. A graded concrete slab serves as an example to illustrate how to consider technical, environmental, and social quality criteria and their interrelations. The evaluation of the design and production process of the graded concrete component shows that it has advantages compared to a conventional solid slab, especially in terms of environmental performance. At the same time, the holistic quality model identifies potential improvements for the technology of graded concrete. It will be shown that the holistic quality model can be used to (a) consider the whole life cycle in decision-making in the early phases and, thus, make the complexity of construction processes manageable for quality and sustainability assessments and (b) make visible interdependencies between different quality and sustainability criteria, to help designers make better-informed decisions regarding the overall quality. The results show how different quality aspects can be assessed and trade-offs are also possible through the understanding of the relationships among characteristics. For this purpose, in addition to the quality assessment of graded concrete, an overview of the interrelations of different quality characteristics is provided. While this article demonstrates how a HQM can support decision-making in design, the validity of the presented evaluation is limited by the data availability and methodological challenges, specifically regarding the quantification of interrelations.
Open Access
The relevance of recyclability for the life cycle assessment of packaging based on Design for Life Cycle
(2022) Keller, Jonas; Scagnetti, Carla; Albrecht, Stefan
The awareness for more environmentally sustainable packaging solutions is steadily growing. With both consumers and manufacturers looking to minimize their impacts on the environment, the need for easy-to-implement and standardized measures strengthening a circular economy rises. In the research, the goal was to determine whether the carbon footprint and circularity of non-food plastic packaging can be improved by simple design changes. The results should then lead to design recommendations, providing a Design for Life Cycle approach. The methodology of the study was to conceptually design a single-use plastic packaging with attributes having positive and negative effects on recyclability. Herein, only design characteristics from products obtainable on the market were regarded. Moreover, a comparison over existing recyclability assessment methods is given. The recyclability was then determined with the selected approach by Cyclos HTP, and a reference calculation was conducted. Life Cycle Assessments were implemented for 14 packaging designs using the GaBi software and the Environmental Footprint method. The results showed that dark color, material compounds, insoluble adhesives, and large labels result in lower recyclability of the single-use packaging. The impacts on climate change range from 0.13 kg CO2-equivalent emissions (100% recyclability) to 0.21 kg CO2-equivalent emissions (0% recyclability) per packaging, showing that lower recyclability leads to a larger carbon footprint in all assessed scenarios. Concluding, the research demonstrated that by applying Design for Life Cycle measures, impacts on climate change can be reduced. Lastly, design recommendations for decision makers are outlined.
Open Access
Insect habitat systems integrated into façades : impact on building physics and awareness of society
(2020) Meier, Linda; Raps, Johanna; Leistner, Philip
Deforestation, intensive farming and the sealing of green spaces are considered to be the main reasons for the global decrease of biodiversity. In this context, the built environment, and in particular vertical surfaces, are still highly underestimated and need to be taken into account. Although it is acknowledged that greened surfaces have beneficial effects, for example, on the microclimate, the vast majority of buildings are still not biodiversity-friendly. Artificial nesting boxes help birds and bats adapt to the change of their habitats. However, insects, with their tremendous significance for insectivorous species and for humans, are mostly neglected or even threatened. The purpose of this holistic approach is to investigate interactions between integrated insect habitat systems in façades and building physical aspects to create test objects. Heat transfer coefficients, thermal bridges, and the risk of condensation inside the buildings were simulated in different arrangements of nesting boxes for wild bees. As a result, conclusions on heat and humidity protection in ventilated façades and external thermal insulation composite systems could be drawn. The following results showed the maintenance of indoor comfort and energy efficiency as well as a low risk of mold. Further investigations analyzed the sound reduction index and fire protection. From a building physical point of view, integrated insect habitat systems could be part of the constructed environment and even link inner-city biotopes. Further challenges and opportunities are identified rather at a socio-ecological and technical level. Without taking into account the civil society and ecological demands of the various species, habitat systems for insects will miss their objectives. Special focus will be put on the skepticism and lack of knowledge of people, as well as on the comfort of the insects.
Open Access
Moving beyond land use intensity types : assessing biodiversity impacts using fuzzy thinking
(2021) Lindner, Jan Paul; Eberle, Ulrike; Knuepffer, Eva; Coelho, Carla R. V.
The impact of land use on biodiversity is a topic that has received considerable attention in life cycle assessment (LCA). The methodology to assess biodiversity in LCA has been improved in the past decades. This paper contributes to this progress by building on the concept of conditions for maintained biodiversity. It describes the theory for the development of mathematical functions representing the impact of land uses and management practices on biodiversity. The method proposed here describes the impact of land use on biodiversity as a decrease in biodiversity potential, capturing the impact of management practices. The method can be applied with weighting between regions, such as ecoregions. The biodiversity potential is calculated through functions that describe not only parameters which are relevant to biodiversity, for example, deadwood in a forest, but also the relationships between those parameters. For example, maximum biodiversity would hypothetically occur when the nutrient balance is ideal and no pesticide is applied. As these relationships may not be readily quantified, we propose the use of fuzzy thinking for biodiversity assessment, using AND/OR operators. The method allows the inclusion of context parameters that represent neither the management nor the land use practice being investigated, but are nevertheless relevant to biodiversity. The parameters and relationships can be defined by either literature or expert interviews. We give recommendations on how to create the biodiversity potential functions by providing the reader with a set of questions that can help build the functions and find the relationship between parameters. We present a simplified case study of paper production in the Scandinavian and Russian Taiga to demonstrate the applicability of the method. We apply the method to two scenarios, one representing an intensive forestry practice, and another representing lower intensity forestry management. The results communicate the differences between the two scenarios quantitatively, but more importantly, are able to provide guidance on improved management. We discuss the advantages of this condition-based approach compared to pre-defined intensity classes. The potential drawbacks of defining potential functions from industry-derived studies are pointed out. This method also provides a less strict approach to a reference situation, consequently allowing the adequate assessment of cases in which the most beneficial biodiversity state is achieved through management practices. The originality of using fuzzy thinking is that it enables land use management practices to be accounted for in LCA without requiring sub-categories for different intensities to be explicitly established, thus moving beyond the classification of land use practices. The proposed method is another LCIA step toward closing the gap between land use management practices and biodiversity conservation goals.

Universität Stuttgart

Browse

Filters

Settings

Sort By

Results per page

Search Results