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Sökning: WFRF:(Tettey Yao)

  • Resultat 1-10 av 27
  • [1]23Nästa
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1.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Cost-optimized energy-efficient building envelope measures for a multi-storey residential building in a cold climate
  • 2019
  • Ingår i: Innovative Solutions for Energy Transitions : Proceedings of the 10th International Conference on Applied Energy (ICAE2018). - Elsevier. ; s. 3760-3767
  • Konferensbidrag (refereegranskat)abstract
    • 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€.
2.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Effects of end-of-life management options for materials on primary energy and greenhouse gas balances of building systems
  • 2019
  • Ingår i: Innovative Solutions for Energy Transitions : Proceedings of the 10th International Conference on Applied Energy (ICAE2018). - Elsevier. ; s. 4246-4253
  • Konferensbidrag (refereegranskat)abstract
    • 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.
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4.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Final energy savings and cost-effectiveness of deep energy renovation of a multi-storey residential building
  • 2017
  • Ingår i: Energy. - Pergamon Press. - 0360-5442. ; 135, s. 563-576
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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5.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Impacts of Common Simulation Assumptions in Sweden on Modelled Energy Balance of a Multi-family Building.
  • 2019
  • Ingår i: Cold Climate HVAC 2018. - Springer. - 978-3-030-00661-7 - 978-3-030-00662-4 ; s. 689-699
  • Konferensbidrag (refereegranskat)abstract
    • Here, we explore key input parameters and common assumptions for energy balance analysis of residential buildings in Sweden and assess their impacts on simulated energy demand of a building. Our analysis is based on dynamic hour-by-hour energy balance modelling of a typical Swedish multi-storey residential building constructed in 1972. The simulation input parameters studied are related to microclimate, building envelope, occupancy behaviour, ventilation, electric and persons heat gains. The results show that assumed indoor temperature set points, internal heat gains and efficiency of ventilation heat recovery systems have significant impact on the simulated energy demand. For microclimate parameters, the outdoor temperature, ground solar reflection and window shading gave significant variations in the simulated space heating and cooling demands. We found that input parameter values and assumptions used for building energy simulation vary significantly in the Swedish context, giving considerably different estimated annual final energy demands for the analysed building. Overall, the estimated annual final space heating demand of the building varied between 50 and 125 kWh/m2 depending on the simulation dataset used. This study suggests that site-specific parameter values may be appropriate for accurate analysis of a building’s energy performance to reduce data input uncertainties, as such factors may have a significant impact on building energy balance and energy savings of retrofit measures.
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6.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Influence of simulation assumptions and input parameters on energy balance calculations of residential buildings
  • 2017
  • Ingår i: Energy. - Elsevier. - 0360-5442. ; 120:1, s. 718-730
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we modelled the influence of different simulation assumptions on energy balances of two variants of a residential building, comprising the building in its existing state and with energy-efficient improvements. We explored how selected parameter combinations and variations affect the energy balances of the building configurations. The selected parameters encompass outdoor microclimate, building thermal envelope and household electrical equipment including technical installations. Our modelling takes into account hourly as well as seasonal profiles of different internal heat gains. The results suggest that the impact of parameter interactions on calculated space heating of buildings is somewhat small and relatively more noticeable for an energy-efficient building in contrast to a conventional building. We find that the influence of parameters combinations is more apparent as more individual parameters are varied. The simulations show that a building's calculated space heating demand is significantly influenced by how heat gains from electrical equipment are modelled. For the analyzed building versions, calculated final energy for space heating differs by 9-14 kWh/m(2) depending on the assumed energy efficiency level for electrical equipment. The influence of electrical equipment on calculated final space heating is proportionally more significant for an energy-efficient building compared to a conventional building. This study shows the influence of different simulation assumptions and parameter combinations when varied simultaneously. (C) 2016 Elsevier Ltd. All rights reserved.
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7.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Life cycle primary energy use of nearly-zero energy building and low-energy building
  • 2017
  • Ingår i: ECEEE 2017 Summer Study : Consumption, Efficiency & Limits. - European Council for an Energy Efficient Economy (ECEEE). ; s. 1075-1081
  • Konferensbidrag (refereegranskat)abstract
    • 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.
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8.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings
  • 2017
  • Ingår i: Energy and Buildings. - Elsevier. - 0378-7788. ; 137, s. 76-89
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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9.
  • Dodoo, Ambrose, 1979-, et al. (författare)
  • Primary energy and carbon dioxide implications of low-energy renovation of a Swedish apartment building
  • 2013
  • Ingår i: Passivhus Norden 2013. ; s. 270-282
  • Konferensbidrag (refereegranskat)abstract
    • 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.
10.
  • Gusev, Alexander, et al. (författare)
  • Atlas of prostate cancer heritability in European and African-American men pinpoints tissue-specific regulation
  • 2016
  • Ingår i: Nature communications. - 2041-1723. ; 7, s. 10979
  • Tidskriftsartikel (refereegranskat)abstract
    • Although genome-wide association studies have identified over 100 risk loci that explain ∼33% of familial risk for prostate cancer (PrCa), their functional effects on risk remain largely unknown. Here we use genotype data from 59,089 men of European and African American ancestries combined with cell-type-specific epigenetic data to build a genomic atlas of single-nucleotide polymorphism (SNP) heritability in PrCa. We find significant differences in heritability between variants in prostate-relevant epigenetic marks defined in normal versus tumour tissue as well as between tissue and cell lines. The majority of SNP heritability lies in regions marked by H3k27 acetylation in prostate adenoc7arcinoma cell line (LNCaP) or by DNaseI hypersensitive sites in cancer cell lines. We find a high degree of similarity between European and African American ancestries suggesting a similar genetic architecture from common variation underlying PrCa risk. Our findings showcase the power of integrating functional annotation with genetic data to understand the genetic basis of PrCa.
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  • Resultat 1-10 av 27
  • [1]23Nästa
 
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