lnu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1234567 101 - 150 av 512
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 101.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Climate change impacts on overheating risk and primary energy use for space conditioning of a Swedish multi-story building2016Ingår i: CLIMA 2016: Proceedings of the 12th REHVA World Congress / [ed] Per Kvols Heiselberg, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study we investigate the potential impacts of future climate change scenarios on overheating risk and primary energy use for space conditioning of a newly built multi-story apartment building in Växjö, Sweden. The building is district heated and potentially cooled by stand-alone air conditioners. We consider climate change scenarios for the period 2050-2059, historical climate of 1961-1990 and recent climate of 1996-2005. The climate change scenarios are based on the representative concentration pathways 4.5 and 8.5. We explore the risk of overheating of the building and analyse the impacts of different strategies for overheating control, including increased airing and solar shading besides mechanical cooling. We investigate the implications of different renewable based electricity supply options for space cooling and ventilation of the building. The results show that the space heating demand is significantly reduced and cooling demand is strongly increased for the building with the future climate scenarios. Furthermore the risk of overheating increases under the climate change scenarios. Among the overheating control strategies analysed, solar shading is the single most effective measure, giving the lowest primary energy use for space conditioning. Complementing the electricity from biomass-fired condensing power plants with solar-based electricity reduced the space conditioning primary energy use by 4-9%. Adding increased airing to the control strategies increased the primary energy use.

  • 102.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Comparative life cycle and carbon footprint analyses of wood building systems designed as conventional or passive house standard2014Ingår i: World Sustainable Building 2014 Barcelona Conference: Sustainable Buildings:Results Are We Moving as quickly as we should? It's up to us! Conference Proceedings Volume 2, GBCe , 2014, s. 284-290Konferensbidrag (Refereegranskat)
  • 103.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Effect of energy efficiency requirements for residential buildings in Sweden on lifecycle primary energy use2014Ingår i: Energy Procedia: INTERNATIONAL CONFERENCE ON APPLIED ENERGY, ICAE2014 / [ed] Yan, J; Lee, DJ; Chou, SK; Desideri, U; Li, H, Elsevier, 2014, Vol. 61, s. 1183-1186Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study we analyze the lifecycle primary energy use of a wood-frame apartment building designed to meet the current Swedish building code or passive house criteria, and heated with district heat or bedrock heat pump. We employ a lifecycle perspective methodology and determine the production, operation and end-of-life primary energy use of the buildings. We find that the passive house requirement strongly reduces the final energy use for heating compared to the current Swedish building code. However, the primary energy use is largely determined by the energy supply system, which is generally outside the mandate of the building standards. Overall, buildings with district heating have lower life-cycle primary energy use than alternatives heated with heat pump. The primary energy for production is small relative to that for operation, but it is more significant as the energy-efficiency standard of building improves and when efficient energy supply is used. Our results show the importance of a system-wide lifecycle perspective in reducing primary energy use in the built environment. A life cycle primary energy perspective is needed to minimize overall primary energy use, and future building energy-efficiency standards may reflect the full energy use during a building's life cycle. This could include primary energy implications for production, operation and end-of-life of buildings.

  • 104.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Energy use and overheating risk of Swedish multi-storey residential buildings under different climate scenarios2016Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 97, s. 534-548Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the extent to which different climate scenarios influence overheating risk, energy use and peak loads for space conditioning of district heated multi-storey buildings in Sweden are explored. Furthermore, the effectiveness of different overheating control measures and the implications of different electricity supply options for space cooling and ventilation are investigated. The analysis is based on buildings with different architectural and energy efficiency configurations including a prefab concrete-frame, a massive timber-frame and a light timber-frame building. Thermal performance of the buildings under low and high Representative Concentration Pathway climate scenarios for 2050–2059 and 2090–2099 are analysed and compared to that under historical climate of 1961–1990 and recent climate of 1996–2005. The study is based on a bottom-up methodology and includes detailed hour-by-hour energy balance and systems analyses. The results show significant changes in the buildings’ thermal performance under the future climate scenarios, relative to the historical and recent climates. Heating demand decreased significantly while cooling demand and overheating risk increased considerably with the future climate scenarios, for all buildings. In contrast to the cooling demand, the relative changes in heating demand of the buildings under the future climate scenarios are somewhat similar. The changes in the space conditioning demands and overheating risk vary for the buildings. Overheating risk was found to be slightly higher for the massive-frame building and slightly lower for the light-frame building.

  • 105.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Life cycle primary energy use and carbon footprint of wood-frame conventional and passive houses with biomass-based energy supply2013Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, s. 834-842Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study the primary energy use and carbon footprint over the life cycle of a wood-frame apartmentbuilding designed either conventionally or to the passive house standard are analyzed. Scenarioswhere the building is heated with electric resistance heaters, bedrock heat pump or cogeneration-baseddistrict heat, all with biomass-based energy supply, are compared. The analysis covers all life cyclephases of the buildings, including extraction of raw materials, processing of raw materials into buildingmaterials, fabrication and assembly of materials into a ready building, operation and use of the buildings,and the demolition of the buildings and the post-use management of the building materials. Theprimary energy analysis encompasses the entire energy chains from the extraction of natural resourcesto the delivered energy services. The carbon footprint accounting includes fossil fuel emissions, cementprocess reaction emissions, potential avoided fossil fuel emissions due to biomass residues substitutionand end-of-life benefit of post-use materials. The results show that the operation of the buildingaccounts for the largest share of life cycle primary energy use. The passive house design reduces theprimary energy use and CO2 emission for heating, and the significance of this reduction depends onthe type of heating and energy supply systems. The choice of end-use heating system strongly influencesthe life cycle impacts. A biomass-based system with cogeneration of district heat and electricitygives low primary energy use and low carbon footprint, even with a conventional design. The amountof biomass residues from the wood products chain is large and can be used to substitute fossil fuels.This significantly reduces the net carbon footprint for both the conventional and passive house designs.This study shows the importance of adopting a life cycle perspective involving production, construction,operation, end-of-life, and energy supply when evaluating the primary energy use and climaticimpacts of both passive and conventional buildings.

  • 106.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Bonakdar, Farshid
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Effects of future climate change scenarios on overheating risk and primary energy use for Swedish residential buildings2014Ingår i: Energy Procedia: INTERNATIONAL CONFERENCE ON APPLIED ENERGY, ICAE2014 / [ed] Yan, J; Lee, DJ; Chou, SK; Desideri, U; Li, H, Elsevier, 2014, Vol. 61, s. 1179-1182Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study we use dynamic computer simulation modelling to investigate the potential impact of future climate change scenarios on the risk of overheating and annual primary energy requirements for space heating and cooling of residential buildings in Växjö, Sweden. The buildings are designed to the energy efficiency level of conventional or passive house, and are assumed to be heated with district heating and cooled with mechanical cooling system. We compare different climate change scenarios to a baseline which represents the climate data of Växjö for 1996-2005. The climate change scenarios are based on projected temperature changes under the representative concentration pathways (RCP) 4.5 and 8.5 scenarios. The result shows that the risk of overheating increases under the climate change scenarios. Furthermore space heating demand is reduced and cooling demand is increased for the analyzed buildings, and the changes are proportionally more significant for the passive compared to the conventional building.

  • 107.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Sathre, Roger
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Climate impacts of wood vs. non-wood buildings2016Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report documents the findings of a project commissioned by the SwedishAssociation of Local Authorities and Regions on energy and climateimplications of building structural-frame materials from a life cycle perspective.The report is compiled by researchers within the Sustainable Built EnvironmentGroup (SBER) at Linnaeus University, Växjö, Sweden, and it addresses theterms of reference of the project agreement, including review of existingliterature and reports on energy and climate implications of wood-frame andnon-wood-frame building systems.The report’s primarily focus is: the effect of material choice on different lifecycle stages of a building; the significance of building frame material in relationto the total primary energy use and climate impact of a building; keymethodological issues linked to life cycle analysis of buildings; and theimportance of system perspective in analysis of a building’s climate impacts.

  • 108.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK. Mittuniversitetet, Östersund.
    Gustavsson, Leif
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sathre, Roger
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Effect of thermal mass on life cycle primary energy balances of a concrete- and a wood-frame building2012Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 92, s. 462-472Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study we analyze the effect of thermal mass on space heating energy use and life cycle primary energy balances of a concrete- and a wood-frame building. The analysis includes primary energy use during the production, operation, and end-of-life phases. Based on hour-by-hour dynamic modeling of heat flows in building mass configurations we calculate the energy saving benefits of thermal mass during the operation phase of the buildings. Our results indicate that the energy savings due to thermal mass is small and varies with the climatic location and energy efficiency levels of the buildings. A concrete-frame building has slightly lower space heating demand than a wood-frame alternative, due to the higher thermal mass of concrete-based materials. Still, a wood-frame building has a lower life cycle primary energy balance than a concrete-frame alternative. This is due primarily to the lower production primary energy use and greater bioenergy recovery benefits of the wood-frame buildings. These advantages outweigh the energy saving benefits of thermal mass. We conclude that the influence of thermal mass on space heating energy use for buildings located in Nordic climate is small and that wood-frame buildings with cogeneration based district heating would be an effective means of reducing primary energy use in the built environment.

  • 109.
    Dodoo, Ambrose
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Gustavsson, Leif
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Sathre, Roger
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Impacts of end-use energy efficiency measures on life cycle primary energy use in an existing Swedish multi-story apartment building2011Ingår i: World Renewable Energy Congress 2011, Linköping, Sweden, May 8-11, Linköping University Electronic Press, 2011Konferensbidrag (Refereegranskat)
  • 110.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Gustavsson, Leif
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sathre, Roger
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Life cycle primary energy analysis of conventional and passive house buildings2011Ingår i: Proceeding SB11, World Sustainable Building Conference, Helsinki, Finland, October 18-21, 2011Konferensbidrag (Refereegranskat)
  • 111.
    Dodoo, Ambrose
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Gustavsson, Leif
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Sathre, Roger
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Life cycle primary energy perspective on retrofitting an existing building to passive house standard2010Ingår i: SB10, Sustainable Community, Espoo, Finland, September 22-24, 2010, 2010Konferensbidrag (Refereegranskat)
  • 112.
    Dodoo, Ambrose
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Gustavsson, Leif
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Sathre, Roger
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Life cycle primary energy use of an apartment building designed to the current Swedish building code or passive house standard2010Ingår i: Passivhus Norden. Aalborg, Denmark, October 7- 8, 2010, 2010Konferensbidrag (Refereegranskat)
  • 113.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Sathre, Roger
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Modeling Carbon Footprint of Wood-Based Products and Buildings2015Ingår i: The Carbon Footprint Handbook / [ed] Subramanian Senthilkannan Muthu, London: CRC Press, 2015, s. 143-162Kapitel i bok, del av antologi (Refereegranskat)
  • 114.
    Dodoo, Ambrose
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Gustavsson, Leif
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK. Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Sathre, Roger
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Primary energy implications of ventilation heat recovery in residential buildings2011Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 43, nr 7, s. 1566-1572Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, we analyze the impact of ventilation heat recovery (VHR) on the operation primary energy use in residential buildings. We calculate the operation primary energy use of a case-study apartment building built to conventional and passive house standard, both with and without VHR, and using different end-use heating systems including electric resistance heating, bedrock heat pump and district heating based on combined heat and power (CHP) production. VHR increases the electrical energy used for ventilation and reduces the heat energy used for space heating. Significantly greater primary energy savings is achieved when VHR is used in resistance heated buildings than in district heated buildings. For district heated buildings the primary energy savings are small. VHR systems can give substantial final energy reduction, but the primary energy benefit depends strongly on the type of heat supply system, and also on the amount of electricity used for VHR and the airtightness of buildings. This study shows the importance of considering the interactions between heat supply systems and VHR systems to reduce primary energy use in buildings.

  • 115.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Sathre, Roger
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    The role of wood in carbon efficient construction. Primary energy and greenhouse gas balances over the life cycle of different wood building systems: Swedish case-study building. €CO2 Work Package 12013Rapport (Övrigt vetenskapligt)
  • 116.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Cost-optimized energy-efficient building envelope measures for a multi-storey residential building in a cold climate2019Ingår i: Innovative Solutions for Energy Transitions: Proceedings of the 10th International Conference on Applied Energy (ICAE2018) / [ed] Yan, J; Yang, HX; Li, H; Chen, X, Elsevier, 2019, Vol. 158, s. 3760-3767Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study we analyse cost-optimal building envelope measures including insulation for attic roof, ground floor and exterior walls, and efficient windows and doors for new buildings. The analysis is based on a multi-storey building in south of Sweden with an expected lifetime of at least 100 years. We integrate dynamic energy simulation, total and marginal economic analysis, and consider different scenarios of real discount rates and annual energy price increases. Our analysis shows that cost-optimal thicknesses of insulations for the building envelope elements are significantly higher than those required to meet the current Swedish building code’s minimum energy requirements. For windows, the cost-optimal U-value is about the same as required to fulfil the minimum requirement of the Swedish building code. Overall, large energy and cost savings are achieved when the cost-optimal measures are cumulatively implemented. Compared to the reference, annual space heating reduction of 28-43% is achieved for the building with the cost-optimal measures under the analysed period of 50 years. The cost savings varied between 21 and 188 k€.

  • 117.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Effects of end-of-life management options for materials on primary energy and greenhouse gas balances of building systems2019Ingår i: Innovative Solutions for Energy Transitions: Proceedings of the 10th International Conference on Applied Energy (ICAE2018) / [ed] Jinyue Yan, Hong-xing Yang, Hailong Li, Xi Chen, Elsevier, 2019, Vol. 158, s. 4246-4253Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study we have analysed the life cycle primary energy and greenhouse gas (GHG) balances of concrete-frame and timber-frame multi-storey building alternatives, designed to meet the current Swedish building code, considering different end-of-life scenarios. The scenarios include recycling of concrete and steel, cascading by recycling of wood into particle board and energy recovery at the end-of-life of the board, energy recovery of wood by combustion, and landfilling of wood with and without landfill gas (LFG) recovery. The energy recovered is assumed to replace fossil coal or gas. Our analysis accounts for energy and GHG flows in the production and end-of-life phases. We estimate the GHG emission changes achieved per unit of difference in finished wood in buildings or in harvest forest biomass between the timber buildings and the concrete building. The results show that the timber building systems give significantly lower life cycle primary energy balances than the concrete building system for all the end-of-life options. The concrete building system gives higher life cycle GHG balances than the timber alternatives for all the end-of-life options, except when wood is landfill without LFG recovery. The end-of-life primary energy and GHG benefit of wood materials is most significant for energy recovery while the benefit of cascading is low. However, replacing fossil gas instead of fossil coal significantly reduce the carbon benefits of the timber alternatives. The benefits of recycling steel and concrete are small. This study shows that end-of-life options for building materials can offer opportunities to reduce energy use and GHG emissions in the built environment.

  • 118.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Final energy savings and cost-effectiveness of deep energy renovation of a multi-storey residential building2017Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 135, s. 563-576Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study we present a method for analysis of cost-effectiveness of end-use energy efficiency measures and demonstrate its application for modelling a wide range of energy renovation measures for a typical 1970s multi-family building in Sweden. The method integrates energy balance and bottom-up economic calculations considering total and marginal investment costs of energy efficiency measures as well as net present value of total and marginal savings of the measures. The energy renovation measures explored include additional insulation to basement walls, exterior walls, and attic floor, improved new windows, efficient electric appliances and lighting, efficient water taps, glazed enclosed balcony systems, and exhaust air ventilation heat recovery systems. The measures are analysed first individually and then designed to form economic packages. Our results show that improved windows give the biggest single final energy savings while resource-efficient taps is the most cost-effective measure for the building. We find that the cost-effectiveness of the energy renovation measures is sensitive to real discount rates and energy price increases. Cost-optimal final heat savings varies between 34% and 51%, depending on the choice of real discount rate and energy price increase. The corresponding electricity savings varies between 35% and 43%. This study shows a method and the significance of various technical and economic-related parameters in achieving deep energy savings cost-efficiently.

  • 119.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Life cycle primary energy use of nearly-zero energy building and low-energy building2017Ingår i: ECEEE 2017 Summer Study: Consumption, Efficiency & Limits, European Council for an Energy Efficient Economy (ECEEE), 2017, s. 1075-1081Konferensbidrag (Refereegranskat)
    Abstract [en]

    Energy legislations are increasingly driving towards buildings with very low operation final energy use as part of efforts to reduce energy use and climate impact of the built environment. In this study we analyse the life cycle primary energy use of a recently constructed Swedish conventional 6-storey apartment building and compare it to variants designed as nearly-zero energy building or as low-energy building with a combination of improved thermal envelope and passive design strategies. We maintain the architectural design of the constructed building and improve the thermal properties of the envelope to achieve a low-energy building and also nearly-zero energy building including solar thermal collectors. We consider scenarios where the building variants are heated with renewable energy using cogenerated district heating, also complemented with solar heating system. We follow the life cycle of the building versions and analyse their total primary energy use, considering the production, operation and end-of-life phases. The results show that the relative significance of the production phase increases as buildings are made to achieve very low operational energy use. The production phase accounts for 17 % of the total primary energy use for production, operation and demolition of the constructed building for a 50-year lifespan. The corresponding values for the nearly-zero energy and low-energy building variants ranges between 30 to 31 %. Overall, the life cycle primary energy use for the nearly-zero energy and low-energy building variants are about 30–35 % lower compared to the constructed building.

  • 120.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Primary energy and carbon dioxide implications of low-energy renovation of a Swedish apartment building2013Ingår i: Passivhus Norden 2013, 2013, s. 270-282Konferensbidrag (Refereegranskat)
    Abstract [en]

    Measures to improve energy efficiency in existing buildings offer a significant opportunity to reduce primary energy use and carbon dioxide (CO2) emissions. The construction of new low energy buildings is important in the long term, but has small effect on the building sector’s overall energy use in the short term, as the rate of addition of new buildings to the building stock is low. In this study we analyse the potential for reducing primary energy use and CO2 emissions in an existing Swedish apartment building with energy efficiency renovation measures. We model changes to a case-study building with an annual final heat energy demand of 94 kWh/m2 to achieve a low-energy building. The modelled changes include improved water taps, windows and doors, increased insulation in attic and exterior walls, electric efficient appliances and installation of a plate heat exchanger in the ventilation system. We analyse the life cycle primary energy and CO2 implications of improving the buildings to a low-energy building. We consider different energy supply systems, including scenarios where the end-use heating technology is resistance heating, electric heat pump or district heating. We find that greater lifecycle primary energy and CO2 reduction are achieved when an electric resistance heated building is renovated than when a district heated building is renovated. Material production primary energy use and CO2 emission become relatively more significant when the operation energy is reduced. However, the increases in material production impacts are strongly offset by greater primary energy and CO2 reductions from the operation phase of the building, resulting in significant lifecycle benefits. Additional roof insulation gives the biggest primary energy efficiency when the building is heated with resistance heating. For electric heat pump or district heating, more electric efficient appliances give the biggest primary energy efficiency. Still the heat supply choice has greater impact on primary energy use and CO2 emissions.

  • 121.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Truong, Nguyen Le
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Primary energy benefits of cost-effective energy renovation of a district heated multi-family building under different energy supply systems2018Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 143, s. 69-90Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The European Union's Directive on energy performance of buildings emphasizes the need to take cost-effectiveness into account when measures are implemented for improved building energy efficiency. In this study, we investigate cost-effective energy renovation measures for a district heated building under different contexts, including varied locations, energy supply systems and economic scenarios. We determine the final and primary energy savings of cost-effective energy renovation packages for the building in the different contexts. The measures analysed include: improved insulation for attic floor, basement walls, and exterior walls; improved windows and doors; resource-efficient taps; heat recovery of exhaust ventilation air; energy-efficient household appliances and lighting. We consider three existing Swedish energy supply systems of varying district heat production scale and tariffs, and also plausible renewable-based energy supply systems. Our analysis calculates the final energy savings of the measures including the cost-effective renovation packages on hourly basis and links these to the different energy supply systems. The cost-effectiveness analysis is based on a double-stage optimization method, considering total and marginal investment costs of renovation measures as well as associated net present values of total and marginal cost savings. The results show that significant final and primary energy savings can be achieved when energy renovation measures are implemented for the building in the different contexts. This study shows that heat demand in existing Swedish building could be about halved while electricity use may be reduced considerably with cost-effective energy renovation measures. The economic viability of the renovation measures is sensitive to the economic regimes especially discount rates and energy price increase.

  • 122.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Mahapatra, Krushna
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Gustavsson, Leif
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Implications of households building and car preferences for primary energy use and carbon dioxide emissions2012Ingår i: ICAE 2012, 2012, s. 249-257Konferensbidrag (Refereegranskat)
  • 123.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Energy Simulation of Existing Swedish Multi-Storey Apartment Building in Växjö: Work Package 2, Task 2.1, carried out by UNI-SE in the Ready Project2016Rapport (Övrigt vetenskapligt)
  • 124.
    Dodoo, Ambrose
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Tettey, Uniben Yao Ayikoe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings2017Ingår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 137, s. 76-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study we explore key parameter values, methods and assumptions used for energy balance modelling of residential buildings in the Swedish context and analyse their effects on calculated energy balance of a typical multi-storey building from 1970s and on energy savings of energy efficiency retrofit measures. The parameters studied are related to microclimate, building envelope, occupancy behaviour, ventilation, and heat gains from electric appliances and persons. Our study shows that assumed indoor air temperature, internal heat gains and efficiency of ventilation heat recovery units have significant effect on the simulated energy performance of the studied building and energy efficiency measures. Of the considered microclimate parameter values and assumptions, the outdoor temperature, ground solar reflection and window shading have significant impact on the simulated space heating and cooling demands. On the contrary, the simulated energy performances are less affected by the variations in air pressure outside and the percentage of wind load that hits the building. We found that input data and assumptions used for energy balance calculations and energy saving analyses vary significantly in the Swedish context. These result in significantly different calculated final energy performance of buildings and energy efficiency measures. To inform accurate analysis of energy performance of building and energy saving measures, input parameters used in simulation models need to be appropriate.

  • 125.
    Dorn, Michael
    Vienna University of Technology.
    3D-Modeling of Dowel-Type Timber Connections2009Rapport (Övrigt vetenskapligt)
  • 126.
    Dorn, Michael
    Vienna University of Technology.
    Investigations on the Serviceability Limit State of Dowel-Type Timber Connections2012Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Dowel-type steel-to-timber connections are commonly used to transfer a large range of loads. Although they are simple to produce and assemble, the load-carrying behavior and the local stress and strain distribution within the connection area are highly complex. In addition to that, wood is a challenging material from an engineering point of view due to its highly anisotropic structure and behavior and due to its natural origin, which results often in inhomogeneities. The failure characteristics of wood are very different in tension and shear and in compression, where brittle failure and plastic-ductile failure modes occur, respectively. The aim of this thesis is to study the load-carrying behavior of dowel-type steel-to-timber connections in detail. This is achieved by performing experimental tests on single-dowel connections. A large variety of influencing parameters is assessed, which include wood density, connection width, the dowel roughness, and the application of reinforcements in order to prevent brittle behavior. Separate stages in the loading history are identified, starting from an initial consolidation phase, the region of maximum stiffness during load increase, and the point of maximum connection strength. Ductility is of great interest as well as the final failure modes. During the experiments, unloading and reloading cycles are performed, where distinctively higher stiffnesses are observed than during the first loading. The results of the experiments are compared to the design practice in Eurocode 5 for strength and stiffness estimation. Strength prediction is conservative except for slender connections, while stiffness prediction complied with experimental results only for connections of intermediate width. The initial consolidation phase of the experiments is then investigated further. It is concluded, that the properties of the bore-hole surface, where not a smooth but a rough surface with valleys and rifts is encountered, is responsible for the initially low stiffness. The contact behavior is studied by conducting experiments on wood with varying surface characteristics, which are a result of using different cutting tools. A mathematical model for the soft contact behavior is proposed, which is based on the results of the experimental tests. It also includes the evolution of non-reversible deformations in the surface layer. Complementing the experiments, a simulation tool suitable for numerically assessing the mechanical behavior of the connections is developed. It allows to perform simulations by means of the Finite Element method on such connections and provides an enhanced insight into the stress and strain distribution in connections compared to the tests. Hereby, a three-dimensional material model for wood is established, which allows to model the anisotropy of wood in the elastic as well as in the plastic domain, based on the theory of small strains and small displacements. The combination of the developed models for the material as well as the contact behavior leads to realistic simulation results, which are verified by comparing model predictions with the experimental results on connections. It is confirmed, that the computed behavior agrees well with the experimental one and that the features observed during the experiments are well reproduced. Due to the limitations of the simulation tool to small deformations, ultimate load and brittle failure modes cannot be predicted. Nevertheless, the influence of various parameters on both can still be estimated. The modeling approach is suitable for application to more complex situations in the future, such as multi-dowel connections or connection loaded by generalized loads. Especially the contact model, which is a unique feature in the thesis, allows a realistic simulation of the distribution of the forces in such statically indeterminant situations

  • 127.
    Dorn, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Proposal for a Failure Surface for Orthotropic Composite Materials2014Ingår i: / [ed] Oñate, Eugenio and Oliver, Xavier and Huerta, Antonio, 2014Konferensbidrag (Refereegranskat)
  • 128.
    Dorn, Michael
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Non-Linear Connection Models in Timber Engineering2016Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE) / [ed] J. Eberhardsteiner, W. Winter, A. Fadai, M. Pöll, Vienna: Vienna University of Technology , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this contribution, a numerical model for connections in engineered timber structures, using specially designed connection elements, is presented. The model considers the non-linear load-displacement relation typical for many types of connections on different levels and is presented on the example of dowel-type connections. The structural levels investigated herein are a) the embedment behaviour of a dowel into wood; b) the behaviour of a singledowel connection; and c) a multi-dowel connection under a general load case typical for structural applications. A special characteristic considered in the formulation of the connector elements is the unloading behaviour, which is characterized by an initial high unloading stiffness but a very low stiffness when the load is fully removed. The latter is due to remaining permanent deformations in the wood as well as in the metal connector. The modelling approach was found to correlate well with experimental data and gave new insight in the behaviour of dowel connections, particularly as regards the unloading and reloading behaviour with alternating load directions on the single-dowel connection scale.

  • 129.
    Dorn, Michael
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    3D-Modeling of Dowel-Type Timber Connections2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Typical elements in structural engineering (beams, trusses, plates and shells) can be investigatedby means of quite simple material models employing a small number of material properties,especially as wooden structures are loaded within the elastic domain only and plasticity is nottaken into account. When investigating details, e.g. connections, three-dimensional stress andstrain distributions occur. At areas with local stress concentrations, elastic limit states maybe reached at low global load levels, but local plasticity need not endanger the stability of theentire structure.

    This study investigates dowel-type steel-to-timber connections. In particular, the behavior ofwood under high pressure loads and when yielding as well as the influences of contact and frictionbetween dowel and wood and of the nonlinearity of steel when yielding on the load carryingcapacity of the connection are analysed. The aim is to createa tool for reliable prediction ofthe strength and deformation characteristics of dowel-type timber connections.

    For this purpose, an elasto-plastic material model for woodwas developed and implemented intothe Finite Element programAbaqususing anUMAT-subroutine. A closed, single-surface Tsai-Wufailure criterion is used in combination with an associatedflow rule. The current model is ableto predict failure in wood (brittle and ductile behavior) locally as well as the different loadcarrying mechanisms (rigid dowel or plastic hinges in the dowel) on a global level. Additionally,a series of experiments is planned for validation.

  • 130.
    Dorn, Michael
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Experiments on the Load-Displacement Behavior of Dowel-Type Steel-To-Timber Connections2011Ingår i: 28th Danubia-Adria-Symposium on Advances in Experimental Mechanics: 28 September - 1 October, 2011, Hotel Magistern, Siófok, Hungary, Budapest: Scientific Society for Mechanical Engineering , 2011, s. 255-256Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dowel-type steel-to-timber connections are typical connections in structural timber-engineering, which can be designed very easily for various loads and load combinations. For practical purpose the design is regulated in national and international codes [1]. Nevertheless, the design codes are not satisfying at the moment. Refined analyses by means of FE-simulations which are currently underway shall provide the basis for improved design rules.

    In order to validate the simulation tool a comprehensive test series (78 tests in total) was carried out. Additionally, detailed insight into the loading behavior of dowel-type connections could be gained as well as into the influence of various factors, e.g. density of wood, dowel length, friction between dowel and wood, load speed, un-/reloading cycles, additionally applied reinforcement, etc.

  • 131.
    Dorn, Michael
    et al.
    Vienna University of Technology.
    Hofstetter, Karin
    Vienna University of Technology.
    Eberhardsteiner, Josef
    Vienna University of Technology.
    Three-Dimensional Modeling of Dowel-Type Steel-to-Timber Connections2011Ingår i: Book of Abstracts of the 18th Inter-Institute Seminar, Budapest, 2011Konferensbidrag (Övrigt vetenskapligt)
  • 132.
    Dorn, Michael
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Nohajová, Viera
    Technical University in Košice, Slovakia.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Investigating Various Influences on the Embedment Strength and Stiffenss of Wood2011Ingår i: 28th Danubia-Adria-Symposium on Advances in Experimental Mechanics: 28 September - 01 October, 2011, Siófok, Hungary / [ed] István Ódor, Lajos Borbás, Budapest: Scientific Society for Mechanical Engineering , 2011, s. 253-254Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many structural problems originate from the insufficient performance of connections. The most common connection type used in timber structures is the dowel-type connection. Dowel-type connections are easy to manufacture and can be designed for a large load range.

    In the formula for determining strength according to EC5 [1], embedment strength of wood is the basic parameter. Embedment strength values are dependent on wood density and dowel diameter. The formula for embedment strength is derived from experiments.

    The purpose of this study is to specify the influence of various parameters on the embedment strength and stiffness of wood specimens under a steel dowel. Strength design in EC5 does not consider for e.g. increased roughness between dowel and wood, neither is the positive influence of reinforcement by e.g. screws covered

    Embedment tests are performed according to the European [2] and American standard [3] for embedment tests and the differences will be reported.

    Embedment tests in fiber direction are performed on wood specimens with different densities, in which moreover the holes were drilled with various drilling devices. Dowels with different roughness (roughened with rasps or engrailment) were inserted, some of the specimens were reinforced by screws to prevent cracking of the wood.

    These embedment tests are the continuation of tests on the contact stiffness of wood on steel and the dependence on wood roughness and density.

  • 133.
    Dorn, Michael
    et al.
    Vienna University of Technology, Austria.
    Karin, de Borst
    University of Glasgow, Scotland.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Numerical Simulations of the Loading Process of Dowel-Type Timber Connections2012Ingår i: CD-ROM Proceedings of the 6th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012) / [ed] J. Eberhardsteiner, H. J. Böhm, F. G. Rammerstorfer, Vienna University of Technology , 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to maximize utilization, numerical simulations are gaining importance in the design of timber structures. Dowel-type steel-to-timber connections are commonly used for a wide variety of loads. The current design generation, namely the Eurocode (EC)5 [1], is based on empirical tests, and lacks in many aspects a stringent mechanical foundation. The optimization of connections plays an important role for the competitiveness of timber structures, which is often restricted due to the inabilityof the design concepts to capture the large variety of fields of applications. The mechanical behavior of these types of connections is mainly driven by stiffness differences between the steel dowel and the wood part, whereby the strength properties of the materials and the geometric layout of the connection considerable affect the connection’s stiffness and strength.

  • 134.
    Dorn, Michael
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Kozłowski, Marcin
    Silesian University of Technology, Poland.
    Serrano, Erik
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Design approaches for timber-glass beams2014Ingår i: Glass, facade, energy : Engineered Transparency International Conference at glasstec: Conference on Glass, Glass Technology, Facade Engineering and Solar Energy, 21 and 22 October 2014 / [ed] Schneider, Jens and Weller, Bernhard, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper relates to the mechanical performance of timber-glass composite beams, which take exceptional advantage of the combination of the materials involved. Beam bending tests were performed with beams made from float glass and heat-strengthened glass. Three different adhesive types were used: silicone, acrylate and epoxy. The test results show that, with a proper design, the timber is able to transfer load after glass failure and hence collapse is delayed and a ductile behavior can be obtained. The results from the tests were compared with an analytical method using the gamma-method and the agreement between the analytical method and the tests are shown to be excellent.

  • 135.
    Dover, Pär
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Berggren, Peter
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Fahlgren, John
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Utvärdering av styvhetsegenskaper hos ett nyutvecklat träbjälklag2006Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    I samband med att intresset för att bygga högre trähus har ökat så krävs nya lösningar för att t.ex. kunna möta efterfrågan på stora öppna ytor och långa spännvidder. Träbjälklag med lång spännvidd har dock oftast svårigheter med att klara kraven på svikt och vibrationer. Ett nyutvecklat förslag på träbjälklag som förmodas klara dessa krav bättre än traditionella träbjälklag har varit utgångspunkten för detta examensarbete där syftet har varit att undersöka bjälklagets styvhet. Detta gjordes laborativt genom att bygga och testa en prototyp av det föreslagna bjälklaget och genom att en numerisk modell baserad på finita element metoden togs fram och användes för att studera hur olika parametrar påverkar bjälklagets styvhetsegenskaper.

    Bjälklagets design bygger på fackverksprincipen i primärriktningen och på balkverkan i sekundärriktningen. De ingående komponenterna har kommit prefabricerade till Växjö universitet där de har monterats ihop till ett fullskaligt bjälklagselement. Elementet har sedan utsatts för ett antal belastningsfall där nedböjningarna uppmätts vilka sedan givit underlag för att få värden på bjälklagets effektiva styvhetsegenskaper.

    Både de laborativa och de simulerade resultaten visar på en hög böjstyvhet i primärriktningen d.v.s. 18,9•106 Nm2/m [EI/b] respektive 18,6•106 Nm2/m [EI/b]. Även böjstyvheten i sekundärriktningen är hög d.v.s. motsvarar 21,2 % respektive 17,1 % av styvheten i primärriktningen.

    I beräkningsmodellen har det dessutom undersökts hur ett övre lager av spånskivor inverkar på bjälklagets styvhet.

  • 136. Epmeier, Hannah
    et al.
    Johansson, Marie
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Byggteknik.
    Kliger, Robert
    Westin, Mats
    Bending creep performance of modified timber2007Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 65, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    The present study is a supplement to Epmeier and Kliger (2005), which investigated the effect of three different modification methods (acetylation, modification with methylated melamine resin and heat treatment in vegetable oil) on four material properties (density, modulus of elasticity (MOE), creep deflection and relative creep) and their inter-relations. In this study, another modification method (furfurylation) and four additional material parameters (“relative stiffness”, i.e. MOE/density, moisture content, change in moisture content and anti-creep efficiency) and their correlations are included. In addition, the creep curves were analysed to assess the development of bending creep performance. The properties were assessed by experimental work on 132 specimens of Scots pine sapwood with dimensions of 45×70×1100 mm3. It was found that modification leads to significant changes in material properties. Furfurylation increases density and reduces creep deflection, relative creep and moisture content. Modified timber tends to deflect and creep significantly less than untreated timber. However, the extent of reduction in relative creep appears not to be related to the extent of reduction in creep deflection. Initial deflection and/or modulus of elasticity are suitable for predicting the creep deflection of untreated and modified timber.

  • 137.
    Ericsson, Joel
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Rusimovic, Goran
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    En jämförande studie mellan spikningsplåtsförband och WT-Tskruvar i limträkonstruktioner2006Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    Detta examensarbete har gjorts på uppdrag av Skanska Teknik med handledning av Johan Sjödin. Arbetets syfte var att jämföra olika limträförband, utförda av antingen spikningsplåtar eller WT-T skruvar, och komma fram till den bästa lösningen med hänsyn till bärförmåga, kostnad och utförandetid. I ett projekt har de spikningsplåtar, som används vid limträförband, börjat rosta under extremt fuktiga förhållanden fastän spikningsplåtarna är rostfria enligt tillverkaren. En fördel med WT-T skruvar är att de är gömda inne i träet och på så sätt inte i direkt kontakt med den aggressiva miljön, men även skyddad mot brand. Andra fördelar med WT-T är att utförandetiden är kort och kostnaden är lägre än spikningsplåtsalternativet. Ett experiment har gjorts för att undersöka hur träet med inborrade WT-T skruvar beter sig under uttorkning.

  • 138.
    Ericsson, Stefan
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Evertsson, Torbjörn
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Energideklaration av Svenska kyrkans byggnader i Växjö: utredning, deklaration och fördjupning nattkyla2008Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    Detta examensarbete syftar till att utreda vilka av Svenska kyrkans byggnader i Växjö som ska energideklareras samt utföra en energideklaration av en kontorsbyggnad. I energideklarationen ingår det även att ge åtgärdsförslag för olika energibesparingsmöjligheter. En fördjupad studie i nattkylning av stommen har också utförts. Examensarbetet är uppdelat i tre huvuddelar, indelning av byggnader, utförande av energideklaration samt fördjupad studie av nattkyla. I den första delen delas byggnaderna in i grupper utifrån verksamhet och byggnadstyp och därefter utreds om de ska energideklareras. Målet med denna indelning av byggnader är att Svenska kyrkan ska få vetskap om vilka av deras byggnader som berörs av lagen om energideklarationer. I andra delen görs en energideklaration för en kontorsbyggnad. Det visar sig att det finns en hel del energibesparande åtgärder som kan göras i kontorsbyggnaden. En del av åtgärderna är endast enkla åtgärder som inte kräver något större ingrepp i byggnaden för att utföras. I den tredje delen genomförs en fördjupad studie i nattkylning av stommen i byggnader, där tung och lätt stomme jämförs gentemot varandra. För att utföra jämförelsen används simuleringsprogrammet IDA Klimat och Energi. Resultatet av simuleringen visar ingen besparing av energi till följd av nattkylning av stommen i den simulerade byggnaden, vilket leder fram till en parameterdiskussion om hur olika parametrar påverkar lönsamheten vid nattkyla.

  • 139.
    Eriksson, Emil
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Tillverkning av betongelement: En studie av lönsamheten vid tillverkning i fältfabrik2006Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [en]

    The suppliers of concrete units have long delivery times at the present situation. To make sure that completion of constructions is not delayed by delivery times, Skanska has been forced to produce its own concrete wall units. The aim of this paper is to find out if it’s profitable for a construction company like Skanska to manufacture concrete units in a temporarily established field factory, rather than buying them from a supplier. The manufacturing and mounting has been studied and the costs have been calculated. The market situation has been investigated by comparing costs and delivery times of several suppliers. The results from the manufacturing and mounting have been compared with the information given by the suppliers, in order to investigate whether Skanskas enterprise is profitable.

  • 140. Eriksson, Jerry
    et al.
    Ludvigsson, Mikael
    Dorn, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Serrano, Erik
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Enquist, Bertil
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Load bearing timber glass composites: A WoodWisdom-Netproject for innovative building system2013Ingår i: COST Action TU0905 Mid-term Conference on Structural Glass / [ed] Jan Belis; Christian Louter; Danijel Mocibob, Boca Raton, Fla: CRC Press, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this three year project, which is part of the WoodWisdom-Net researchprogram, is to develop an innovative load bearing building system composed of timberglasscomposites. The structural loads applied onto these composites will be transferred to, andsupported by, the glass component, in contrary to today’s traditional solutions where glass elementsonly function as an environmental shield. Using such structural elements will make itpossible to largely increase the glass surface in buildings, allowing the presence of more naturallight in personal homes and office buildings.

    Timber-glass shear walls and beams will be developed taking into consideration long-term behaviorand seismic performance. Design concepts, feasibility studies and performance assessmentsof these components will be performed in order to improve the overall performance. Theproject also includes the development of new design calculations as well as the optimization ofmanufacturing methods.

    Material properties of timber, glass and adhesives will be determined from small and large scaleexperimental investigations, and will be used as input for theoretical calculations and modelingwork. The projects industrial partners will function as expertise and take part in the developmentand construction of demonstration objects.

    The project consortium is composed of academic and industrial partners from Austria, Sweden,Germany, Turkey, Slovenia, Chile, and Brazil. This paper presents material specifications andresults from small scale testing performed by the Swedish project partners.

  • 141.
    Eriksson, Jonatan
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Sonesson, Simon
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Dimensionering av vindstabiliserande väggar i ett trägarage2017Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I rapporten undersöks ett trägarage från Myresjöhus med avseende på globalvindstabilitet, där skivbeklädda regelväggar används som stabiliserande element.Rapporten analyserar också olika typer av skivmaterial ur stabiliseringssynpunkt,samt hur utformningen av garaget påverkar den totala horisontalstabiliteten.Resultatet redovisar en lösning på hur skivväggarna i garaget kan utformas för attklara av de yttre vindlasterna.

  • 142.
    Erlandsson, Sandra
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Matrinsson, Therese
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Utformning av ett miljöcertifierat flerfamiljshus av planelement2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En ökad bostadskris och allt högre miljökrav gör att Sveriges byggnadsbransch står inför en stor utmaning under den närmaste tiden. Allt fler småhusföretag känner att de vill utveckla sina produkter så att de passar bostadsmarknaden. Efter samarbete med Vimmerbyhus har ett ritningsförslag på ett prefabricerat flerbostadshus i tre våningar tagits fram. Det framtagna förslaget har även fått en miljöcertifiering inom Miljöbyggnad.

    Studien innehåller val av byggnadens design samt inre utformning av ytor. Sveriges lagar och krav inom ändrings- och nybebyggelse är här av stor vikt. Det ställdes också vissa krav på designen av byggnaden på grund av att planelementen byggs i fabrik för att sedan fraktas och sättas ihop på byggplatsen. En jämförelse mellan fyra olika miljöcerifieringar gjordes innan Miljöbyggnad valdes som den mest passande. Här utreddes och beräknades olika aspekter inom energi, material och inomhusklimat.

  • 143. Fagerlund, Göran
    et al.
    Janz, Mårten
    Johannesson, Björn
    Effect of Frost Damage on Bond between Reinforcement and Concrete – A contribution to the BRITE/EURAM project BREU-CT92-0591, Internal LTH Report, TVBM 90161994Rapport (Övrigt vetenskapligt)
  • 144.
    Fagerlund, Göran
    et al.
    Lund University.
    Johannesson, Björn
    Lund University.
    Betong för lagring av flytande naturgas, undersökning steg II: Inverkan av mycket hög fuktnivå, Inverkan av extremt låg temperatur, -196°C2005Rapport (Övrigt vetenskapligt)
  • 145.
    Fagerlund, Göran
    et al.
    Lund University.
    Johannesson, Björn
    Lund University.
    Freezable Water and Frost Resistance of Concrete at Very Low Temperature2005Ingår i: XIX Symposium on Nordic Concrete Research & Development: 12-15 June, 2005, Sandefjord, Norway, Sandefjord, Norway, 2005Konferensbidrag (Refereegranskat)
  • 146.
    Falkstål, Linus
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Entreprenöriellt lärande som verktyg i en föränderlig värld: En studie om värdeskapande lärande, entreprenöriella förmågor och dess inverkningar på problemlösning i matematik.2018Självständigt arbete på avancerad nivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Studien är en pedagogisk designforskning som genom en intervention belyser hur de entreprenöriella förmågorna komplexitet, ansvar och samverkan framträder genom en kombination av metoderna värdeskapande lärande och matematisk modellering. Studien avser också att belysa om metoderna kan bidra till ett kontextuellt och strategiskt matematiskt kunnande. Resultatet består av en beskrivning och analys av de förmågor som framträtt samt en analys av de designprinciper som användes för att tillverka den uppgift som eleverna använde under projektets gång. Resultatet visar att kombinationen av metoderna värdeskapande lärande och matematisk modellering, dels genom sin verklighetsanknytning och uppmuntrande till elevers engagemang, skapar goda möjligheter för ovanstående förmågors framträdande. Den andra delen av resultatet visar att eleverna behöver ges en god förförståelse för att bibehålla ett matematiskt fokus igenom hela uppgiftsprocessen.

  • 147.
    Filchev, Ivan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Buckling and geometric nonlinear FE analysis of pitched large-spanroof structure of wood2016Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    An arched structure provides an effective load carrying system for large span structures. When it comes to long span roof structures, timber arches are one of the best solutions from both structural and aesthetical point of view. Glulam arched structures are often designed using slender elements due to economic consideration. Such slender cross-section shape increases the risk of instability.

    Instability analysis of straight members such as beam and column are explicitly defined in Eurocode. However, for instability of curved members no analytical approach is provided in the code, thus some numerical method is required. Nonetheless, an approximation is frequently used to obtain the effective buckling length for the arched structures in the plane of arches.

    In this master thesis a linear buckling analysis is carried out in Abaqus to obtain an optimal effective buckling length both in-plane and out-of-plane for circular glulam arched structures. The elastic springs are used to simulate the overall stiffness of the bracing system.

    The results obtained by the FE simulations are compared with a simple approximation method. Besides, the forces acting on the bracings system is obtained based on 3D geometric nonlinear stress analysis of the timber trusses.

    Our findings conclude that the approximation method overestimates the effective buckling length for the circular glulam arched structures. In addition, the study indicates that the position of the lateral supports along the length of the arch is an important design aspect for buckling behaviour of the arched structures. Moreover, in order to acquire an effective structure lateral supports are needed both in extrados and intrados.

    Furthermore, instead of using elastic spring elements to simulate the overall stiffness of the bracing system, a full 3D simulation of two parallel arches was performed. It was shown that the springs are stronger than the real bracing system for the studied arch.

  • 148.
    Florisson, Sara
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Vessby, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    A numerical study of the effect of green-state moisture content on stress development in timber boards during drying2019Ingår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 51, nr 1, s. 41-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Timber boards manufactured with a traditional sawing pattern often contain both heartwood andsapwood. In such boards, internal constraints can occur during drying because of a radial variation in greenstate(GS) MC between the heartwood (30-60%) and sapwood region (120-200%). Despite such knowledge,the initial MC is seldom considered when evaluating kiln-drying schedules. The effect of GS MC on thedevelopment of tangential tensile stress during drying is studied for four types of timber boards. A numericalmodel was developed that can simulate transient nonlinear orthotropic moisture flow and moisture–inducedstress and distortion in wood with the use of the finite element method. The stress analysis considers elastic,hygroscopic, and mechano-sorptive strain. The study shows that the GS MC does not significantly influencethe maximum stress state, but that it does influence the time at which the maximum tangential tensile stressoccurs at different exchange surfaces. This results in several periods in the drying schedule where unfavorablehigh stress situations in the tangential direction arise, which could lead to crack propagation.

  • 149.
    Florisson, Sara
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Vessby, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Modelling of mechano-sorption in clear wood by using an orthotropic non-linear moisture flow and stress model2018Ingår i: WCTE 2018 - World Conference on Timber Engineering: 2018 World Conference on Timber Engineering, WCTE 2018; COEX Convention and Exhibition CenterSeoul; South Korea, 20-23 August 2018, World Conference on Timber Engineering (WCTE) , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The European design standard for timber structures provides, besides obligatory safety requirements, a set of general serviceability requirements. Despite their generality, they have been proven important in design of timber structures, especially in varying climatic conditions, where the time dependent deflection can have a dominant role in long term performance. The total deformation consists of instantaneous elastic deformation, hygroscopic deformation, time dependent creep and mechano-sorptive deformation. The three latter deformations are influenced by climate, and when the change in climate is considerable over time, the deflection will significantly increase. In this paper a test-setup is created to study the effect of mechano-sorption on the global deflection of clear wood samples. The samples are loaded in a three-point bending test subjected to a constant mechanical load combined with a cyclic climatic load. The moisture induced stress and bending distortion were simulated by taking into account elastic, hygroscopic and mechano-sorptive strain. The non-linear moisture flow was simulated using Fick’s law. A parametric study was performed to obtain a better understanding of the constitutive equation, especially the term related to the moisture and temperature dependent diffusion coefficient. In addition to the simulations, an experiment was performed to verify the global deflection and mass change. The obtained results show that the mechano-sorption behaviour of the tested clear wood samples can be modelled, but an improvement of both the experimental setup and the model is required to come to more accurate conclusions on this type of long-term material behaviour.

  • 150.
    Fransson, Mattias
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Jamtlien, Mattias
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Slöseri i produktionsflödet: Analys av en platsgjuten betongvägg2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Höga byggkostnader och betydande bostadsbrist i Sverige visar att ett effektivare bostadsbyggande krävs. En reducering av slöseri i byggprocessen bidrar till en effektivisering av både tid och kostnad. För att öka förståelsen för vikten av effektivisering synliggör den här studien slöseri i produktionsflödet för en platsgjuten betongvägg i ett bostadsprojekt. Studien visar även var i produktionsflödet det finns förbättringsmöjligheter.

    Slöseriet synliggjordes genom en tidsstudie som visade på stor potential till förbättring i bostadsprojektets resursflöde, materialflöde och informationsflöde. Mycket tyder på att dessa brister i produktionsflödet beror på allt för kort byggtid, vilket leder till att en fullgod planering inte alltid utförs.

1234567 101 - 150 av 512
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf