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  • 1.
    Abolghasemi Moghaddam, Saman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    The effects of low-emissivity window films on thermal comfort and energy performance of a historic stone building in cold climate: computer simulations with "IDA ICE"2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Low-emissivity (low-E) window films are designed to improve the energy performance of windows and prevent indoor overheating by solar radiation. These films can be applied to different types of glazing units without the need for changing the whole window. This characteristic offers the possibility to improve the energy performance of the window of old and historic buildings for which preservation regulations say windows should remain more or less unchanged. This research aims to figure out to what extent a low-E window film can improve thermal comfort and energy performance of an old three-storey historic stone building in the cold climate of Mid-Sweden. In this research, first, with help of the simulation software “IDA ICE”, the entire building was modelled without window films in a one-year simulation. Second step was to add the low-E window films (3M Thinsulate Climate Control 75 (CC75)) to all the windows and repeat the simulation. Comparison between the results of the two cases revealed an improvement in energy use reduction as well as the thermal comfort when applying the films. For the application of the window films, a cost analysis using payback method was carried out which showed a long- time payback period. Although an investment with a long-time payback period is considered as a disadvantage, for historic buildings with very strict retrofit regulations specially when it comes to the building’s facades, application of the low-emissivity window films for better energy performance and thermal comfort is among the recommendable measures, but not necessarily the best.

  • 2.
    Alcoverro Colom, Pau
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    A new energy model for the Lakshadweep islands: Change from a diesel-based model to a hybrid model with renewable energy systems considering the ecological fragility of the islands2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 3.
    Aljaberi, Saif
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Majeed, Aram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Energisimulering i modulhus: Fallstudie för uppskattning av energiprestanda och därefter energieffektivisera enligt passivhusstandaren2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    The Building sector is today an important sector in our society, which means that more people move from the urban area to the big cities, which in turn increases building production. The building and service sector is the largest energy waste in Sweden and internationally, which is about 40% of Sweden's total energy use and 60% of that energy goes to heating. The EU Directive Energy Performance of Buildings Directive (EPBD), implemented the concept of near zero-energy houses, which comes into full force in 2020, which means that all newly-built buildings must be energy-efficient with better energy performance than todays buildings. This is in connection with the need of houses/buildings and rental costs continuing to increase. For this reason, Ljusbo Hyreshus AB has invented a solution that includes both climatesmart rental apartments and cheap rental costs, which has attracted more than 20 communes (kommuner in Sweden) to offer land for these apartments. The purpose of this thesis is to find out the energy performance of one of Ljusbo Hyreshus AB's prototype module houses. Furthermore, improvement proposals would be developed to make the module house more energy efficient. The prototype house consisted of a single-storey modularhouse that stay in Söderhamn, which has been chosen in this thesis for further investigations. The house had a total area of 45 m2 and consisted of 3 rooms and kitchen. In this case study, the energy performance has been developed using analysis methods in the form of hand calculations and the energy signature method. Subsequently, the result of the analysis would be validated and would form the basis for later identification of various energy efficiency measures that contributed to the reduction of energy performance in the house and thereby achieved the passive house standard. The result shows that the modularhouse does not fullfil BBR's requirements at present, because the house misses important components which is important for energy performance. For this reason, improvement proposals, specifically regarding the climate shell, on energy efficiency measures have been developed in this report. With the help of these energy efficiency measures, which mainly consist of additional insulation and energy-efficient windows and with an energy-efficient ventilation system with heat recovery (FTX) and an installed air-water heat pump, the passive house standard has been possible to achieve. Future measures, such as the installation of solar cells, have also been examined in the report. This is due to converting the building from a passive house to a plus energy house.

  • 4.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Reducing energy usage in multi-family housing2019In: 2019 9th International Conference on Future Environment and Energy 9–11 January 2019, Osaka, Japan, Institute of Physics Publishing (IOPP), 2019, Vol. 257, article id 012030Conference paper (Refereed)
    Abstract [en]

    The energy usage in residential sector have been around 22% of the total energy use in the world and increasing due to the population growth and higher living standards. The energy sources for this are made up primarily of non-renewable energy resources which generates a large amount of global greenhouse gases. A lot of countries have implemented various regulations and rules to reduce the energy usage in buildings and promoting the use of renewable energy technologies. This paper presents a parametric study of a typical multi-family building in its pre-design stage. The climate location used is Sweden (Gothenburg) and Japan (Osaka). The aim of the study is to compare various configurations and to examine how they affect the energy use. The most interesting configurations are the use of heat pump and solar cells. Other configurations that are examined are infiltration levels, pressure coefficients, wind impact, ventilation with heat recovery, ventilation scheduling, building orientation and finally changing U-values in the building material. Results of this study show that the energy saving, by utilizing a heat pump and solar panels, can reduce the total energy use by 34.9% for Gothenburg and 32% for Osaka. The results also show that the difference in total energy use between the two cities reduce substantially (3% difference) when utilizing a heat pump in combination with solar panels.

  • 5.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment: Heating Mode2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 10, article id 1835Article in journal (Refereed)
    Abstract [en]

    A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

  • 6.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 7, article id 1354Article in journal (Refereed)
    Abstract [en]

    The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

  • 7.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Choonya, Gasper
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment2019In: Buildings, ISSN 2075-5309, E-ISSN 2075-5309, Vol. 9, no 7, article id 169Article in journal (Refereed)
    Abstract [en]

    An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.

  • 8.
    Andersson, Emelie
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Aziz, Shniar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    En jämförelse mellan gröna-, metall- och gråa tak för ett oisolerat parkeringshus utifrån dess olika temperaturer och dagvattenhantering2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since climate change increases and changes constantly, it contributes to higher average temperatures, ice melting and has a great impact on our ecosystem. This will then lead to a warmer climate, which means increased precipitation and milder winters. One of the reasons to climate change is urbanization, meaning people moving to the cities. To succeed in changing the climate, international cooperation and common goals are required. At the northern part of Brynäs, in the municipality of Gävle, work is currently in progress around the area where the factory of Läkerol was once standing. The area continues to be rebuilt and the outcome will eventually be called Godisfabriken. There, amongst other, a car park will be built for the newly built homes. The aim of this study is to compare metal roofs, grey concrete roofs and green roofs within the two aspects of stormwater management and temperature. Then analyse which alternative of these three roofs would be most advantageous for the car park of Godisfabriken.

     

    The focused roofs are green, metal and concrete. A green roof is when it's completely or partly covered by a layer of vegetation and metal roofs are different sheet roofs with steel and aluminium-zinc. Grey roofs are made of concrete which works as both floor and ceiling. A building's roof affects which air temperature the surroundings has with its slope, vegetation and surrounding buildings. Another problem with urbanization and a warmer climate is stormwater management, which means rain and melted snow from roofs, parking areas and other hard surfaces.

     

    The method includes a literature study and calculations. The literature study gave research on temperature for all roofs as well as stormwater management for green roofs. Calculations were made for stormwater management and temperature with its flow, absorption, reflectance and heat transfer.

     

    The literature study and the calculations showed that green roofs have a high SRI value of 80 while the remaining roof is at around 40. The higher SRI, the lower surface temperatures on the material. This is proven in both methods when green roofs according to the literature study received a maximum surface temperature of 38 °C and 48 °C. According to the literature study green roofs can preserve more than 50 % of the rainwater. They also had a water flow rate of 1.97 l/s, which is less than half of what the metal roof got in the calculations. Since green roofs had both low air and surface temperatures, as well as longer drainage times and most absorbed water, green roofs are a more suitable choice than metal and grey concrete.

  • 9.
    Andersson, Harald
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Numerical and experimental study of confluent jets supply device with variable airflow2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In recent years, application of confluent jets for design of ventilation supply devices has been studied. Similarly, numerus studies have been made on the potential and application of variable air volume (VAV) in order to reduce the energy demand of ventilation systems. This study investigates the combination of supply devices based on confluent jets and VAV, both in terms of the nearfield flow behavior of the device and the impact on thermal comfort, indoor air quality and energy efficiency on a classroom-level space when the airflow rate is varied.

    The method used in this study is an experimental field study where the confluent jets-based supply devices were compared to the previously installed displacement ventilation. The field study evaluated the energy efficiency, thermal comfort and indoor air quality of the two systems. In the case of the confluent jets supply devices, airflow rate was varied in order to see what impact the variation had on the performance of the system for each airflow rate. Furthermore, the confluent jets supply devices were investigated both experimentally and numerically in a well insulated test room to get high resolution data on the particular flow characteristics for this type of supply device when the airflow rate is varied. The results from the field study show nearly uniform distribution of the local mean age of air in the occupied zone, even in the cases of relatively low airflow rates. The airflow rates have no significant effect on the degree of mixing. The thermal comfort in the classroom was increased when the airflow rate was adapted to the heat load compared to the displacement system. The results lead to the conclusion that the combination of supply devices based on confluent jets can reduce energy usage in the school while maintaining indoor air quality and increasing the thermal comfort in the occupied zone.

    The results from the experimental and numerical study show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for different airflow rates.

    The results from both studies show that the airflow rate does not affect the distribution of the airflow on both near-field and room level. The distribution of air is nearly uniform in the case of the near-field results and the room-level measurement shows a completely uniform degree of mixing and air quality in the occupied zone for each airflow rate. This means that there is potential for combining these two schemes for designing air distribution systems with high energy efficiency and high thermal comfort and indoor air quality.

  • 10.
    Andersson, Martin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Jonsson, Andreas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Nyström, Niklas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Insvällning av olimmade och limmade trädymlingar2019Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    Wood is a renewable material, unlike many other building materials. The amount of wood used in the construction industry can be increased by using wooden dowels as a substitute for screws and nails. Screws and nails are made of metals, which are non-renewable materials. The manufacturing process of metal-based materials is more energy consuming than it is for wooden materials and therefore it has a greater impact on our global environment.The purpose of this study was to investigate the adhesion capacity of wooden dowel-joints, non-glued and glued made out of beech and pine. The attachment of the non-glued wooden dowels was achieved by swelling of the wood. Swelling was achieved by first drying the wooden dowels in an oven and then letting them acclimatize with the surrounding materials and the relative air humidity. The adhesion capacity of the wooden dowels should be able to compete with the withdrawal strength of nails to be practically useful.Tensile strength tests have been carried out in the laboratory in house 45 at the University of Gavle to determine the adhesion capacity of wooden dowel-joints. The tensile strength tests were performed with a Shimadzu AG-X machine. The results of the tests have been compared with the theoretical withdrawal strength for nails. Characteristic strength values have also been calculated from the tensile strength test results for the wooden dowels.The results of the study shows that only the glued wooden dowels can compete with the withdrawal strength of nails. Glued wooden dowels can therefore be a substitute for screws and nails. The calculated characteristic values for glued beech-dowels and glued pine-dowels are 5,2 kN respectively 4,3 kN.

  • 11.
    Arfan, Muhammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. 202100-2890.
    Biogas Value Chain in Gävleborg: Feedstock, Production and Use2019Report (Other academic)
    Abstract [en]

    This report aims to identify the current status and future opportunities for biogas as an alternative fuel for road transport in the Gävleborg region. The regional actors along the value chain are mapped by their role in feedstock supply, production and use of the biogas. Mapping and analysis of biogas development generally in Sweden and particularly in the Gävleborg region has been conducted primarily through literature, national and regional statistics and through interviews with the regional actors. About 15 companies were reached through emails and phone calls during the interview process.

    In 2017, about 3.5-4.0 million Nm3 of raw biogas (50-65% CH4) was produced in the region of which 3.6 GWh was upgraded. The region has two plants with upgrading facilities, one in Forsbacka, which produces gas mainly from food waste and Duvbacken, the wastewater treatment plant in Gävle. The gas produced at these two big facilities is upgraded and mostly used as transport fuel in the region, and for the industry. Gas produced from other sources is either used for heat and electricity production or flared to avoid methane emissions to the environment. The region has 14 buses and more than 500 other vehicles running on biogas. The gas infrastructure is not well developed in the region except for two filling stations situated in Gävle and Forsbacka. However, some developments on building biogas infrastructure for transport are in process.

    Analysis of interviews with actors and literature studies revealed that the region has much more feedstock for biogas production than used in the currently installed capacity of biogas technologies. Many actors showed great interest in its use as transport fuel but had very serious concerns about its future scope. Lack of supporting infrastructure such as filling stations, very low market demand and regional long-term strategies on biogas as transport fuel are considered barriers in the sector´s further development in the region. The value chain actors need to work more closely to get the most out of this valuable resource. Additionally, future planning on biogas should also consider its other uses such as an energy source for manufacturing industry, shipping and as raw material for chemicals or intermediate products.

  • 12.
    Bahrami, Alireza
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Matinrad, Sina
    Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Response of steel beam-to-column bolted connections to blast loading2019In: International Journal of Recent Technology and Engineering, ISSN 2277-3878, Vol. 8, no 3, p. 3639-3648Article in journal (Refereed)
    Abstract [en]

    In this research, response of steel beam-to-column bolted connections to blast loading is investigated. Nonlinear analyses of the connections are performed using the finite element software ABAQUS. In order to demonstrate the accuracy of the finite element modelling, an experimental test of a steel beam-to-column bolted connection is modelled. Comparison of the obtained result from the modelling with that of the corresponding experimental test verifies the modelling. Then, a 5-storey steel building is designed using ETABS software from which a beam-to-column connection of the ground floor is selected for the nonlinear analysis in ABAQUS. Thereafter, the components of the selected connection are designed. Finally, the connection is nonlinearly analysed considering parameters as the distance from the blast centre (2.5 m, 5 m, and 10 m) and blast power (500 kg, 1000 kg, and 2000 kg TNT equivalent mass of explosive). Effects of these parameters on the response of the connection are evaluated. Failure modes of the connections are assessed, too.

  • 13.
    Bahrami, Alireza
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Yavari, Mojtaba
    Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Hysteretic assessment of steel-concrete composite shear walls2019In: International Journal of Recent Technology and Engineering, ISSN 2277-3878, Vol. 8, no 2, p. 5640-5645Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the hysteretic assessment of steel-concrete composite shear walls with reinforced concrete on one side of the steel plate. Finite element software ABAQUS is utilised to conduct this research. An experimental test on a composite shear wall is simulated to do the verification of the modelling. Then, modelling result is compared with the experimental test result which shows an insignificant difference between them and therefore uncovers the accuracy of the modelling. Thereafter, different parameters are considered to investigate their effects on the response of the walls. Thickness of reinforced concrete, steel plate thickness, and number of shear studs are studied as parameters. It is concluded that changing reinforced concrete thickness and number of shear studs do not considerably affect the ultimate load capacity, ductility, and energy dissipation of the walls. However, increasing the steel plate thickness enhances the ultimate load capacity, ductility, and energy dissipation. In addition, out-of-plane displacement of the walls is evaluated.

  • 14.
    Balciunas, Dominykas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Thermoeconomic analysis of LNG physical exergy use for electricity production in small-scale satellite regasification stations2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Liquefied natural gas (LNG) cold utilization in small scale regasification stations is a novel topic in the industry, while such systems have been proven feasible in large scale LNG facilities. Cold recovery and utilization in LNG regasification facilities would increase the thermodynamic efficiency and reduce cold pollution. The aim of the study is to analyze the possibility to apply industry-proven thermodynamic cycles in small scale satellite regasification stations for electricity production, taking the characteristics of a real-world regasification station project in Druskininkai, Lithuania for which useful cold utilization is not currently planned.

    Direct Expansion (DE) and Rankine (ORC) Cycles are analyzed together with cascading using Aspen Hysys software to find the optimal solution considering thermal and exergy efficiency as well as the payback period.

    Thermoeconomically feasible retrofit solutions of approximately 13% thermal efficiency and approximately 17% exergy efficiency showing payback periods of 5 to 10 years and 3.3 to 6 thousand euro additional capital expenditure (CAPEX) per net kW of power production are found.

    Increase in complexity of thermodynamic cycles is directly proportional to both increased thermodynamic efficiencies and capital costs and the study proves that there is a limit at which increase in thermodynamic efficiency of a cycle by cascading becomes economically infeasible. Future work is suggested to improve the accuracy of the results by rigorous design to evaluate pressure drops as well as improvements in economic analysis by utilizing the discounted cash flow methodology. Sensitivity analysis of LNG physical and chemical conditions as well as ambient air could be performed whereas changes in working fluid and better engineering of the part related to intial heat exchange could improve thermodynamic efficiencies. Alternative solutions with a higher temperature heat source are also suggested.

  • 15.
    Barthel, Stephan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Colding, Johan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Stockholms Universitet.
    A Critical Perspective on the “Smart City” Model2017Other (Other (popular science, discussion, etc.))
    Abstract [en]

    As urban ecologists we support developing smoother traffic systems, providing citizens with more easily accessible information, and of course promoting citizen-participation and local democracy in political decision-making. However, and as is normally the common destiny when new models for sustainable development are appearing, investments in these “smarter” models run the risk of making people blind to problems that need more immediate concern. In short, governance is a matter of prioritizing among different goals. Governance is also about making sure that strong and powerful enterprises and business interests do not hijack the public debate

  • 16.
    Barthel, Stephan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Stockholm University.
    Isendahl, Christian
    Göteborgs Universitet.
    Vis, Ben
    University of Kent, UK.
    Drescher, Axel
    University of Erlangen-Nuernberg, Germany.
    Evans, Dan
    Lancaster University, UK.
    van Timmeren, Arjan
    TU Delft, The Netherlands.
    Global urbanization and food production in direct competition for land: Leverage places to mitigate impacts on SDG2 and on the Earth System2019In: The Anthropocene Review, ISSN 2053-0196, Vol. 6, no 1-2, p. 71-97Article in journal (Refereed)
    Abstract [en]

    Global urbanization and food production are in direct competition for land. This paper carries outa critical review of how displacing crop production from urban and peri-urban land to other areas– because of issues related to soil quality – will demand a substantially larger proportion of theEarth’s terrestrial land surface than the surface area lost to urban encroachment. Such relationshipsmay trigger further distancing effects and unfair social-ecological teleconnections. It risks also settingin motion amplifying effects within the Earth System. In combination, such multiple stressors set thescene for food riots in cities of the Global South. Our review identifies viable leverage points on whichto act in order to navigate urban expansion away from fertile croplands. We first elaborate on thepolitical complexities in declaring urban and peri-urban lands with fertile soils as one global commons.We find that the combination of an advisory global policy aligned with regional policies enablingrobust common properties rights for bottom-up actors and movements in urban and peri-urbanagriculture (UPA) as multi-level leverage places to intervene. To substantiate the ability of aligningglobal advisory policy with regional planning, we review both past and contemporary examples whereempowering local social-ecological UPA practices and circular economies have had a stimulatingeffect on urban resilience and helped preserve, restore, and maintain urban lands with healthy soils.

  • 17.
    Bergström, Viktor
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Tölli, Emil
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Kolfiberförstärkning av limträbalkar: Fuktens inverkan på förstärkningen2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The point with this exam-essay is to study how the strength in glulam beams reinforced with carbon fiber will differentiate with an increased relative humidity (RH). The literature study brings up older work and science in the field that focuses on different reinforcement that can improve the strength in glulam beams.Glulam has higher strength than regular wood, this is due to how glulam is being constructed. When the usage limit condition is being determined the length of the beam will be a factor in deciding highest allowed bending on the beam. Carbon fiber, that has a greater strength than glulam can be used as a reinforcement on the glulam to give it higher strength. When the relative humidity is increased the glulam’s strength will decrease, the goal was to study how great the strength of the reinforced glulam beams would be when the relative humidity in the beams was being increased.In this essay a total of 26 glulam-samples was bent until they reached breaking point, out of these 26 samples half of them will be reinforced with carbon fiber underneath the beam. Half of the samples will be submerged in water, both reinforced and regular beams, where they will stay in two weeks until they are brought up again for bending-tests.The reinforced beams did not show an increase in torque capacity when compared to the non-reinforced beams when analyzing the average force. When analyzing the calculated 95 % -fractile the reinforced beams did show an increase in torque capacity. The dry reinforced glulam-beams showed an increase with 4,8 % and the wet reinforced glulam-beams showed an increase with 13,3 %.

  • 18.
    Blomberg, Emil
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Boqvist, Simon
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Lauridsen, Markus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Tvärkraftsförstärkning av limträ med inlimmade gängstänger2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien var att undersöka hur tvärkraftskapaciteten i limträ påverkades om den förstärktes med inlimmade gängstänger samt att studera samverkan mellan limträ och gängstänger.

    En litteraturstudie genomfördes för att ta del av tidigare forskning. Förstärkning av tvärkraftskapaciteten hos limträbalkar är ett område där begränsad forskning skett. Ahlskog och Ross (2015) berörde detta område om hur limträ förstärkts mot tvärkraftbrott med pålimmade träribbor på utsidan. Resultatet från Ahlskog och Ross (2015) visade att deras förstärkningsmetod medförde en ökad tvärkraftskapacitet på 11 %. Denna studie var en vidareutveckling på Ahlskog och Ross (2015) arbete men med en ny förstärkningsmetod med inlimmade gängstänger i olika vinklar mot fiberriktningen.

    Testet bestod av fem olika provserier med åtta prover i varje serie. Provserie 1 var oförstärkt. Provserie 2 och 4 var förstärkta med inlimmade gänstänger i två olika vinklar mot fiberriktningen och testades med avseende för tvärkraftkapaciteten och jämfördes mot den oförstärkta. Provserie 3 och 5 var förstärkta på samma sätt som provserie 2 och 4 men provbitarna var klyvda i mitten och testades med avseende på gängstängernas hållfasthet och jämfördes mot provserie 2 och 4 för att undersöka samverkan. Provbitarna skruvades fast i två anhåll som placerades i tryckprovmaskinen som utsatte provbitarna med belastning tills brott inträffade. Maskinen var kopplad till en dator som registrerade samtliga värden i maskinens datorprogram Trapezium X.

    Studien resulterade i en ökning av tvärkraftkapaciteten på 13 % för provserie 2 förstärkt 45° och 1,0 % för provserie 4 förstärkt 90° jämfört med provserie 1. Samverkan mellan limträ och gängstänger resulterade i 32 % samverkan för provserie 2 förstärkt 45° och 4 % samverkan för provserie 4 förstärkt 90°. Resultatet hade förbättrats och visat en tydligare ökning av tvärkraftskapaciteten om fler felkällor hade beaktats i ett tidigare skede. En av dessa felkällor var torrsprickor, vilket resulterade i att provbitarna gav ett lägre värde gentemot de teoretiska beräkningarna.

  • 19.
    Blomqvist, Stefan
    et al.
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Amiri, Shahnaz
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Rohdin, Patrik
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Ödlund, Louise
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Analyzing the performance and control of a hydronic pavement system in a district heating network2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 11, article id 2078Article in journal (Refereed)
    Abstract [en]

    A hydronic pavement system (HPS) is an alternative method to clear snow and ice, which avoids the use of salt, sand, and fossil fuel in conventional snow clearance, and minimizes the risk of accidents. The aim is to analyze the performance of different control strategies for a 35,000 m2 HPS utilizing heat from a district heating and cooling (DHC) system. The key performance indicators are (1) energy performance of the HPS, and (2) primary energy use, (3) electricity production and (4) greenhouse gas (GHG) emissions from the DHC system. The methodology uses a simulation model of the HPS and an optimization model of the DHC system. Three operational strategies are analyzed: A reference scenario based on the current control strategy, and scenarios where the HPS is shut down at temperatures below −10 ◦C and −5 ◦C. The study shows that the DHC return temperature is suitable for use. By operational strategies, use during peak demand in the DHC system can be avoided, resulting in reduced use of fossil fuel. Moreover, the energy use of the HPS could be reduced by 10% and the local GHG emissions by 25%. The study emphasizes that the HPS may have positive effects on global GHG emissions, as it enables electricity production from renewable resources. 

  • 20.
    Bondsman, Benjamin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Al, Barzan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Hedlund, Felix
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Dimensionering av höga balkar enligt fackverksanalogi: -En parametrisk studie2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 21.
    Bordes Roca, Adria
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Impacts of implementation of electric scooters in daily transport: case study in Gavle2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 22.
    Braat-Eggen, Ella
    et al.
    Avans University of Applied Sciences, Tilburg, the Netherlands; Eindhoven University of Technology, the Netherlands .
    Keus van de Poll, Marijke
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Hornikx, Maarten
    Eindhoven University of Technology, the Netherlands.
    Kohlrausch, Armin
    Eindhoven University of Technology, the Netherlands.
    Auditory distraction in open-plan study environments: Effects of background speech and reverberation time on a collaboration task2019In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 154, p. 148-160Article in journal (Refereed)
    Abstract [en]

    Previous research has shown that semantic-based tasks are negatively influenced by semantic aspects in background speech. Collaboration is an important task in open-plan study environments and is a semantic task which might be disrupted by background speech. Therefore, the aim of this study was to analyze the influence of irrelevant background speech on student-collaboration. Participants worked in pairs to solve spot-the-difference puzzles, by using the 'DiapixUK' collaboration task, while they were exposed to different background sound scenarios. The composed sound scenarios varied in semantic content (mother tongue and foreign language background speech)and reverberation time (short vs long), the latter affecting speech intelligibility. Although a longer reverberation time decreases the intelligibility of background speech and a foreign language decreases meaningfulness of speech, no significant changes in performance were found. On the other hand, the data show an increased perceived disturbance for a longer reverberation time, which we interpret as an increased difficulty of interpersonal communication in the collaboration task due to the increased level of the background speech. The quiet reference condition was the most preferred sound condition which is in line with both the effect of a low background sound level and the absence of semantic interference. 

  • 23.
    Buccolieri, Riccardo
    et al.
    Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, University of Salento, Lecce, Italy.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Di Sabatino, Silvana
    Department of Physics and Astronomy, University of Bologna, Bologna, Italy.
    The drag force distribution within regular arrays of cubes and its relation to cross ventilation – Theoretical and experimental analyses2019In: Journal of Wind Engineering and Industrial Aerodynamics, ISSN 0167-6105, E-ISSN 1872-8197, Vol. 189, p. 91-103Article in journal (Refereed)
    Abstract [en]

    A novel set of wind tunnel measurements of the drag force and its spatial distribution along aligned arrays of cubes of height H and planar area index λ p (air gap between cubes) equal to 0.028 (5H) to 0.69 (0.2H) is presented and analysed. Two different types of measurements are compared: one type where the drag force is obtained using the standard load cell method, another type where the drag force is estimated by measuring the pressure difference between windward and the leeward façades. Results show that the drag force is nearly uniformly distributed for lower λ p (0.028 and 0.0625), it decreases up to 50% at the second row for λ p = 0.11, and it sharply decreases for larger λ p (from 0.25 to 0.69) where the force mostly acts on the first row. It follows that for the lowest λ p the drag force typically formulated as a drag area corresponds to the total frontal area of the array, whereas for large λ p the drag area corresponds to the area of the first row. By assessing the driving pressure for ventilation from the drag force, the analysis is extended to estimate the cross ventilation as an example of application of this type of measurements. 

  • 24.
    Bäcklin, Malin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Söderlund, Sandra
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Nudging mot hållbara transportbeteenden: Med framing som verktyg?: En experimentell enkätstudie om framings påverkan på studenters skattning av miljöattityder, intentioner och attityder till resvanor och val av färdmedel2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Greenhouse gas emissions from passenger cars have a negative impact on the climate and have led us to face major challenges today. To reduce greenhouse gas emissions, people need to change their transport behavior. Nudging is a concept that is used to supplement existing measures and is based on the fact that a selection situation is arranged in a way that helps man to make a desirable decision without limiting the individual's freedom of choice. There are different types of nudge tools, one of which is about producing information. Framing means that a certain type of information is presented in a certain way by highlighting a particular problem via communication texts. The main purpose of the present study is to demonstrate, by means of a questionnaire survey, whether, and if so, how, presentation of information and images affect how people estimate their environmental attitudes, as well as attitudes and intentions to travel habits and choice of means of transport. A sub-purpose is also to investigate whether framing of geographical distance affects the estimation in the survey differently.

    The survey was answered by 120 students at the University of Gävle. The questionnaire contained questions that measured general environmental attitudes and self-constructed issues that measured the students' attitudes and intentions to their travel habits and choice of means of transport. Three questionnaires were designed, two of which contained information on the problem of greenhouse gas emissions from passenger cars, and a supplementary picture from a geographically local and global perspective. The results showed that framing had no significant impact on how the students estimated their environmental attitudes, or their attitudes and intentions to travel habits and choice of means of transport. The results also did not indicate any differences between how geographical framing affected the estimate. Based on the results, the methodical procedure has been discussed. One assumption is that the framing had a greater chance of giving an effect if the message was sharper and more worrying, and if the selection was made in a different population than students. The results, however, demonstrate the importance of continuing to test different nudges, including the nudge tool framing, in different contexts and that they are tested on a small scale before being implemented on a larger scale.

  • 25.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Costeira, João
    Department of Earth Sciences, University of Minho, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Electrical and Thermal Performance Evaluation of a District Heating System Composed of Asymmetric low concentration PVT Solar Collector Prototypes2018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A., INTL SOLAR ENERGY SOC , 2018, p. 755-763Conference paper (Refereed)
    Abstract [en]

    Photovoltaic-Thermal (PVT) solar collectors generate electricity and heat from the same gross area. The annual electrical and thermal yields of these systems are dependent on the PVT collector technology, as well as the climate and the type of solar thermal system implemented. This review presents an evaluation of a district heating system composed of 20 asymmetric hybrid low concentrator PVT (C-PVT) solar collector prototypes. The system is installed in a South wall facade in order to maximise the available space (with a tilt of 20 degrees and an orientation of 5 degrees W). The thermal system is connected to the district heating network, thus heating the University buildings. On the other hand, the electrical system is grid-connected, where it feeds the grid directly. Real measurement data has been collected and compared with a thermal (through ScenoCalc tool) and electrical performance models. The annual thermal and electrical yield achieved 86% and 89% of the simulated thermal and electrical yield, respectively.

  • 26.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Performance Evaluation of Non-Uniform Illumination on a Transverse Bifacial PVT Receiver in Combination with a CPC Geometry2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 194, p. 696-708Article in journal (Refereed)
    Abstract [en]

    PVT collectors co-generate electricity and heat from the same gross area, thus achieving higher combined heat and electric yields. A comprehensive evaluation has been carried out on non-uniform solar irradiation profile distributions on four symmetric low concentration CPC PVT (LCPVT) solar collector design concepts. Additionally, an electrical and thermal performance evaluation of symmetric truncated LCPVT solar collectors based on a CPC reflector geometry with a central transverse bifacial PVT receiver has been carried out, through a numerical ray-tracing model software and a multi-paradigm numerical computing environment software. A simplified thermal (quasi-dynamic testing method for liquid heating collectors described in the international standard for solar thermal collectors ISO 9806:2017) and electrical performance models were employed to evaluate the LCPVT design concepts. The evaluation was carried out for heating Domestic Hot Water (DHW) for a Single Family House (SFH) in Fayoum (Egypt), where energy yields between 351 and 391 kWh/m2/year have been achieved. The non-uniform solar irradiation assessment showed that the PV cells are exposed to high levels of radiation due to the specific reflector geometry. Furthermore, the study showed that the CPC geometries are very sensitive to the shading effect, as partial shadowing is substantial for high incidence angles.

  • 27.
    Carlander, Jakob
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Trygg, Kristina
    Technology and Social Change, Linköping University, Linköping, Sweden.
    Moshfegh, Bahram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Integration of measurements and time diaries as complementary measures to improve resolution of BES2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 11, article id 2072Article in journal (Refereed)
    Abstract [en]

    Building energy simulation (BES) models rely on a variety of different input data, and the more accurate the input data are, the more accurate the model will be in predicting energy use. The objective of this paper is to show a method for obtaining higher accuracy in building energy simulations of existing buildings by combining time diaries with data from logged measurements, and also to show that more variety is needed in template values of user input data in different kinds of buildings. The case studied in this article is a retirement home in Linköping, Sweden. Results from time diaries and interviews were combined with logged measurements of electricity, temperature, and CO2 levels to create detailed occupant behavior schedules for use in BES models. Two BES models were compared, one with highly detailed schedules of occupancy, electricity use, and airing, and one using standardized input data of occupant behavior. The largest differences between the models could be seen in energy losses due to airing and in household electricity use, where the one with standardized user input data had a higher amount of electricity use and less losses due to airing of 39% and 99%, respectively. Time diaries and interviews, together with logged measurements, can be great tools to detect behavior that affects energy use in buildings. They can also be used to create detailed schedules and behavioral models, and to help develop standardized user input data for more types of buildings. This will help improve the accuracy of BES models so the energy efficiency gap can be reduced. 

  • 28.
    Carlos-Pinedo, Sandra
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Wang, Zhao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Methane yield from SS-AD: Experiences to learn by a full spectrum analysis at laboratory-, pilot- and full-scale2019In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 127, article id 105270Article, review/survey (Refereed)
    Abstract [en]

    Solid-state anaerobic digestion (SS-AD) takes place when solid content of the substrate is higher than 15%. Some advantages of this technology have been recognized as e.g., less required water added to raw feedstock and consequently minimized digester size and cost, higher volumetric organic loading rates (OLR) that may lead to higher efficiency methane yield and better acceptance of a wide range of feedstocks. However, scientific studies of SS-AD at pilot- and full-scale are very few and difficulties have been reported in operating SS-AD, especially when the system undergoes a scale-up, where methane production is the purpose. As a result, this review gives a summary of scientific studies for SS-AD processes at laboratory-, pilot- and full-scale, where a great diversity of substrate composition, reactor design and operational parameters have been categorized, and their performances in terms of methane yield have been analyzed. This, in turn, helps to identify that factors affecting methane yields at different scales arise mainly from operational conditions as well as the characteristic of feedstocks. This review even contributes to suggest several strategies for improvement of methane yield at full-scale.

  • 29.
    Casanaba, Pablo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Development of a Simple and Cheap Equipment for monitoring the solar Irradiance on PV modules.2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Increased use of renewable energies that is taking place all over the world is having a very important impact on the photovoltaic solar energy industry. This means of obtaining electrical energy is one of the most promising ones nowadays, thanks to the fact that it is a technology of easy installation and maintenance. However, the number of hours that a photovoltaic system works at maximum power depends almost entirely on environmental conditions, mainly in terms of solar irradiance.Solar irradiance is a magnitude that measures the power released by sunlight per unit area; the higher it is, the more power the photovoltaic system will generate.Therefore, it is very important to measure this magnitude in order to obtain data that either can give information about which is the best place to install a photovoltaic system or expect the device performance.Unfortunately, sensors used nowadays to measure this magnitude are quite expensive. The most widely used are the so-called pyranometers, with an average cost of between 8000 SEK to 10000 SEK, and solar reference cells, which can be quite cheaper (1000 SEK), but also can be the most expensive devices on the market depending on the features they have (some reference cells cost 20000 SEK).In this thesis, a solar irradiance sensor based on the treatment of a current generated by a silicon photodiode has been designed, built and calibrated. The signal generated by the device is a voltage that has been obtained by means of a current-to-voltage converter amplifier stage. Once the construction of the circuit was completed, it was tested on the roof of Hall 45 located in the University of Gävle. The testing was carried out on 13, 14 and 15 May 2019, and it consisted in the comparison of the signal generated by the new device and the signals generated by a pyranometer and a solar cell.The result is a device priced at 200 SEK, which shows acceptable levels of accuracy during central daylight hours but shows a strong angular dependence on incident light during sunrise and sunset.

  • 30.
    Cebollada Alvarez, Virginia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Evaluation of the performance of optimizerbased PV systems under shading conditions2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Total or partial shading conditions have a detrimental impact in the output energy ofphotovoltaic (PV) systems and in the semiconductor materials PV technologies are made of.Residential PV installations are very likely to be exposed to shade projected by nearbyobjects such as buildings or neighboring trees. The electrical configuration of PV systems iscrucial to mitigate the shading effect, as it is the use of power optimizers. This study assessesthe shading impact on two different types of residential PV systems to verify gains associatedwith SolarEdge optimizers and support product marketing. It aspires to help PV ownersselect power inverters that maximize the annual energy produced. Experiments have beenperformed simulating snow coverage and tree shading on a string-based system (Fronius)and an optimizer-based system (SolarEdge). Findings demonstrated the decrease in lossesfrom partial shading conditions with power optimizers. SolarEdge optimizers reduceshading power losses from 50% to 29% in comparison to a standard string system whensimulated snow coverage is applied. Results also showed that SolarEdge system decreasedtree shading losses from 17% to 13% in comparison to string-based system.

  • 31.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Mapping tracer gas concentrations using a modified Low Third Derivative method: numerical study2019In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 18, no 2, p. 136-151Article in journal (Refereed)
    Abstract [en]

    In indoor applications, computed tomography is the process of transforming a network of intersecting attenuation measurements into a spatially resolved two-dimensional concentration map. In this study the Low Third Derivative method (LTD) was numerically evaluated and optimized for different conditions. A modified version of the LTD algorithm (LTDm) was proposed and evaluated against the original version. Eight test maps were reconstructed under different conditions, such as weight ratio, pixel resolution, beam density and measurement noise. Performance of both LTD algorithms was found to be intimately related to the number of peaks and complexity in the test map and the steepness of the peaks. The LTDm algorithm improved the quality, especially for concentration maps including steep gradients and regions with very low concentrations. The LTDm method heavily lessened aliasing distortions and efficiently minimized the effects of noise.

  • 32.
    Cehlin, Mathias
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Ameen, Arman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office2019In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 22, p. 56-65Article in journal (Refereed)
    Abstract [en]

    The traditional air distribution and supply devices in ventilated rooms are not always able to effectively remove excess heat from the space. Therefore, chilled beams, especially the active systems, are used to achieve the desired cooling demand. The focus of this paper was the potential benefit of a newly designed active chilled beam (ACB) system, to improve heat removal effectiveness local thermal condition and indoor air quality in the occupants’ breathing zone. The system based on 1-way flow design (1W-ACB) was installed in an open-plan office and its performance was studied by analysing the temperatures, velocities and tracer gas concentrations in predetermined risky zones. The system was compared against a traditional 4-way flow design (4W-ACB).

    The obtained results showed that heat removal effectiveness was slightly higher for the 1W-ACB system compared to the 4W-ACB system. The local thermal condition was very good close to the workstations when using 1W-ACB. The benefits of the new system were also shown in the occupied zone by analysing the mean age of air and air-change effectiveness (ACE) in the breathing level at the workstation locations. The 1W-ACB system provided air with lower mean age (fresher air), and therefore higher ACE, near the breathing zone at the workstations compared to the 4W-ACB. On the other hand, the 4W-ACB system had the advantage of providing high thermal and mean age of air uniformity throughout the room.

  • 33.
    Chacin, Luís
    et al.
    Loughborough University, UK.
    Rangel, Simon
    FEUP, Porto, (Portugal.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Impact study of operating temperatures and cell layout under different concentration factors in a CPC-PV solar collector in combination with a vertical glass receiver composed by bifacial cells2019In: Impact study of operating temperatures and cell layout under different concentration factors in a CPC-PV solar collector in combination with a vertical glass receiver composed by bifacial cells / [ed] SWC-SHC, 2019Conference paper (Refereed)
    Abstract [en]

    Solar Collectors with Compound Parabolic Concentrator (CPC) reflectors redirect solar irradiance into the receiver (placed in optimal position). The concept of such devices is to reduce the installation area and energy costs [1]. This research focuses on the behaviour and efficiency of a stationary CPC-PV solar collector. Each trough of this collector has different concentration factors (1.25 and 1.66) with vertically placed bi-facial cell receivers. An analysis of the electrical efficiency is performed in order to evaluate the viability of a CPC geometry with a vertical bifacial PV receiver. Furthermore, an investigation on bifacial cells performance due to concentration (and consequently increased cell temperature) is carried out. A numerical simulation of the yearly available radiation and the Incident Angle Modifiers (IAM) for each geometry is also conducted. Finally, a comparison between the simulations and the outdoor testing on the prototype collector is detailed. The tests took place in Gävle, Sweden (61º Latitude). The results showed that higher concentration factors led to larger operating temperatures (114ºC for a concentration factor of 1.66 and 96ºC for a concentration factor of 1.25). Although this may compromise the cell performance and shorten the device’s life cycle, it is shown that appropriate ventilation will allow manageable operating temperatures.

  • 34.
    Choonya, Gasper
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental investigation of ventilation performance of corner placed stratum ventilation in an office environment2019Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Energy use in buildings account for about one third of the total global energy supply and contributes as much as 30% of the anthropogenic greenhouse gas emissions. It is estimated that energy use in buildings will increase to 67% by 2030. The need for better thermal comfort and air quality in indoor environments is the leading cause for high energy use in buildings.  Heating, ventilation and air conditioning systems take up about 50% of the total energy use in buildings which is about 10-20% of the national energy use in most developed countries. The development and adoption of sustainable ventilation systems is a viable solution to mitigate climate change and curtail carbon emissions.

    The experimental study was conducted in a room resembling a modern office in a laboratory environment. The study involved investigating the ability of the system to provide cooling and heating. Concentration decay tracer gas technique using Sulphur hexafluoride (SF6) gas was used to determine the local air change index and air change efficiency in the room. Low-velocity omni-directional thermistor anemometer type CTA88 were used to measure the air velocity and temperature in the room. Smoke was used to visualise the flow patterns created in the room.  The climate chamber was used to mimic climatic conditions in winter. Fifteen cases were investigated with five air flow rates set points (30, 40, 50, 60 and 70 l/s) at three supply air temperatures, i.e., 17.6 °C, 21.0 °C and 25.3 °C.

    The results of the local air change index and air change efficiency for the nominal supply temperature of 17.6 °C showed that the system had strong characteristics of a mixing ventilation system. At the supply air temperature of 21.0 °C, the performance of the system deteriorated slightly to below that of a mixing ventilation system and could not satisfactorily provide heating at supply temperature of 25.3 °C. Better performance of the system at all supply air temperature setpoints was observed at lower airflow rates. At all supply air temperature setpoints, relatively higher degree of temperature stratification was observed at lower supply. The draught rate levels decreased with increase in supply air temperature and height. The location of the air inlet terminals in relation to the workstations had significant effect on the performance of the system. The stratum ventilation system did not work efficiently because the air streams were heavily mixed before reaching the occupants.

  • 35.
    Christopher, Magnusson
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Förbättrat inomhusklimat med lägre energiförbrukning i öppet kontorslandskap: Ventilationens påverkan på inomhusklimatet och termisk komfort2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag spenderas en stor del av vår tid inomhus, det ställer krav på inomhusluften.  Koldioxid och andra föroreningar, som stannar i luften vid dåligt ventilerade  lokaler, påverkar negativt och är bevisat att påverka prestationen och produktiviteten  hos människor i specifika uppgifter. Idag läggs mycket fokus på miljösmarta  lösningar och effektiviseringar, men ibland glöms inomhusklimatet bort. För att  människor ska få en behaglig upplevelse av inomhusklimatet krävs  kvalité på inomhusluften men också på den termiska komforten. Huvudsyftet med examensarbetet är att förklara hur det går att uppnå  förbättrat inomhusklimat och samtidigt minska energiförbrukningen. Genom att minska energibehovet kan företag bli mer konkurrenskraftiga och samtidigt rusta sig mot de stigande elpriserna. Det finns även en ekonomisk fördel för företag såväl som för privata bostäder. Examensarbetet består utav en fallstudie, där luftenstemperatur och fuktighet kommer at loggas och data genereras. Loggning kommer att  ske vid två tillfällen. Först i början för att få en uppfattning om varför  personalen upplever dåligt inomhusklimat och sedan efter justering av luftflödena  för att se skillnaden i förändringen av inomhusklimatet och energipåverkan.   Genom att justera systemet och sammanställa resultat har forskningsfrågan ”Kan inomhusklimatet förbättras samtidigt och samtidigt minska energiförbrukningen?”  besvarats. Litteraturstudien visar att om alternativa ventilationsprinciper  används, istället för det konventionella omblandande systemet, går det att minska  energiförbrukningen samtidigt som inomhusklimatet förbättras. Detta har gjorts  genom att golvventilation använts där tilluften tillförts lågt och undertempererad för att luften ska stiga genom de termiska krafterna. Resultatet visar att termisk komfort försämrats enligt enkätstudierna, men samtidigt visar det en förbättring av  inneklimatet i enskilda frågor. Mätresultaten indikerar även på förbättrad  ventilation och inomhusklimat. Slutligen presenterades energibesparingsåtgärder som företaget kan göra för att minska energibehovet och samtidigt förbättra den termiska komforten.

  • 36.
    Colding, Johan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. The Beijer Institute of Ecological Economics, The Royal Swedish Academy of Sciences, Sweden; Stockholm Resilience Centre, Stockholm University, Sweden.
    Barthel, Stephan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Stockholm Resilience Centre, Stockholm University, Sweden.
    Exploring the social-ecological systems discourse 20 years later2019In: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 24, no 1, p. 423-432, article id 2Article in journal (Refereed)
    Abstract [en]

    This paper explores the 20-year evolution of the social-ecological systems framework (SESs). Although a first definition of SES dates back to 1988, Berkes and Folke more thoroughly used the concept in 1998 to analyze resilience in local resource management systems. Since then studies of interlinked human and natural systems have emerged as a field on its own right, promoting interdisciplinary dialogue and collaboration in a wide set of fields and practices. As the SES concept celebrates its 20-year existence we decided to make an overview of how authors use the concept in relation to research that deals with social and ecological linkages. Hence, we conducted a review of the SES concept using the Scopus database, analyzing a random set of journal articles on social-ecological systems (n = 50) regarding definitions of SES, authors’ main sources of inspiration in using the concept, as well as document type, subject area, and other relevant information. Although there is a steady increase of SES publications, we found that 61% of the papers analyzed did not even provide a definition of the term social-ecological system(s), a shortcoming that makes case comparisons difficult and reduces the usefulness of the concept. We also found three common SES frameworks that authors seem to be most commonly inspired by, referred to here as the original, the robustness, and multitier frameworks, respectively. The first can be characterized as a descriptive framework, the latter two more as diagnostic frameworks, useful for modeling. Although it would be a bit presumptuous of us to come up with a more thorough definition of the SES concept in this paper, we urge SES scholars to be more meticulous in making explicit what they mean by a social-ecological system when conducting SES research. 

  • 37.
    Colding, Johan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Stockholm Resilience Centre, Stockholms Universitet; Royal Swedish Academy of Sciences.
    Barthel, Stephan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Stockholm Resilience Centre, Stockholms Universitet.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Wicked Problems of Smart Cities2019In: Smart Cities, ISSN 2624-6511, Vol. 2, no 4, p. 512-521Article in journal (Refereed)
    Abstract [en]

    It is often uncritically assumed that, when digital technologies are integrated into the operation of city functions, they inevitably contribute to sustainable urban development. Such a notion rests largely on the belief that Information and Communication Technology (ICT) solutions pave the way for more democratic forms of planning, and that ‘smart’ technological devices result in a range of environmental benefits, e.g., energy efficiency and the mitigation of global warming. Drawing on the scientific literature that deals with ‘smart cities’, we here elaborate on how both propositions fail to consider drawbacks that could be characterized as ‘wicked’, i.e., problems that lack simplistic solutions and straightforward planning responses, and which often come about as ‘management surprises’, as a byproduct of achieving sustainability. We here deal with problems related to public choice constraints, ‘non-choice default technologies’ and the costs of automation for human learning and resilience. To avoid undemocratic forms of planning and too strong a dependence on non-choice default technologies, e.g., smart phones, we recommend that planners and policy makers safeguard redundancy in public-choice options by maintaining a wide range of alternative choices, including analog ones. Resilience thinking could help planners deal more effectively with the ‘wickedness’ of an increasingly hyper-connected society.

  • 38.
    Costeira, João
    et al.
    University of Minho, Portugal.
    Vieira, Manuel
    University of Minho, Portugal.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Development of a compact and didactic solar energy kit using Arduino2018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A., INTL SOLAR ENERGY SOC , 2018, p. 1663-1667Conference paper (Refereed)
    Abstract [en]

    When the sun rises, so does the key element that will shape the future of the world energy landscape. It is not an understatement to say that the solar energy industry is beginning to lead the path towards a sustainable future for all of us. However, the awareness of the potential of this amazing source of energy must begin from the most basic levels of education all the way to university. The scope of this paper is to display a new compact and didactic solar energy kit with the potential to replace current high cost and complex solar energy kits. These solutions are often too expensive and therefore unavailable for most of Europe’s public schools. As such, an equipment was developed using an open-source platform called Arduino that will enable students to conduct practical experiments in a fast, effective and simple manner and thus allow students to acquire the proper expertise in areas like energy, electronics, and programming.

  • 39.
    Ehn, Jenny
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energikartläggning med fokus på ventilation: En fallstudie som undersöker underhåll och dess inverkan på fastigheter2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att kunna reducera de effekter som klimatförändringarna orsakar behöver energisystemen effektiviseras. Eftersom fastighetsbeståndet idag mestadels består av äldre byggnader, blir renoveringar och effektiviseringar viktiga för att kunna få ner energianvändningen. För att renovering och effektivisering ska gynna både klimatet och fastighetsägaren bör det planeras långsiktigt redan från start samt inkludera ett livscykeltänk. Syftet med detta arbete är att utföra en energikartläggning av en kontorsbyggnad från 1988 som är belägen i Gävle samt presentera eventuella energibesparingsåtgärder. Huvudfokus har varit på frågan om hur olika typer av underhåll och underhållsskulder påverkar en fastighet, med störst inriktning på den tekniska utrustningen. Metoder som använts i arbetet har varierat från praktiska mätningar till en litteraturstudie och intervjuer. För att få en inblick om förvaltningsbolag vet vad en underhållsskuld är skickades en enkät ut med några frågor kring ämnet. Energikartläggningen visade att kontorsbyggnaden är i bra skick och de åtgärder som presenteras berör ventilation och värmesystemet. Ett byte av ventilationsaggregatet föreslås som reducerar värmeanvändningen med 15 % och elanvändningen med 28% samt minskar utsläppen med 2,7 ton CO2 per år. Återbetalningstiden är lång, men en LCC-kalkyl beräknad på 20 år redovisar att bytet är lönsamt långsiktigt. Behålls det gamla aggregatet kan tilluftstemperaturen sänkas och innetemperaturen justeras ned med någon grad. Detta bidrar till att reducera värmeanvändningen med 13 %. Resultatet som framkom i litteraturstudien samt intervjuer visar att eftersatt underhåll leder till att fastighetens värde minskar och att pålitligheten för systemen reduceras, vilket ökar risken för dåligt inneklimat. Det förebyggande underhållet syftar till att utrustningen ska hålla optimal prestanda medans felavhjälpande underhåll sker när komponenten tappat sin funktion. Förebyggande underhåll visar sig mer kostnadseffektivt jämfört med felavhjälpande underhåll. Arbetsbelastningen och underhållskostnaden kommer öka i takt med underhållsskulden samtidigt som en försämring av fastighetens livslängd sker. Sammanställningen av enkäten visade att förvaltningsbolagen har koll på vad en underhållsskuld är och att de svarande bolagen jobbar med ett livcykeltänk.

    Nyckelord: Energikartläggning, Energieffektivisering, Underhåll

  • 40.
    Ehrling, Lena
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Kemisk klassning och klassning av särskilda förorenande ämnen i Tökilsbäcken: problematik kring antropogena metallers inverkan på naturmiljöer2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In order to monitor environmental changes in Swedish lakes and watercourses, a classification

    of ecological and chemical status was evaluated. These factors provide information on the status

    of the watercourse and include a number of parameters that are put together into a final

    classification. Tökilsbäcken is a seven-kilometre natural watercourse that has its effluent in

    Gavleån. The watercourse flows mostly through a forest landscape. Approximately three kilometres

    upstream of the effluent, there is an outlet to Tökilsbäcken from a small stream where

    a landfill lets out it´s purified leachate.

    To classify what is called specific pollutants in Swedish environmental legislation the annual

    average values were obtained for good status for the metals copper, chromium and zinc. These

    three metals are a part of the classification of ecological status. When investigating the

    classification for chemical status, limit values for the metals was obtained for lead, cadmium

    and nickel. All limiting values have been obtained from Havs- och vattenmyndighetens regulations

    on classification and environmental quality standards (HVMFS, 2013).

    A compilation of existing sampling reports during the years 2011-2018 from three sampling

    points, analyses of metal contents in water mosses and bottom fauna (Unpublished material,

    SUEZ) was performed and compiled in text and graphs.

    The result of this study shows that the three metals included in the classification of ecological

    status receive classification good status concerning copper, chromium and zinc in the two

    sampling points located in Tökilsbäcken. At the third test point located upstream of the small

    stream, the classification will not achieve good status due to the increased annual average

    value of chromium in 2011. When chemical status was classified, good chemical surface water

    status was achieved at all test points over the period 2011-2018 concerning lead, cadmium

    and nickel.

    When analysing annual average values the levels of copper, zinc and lead where highest at

    sample point upstream, then downstream and the lowest levels where found in the outlet. For

    the metals chromium and nickel the highest levels where found in sample point outlet, then

    downstream and the lowest values where found in upstream. The levels of cadmium has increased

    over time but only marginal differences where seen for the three sample points. Only

    regarding the six investigated metals it is concluded that the emissions of chromium, nickel

    the increased levels of cadmium or the cocktaileffect are most likely to the degradation of bottom

    fauna downstream compared to upstream.

    Despite these promising results, there is some uncertainties about the tool for calculating bioavailability.

    This because no or very small correlation could be found between samplings of

    metal contents in water mosses and the levels of bioavailable metals in the watercourse. Also,

    issues concerning limit values and that the limits for metals occur in concentrations and not in

    actual amounts of metals, are discussed.

  • 41.
    Elliott, Emily M.
    et al.
    Department of Psychology, Louisiana State University, Baton Rouge, LA, USA.
    Marsh, John E.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. University of Central Lancashire, Preston, UK.
    Zeringue, Jenna
    Department of Psychology, Louisiana State University, Baton Rouge, LA, USA.
    McGill, Corey I.
    Department of Psychology, Louisiana State University, Baton Rouge, LA, USA.
    Are individual differences in auditory processing related to auditory distraction by irrelevant sound?: A replication study2019In: Memory & Cognition, ISSN 0090-502X, E-ISSN 1532-5946Article in journal (Refereed)
    Abstract [en]

    Irrelevant sounds can be very distracting, especially when trying to recall information according to its serial order. The irrelevant sound effect (ISE) has been studied in the literature for more than 40 years, yet many questions remain. One goal that has received little attention involves the discernment of a predictive factor, or individual difference characteristic, that would help to determine the size of the ISE. The current experiments were designed to replicate and extend prior work by Macken, Phelps, and Jones (Psychonomic Bulletin & Review, 16, 139-144, 2009), who demonstrated a significant predictive relationship between the size of the ISE and a type of auditory processing called global pattern matching. The authors also found a relationship between auditory processing involving deliberate recoding of sounds and serial order recall performance in silence. Across two experiments, this dissociation was not replicated. Additionally, the two types of auditory processing were not significantly correlated with each other. The lack of a clear pattern of findings replicating the Macken et al. (Psychonomic Bulletin & Review, 16, 139-144, 2009) study raises several questions regarding the need for future research on the characteristics of these auditory processing tasks, and the stability of the measurement of the ISE itself.

  • 42.
    Elofsson, Fredrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Optimering av last och produktion i Gävles fjärrvärmenät: Reducering av effekttoppar via värmelagring i byggnader2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    District heating is today the most common way of providing a building with heat and hot water in Sweden. It is an environmentally friendly product mostly used with renewable fuel. However, at power peaks most companies use production units that are more expensive and worse for the environment and should therefore be avoided as much as possible. This can be done with a method called load management. When a power peak occurs, the heat supply to buildings connected to the district heating system can be temporarily reduced. The heat energy can later be returned when the heat demand is lower. Thanks to the heat inertia of the buildings, the indoor temperature will not fall within the time frame for the load management. Historical data has been analysed to identify when and why power peaks occur in the district heating network. Power peaks throughout the district heating network have proved difficult to identify. However, for individual consumers clear patterns of power peaks have emerged. These power peaks mainly occur because of large use of hot water but also because of the shifting outdoor temperature. In order to see how the production cost would differ from the actual outcome load management was applied for Gävle's district heating 2018. The load management was calculated manually by identifying the most expensive production unit on an hourly basis. If a cheaper production unit had the potential to deliver higher power the next hour, the production was moved to the cheaper production unit. The process was repeated for each hour during 2018. After carrying out load management for Gävle's district heating network, 1 457 MWh had been shifted to a cheaper production unit. This resulted in a financial saving of 1,0 % of the total production cost. The environmental savings showed a reduction from 6.1 to 5.9 g CO2eq /kWh a total of 197 tonne CO2eq. In the exact same way, a load management was performed for a scenario where Gävle and Sandviken's district heating network were connected. The gain for a load management with Sandviken will be considerably larger, a reduced production cost of 3.6 % is possible. The environmental savings showed a reduction from 8.4 to 7.8 CO2eq /kWh a total of 575 tonne CO2eq. For future efficient load management, buildings should be divided into different classes depending on the building's time constant. User patterns for the entire district heating network have proved difficult to detect. Artificial intelligence can be an option for short-term forecasting of the power output

  • 43.
    Enver, Pekin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Minska matsvinnet i skolan: Ett pilotprojekt på tre grundskolor i Ljusdals kommun2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The author (Enver Pekin) has chosen to dwell into the subject of wasted foods and more specifically wasted foods in elementary schools.

    Food waste can be divided into two subgroups; food waste such as fish bones, coffee grounds, and egg shells, and wasted food that could have been saved had it been handled differently. Both food waste and wasted foods occur in every part of the grocery chain and impact our environment negatively. The production of grocery in of itself impact our environment through, among other things, greenhouse gases and the over fertilisation of substances such as nitrogen and phosphorus.

    Some estimations show that up to one third of all produced foods are thrown. This impacts the environment in ways that are unnecessary and even unsustainable in regard to how we use vital resources such as fresh water and natural grounds. Swedish school kitchens throw an estimated 50 000 tons of food per year, half of which are regarded as wasted foods.

    This study’s objective has been to examine how information campaigns impact the school children’s behaviour. For this purpose, an experiment has been designed and implemented on three selected schools in the province of Ljusdal. The aim has been to get the students to throw less food. Earlier research has shown that there is a possibility of reducing wasted foods with up to 20 %.

    Results of this experiment have shown that wasted foods in regard to plate portions has been reduced by 29 %. The results thereby corroborate earlier research which implies that information campaigns could eventually be used as a means to impact behaviour. How information campaigns are designed could also be of significance in regard to the resulting outcome.

  • 44.
    Erezkano Garai, Garazi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Heat transfer evaluation of a window with a ”hot box” set-up in a 18th century stone building by using COMSOL software2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The hot box technique is an experimental method to achieve the U-value of elements in stationary conditions; however, it is not always possible to work in stationary conditions in real world. This thesis consisted of evaluating the heat transfer of a window of a historical building with a unique hot box set-up. The window had a low emissivity plastic film to improve thermal efficiency, and the hot box was unique because the outside temperature could not be controlled. The applicability of the hot box technique to dynamic conditions was assessed using COMSOL Multiphysics 5.3. COMSOL Multiphysics is a finite element method solver software with a heat transfer module. Two heat transfer simulations were conducted in 2D based on the indoor and outdoor temperature when the hot box was in operation. First, a stationary study was carried when the outdoor temperature remained stable for 1 day. Then, the study was extended to a transient study to analyze in detail the effect of the external temperature fluctuations for 5 days. The results indicate that a cautious approach should be taken when applying the hot box technique under transient conditions, but that stationary conditions could not be achieved during one day. Nevertheless, the reliability of the simulation solution could have improved more.

  • 45.
    Eriksson, Christoffer
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Khorshed, Dorothy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Fallstudie om hur Gävle kommun kan minska sitt dricksvattensvinn2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To ensure sustainable development UN approved 17 sustainable development goals in the year of 2015, in which goal six specifies to ensure water and sanitation for all, and specified in goal six target indicator four, in a more effective way. To have an average of 24% in losses of the total amount of produced drinking water in Sweden is not effective, and Gävle municipality isn´t any better with their recorded drinking water wastage between 28-40% the last years. A big part of the losses of drinking water are assumed to be water that the municipality uses within their daily work such as rinsing of the drinking water network and inadequate measurements of the used drinking water. The aim of this study is to create groundwork for an action plan for how Gästrike Vatten can work to minimize their drinking water losses in Gävle municipality.To identify what the organization considers to be most important is a good first step in creating an action plan, to then select key elements to which goals can be phrased to ese future comparisons with similar organizations. Through internet research, surveys, interviews, computer analysis, in addition literature searches Gävle munici-palities condition of soil, dimensions- and materials of the drinking water network have been established.Gävle Vatten works actively to reduce their commercial drinking water losses by sealing water hydrants and installing water kiosks all around the municipality. The first step to localize leaks in the network is by district division which seven out of the eight respondents use. Acoustic leak detection is the most common secondary step to localize leaks more accurately that Gävle municipality uses, however certain difficulties can emerge. Most of the new drinking water pipelines are made from plastic, which has a lower sound conductivity then pipelines made from metal.It is a continual process to reduce ones drinking water losses to an acceptable level, one which Gävle municipality has already started. To potentiate the effect of their work an action plan is recommended within the organization to identify goals and ways to achieve them so that the company’s resources can be distributed accord-ingly. Their next step can be to work with active leak detection, more specifically with gas injection that works well on metal as well as plastic pipelines. To acquire more accurate measurements of the consumed drinking water, digital water meters are recommended at the consumers.The authors believe that Gävle municipality has good conditions to continue devel-oping their work to minimize their drinking water losses.

  • 46.
    Estaña Garcia, Guillermo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Ruiz Julian, Iñigo
    Feasibility of converting a Science Park in a cold climate into an “off-grid” facility using renewable energies and seasonal storage systems2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The collateral effects of fossil fuels push humanity to seek solutions to these adversities. Energy efficiency and renewable energies have gone from being almost imaginary concepts to necessary. Several studies have shown that self-sufficiency through photovoltaic systems and wind energy is possible. In addition, it is necessary a storage of the surpluses of both since it increases notably the efficiency of these systems and supposes to the short/medium term a saving of money in the consumer. Due to the mentioned before, the aim of the thesis is to convert a science park located in a cold climate such as Sweden into a complex that does not depend energetically on external sources. For this purpose, a series of data from the park were first collected and then simulated and optimised using the HOMER software for different energy configurations. At the same time, a computer code was created in MatLab to enable the energy produced to be used responsibly. The proposed system consists of PV panels, wind turbines and a battery. Thanks to it, a 64 % renewable fraction is achieved, which means a reduction of 27.45 tons of CO2 per year. In addition, through the energy management system created, the electricity contract is reduced, reducing the purchase of electricity during peak hours. It is concluded that the implementation of both proposed systems contributes significantly to the achievement of the sustainable goals set for 2 030 by the main world leaders, even though a total disconnection with the electrical grid has not been achieved.

  • 47.
    Etxeberria, Aitor
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    CFD simulation and analysis of glazing bar effects on heat and airflow inside a two-pane window2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 48.
    Falk Dikici, Selina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Visualisering och kvantifiering av klorparaffiner: En studie av flödet av klorparaffiner på Rörverk 98, Sandvik AB2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sandvik AB is an industrial group with operations throughout the world. One of the company's three business areas, Sandvik Materials Technology, develops and manu-factures stainless steel products. In production, they seek to replace hazardous mate-rials/substances with less hazardous alternatives or minimize the use of them. A sus-pected environmentally hazardous substance used in industry is chloroparaffins. Sandvik AB manufactures seamless stainless steel tubes with pilgering, where chlo-roparaffins (chlorine oil) are used as lubricants and coolants and these have an im-portant role for the production and for productivity. Sandvik AB uses chlorine oil containing long-chain chloroparaffins. During pilgering, the lubricant is added in conjunction with the activities that make the steel pipes come into contact with the steel tools. The purpose of the study was to carry out a survey of the flow of chloro-paraffins on one of Sandvik's tube plants, Rörverk 98. This has been done by apply-ing the substance flow analysis method (SFA), which is a tool used for analyzing a single substance in a given system. In this study, SFA was applied through six steps. In steps 1 and 2, study objectives and systems are defined. The aim was to convey new dimensions of information to the company and that the approach would be clearly and comprehensively reported. The system definition was to investigate the chlorine paraffin flow, at Rörverk 98, for 28 months. In steps 3 and 4, an inventory and design of the flow chart were carried out. The survey has been carried out through a literature review of Sandvik AB's reports and visits with interviews at the plant. With information from the inventory, a flow chart was created and flows were quantified. In step 5, the mass balance between incoming and outgoing flows was calculated using layers, this is the primary flow. In the last step, step 6, the re-sult was interpreted by applying the HS-method used to calculate the uncertainty of the results. The uncertainty factor is used to calculate a possible minimum and max-imum flow. The result of the survey has been visualized by creating a clear picture of the system and the chlorine paraffin flow and the risk of spillage on/from the pipeline. Within the study's system boundary, it is identified that there is a risk of spreading via emissions to air as well as by drips from cranes outside the plant. The mass balance resulted in a primary flow with a difference of 2.2% kg Cl between in-coming flow and outgoing flow with bearing. The difference may be due to inaccu-racies in inventory data or knowledge gaps such as unknown emissions. The im-provement measures recommended that Sandvik AB shall carry out regularly docu-mented inventory of flows and stocks, thereby gaining a greater insight into the chlorine paraffin flow. Lack of information about the substance made it difficult to determine how they can behave in the system. Future studies are required to deter-mine the environmental impact of long-chain chlorinated paraffins.

  • 49.
    Frojdén, Jonathan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Betydelsen av brännbart och obrännbart material i ett brandförlopp: En jämförande studie2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I och med de ändringar som trädde i kraft 1993/94 då funktionskrav för konstruktioner infördes istället för de enskilda materialens egenskaper lade grunden till att det numer är möjligt att bygga byggnader som kräver en hög grad av brandskydd i trä och andra material baserade på brännbart material. Denna ändring innebar bland annat att nya och innovativa produkter hade chans att etablera sig på den svenska marknaden, såsom isolering tillverkad av returpapper och träfiber. I och med träets naturliga förmåga att till viss grad motstå brand, bland annat genom att bilda ett skyddande kolskikt, i kombination med tillsats av flamskyddsmedel som försvårar antändning ytterligare resulterar i att dessa material numer har möjlighet att konkurrera mot obrännbara material gällande brandsäkerhet i byggnader.

    De testmetoder som idag avgör en produkts brandklass sker under kontrollerade former med temperaturer som inte motsvarar en fullt utvecklad brand. Detta medför att det utifrån ett materials brandklass, eller s.k. euroklass, inte går att förutse materialets brandmotstånd under en fullt utvecklad brand. Inte heller under ett så kallat Room Corner Test, som ska motsvara brandens tidiga skede, har det visat sig att euroklassen inte alltid motsvarar de krav som ställs för att förhindra vidare förbränning och övertändning. Däremot går det att utifrån euroklass se mönster i dess klassificering och förmåga att sprida glödbrand.

  • 50.
    Giusti, Matteo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Connecting land: vision and synergies for nature-connecting habitats2019In: Cities & Health, ISSN 2374-8834Article in journal (Refereed)
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