| 1. |
- Säwén, Toivo, 1993
(author)
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Early Stage Architectural Design Practice Perspectives on Life Cycle Building Performance Assessment
- 2023
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Licentiate thesis (other academic/artistic)abstract
- Architectural practitioners can avoid negative social and environmental impacts of new construction by making decisions supported by impact quantification during design processes. However, most software tools developed for such quantification see little use in practice, especially in early design stages when decisions have the greatest influence. To identify ways for software developers to overcome this situation, a thorough literature meta-review of previously performed tool reviews was combined with interviews applying a practice lens. The first key finding is that a possible explanation for the low tool uptake in practice could be a missing practice perspective in previous tool development efforts. In a literature meta-review of publications on life cycle building performance tools identifying previously applied perspectives, most previous tool reviews were found to support tool development and selection, while disregarding how tools can be integrated in existing practices and design processes. As a proposed solution, a framework for defining software requirements using a practice perspective was developed. The second key finding is that a practice perspective could be applied during software development by implementing qualitative methodologies. Nine architectural practitioners in Sweden, Norway and France were interviewed using the interview to the double, a projective technique in which the interviewee is asked to describe their next workday in detail so that their tasks can be assumed by an imagined body double. The design activities described by the respondents were sequenced into user narratives which could serve as starting points for participatory software development processes within the architectural practice. The outcomes - a proposed framework for practice-centric software requirements, and a proposed methodology for collecting these requirements using a practice lens - indicate a research direction toward software development efforts which aligns with design process, architectural practice, and tool user needs. In the next stage of the research this direction will be pursued through application of the developed methodologies in participatory development case studies in early-stage architectural design practice.
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| 2. |
- Ylva, Berglund, et al.
(author)
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Framsynt efterord
- 2013
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In: Mellanrum. Fem års seminarier om social hållbarhet och stadsutveckling i Göteborg.
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Book chapter (other academic/artistic)
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| 3. |
- Mangold, Mikael, 1982, et al.
(author)
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Building ownership, renovation investments, and energy performance - A study of multi-family dwellings in Gothenburg
- 2018
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In: Sustainability. - : MDPI AG. - 2071-1050. ; 10:5
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Journal article (peer-reviewed)abstract
- The European building stock was renewed at a rapid pace during the period 1950-1975. In many European countries, the building stock from this time needs to be renovated, and there are opportunities to introduce energy efficiency measures in the renovation process. Information availability and increasingly available analysis tools make it possible to assess the impact of policy and regulation. This article describes methods developed for analyzing investments in renovation and energy performance based on building ownership and inhabitant socio-economic information developed for Swedish authorities, to be used for the Swedish national renovations strategy in 2019. This was done by analyzing measured energy usage and renovation investments made during the last 30 years, coupled with building specific official information of buildings and resident area characteristics, for multi-family dwellings in Gothenburg (N = 6319). The statistical analyses show that more costly renovations lead to decreasing energy usage for heating, but buildings that have been renovated during the last decades have a higher energy usage when accounting for current heating system, ownership, and resident socio-economic background. It is appropriate to include an affordability aspect in larger renovation projects since economically disadvantaged groups are over-represented in buildings with poorer energy performance.
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| 4. |
- Rempling, Rasmus, 1976, et al.
(author)
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Utmattning
- 2021
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In: Betonghandbok material - Hårdnad betong, fysikaliska egenskaper och beständighet. - 9789179170882 ; , s. 485-510
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Book chapter (other academic/artistic)
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| 5. |
- Eriksson, Per-Erik, et al.
(author)
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Collaborative Procurement Strategies for Infrastructure Projects : A Multiple Case Study
- 2019
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In: Proceedings of the Institution of Civil Engineers. - : Institution of Civil Engineers (ICE). - 1751-4304 .- 1751-4312. ; 172:5, s. 197-205
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Journal article (peer-reviewed)abstract
- With the announcement to tender a project, several strategic decisions are made that have significant impact on the innovation and efficiency potential of a project. The purpose of this study is to investigate and compare how different types of integrative and collaborative procurement strategies may enhance the opportunities for improved efficiency and innovation in infrastructure projects. Hence, it contributes to the scientific debate on buyer-supplier relationships in relation to project performance. Furthermore, it guides public client organizations in steering explicitly for integration and innovation in their projects. Interview-based case studies of ten public infrastructure projects procured based on four different types of collaborative procurement strategies in Sweden and the Netherlands were conducted. The findings indicate that the duration of the collaboration is fundamental in setting the limits for innovation, and that early involvement as well as long-term commitments in maintenance open up for more innovation. Naturally, the potential for increased efficiency is higher than for innovation, and also occurs in collaborations with limited duration. The findings confirm the importance of a learning perspective on procurement strategies for public client organizations and show the importance of explicit considerations on incentives and project governance issues in the front-end phase of a project.
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| 6. |
- Mathern, Alexandre, 1986, et al.
(author)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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In: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Research review (peer-reviewed)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 7. |
- Brusselaers, Nicolas, 1993-
(author)
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The impact of off-site construction transport on air quality
- 2023
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Book (peer-reviewed)abstract
- While transport is inevitable in our economy and daily lives, it also engenders negative effects on the society and environment. The effects of air pollution are responsible for more than 364,200 premature deaths in Europe each year. Most urban areas still exceed the NOx and PM WHO air quality guidelines, of which a large share of pollutants is attributable to freight transport. The construction sector forms no exception, as it intrinsically strongly relies on off-site logistics activities, i.e. transports to and from sites. Although construction works lead to an urban economic uptake on the long-haul, the environmental nuisances from construction logistic (CL) activities during the works have so far been overlooked. This thesis focuses on the air quality impact of off-site construction transport, covering four main parts. First, as there is a lack of knowledge within cities on how to set construction transport demands and how to involve actors in these processes, a stakeholder framework is presented. Next, I identify the available and required transport data (and digitization possibilities) to assess the sector’s environmental impact, such as On-Board Units. Secondly, impact assessments were conducted across various construction supply chain implementations, on single-site, city-wide and national level. Hence, a methodological approach to derive construction-related vehicles from Heavy-Goods Vehicle (HGV) traffic based on algorithmic and geospatial analyses is proposed. Results indicate that construction transport represents 26.40% of total HGV traffic in the Brussels-Capital Region (BCR), generating €45,631.85 of external costs per workday, and 17.58% in Belgium (or €1.45mio per day). Subsequently, the framework was deployed to assess the transport performance of the multimodal Brussels Construction Consolidation Centre. The use of this setup can mitigate external costs by up to 59% compared to business-as-usual operations, most notably on congestion and climate change costs. However, improvements are necessary to tackle local emissions, attributable to less performant -yet ubiquitous- vessel engines. Air pollution damage costs also remain high on city level analyses, with CL inflicting €55,123.07 per month (or €2,505.59 per workday) in the BCR. A fortiori, with the growing concern on urban air quality, this raises the question of where, when and by whom the most exposure costs are inflicted. So far, the geo-temporal link between the emitting freight vehicle and its receptor densities was considered static. The third part introduces a dynamic impact-pathway approach, highlighting that PM & NO2 source impacts engender €61.604 of health costs in the BCR each day. Large differences were found on the local level compared to the traditional static approach, indicating that the proposed dynamic methodology should be used for micro-scale analyses (on link, building or neighborhood level). Striking is that vulnerable population segments such as toddlers, school children and elderly, who are more sensible to the effects of air pollution, incur 60.28% of the total health costs, although these segments represent only a quarter of the BCR population. Moreover, a strong overlap was found between the receptor’s presence (in particular children) and peak freight traffic movements. The fourth part investigates the exposure effects when off-site construction transport flows are spatiotemporally rerouted around air pollution hotspots. Although an increase in emissions is observed due to higher travelled distances and slower driving speeds, results show that the inflicted health costs can be mitigated up to 25.53%. Conclusively, this study suggests to decouple policies from absolute transport emissions and focus on the actual health impact, considering the spatiotemporal relationship of both emissions and receptors. Although tailoring a one-size-fits-all construction logistic plan can initially prove to be difficult due to the unique character of each construction site’s supply chain, the conducted studies also show that this individual complexity can be overcome by overall better integrated urban transport planning, and can ultimately lead to significant sustainability benefits.
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| 8. |
- Aldenlöv, Jens, et al.
(author)
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Public procurement of railway infrastructuremaintenance : a literature review
- 2017
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In: Proceedings of the 9th Nordic Conference on Construction Economics and Organization. - Lyngby : Polyteknisk Boghandel og Forlag. - 9788750211259 ; , s. 10-21
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Conference paper (peer-reviewed)abstract
- The maintenance of railway infrastructure has in several instances been changed from government-based to being based on public procurement, with varying degrees of flexibility for the contractor to design their maintenance work. The purpose of-giving contractors a larger freedom of choice of how to perform maintenance is to stimulate them to innovate and develop their maintenance processes. Since the contracts differ in between and there are changes in government policies over time that affects both existing and new contracts, a comparison between different contracts becomes challenging. A literature review has been conducted to understand the change in procurement strategy and how to encourage contractors to innovate. The research questions include: What procurement strategies are there? How is maintenance evaluated? How does procurement affect the innovation opportunities for entrepreneurs?The literature review focuses on railway maintenance and contract design between client and contractor. In total, 17 articles matched the search criteria and were selected for the review. To have successful maintenance service, five articles suggested partnering as a strategy with common goals in combination with good communication during the entirety of the contract. When selecting incentive plan, four articles mentions that a focus on performance-based incentives in combination with riskmanagement is better rather than actual payment schemes. The reason being that payment is often themain cause of conflicts between client and contractor. The scientific literature suggests that improvement in incentives improves quality of maintenance, decreases delays and technical failures. The conclusion from the literature review is that partnering in railway maintenance is considered successful. With accurate knowledge about railway assets the incentive plan becomes accurate which reduces costs.The literature review is a part of a research project with an overall goal to develop a model to guide the selection of appropriate type of procurement strategy, contract and control of maintenance for a moresustainable railway system.
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| 9. |
- Rempling, Rasmus, 1976, et al.
(author)
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Performance requirements for Swedish transport infrastructure - A pre-study of challenges and possibilities
- 2022
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Reports (other academic/artistic)abstract
- In recent years, significant worldwide research has been conducted regarding the performance assessment of bridges and the concept of performance indicator has been introduced However, there are still significant discrepancies in how these indicators are obtained and used. Simultaneously, it is desirable to achieve processes and methods that are direct, i.e. that measured values are directly compared with projected values over time. This project concerns methods for verification of technical performance requirements. The feasibility study brought together interdisciplinary researchers, consultants, and entrepreneurs to gather knowledge, anchor the research agenda, and implement performance requirements. The project concludes that there is a need for a “Holistic multi-parameter verification/validation system” that relies on the knowledge gained in structural health monitoring research.
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| 10. |
- Schade, Jutta, et al.
(author)
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Sjunde huset i Kiruna
- 2016
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In: Husbyggaren. - Stockholm. - 0018-7968. ; :4, s. 29-31
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Journal article (pop. science, debate, etc.)
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| 11. |
- Shadram, Farshid, 1987-
(author)
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Assessment and optimization of life cycle enrgy use in buildings
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Buildings account for 40% of all energy use in European countries. The European Union (EU) therefore encourages member states to adopt Energy Efficiency Measures (EEMs) and implement energy-efficient practices during building design to minimize the energy use of buildings. However, recent studies have shown that energy-efficient buildings may not always outperform conventional buildings in terms of Life Cycle Energy (LCE) use. This is mainly due to the trade-off between embodied and operational energy, and a reliance on EEMs that reduce operational energy while sometimes increasing embodied energy and LCE use. To improve buildings’ environmental performance, the impact of different EEMs on buildings’ energy use needs to be assessed from a lifecycle perspective, and methods for identifying optimal combinations of EEMs that minimize LCE use should be developed. Ideally, these methods should be integrated with building information modelling (BIM) to enable seamless data exchange and to help Architecture, Engineering and Construction (AEC) practitioners make optimal design decisions relating to EEMs. The work presented in this thesis had two overall objectives: (1) to explore the scope for developing BIM-supported method(s) for assessing and optimizing the impact of EEMs on buildings’ LCE use during the design process, and (2) use the BIM-supported method(s) for exploring the impact of various EEMs that are implemented and modified during the building design process on the buildings’ LCE use.The work presented in this thesis is based on an exploratory research design involving iterative cycles of (1) problem identification, (2) method development, (3) method examination, and (4) theory suggestion. In step 1, problems were identified by conducting literature studies and workshops with AEC practitioners, and analyzing archival data. In step 2, prototyping was used to develop methods to overcome the identified problems. In step 3, the applicability of these methods (or prototypes) was tested in case studies on actual and hypothetical building projects. Three case studies were conducted – one dealing with a low energy dwelling located in Kiruna, Sweden; another dealing with a multifamily residential building in Uppsala, Sweden; and a third dealing with a hypothetical multifamily residential building in Stockholm, Sweden. In step 4, the results were compared to existing theories to strengthen existing knowledge and identify previously unrecognized findings.In relation to the first objective, the results obtained show that the factors and activities required to develop BIM-supported method(s) for assessing and optimizing the impact of EEMs on a building’s LCE use during the design phase are:• A database that stores external and building project data (e.g. BIM data) and links it to be used for assessment and optimization, providing access to the data whenever needed.• The development of interfaces using middleware applications to ensure interoperability and seamless automated exchange of information between BIM and other systems.• Predefined objects (i.e. building part and component recipes) that are stored in a database and linked to inventories and Environmental Product Declarations (EPDs) for the relevant materials, enabling assessment of the buildings’ embodied energy and LCE use.• The application of multi-objective optimization techniques (e.g. Pareto-based genetic algorithms) to identify optimal solution(s) for EEMs that minimize (optimize) the building’s LCE use.In relation to the second objective of the thesis, the results obtained indicate that:• EEMs that are implemented and modified during the detailed design phase have much less influence on the building’s LCE use than those implemented in the early design phase. Highly influential EEMs related to the early design phase which were tested herein were the building’s shape, orientation, Window to Wall Ratio (WWR), and the selection of materials used in the building envelope.• Generally, thickening roof insulation has a strong beneficial effect on LCE use for buildings in Sweden.• For buildings using energy sources with high primary energy factors, the most effective way to reduce LCE use may be to implement many EEMs that reduce operational energy use. However, this approach may be less helpful for buildings using greener energy sources because in such cases the embodied energy may have a greater effect on the final LCE use.• The embodied energies of materials in the same class can vary significantly between suppliers. Such differences in embodied energy can be identified by considering the suppliers’ EPDs, the energetic contributions due to their mode of transportation from the site of production, and the distance between the site of production and the construction site.• If the developed optimization approach is used to identify optimal combinations of EEMs in the early design phase, designers can freely choose from a wide range of building shapes without greatly affecting LCE use. However, without early phase optimization, designs that use different building shapes may exhibit significantly different LCE use values.The results provide both theoretical and practical contributions that may be useful to researchers and AEC practitioners seeking to develop BIM-supported design processes and to reduce buildings’ LCE use by adopting appropriate EEMs. The results also show that embodied energy can be a major component of a building’s LCE use if the building’s design relies heavily on EEMs designed solely to reduce operational energy use. Policy makers and governmental bodies are thus advised to update regulations and building codes to reflect the importance of embodied energy so as to minimize the LCE use of new and retrofitting building projects.
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| 12. |
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| 13. |
- Mathern, Alexandre, 1986
(author)
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Addressing the complexity of sustainability-driven structural design: Computational design, optimization, and decision making
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Being one of the sectors with the largest environmental burden and high socio-economic impacts sets high requirements on the construction industry. At the same time, this provides the sector with great opportunities to contribute to the globally pursued sustainability transition. To cope with the increasing need for infrastructure and, at the same time, limit their sustainability impacts, changes and innovation in the construction sector are required. The greatest possibility to limit the sustainability impact of construction works is at the early design phase of construction projects, as many of the choices influencing sustainability are made at that point. Traditionally, an early choice of a preferred design is often made based on limited knowledge and past experience, considering only a handful of options. This preferred design is then taken on to the successive stages in the stepwise design process, leading to suboptimization. Alternatively, many different design choices could be considered and evaluated in a more holistic approach in order to find the most sustainable design for a particular application. However, finding design solutions that offer the best sustainability performance and fulfil all structural, performance and buildability requirements, require methods that allow considering different design options, analysing them, and assessing their sustainability. The aim of this thesis is to explore and develop methods enabling structural engineers to take sustainability objectives into account in the design of structures. Throughout this thesis, a number of methods have been explored to take sustainability aspects into account in the structural design process. As a first step, highly parameterized computer codes for sustainability-driven design have been developed. These codes interoperate with FE analysis software to automatically model and analyse design concepts over the whole design space and verify compliance with structural design standards. The codes were complemented with a harmonized method for life cycle sustainability performance assessment, in line with the state-of-the-art standards. Here, sustainability criteria were defined covering environmental, social, economic, buildability and structural performance for multi-criteria assessment of design concepts. To identify the most sustainable designs within the set, multi-objective optimization algorithms were used. Algorithms that address the high expense of constraint function evaluations of structural design problems were developed and integrated in the parameterized computer codes for sustainability-driven design. To ensure the applicability and validity of these methods, case studies based on real-world projects and common structural engineering problems were used in this thesis. Case studies for bridges and wind turbine foundations as well as a benchmark case of a reinforced concrete beam were investigated. The case studies highlight the potential of the methods explored to support the design of more sustainable structures, as well as the applicability of the methods in structural engineering practice. It is concluded that it is possible and beneficial to combine computational design, life cycle sustainability assessment, and multi-objective design optimization as a basis for decision making in the design phase of civil engineering projects. A wide adoption of such a sustainability-driven design optimization approach in structural engineering practice can directly improve the sustainability of the construction sector.
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| 14. |
- Eriksson, Per-Erik, et al.
(author)
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Managing complex projects in the infrastructure sector : A structural equation model for flexibility-focused project management
- 2017
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In: International Journal of Project Management. - : Elsevier. - 0263-7863 .- 1873-4634. ; 35:8, s. 1512-1523
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Journal article (peer-reviewed)abstract
- Complex construction projects in the infrastructure sector are often beset with delays, which cause benefit shortfalls and increased costs. Prior project management literature and practice have mostly adopted a traditional control-focused approach, but recent research suggests that complex projects need more flexible practices to manage inevitable project change. Thus, the objectives of this study were to develop and empirically test a model for flexibility-focused project management practices to improve time performance in complex projects in the infrastructure sector. Based on empirical data from 138 construction projects procured and managed by the Swedish Transport Administration, the structural equation model shows that complexity and collaboration drive explorative learning, which improves adaptation and thereby improves time performance. Hence, the empirical test verifies that flexibility-focused project management practices based on collaboration, explorative learning, and adaptation enhance time performance in complex projects in the infrastructure sector.
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| 15. |
- Dervishaj, Arlind
(author)
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Sunlight Autonomy for Sustainable Buildings and Cities : Maximizing daylight potential outdoors and indoors
- 2024
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Conference paper (peer-reviewed)abstract
- Daylight, both outdoors and indoors, is essential for human well-being. However, daylight provision often faces challenges in various climates and locations, due to factors such as shortcomings in regulations, urban densification, deregulation or special exemptions, and the limitations of existing daylight and sunlight evaluation methods. To address these issues, we propose the Sunlight Autonomy, a new methodology and set of metrics, that aims to overcome the limitations of existing early-stage daylighting metrics and is valuable for urban planning and architectural design purposes.
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| 16. |
- Desivyana, Nindya, 1997, et al.
(author)
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Challenges in the adoption of sustainable criteria in the Swedish property development industry
- 2023
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In: Procedia Computer Science. - : Elsevier BV. - 1877-0509. ; 219, s. 1752-1759
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Conference paper (peer-reviewed)abstract
- The construction industry is facing an increased focus on sustainability and climate neutrality, causing property developers to implement new requirements into the procurement documents, which are also driven by the national agenda. This study explores the current state of sustainability practice among Swedish property developers and identifies the main obstacles to expand further the implementation of the sustainability criteria. How the property developers define and implement sustainability requirements has been assessed through qualitative semi-structured interviews, focusing on sustainability certification systems, Life Cycle Assessment (LCA), and social sustainability. The results show usage of sustainability certification systems for marketing purposes and high awareness and practice of LCA, even though the accuracy of LCA was questioned. This study also identified guideline gaps for circular economy and social sustainability measurements, which could relate to low initiatives from the certification systems.
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| 17. |
- Femenias, Paula, 1966, et al.
(author)
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Från omfattande till varsam renovering
- 2019
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In: Hållbar renovering ur ett helhetsperspektiv: En antologi från forskningsmiljön SIRen. - 9789188722652 ; , s. 47-54
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Book chapter (other academic/artistic)
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| 18. |
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| 19. |
- Saukkoriipi, Lasse, 1977, et al.
(author)
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Measurement of waste and productivity in relation to lean thinking
- 2007
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In: Proceedings of 15th annual conference of the International Group for Lean Construction. - East Lansing : Michigan State University Press. ; , s. 67-76
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Journal article (peer-reviewed)abstract
- In the Swedish construction sector there have been debates concerning what can be done about the current low productivity and the high levels of wastes. During the last few years it has become more common to utilize principles from lean construction as a way to enhance the problems concerning the levels of productivity and waste. The aim of this paper is to do a literature review on measurement of waste and productivity. Terms waste and productivity will be compared and discussed in relation to lean construction. Furthermore this paper will highlight the use of lean philosophy to reduce waste and improve productivity in the Swedish construction industries. The study shows that the term ‘waste’ is more closely related to lean thinking than productivity is, but both terms are according to our analysis nonetheless important when striving for cost reductions. Furthermore there is a need of changing in the way of thinking in order to create a value added activities that can cut down production cost in the Swedish construction industries.
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| 20. |
- van Eldert, Jeroen, 1987-, et al.
(author)
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Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling
- 2020
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In: Rock Mechanics and Rock Engineering. - : Springer. - 0723-2632 .- 1434-453X. ; 53:3, s. 1349-1358
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Journal article (peer-reviewed)abstract
- A tunnelling project is normally initiated with a site investigation to determine the in situ rock mass conditions and to generate the basis for the tunnel design and rock support. However, since site investigations often are based on limited information (surface mapping, geophysical profiles, few bore holes, etc.), the estimation of the rock mass conditions may contain inaccuracies, resulting in underestimating the required rock support. The study hypothesised that these inaccuracies could be reduced using Measurement While Drilling (MWD) technology to assist in the decision-making process. A case study of two tunnels in the Stockholm bypass found the rock mass quality was severely overestimated by the site investigation; more than 45% of the investigated sections had a lower rock mass quality than expected. MWD data were recorded in 25 m grout holes and 6 m blast holes. The MWD data were normalised so that the long grout holes with larger hole diameters and the shorter blast holes with smaller hole diameters gave similar results. With normalised MWD data, it was possible to mimic the tunnel contour mapping; results showed good correlation with mapped Q-value and installed rock support. MWD technology can improve the accuracy of forecasting the rock mass ahead of the face. It can bridge the information gap between the early, somewhat uncertain geotechnical site investigation and the geological mapping done after excavation to optimise rock support.
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| 21. |
- Checinska, Aleksandra, et al.
(author)
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Microbiomes of the dust particles collected from the International Space Station and Spacecraft Assembly Facilities
- 2015
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In: Microbiome. - : Springer Science and Business Media LLC. - 2049-2618. ; 3
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Journal article (peer-reviewed)abstract
- Background - The International Space Station (ISS) is a unique built environment due to the effects of microgravity, space radiation, elevated carbon dioxide levels, and especially continuous human habitation. Understanding the composition of the ISS microbial community will facilitate further development of safety and maintenance practices. The primary goal of this study was to characterize the viable microbiome of the ISS-built environment. A second objective was to determine if the built environments of Earth-based cleanrooms associated with space exploration are an appropriate model of the ISS environment. Results - Samples collected from the ISS and two cleanrooms at the Jet Propulsion Laboratory (JPL, Pasadena, CA) were analyzed by traditional cultivation, adenosine triphosphate (ATP), and propidium monoazide–quantitative polymerase chain reaction (PMA-qPCR) assays to estimate viable microbial populations. The 16S rRNA gene Illumina iTag sequencing was used to elucidate microbial diversity and explore differences between ISS and cleanroom microbiomes. Statistical analyses showed that members of the phyla Actinobacteria, Firmicutes, and Proteobacteria were dominant in the samples examined but varied in abundance. Actinobacteria were predominant in the ISS samples whereas Proteobacteria, least abundant in the ISS, dominated in the cleanroom samples. The viable bacterial populations seen by PMA treatment were greatly decreased. However, the treatment did not appear to have an effect on the bacterial composition (diversity) associated with each sampling site. Conclusions - The results of this study provide strong evidence that specific human skin-associated microorganisms make a substantial contribution to the ISS microbiome, which is not the case in Earth-based cleanrooms. For example, Corynebacterium and Propionibacterium (Actinobacteria) but not Staphylococcus (Firmicutes) species are dominant on the ISS in terms of viable and total bacterial community composition. The results obtained will facilitate future studies to determine how stable the ISS environment is over time. The present results also demonstrate the value of measuring viable cell diversity and population size at any sampling site. This information can be used to identify sites that can be targeted for more stringent cleaning. Finally, the results will allow comparisons with other built sites and facilitate future improvements on the ISS that will ensure astronaut health.
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| 22. |
- Abarenkov, Kessy, et al.
(author)
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Annotating public fungal ITS sequences from the built environment according to the MIxS-Built Environment standard – a report from a May 23-24, 2016 workshop (Gothenburg, Sweden)
- 2016
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In: MycoKeys. - : Pensoft Publishers. - 1314-4057 .- 1314-4049. ; 16, s. 1-15
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Journal article (peer-reviewed)abstract
- Recent molecular studies have identified substantial fungal diversity in indoor environments. Fungi and fungal particles have been linked to a range of potentially unwanted effects in the built environment, including asthma, decay of building materials, and food spoilage. The study of the built mycobiome is hampered by a number of constraints, one of which is the poor state of the metadata annotation of fungal DNA sequences from the built environment in public databases. In order to enable precise interrogation of such data – for example, “retrieve all fungal sequences recovered from bathrooms” – a workshop was organized at the University of Gothenburg (May 23-24, 2016) to annotate public fungal barcode (ITS) sequences according to the MIxS-Built Environment annotation standard (http://gensc.org/mixs/). The 36 participants assembled a total of 45,488 data points from the published literature, including the addition of 8,430 instances of countries of collection from a total of 83 countries, 5,801 instances of building types, and 3,876 instances of surface-air contaminants. The results were implemented in the UNITE database for molecular identification of fungi (http://unite.ut.ee) and were shared with other online resources. Data obtained from human/animal pathogenic fungi will furthermore be verified on culture based metadata for subsequent inclusion in the ISHAM-ITS database (http://its.mycologylab.org).
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| 23. |
- Karrbom Gustavsson, Tina, 1973-, et al.
(author)
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Procurement Research: Current State and Future Challenges in the Nordic Countries
- 2019
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In: 10th Nordic Conference on Construction Economics and Organization (Emerald Reach Proceedings Series, Volume 2). - : Emerald Group Publishing Limited. ; 2, s. 195-204
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Conference paper (peer-reviewed)abstract
- PurposeThe purpose of the study is to map previous and current construction procurement research to further develop the research in the Nordic counties.Design/Methodology/ApproachMapping of previous and current research based on search in national database. The analysis is based on research perspectives, empirical contexts and research methods.FindingsThat the blind spots are partly overlapping, but that there is potential for knowledge transfer in some areas. There is also the potential for a Nordic research program on one or several of the blind spots.Research Limitations/ImplicationsThe study is limited to PhD and licentiate-thesis reports in Norway and Sweden. Further research should include the other Nordic countries and a more extensive literature review including journal articles to broaden the scope. Findings have implications on collaborative Nordic research initiatives, knowledge transfer and in a longer perspective on the level of procurement knowledge in industry and society.Practical ImplicationsFindings provide a base for future research collaborations, initiatives and applications.Originality/ValueFindings provide a comprehensive understanding of construction procurement research in the Nordic countries, starting with Norway and Sweden. This understanding is needed for developing research collaborations and applications.
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| 24. |
- Larsson, Bengt, 1943-, et al.
(author)
-
The Effect and Cost Impact of Poor Airtightness : Information for Developers and Clients
- 2007
-
In: Thermal Performance of the Exterior Envelopes of Whole Buildings. - Orlando : ASHRAE. - 2166-8469. - 9781933742281
-
Conference paper (peer-reviewed)abstract
- Air movements in and through the building envelope affect the flows of not only heat, but also moisture, gases and particles, in a building. They often play a decisive part in determining moisture conditions, and thus indoor environmental conditions in the building, and ultimately, the durability of the building structure. Air flows affect thermal comfort and ventilation, and thus air quality. In addition, they also cause heat loss, both directly via ventilation, and through their effect on the performance of what are intended to be high-insulation structures.A previous joint project between SP Technical Research Institute of Sweden and Chalmers University of Technology investigated the importance of airtightness in the construction process. The project found that many types of damage and problems were caused by poor airtightness, that airtightness was seldom given the proper consideration that it deserved and that there was a major need for information on the effect of poor airtightness. One of the conclusions was that it is important to get developers/clients to treat airtightness more seriously.The objective of the follow-on project that is described here is therefore to make developers/clients (more) aware of the potential damage that can be caused by poor airtightness, together with the “cost” of this damage/problem in a life-cycle perspective. Hopefully, developers/clients will then specify and monitor airtightness requirements more clearly. The aim is therefore to develop tools and methods for informing developers/clients of the importance of good airtightness, and of the resulting extra costs that incur from paying insufficient attention to airtightness.The project has identified and assessed various consequences of poor airtightness, such as increased energy use, reduced thermal comfort, reduced air quality and moisture damages.The cost calculations show that the developer/client would benefit in most cases from an increased standard and follow up on airtightness. We have projected the work with three different levels of ambition: 0.2, 0.4 and 0.6 l/m2s (at 50 Pa pressure difference), and believe that the optimal airtightness lies somewhere in the region of these values, depending on the buildings use and equipment.
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| 25. |
- Rempling, Rasmus, 1976, et al.
(author)
-
Research Roadmap - Information Integration in Construction
- 2019
-
Reports (other academic/artistic)abstract
- This Roadmap is developed for a challenging Global environment where fundamental paradigms such as data generation and analysis, are shifting at a seismic rate, while change in Construction Industries across the Globe is, in the main, confined to large-scale projects and slow. Against this background, the authors set out to also give a ‘voice’ to small-to-medium scale projects through which the construction output Worldwide is delivered. Hence, project scale was one of the key considerations throughout this Roadmap. Moreover, the authors conceptualized data integration by taking the realities of doing business’ in construction into consideration. The emergent framework facilitates the discussion of knowledge and data integration at organisational, team, operational and technical levels across key project phases. This approach recognizes that business is done through projects but change can only come about if appropriate organizational structures and processes are put in place. Last, but not least, the authors strived to ensure that data integration was not considered solely from a technical perspective. Organisational, team and individual aspects of data integration were integrated in the research framework. Through our work the individual’s willingness to collaborate emerged as a critical driver for high levels of integration, while our survey did identify “Reluctance to work across professional boundaries” as a major barrier to integration. Hence, we conclude that research on integration should pay due attention to the individual.
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| 26. |
- Thunberg, Micael, 1986-, et al.
(author)
-
Categorising on-site problems : A supply chain management perspective on construction projects
- 2017
-
In: Construction Innovation. - : Emerald Group Publishing Limited. - 1471-4175 .- 1477-0857. ; 17:1, s. 90-111
-
Journal article (peer-reviewed)abstract
- Purpose - This study aims to identify and categorise common on-site problems from a supply chain management (SCM) perspective and to trace the origin of these problems in the construction project process, the supply chain or in the intersection between these processes. This allows for identification of how on-site problems affect SCM in construction projects and how they can be mitigated. Design/methodology/approach - A literature review in combination with semi-structured interviews was used to identify on-site problems. This enabled triangulation and strengthened both construct validity and internal validity. Findings - On-site problems can be categorised in one of the four following categories: material flows, internal communication, external communication or complexity. The first category has its origin in the supply chain, the second in the construction project process, the third in the supply chain-construction process intersection on site and the fourth in the construction project as a whole. The findings conclude that on-site problems often originate from construction companies' lack of supply chain orientation. Research limitations/implications - It is suggested that supply chain planning (SCP) can facilitate on-site problem mitigation in construction project management. This extends the body of knowledge of SCP in construction project management and supports the development of effective on-site construction project management. Practical implications - The results show that SCP can aid construction project management in handling on-site problems earlier in the project process. Originality/value - The main value lies in extending the body of knowledge in construction project management research by applying an SCM perspective and by introducing SCP to support more effective construction project management.
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| 27. |
- Bröchner, Jan, 1948, et al.
(author)
-
Construction productivity measures for innovation projects
- 2012
-
In: Journal of Construction Engineering and Management - ASCE. - 1943-7862 .- 0733-9364. ; 138:5, s. 670-677
-
Journal article (peer-reviewed)abstract
- A 30-year retrospective analysis of resource use in a range of new construction and repair projects reveals insignificant productivity increase when applying traditional narrow measures, as shown in a case study of beam bridges. It appears as necessary to estimate hidden quality changes in both outputs and inputs. Changes in government regulations, in specifications, and the development of nonprice criteria for contract award emerge as important. Schemes for benchmarking the performance of construction projects as well as life-cycle analyses suggest that customer risk aversion and effects on customer productivity should be taken into account. The outcome is a set of measurements that can be applied to the selection of any type of proposed new construction or repair technology innovation according to their potential impact on industry productivity.
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| 28. |
- Roupé, Mattias, 1975, et al.
(author)
-
Immersive visualization of Building Information Models
- 2016
-
In: Living Systems and Micro-Utopias: Towards Continuous Designing, Proceedings of the 21st International Conference of the Association for Computer-Aided Architectural Design Research in Asia (CAADRIA 2016). - 9789881902672 ; , s. 673-682
-
Conference paper (peer-reviewed)abstract
- The design process of a building often involves many different actors and people with different experiences, level of knowledge and ability to interpret information. The most common information media in these processes are 2D-drawings, documents and 3D images of design. These media can be difficult to interpret and understand and could cause communication difficulties and design errors. However, in this context, Building Information Modelling (BIM) and Virtual Reality (VR) have been shown to offer an efficient communication platform. In this paper we present and evaluate a portable immersive visualization system that uses the BIMs directly from the design tools. The system is validated in a real construction project, where the dif-ferent disciplines in the design process used the system. The result was collected through interviews and observation during usage of the system. All the participants expressed that this type of visual interface helped them to get another level of understanding and perception of space, which lead to better decision-making process and resolving of design issues.
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| 29. |
- Bröchner, Jan, 1948, et al.
(author)
-
From ideas to construction innovations: firms and universities collaborating
- 2016
-
In: Construction Economics and Building. - 2204-9029. ; 16:1, s. 76-89
-
Journal article (peer-reviewed)abstract
- The purpose here is to study patterns of project collaboration found in one government supported programme for construction innovation. Preferred types of interaction were identified using data from two questionnaire surveys, one with experienced construction sector respondents and one aimed at construction researchers. All sixteen development projects within the Swedish Bygginnovationen programme were investigated, relying on documents and a survey of project managers. Important types of interaction, according to construction respondents, are informal contacts, joint research projects and staff mobility. For university respondents, informal contacts is also seen as the most important type of interaction, followed by MSc thesis work in firms and industrial PhD candidates. Grant applicants from manufacturing depended more on university laboratories and were less sensitive to firm/university distance. Laboratory use was also more frequent for projects relying on the field of materials engineering. In conclusion, there is a consensus about which types of collaboration are valuable. The broadness of participation in the programme, ranging over many industries, both as to origin of ideas and ultimate applications, reaches beyond narrow interpretations of the construction industry. Policy makers should recognize the innovation importance of university laboratory facilities and field testing, rather than seeing researchers as sources of ideas.
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| 30. |
- Jansson, Gustav, et al.
(author)
-
Requirements transformation in construction design
- 2010
-
In: CIB W78 27th International Conference on Applications of IT in the AEC Industry & Accelerating BIM Research Workshop.
-
Conference paper (other academic/artistic)abstract
- Transformation of performance requirements to technical solutions and production parameters is central for architects and engineers in the design process. Construction industry suffers from low efficiency in design, and the information flow creating bottlenecks for the production process. Tracing and managing information through design process needs standards both for requirements and Building Information Models in a life cycle perspective. Structuring functional requirements is of great interest for the construction industry and especially for companies developing industrialised housing system that often have control over the whole manufacturing process. The delivery of a new low-carbon economy in Europe puts pressure on the construction industry to reduce the energy consumption for buildings. Therefore is one national standard for energy requirements tested on a building system and evaluated in an Information and Communication Technology-environment (ICT) that supports the design process for industrialised construction. The result of the research shows that the transformation of requirements to technical solutions needs functionality that supports the design process by using standards for requirements. A rigid building system based on well defined design tasks together with a technical platform, both for spaces and physical elements, work as a backbone for development of ICT support systems. Product Life Cycle Support (PLCS), as a standard that enables flexibility in categorisation of information through the construction design.
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| 31. |
- Mathern, Alexandre, 1986, et al.
(author)
-
Practical metamodel‑assisted multi‑objective design optimization for improved sustainability and buildability of wind turbine foundations
- 2022
-
In: Structural and Multidisciplinary Optimization. - : Springer Science and Business Media LLC. - 1615-1488 .- 1615-147X. ; 65:2
-
Journal article (peer-reviewed)abstract
- In this work, we study the potential of using kriging metamodelling to perform multi-objective structural design optimization using finite element analysis software and design standards while keeping the computational efforts low. A method is proposed, which includes sustainability and buildability objectives, and it is applied to a case study of reinforced concrete foundations for wind turbines based on data from a large Swedish wind farm project. Sensitivity analyses are conducted to investigate the influence of the penalty factor applied to unfeasible solutions and the size of the initial sample generated by Latin hypercube sampling. A multi-objective optimization is then performed to obtain the optimum designs for different weight combinations for the four objectives considered. Results show that the kriging-obtained designs from samples of 20 designs outperform the best designs in the samples of 1000 designs. The optimum designs obtained by the proposed method have a sustainability impact 8–15% lower than the designs developed by traditional methods.
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| 32. |
- Shadram, Farshid, 1987-, et al.
(author)
-
Improving Life Cycle Sustainability and Profitability of Buildings through Optimization: A Case Study
- 2022
-
In: Buildings. - : MDPI. - 2075-5309. ; 12:4
-
Journal article (peer-reviewed)abstract
- Building developers are continuously seeking solutions to increase saleable/rentable floor area and thus the profitability of investments, especially in large/dense cities where the real estate/rental values are high and shortage of available land results in smaller building footprints. Application of passive energy efficiency measures (e.g., thick insulation in walls) not only affects the life cycle sustainability of buildings, but also the floor area and its profitability. This can affect the decisions made on the choice of measures when aiming to improve sustainability. In line with limited studies in this context, a case study is presented here in which multi-objective optimization was used to explore the impact of various passive energy efficiency measures on the life cycle sustainability when accounting for the profitability of the floor area. The building case was a high-rise apartment based on a standardized building concept situated in different locations in Sweden, namely Vindeln, Gothenburg, and Stockholm. The findings indicated that, regardless of the location, use of (1) thick cellulose coating for the roof, and (2) moderately thick expanded polystyrene for the floor, were necessary to improve the life cycle sustainability. However, the optimal wall insulation was dependent on the location; in locations with high real estate values, the scope for using thick and conventional insulations (mineral wool/cellulose) was limited due to the significant economic loss caused by floor area reductions. In general, the optimization identified optimal solutions that could save up to 1410.7 GJ energy, 23 tonnes CO2e, and 248.4 TEUR cost from a life cycle perspective relative to the building’s initial design.
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| 33. |
- Viklund, Emma, et al.
(author)
-
Modularization based on commonalities in house-building requirements
- 2017
-
In: ICCREM 2016. - Reston, VA : American Society of Civil Engineers (ASCE). - 9780784480274 ; , s. 126-134
-
Conference paper (peer-reviewed)abstract
- Some of the requirements governing the design of houses are common between projects. This opens up for using modularization based on product commonalities. Though modularization is well known in the manufacturing industry, its use in house-building contexts is less studied. Even more scarce is research focusing on how requirement commonalities between one-of-a-kind products are found and managed in a modularization process. In this research, modularization from a requirements management perspective is empirically explored using a case study approach. Though the studied modularization process can be described as sequential, the process steps are highly interrelated, with overlaps and iterations. Commonalities are found by functional decomposition of the customer's portfolio projects, tracing technical solutions back to their initial requirements. These are balanced with the customer's requirements on the product and on the design automation tool. The requirement list is continuously updated based on portfolio analysis and communication of modularization results to the customer
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| 34. |
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| 35. |
- Hagbert, Pernilla, 1986
(author)
-
Den gröna byggbranschens paradox
- 2013
-
In: Att svära i kyrkan - tjugofyra röster om evig tillväxt på en ändlig planet. - 9789198146707 ; , s. 206-217
-
Book chapter (other academic/artistic)
|
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| 36. |
|
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| 37. |
- Karrbom Gustavsson, Tina, et al.
(author)
-
A program perspective on partnering as supply chain integration
- 2017
-
In: Proceedings of the 9th Nordic Conference on Construction Economics and Organization. - Lyngby : Polyteknisk Boghandel og Forlag. - 9788750211259
-
Conference paper (peer-reviewed)abstract
- Major complex urban development projects are challenging and put pressure on coordination, cooperation and integration between a multitude of various interdependent construction projects and supply chains. While prior studies on supply chain integration mostly concern continuous exchanges in manufacturing industries, there is less research on discontinuous exchanges in project-based supply chains. This knowledge gap has resulted in an increased interest for partnering as supply chain integration in project-based supply chains and there is a conceptual and practical framework developed for understanding partnering as a multidimensional construct including four dimensions of supply chain integration: strength, scope, duration and depth of integration. This framework is useful for investigating separate projects but fails to acknowledge the program perspective including inter-project coordination and the interdependence between different projects and supply chains in the same program.The purpose of this study is to investigate how SCI may be achieved across projects within the same program. Findings are drawn from a case study of Stockholm Royal Seaport. Each stage of Stockholm Royal Seaport can be studied as a program including a multitude of interdependent and parallel projects performed within a limited timeframe and a limited area. The findings suggest that supply chain integration between projects is as important as within projects and the theoretical implications suggest an additional dimension to the multidimensional partnering framework when taking a program perspective. Partnering as supply chain integration has a width dimension on program management level that is more challenging to manage since formal procurement and contracting mechanisms are put in place mainly at the project level, not the program level.
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| 38. |
- Silfwerbrand, Johan, et al.
(author)
-
Performance-based requirements in design-build contracting for highway construction and maintenance
- 2019
-
In: FIB 2018 - Proceedings for the 2018 fib Congress. - : Federation Internationale du Beton (fib). ; , s. 470-478, s. 470-478
-
Conference paper (peer-reviewed)abstract
- Design-build contracts with performance-based specifications are believed to raise productivity and the innovation rate. However, performance-based requirements used in specifications for highway and bridge contracts may suffer from being too detailed or too difficult to verify. A Swedish research project has been devoted to this issue. The aims were (i) to develop a definition of performance-based requirements and (ii) to evaluate performance-based requirements used in Swedish design-build contracts. The project consisted of three parts: (i) literature survey, (ii) investigation of current documents produced and used by the Swedish Transport Administration for design-build contracts, and (iii) case studies of six design-build contracts with performance-based requirements, including an analysis of specification documents and interviews with both client and contractor project managers. Current performance-based specifications show different degrees of detail. Measurable requirements are more frequently used on roads, and in particular on road surfaces, than on bridges. Further development is needed to promote technical innovations. Less detailed specifications and a shift to design-build-operate contracts with prolonged maintenance responsibility would also encourage the choice of more durable and long-lasting (=sustainable) solutions. The emphasis on Life Cycle Cost (LCC) in the reformulated contract award criteria in the EU public procurement directive might be insufficient to strengthen the competitive power of concrete pavements as compared to asphalt pavements, unless specifications are supported by Life Cycle Analysis (LCA) and the choice of contract type is reconsidered.
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| 39. |
- Gschösser, Florian, et al.
(author)
-
Hidden Ecological Potentials in the Production of Materials for Swiss Road Pavements
- 2012
-
In: Journal of Management in Engineering - ASCE. - 0742-597X. ; 27:1, s. 13-21
-
Journal article (peer-reviewed)abstract
- Sustainability has become a major concern in the field of civil infrastructures in recent years. Developing road construction projects with lower ecological impacts over a project’s entire life cycle can help in making road infrastructure contribute to sustainable development. This study focuses on the ecological potentials in the production of road materials used in Swiss road pavements. The environmental assessment was performed using a cradle-to-gate life-cycle assessment (LCA) approach in which all processes from the raw material extraction to the finished product were considered. The comparison of the results of the best-case asphalt pavement and the standard asphalt pavement for Swiss highway construction shows ecological potentials of up to 55%. Use of the best-case concrete pavement lowers the environmental impact by up to 53% in comparison to the worst-case concrete pavement for Swiss highways. Concerning composite pavements, the best-case variant offers an ecological potential 38% higher than the standard pavement.
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| 40. |
- Mathern, Alexandre, 1986, et al.
(author)
-
Experimental study of time-dependent properties of a low-pH concrete for deposition tunnels
- 2018
-
In: fib Symposium. - 2617-4820. ; , s. 1726-1735
-
Conference paper (peer-reviewed)abstract
- The Swedish Nuclear Fuel and Waste Management Company developed a method for the final disposal of canisters for spent nuclear fuel in tunnels at depths of about 500 meters. The concept for closure of the deposition tunnels is based on a bentonite seal supported by a spherical concrete dome structure. In order to fulfil the requirements specific to the repository concept, a special mix of low-pH self-compacting concrete was developed. A series of large-scale castings and laboratory tests were conducted to gain experience on this low-pH concrete mix, in conjunction with the full-scale demonstration test of an unreinforced concrete dome plug in the underground hard rock laboratory in Äspö, Sweden. The laboratory tests aimed at studying the creep properties under high sustained compressive stresses of the low-pH concrete mix, its shrinkage properties and the properties of the rock-concrete interface. This paper provides an overview of these tests and analyses the latest results of the recently completed creep tests, which include 6 years of measurements. These results allow to improve understanding of the structural behaviour of the concrete plug and to assess the effects of the very high pressure acting on the plug on its deformations, cracking and water tightness.
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| 41. |
- Sayahi, Faez
(author)
-
Application of ILD2300-10 Laser Sensor on Measuring the Vertical Displacement of Fresh Concrete Surface : Technical report
- 2017
-
Reports (pop. science, debate, etc.)abstract
- Early age (< 24 h after mixing) behaviour of concrete is very critical as it may cause cracking, which eventually can dramatically influence the aesthetic, durability and serviceability of the structure. In order to have a general comprehension of the phenomenon and the governing mechanism, it is essential to measure and monitor various parameters. One of these parameters is the vertical displacement (settlement) of the concrete that can give a clue of the rheology, stiffening and approximate capillary pressure onset.After casting the concrete the solid particles of the mixture start to settle under the gravitational forces. This settlement starts immediately after placing the mixture in the mould and continues until the solid skeleton of the concrete is stiff enough to hold the weight of the particles. In such case the settlement either stops or increases with lower rate.This technical report, summarizes tests performed at Luleå University of Technology in order to evaluate the function of ILD2300-10 laser sensor (manufactured by Micro-Epsilon Snsotest AB) in measuring the settlement of fresh concrete. The laser sensor was used to measure the vertical displacement of both conventional and self-compacting concrete (SCC) cast in a mould made according to the ASTM C 1579 standard. Both mixtures had 0.67 water-cement ratio (w/c). The results show very accurate readings of the concrete settlement which clearly shows the differences of the two concrete types. Moreover, it was found that the sensor is very practical on the moist concrete and the thin water layer that covers the surface after casting does not have any significant influence on the accuracy of the measurements.However, it was noticed that the sensor is not efficient to measure the vertical displacement when airflow blows across the concrete surface.
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| 42. |
- Acuña, José, 1982-
(author)
-
Distributed thermal response tests : New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes
- 2013
-
Artistic work (other academic/artistic)abstract
- U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.
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| 43. |
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| 44. |
- Dervishaj, Arlind, et al.
(author)
-
A digital workflow for assessing lifespan, carbonation, and embodied carbon of reusing concrete in buildings
- 2024
-
In: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 96, s. 1-23
-
Journal article (peer-reviewed)abstract
- Concrete is the most used construction material, accounting for 8% of global CO2 emissions. Various strategies aim to reduce concrete's embodied carbon, such as using supplementary cementitious materials, utilizing cleaner energy, and carbonation. However, a large potential lies in reusing concrete for new buildings in a Circular Economy, thereby closing material loops and avoiding CO2 emissions.This study focuses on the reuse of precast concrete elements. We present a digital workflow for assessing reuse by predicting the remaining service life, estimating CO2 uptake by natural carbonation, and calculating the embodied carbon savings of concrete reuse. Both carbonation rates from EN 16757 and our investigation were applied to a case study building.While EN 16757 rates suggest that most precast elements have reached the end of their service life, our assessment shows that these elements have a sufficient lifespan for reuse. Plaster and coverings significantly delay carbonation and extend service life. During the first service life following EN 16757, carbonation was 19,2 kg CO2/m3, whereas our prediction was 5,4 kg CO2/m3. Moreover, CO2 uptake during service life, including reuse, was less than 6% of the embodied carbon. The climate benefits of reuse greatly exceeded those of carbonation.Furthermore, carbonation did not have a decisive influence when applying Cut-Off, Distributed, and End-of-Life allocations for assessing embodied carbon of re-used elements in subsequent life cycles. The digital workflow is useful in quickly assessing lifespan, carbonation, and embodied carbon of concrete. It can be leveraged as a decision-making tool when designing for reuse.
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| 45. |
- Jensen, Patrik, et al.
(author)
-
Applying products in product platforms in the AEC firm
- 2014
-
In: Computing in civil and building engineering. - Reston, VA : American Society of Civil Engineers (ASCE). - 9780784413616 ; , s. 1062-1069
-
Conference paper (peer-reviewed)abstract
- A 5 step method for developing configurable “products in product” platforms to be used in an engineer-to-order (ETO) design process is proposed. The idea is based on the transformation of typical product architectures into modular design platforms where standard and variant modules are identified and developed. The platform modules can then be configured and combined with traditional design methods to meet the project specific requirements in the design process. Based on 1193 project designs, several configurable “products in product” were identified and developed in a real case study using the proposed method.
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| 46. |
- Laurell-Stenlund, Kristina, et al.
(author)
-
Projekt: Nya Giron
- 2011
-
Other publication (pop. science, debate, etc.)abstract
- Finansierat av Tillväxtverket EU-Mål 3/Finaced by the European Regional Development Fund
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| 47. |
- Nilforoush, Rasoul, et al.
(author)
-
Tensile breakout capacity of cast-in-place headed anchors in concrete
- 2017
-
In: XXIIIth Symposium on Nordic Concrete Research & Developement. - Oslo, Norway. - 9788282080569 ; , s. 235-238
-
Conference paper (peer-reviewed)abstract
- The influence of member thickness, size of anchor head, and orthogonal surface reinforcement on the tensile breakout capacity of cast-in-place headed anchors was studied both numerically and experimentally. The aim of this paper is to form a background for developing improved methods for the design of new fastening systems as well as the assessment of the current anchorage systems in practice. Numerical and experimental results showed that the tensile breakout capacity of anchor bolts increases by increasing the member thickness or if surface reinforcement is present. Furthermore, the anchorage capacity increases with increasing the anchor head size.
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| 48. |
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| 49. |
- Schade, Jutta, et al.
(author)
-
The thermal performance of a green roof on a highly insulated building in a sub-arctic climate
- 2021
-
In: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 241
-
Journal article (peer-reviewed)abstract
- Green roofs are complex systems, with a vegetation layer covering the outermost surface of the building shell. An effective design may confer environmental and energy benefits. Most field studies evaluating green roof performance have been conducted in warmer climates with few studies of full-scale green roofs in cold regions. No study has so far evaluated the energy performance of a green roof in a sub-arctic climate. This study demonstrates the heat flow and thermal effect of an extensive green roof versus a black bare roof area on a highly insulated building in the sub-arctic town of Kiruna, Sweden, for the period from November 2016 to February 2018. Measured temperature and heat flux values were consistently higher and more variable for the black roof than the green roof, except during the snow-covered winter months when the responses were similar. The cumulative heat flux showed that the net heat loss was greater through the black than the green roof, but the values remained low. Overall, the study confirms that the energy benefit of a green roof on a highly insulated building in a subarctic climate is low.
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| 50. |
- Simonsson, Peter, et al.
(author)
-
'Learning to see' the effects of improved workflow in civil engineering projects
- 2012
-
In: Lean Construction Journal. - 1555-1369. ; , s. 35-48
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Journal article (peer-reviewed)abstract
- Research Question/Hypothesis: Value Stream Mapping (VSM) can, independent of work repetition, improve the performance of civil engineering projects by allowing the site management to visualize the flows of materials, resources and information.Purpose: The purpose is to show how VSM can be used by on-site practitioners to see the day-to-day flow of work, to understand the effect of straight-forward improvements to workflow, and to see the effect of applying industrialized working methods.Research Method: Applicability of VSM to civil engineering is examined through the fixing of reinforcement in two bridge construction projects. A traditional bridge was used to map (current state) and improve (future state) workflow. The potential of modern production methods are then analyzed in a second bridge project (ideal state).Findings: Allowing the site management to visualize and to see workflow improves the work performance of the two studied bridges. Addition of easy to understand and calculable metrics for lead time, inventory level and manufacturing costs, emphasize the potential savings of reactive and proactive workflow measures (≈ 80-90 %).Limitations: The paper considers fixing of reinforcement in two bridge construction projects. Additionally, the so-called future state bridge was not actually constructed, i.e. the savings stated for the future state, even if reasonable, are an approximation.Implications: The framework to visualize current, future and ideal workflow provides a framework to extend the VSM methodology to civil engineering projects.Value for practitioners: To overcome the sub-optimized mindset in civil engineering that repeatedly leads to the same practice, the paper proposes a straightforward and easy to use framework to visualize and analyze effects of workflow improvements.
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