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  • 51.
    Hwit, Emil
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Rekommenderad framledningstemperatur i fjärrvärmenät baserat på rökgaskondensering: En beräkningsundersökning av rökgaskondensering och fjärrvärme i en medelstor svensk stad2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The most common way of heating buildings in Sweden is by district heating, more than half of all the locales and homes is heated this way. Flue gas condensation is the third largest contributor of energy in district heating at 11 %. The importance of its efficiency is thereby big.

    Flue gas condensation can be installed at combustion boilers to increase the efficiency, it can be used in combination with most fuels that exhaust steam. The flue gas condensation has an important role by harnessing the energy in flue gases and cleansing it from environmental hazards.

    The flue gas condensation unit on Stora Enso Kvarnsveden Mill is owned by Borlänge‑Energi. They want to know if the condenser is operating as effective as it could be. This report investigates how the condenser and external heater at Stora Enso Kvarnsveden Mill is affected by different supply and return temperatures as well as what the production costs of the energy is.

    The calculations have been accomplished by using the density, specific heat capacity, flow- and temperature differences in Excel. All the calculations have originated from the median value for each month and used in comparison. The basis of the calculations is data that has been collected in the period of January 2015 to December 2018.

    The results indicate that increasing the supply temperature to 95 °C increases the energy costs by about 2 500 000 SEK per year. These costs can be reduced by 400 000 SEK per year by decreasing the return temperature to 40 °C. If the supply temperature is instead decreased to 75 °C when the temperature outside is higher than -1 °C, the costs decreases. A low supply temperature leads to less wear on the pipes, less heat losses, less fuel consumption and less emissions. This temperature reduction can decrease the costs by 620 000 SEK per year.

    If the return temperature is reduced but the supply temperature retained as it is today the costs could decrease by over 400 000 SEK per year. And by reducing both the supply and return temperature a cost saving of over 1 000 000 SEK per year could be achieved.

    The recommendation is therefore a lowering of the supply temperature to 75 °C when the temperature outside is warmer than -1 °C.

    The recommended supply temperature is:

    • 75 °C when the temperature outside is warmer than -1 °C
    • 80 °C between -2 and -4 °C
    • 85 °C at -5 °C,
    • 90 °C between -6 and ‑7 °C
    • 95 °C between -8 and -11 °C
  • 52.
    Igartua Irazustabarrena, Amaia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Analysis of the reduction of the energy demand of a house by using a glass structure2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study focuses on the effects that a greenhouse can have in the energy demand of a regular Swedish dwelling. Based on the layouts and information that Fiskarhedenvillan house constructor company supplied, a simulation model was built on IDA ICE and a greenhouse was placed attached to the house. The results show an energy reduction of 12 % in heating by placing a greenhouse next to the house in the south façade, as well as the possibility to use the space for growing plants. An analysis about the change in the orientation of the house was done in which it was proved that south orientation implies the lowest energy demand. Lastly, the possibility of installing a heater in the greenhouse was studied by making an energy analysis of it, in order to consider the chance to use the greenhouse as another common area all over the year.

  • 53.
    Isendahl, Christian
    et al.
    University of Gothenburg, Department of Historical Studies, Archaeology, Gothenburg, 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 Center, Stockholm, Sweden.
    Archaeology, history, and urban food security Integrating cross-cultural and long-term perspectives2018In: ROUTLEDGE HANDBOOK OF LANDSCAPE AND FOOD / [ed] Zeunert, J; Waterman, T, ROUTLEDGE , 2018, p. 61-72Chapter in book (Other academic)
  • 54.
    Jahedi, Mohammad
    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.
    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. Department of Management and Engineering, Linköping University.
    Quenching a rotary hollow cylinder by multiple configurations of water-impinging jets2019In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 137, p. 124-137Article in journal (Refereed)
    Abstract [en]

    Experiments have been conducted to analyze quenching of a hot rotary hollow cylinder by one and two rows of water-impinging jets. Sub-cooled water jets (ΔTsub = 45–85 K) with flow rate 8006 to 36,738 impinged on hollow cylinder with rotation speed 10 to 70 rpm at various initial wall superheat temperatures from 250 to 600ºC. Jet-to-jet and jet-to-surface spacing varied between 4 to 10d and 1.5 to 7d respectively and angular position of impinging jets were tested from 0 to 135º. Effectiveness of the defined parameters on stagnation point’s local average heat flux was found lower in the film and nucleate boiling compare to transition boiling regime where rotation speed had the highest impact. Characteristic of maximum heat flux (MHF) at stagnation point and upwash flow point were analyzed based on surface heat flux, time and temperature corresponding to MHF. Same maximum heat flux levels were captured in the both points which reveals importance of the flow behavior at the upwash flow point. The effectiveness of the parameters to improve average heat transfer was studied based on cooling area of each water impingingjet in the multiple configurations. Higher average heat transfer was obtained by increasing flow rate and subcooling temperature and lower initial wall superheat temperature corresponding to onset of transition boiling regime.

  • 55.
    Jakobsson, Malin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Lund, Elin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Organisatoriska förutsättningar vid implementering av kommunala miljöstrategier2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The following study deals with organizational conditions that affect the implementation of municipal environmental strategies. It aims to increase understanding of and contribute with material of empirical studies of implementing the environmental responsibility of municipalities. The aim of the study was to identify how organizational conditions affect the implementation of environmental strategies and to present solutions to how municipalities can handle the challenges that occur when environmental strategy work is to be incorporated and implemented in a municipality. In order to provide answers to whether there were any, and in that case which, organizational conditions that could promote or hinder municipalities' ability to implement environmental strategies, a literature study and a case study of a medium-sized Swedish municipality was conducted with the aim of collecting experience-based knowledge. The result shows that it is difficult to point out the influence of individual organizational conditions on the implementation process, as they interact. However, the implications are that the organization's structure, culture and leadership influence the work process. Limitation of or the uncertainty on access to resources is highlighted as an obstacle in the work with the environmental strategy. It is pointed out that it will most likely not be an increased resource supply, but instead it is necessary to prioritize what the tax money will be used for. Furthermore, the existence of target conflicts has proved to be a challenge that municipalities need to handle. Target conflicts have been spotted between environmental goals and other municipal goals. Because municipalities generally work on the basis of many, and sometimes conflicting, goals, the ability to prioritize is central. To succeed with the environmental work, municipalities are recommended to identify and enable synergies between the environmental goals and other welfare goals.

  • 56.
    Johansson, Ida
    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.
    Mardan, Nawzad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cornelis, Erwin
    Tractebel Engineering S.A., Brussels, Belgium.
    Kimura, Osamu
    Socio-Economic Research Center, Central Research Institute of Electric Power Industry, Tokyo, Japan.
    Thollander, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Designing Policies and Programmes for Improved Energy Efficiency in Industrial SMEs2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 7, article id 1338Article, review/survey (Refereed)
    Abstract [en]

    Climate change, due to anthropogenic emissions of greenhouse gases, is driving policymakers to make decisions to promote more efficient energy use. Improved industrial energy efficiency is said to play a key role in the transition to more carbon-neutral energy systems. In most countries, industrial small and medium-sized enterprises (SMEs) represent 95% or more of the total number of companies. Thus, SMEs, apart from using energy, are a major driver in the economy with regard to innovation, GDP growth, employment, investments, exports, etc. Despite this, research and policy activities related to SMEs have been scarce, calling for contributions in the field. Therefore, the aim of this paper is to critically assess how adequate energy efficiency policy programmes for industrial SMEs could be designed. Results show that scientific publications in the field differ in scope and origin, but a major emphasis of the scientific papers has been on barriers to and drivers for energy efficiency. Scientific contributions from studies of energy policy programmes primarily cover energy audit programmes and show that the major energy efficiency measures from industrial SMEs are found in support processes. The review further reveals an imbalance in geographic scope of the papers within the field, where a vast majority of the papers emanate from Europe, calling for scientific publications from other parts of the world. The study synthesizes the findings into a general method on how to design efficiency programs for the sector.

  • 57.
    Jönsson, Petra
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Mattsson, Julia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    "Jag har inget emot kollektivtrafiken om jag säger så, men...": En kvalitativ studie om män och kvinnors resvanor och inställningar till arbetspendling2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The traffic sector is responsible for the greatest amount of greenhouse emissions in Sweden because of its combustion of fossil fuels. Sandviken is the municipality in Gävleborg county that uses the least amount of public transportation in form of bus traffic. The aim of this study is to gain an understanding through qualitative research how the individual looks and reflects upon their own commuting, and to identify which factors that mostly affects the individuals commuting habits. The study is geo-graphically delimited to look to Sandbacka Park. The amount of interview partici-pants was in total 18, seven women and eleven men. The main themes that could be identified from the interviews was stress, environmental awareness, flexibility, effi-ciency and control. The average distance to the workplace was about 19,25 km. In total stated 73% of men and 57% of women that car was the main mode of transport to the workplace. This means that more men than women travelled by car to the workplace, and also show more positive feeling to car use. Many of the par-ticipants of the interview had knowledge of climate change and the connection it has to transportation but could still defend their own individual car use. Some of the men that were interviewed claimed to have a greater need of flexibility and maintain status, which can be an explanation as to why the need of car use is greater with men than women. 42% of women and 27% of men commutes which more sustainable modes of transportation, such as public transportation and walking or bicycling. Two of the women who commuted with public transportation expressed content with their mode of transportation. They had also during the interviews mentioned an environmental awareness, which shows that there is a connection between mak-ing sustainable choices and being content with the chosen more sustainable mode of transportation. The results from Sandbacka Park is generalizable to other work-places with the same kind of prerequisites. This study shows that men have more positive emotions connected to car use and uses the car more as a mode of commut-ing to work. During future studies it may be of importance to focus more on longer interviews timewise to create an even greater understanding of the individuals need and prerequisites when commuting. With a greater sample size a more generalisable result could have been achieved.Key words: Commuting, stress, public transportation, commute mode, travel mode choice, gender

  • 58.
    Keus van de Poll, Marijke
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Sjödin, Louise
    Gösta Ekman Laboratory, Department of Psychology, Stockholm University, Stockholm, Sweden.
    Nilsson, Mats
    Gösta Ekman Laboratory, Department of Psychology, Stockholm University, Stockholm, Sweden.
    Disruption of writing by background speech: does sound source location and number of voices matter?2019In: Applied Cognitive Psychology, ISSN 0888-4080, E-ISSN 1099-0720, Vol. 33, no 4, p. 537-543Article in journal (Refereed)
    Abstract [en]

    It is not unusual that people have to write in an environment where background speech is present. Background speech can vary in both speech intelligibility and location of the sound source. Earlier research has shown disruptive effects of background speech on writing performance. To expand and reinforce this knowledge, the present study investigated the role of number of voices and sound source location in the relation between background speech and writing performance. Participants wrote texts in quiet or in background speech existing of one or seven voices talking simultaneously, located in front of or behind them. Overall, one voice was more disruptive than seven voices talking simultaneously. Self-reports showed that sound from the front was more disruptive compared to sound from behind. Results are in line with theory of interference-by-process, attentional capture and the cross-modal theory of attention. The relevance of the results for open-office environments is discussed.

  • 59.
    Khosravi Bakhtiari, Hossein
    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 Construction, Gavlefastigheter Company, Gävle, Sweden.
    Akander, Jan
    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.
    Evaluation of Thermal Comfort in a Historic Building Refurbished to an Office Building with Modernized HVAC Systems2019In: Advances in Building Energy Research, ISSN 1751-2549, E-ISSN 1756-2201Article in journal (Refereed)
    Abstract [en]

    Envelopes with low thermal performance are common characteristics in European historic buildings, causing higher energy demand and insufficient thermal comfort. This paper presents the results of a study on indoor environmental quality (IEQ), with special focus on thermal comfort, in the historic City Hall of Gävle, Sweden, now used as an office building. There are two modern heat recovery ventilation systems with displacement ventilation supply devices. The district heating network heats the building via pre-heat supply air and radiators. Summer cooling comes from electric heat pump ejecting heat into the exhaust ventilation air. A building management system (BMS) controls the heating, ventilation and air-conditioning (HVAC) equipment. The methodology included on-site measurements, BMS data logging and evaluating the occupants’ perception of a summer and a winter period indoor environment using a standardized questionnaire. In conclusion, indoor environmental quality in this historic building is unsatisfactory. Stuffy air, too high, too low and varying room temperatures, lighting problems and noise are constant issues. Although it is equipped with modern ventilation systems, there are still possibilities for improving thermal comfort by improved control strategies, since upgrading the building’s envelope is not allowed according to the Swedish Building Regulations in historic buildings with heritage value.

  • 60.
    Kjörling, Cecilia
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Forsberg, Olivia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    En byggnads koldioxidavtryck och dess materialavfall vid produktion2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 61.
    Korkmaz, Ebubekir
    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.
    Lundstöm, Jerry
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Böjprovning av spikplåtsskarvad träbalk2019Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    This thesis examines the bearing capacity, stiffness, shear and moment force of a continuous wooden beam and how the parameters of the beam changes when the beam is spliced ​​with nail plate. A literature study has been conducted to examine which studies have been carried out in this field.

    Construction timber is the most common wooden element for wooden constructions but has limitations in available lengths since the maximum length manufactured is 5400 mm. If larger lengths are required, splicing must occur or use of other materials.   The study examines a 2 series, a 3-point series (moment and shear) and a 4-point series (moment). Each series consists off 3 trials in each series to see how shear and moment force affect the strength. The study also shows which off the joints that gives the least strength. The samples are tested in a draw and pressure machine lying on 2 supports and with a point load for the 3-point method and 2-point loads for the 4-point method. In the trials pressure is applied until the beams break. The study investigates the lab results, fracture state and use state for the wooden beams being tested. The result of the study shows that a splicing will lower the wood's carrying capacity between 21-60% compared to a non-spliced beam for the 3-point method and a reduction of 40-66% compared to a non-spliced beam for the 4-point method. Despite the lowered bearing capacity all the experiments are still within the characteristic value and approved for use. A larger dimension on the nail plate would probably have given a better value.

  • 62.
    Kurdia, Ali
    et al.
    Högskolan Dalarna, Borlänge, Sweden.
    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.
    Pius, George
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Ollas, Patrik
    RISE Research Institutes of Sweden, Borås, Sweden.
    Olsson, Olle
    Absolicon, Gävle, Sweden.
    Quasi-Dynamic Testing of a Novel Concentrating Photovoltaic Solar Collector According to ISO 9806:20132018In: 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. 1262-1273Conference paper (Refereed)
    Abstract [en]

    Testing and certification of solar thermal collectors has been widely researched and improved over the years, however, many of the developments in the test standards has been focused primarily on generic flat plate collectors. In this study, the focus was on depicting the applicability of the current standard in characterizing the performance of a novel concentrating solar collector of design. The applicability of the Quasi-Dynamic Testing (QDT) method for collector certification, by the ISO 9806:2013, is studied to be used in characterizing the novel concentrating PVT collector, and to point out the weaknesses observed, and essential additions required.

  • 63.
    La Fleur, Lina
    et al.
    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.
    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.
    Energy renovation versus demolition and construction of a new building—a comparative analysis of a Swedish multi-family building2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 11, article id 2218Article in journal (Refereed)
    Abstract [en]

    This study addresses the life cycle costs (LCC) of energy renovation, and the demolition and construction of a new building. A comparison is made between LCC optimal energy renovations of four different building types with thermal performance, representing Swedish constructions from the 1940s, 1950s, 1960s, and 1970s, as well as the demolition of the building and construction of a new building that complies with the Swedish building code. A Swedish multi-family building from the 1960s is used as a reference building. LCC optimal energy renovations are identified with energy saving targets ranging between 10% and 70%, in addition to the lowest possible life cycle cost. The analyses show that an ambitious energy renovation is not cost-optimal in any of the studied buildings, if achieving the lowest LCC is the objective function. The cost of the demolition and construction of a new building is higher compared to energy renovation to the same energy performance. The higher rent in new buildings does not compensate for the higher cost of new construction. A more ambitious renovation is required in buildings that have a shape factor with a high internal volume to heated floor area ratio. © 2019 by the authors.

  • 64.
    Lanca, Miguel
    et al.
    Instituto Superior Técnico, Lisbon University, 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.
    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.
    Numerical Simulation of the Thermal Performance of Four Concentrating Collectors with Bifacial PV Cells2018In: 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. 810-821Conference paper (Refereed)
    Abstract [en]

    Bifacial photovoltaic cells can produce electricity from the incoming solar radiation on both sides. Used in combination with concentrating solar technology, bifacial photovoltaic cells can see its electrical output further augmented, thus decreasing the cost per kWh. It is known, however, that the efficiency reduction when these cells are exposed to increased temperatures is a relevant factor. This can happen, for example, when they are mounted on a glassed collector or receiver. In this study, a thermal analysis is carried out on four prototypes of concentrating collectors with bifacial PV cells. Results show that, as expected, when glass and gables are removed from the collector, much better heat dissipation is achieved, thus resulting in favorable cell operation conditions.

  • 65.
    Larsson, Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Småskalig kraftvärmeproduktion för ett medelstort svenskt industriföretag: Potentialen för konventionell Rankinecykel2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The emissions of greenhouse gases need to decrease rapidly over the coming decades. Sweden has set the target to achieve net zero emissions by 2045. The industrial sector plays a crucial role in that conversion by reducing its energy needs and to convert from fossil fuels to renewables.

    This conversion will require a more robust and reliable energy system were todays centralized system has been supplemented by small decentralized production facilities. To produce heat and power closer to the consumers means less transmission losses. Small scale combined heat and power (CHP) production based on biofuels or excess heat could be a solution to reduce greenhouse gas emissions.

    The purpose of this paper is to evaluate the possibility for a mid-size Swedish industrial company to produce its own base load of heat and power with a conventional Rankine cycle. Also to evaluate the production costs depending on the size of the plant.

    The work has consisted of data collection from different manufacturers of steam turbines and steam boilers, a calculation model has been made in Excel to compare different plant sizes and in different operating scenarios. Economical evaluations has been made with the Pay-off method and the net present value method (NPV).

    The result shows that production costs for facilities with steam turbines in the size range of 10 – 100 kWel is well below the price of bought electricity and district heating. The economical evaluation generally shows on short pay-off times and positive NPV.

    A comparison of the CHP plants shows that the electric efficiency is low and the total efficiency sometimes can be lower than for the existing heat supplier of the company. This means that a switch to local CHP will have a negative impact from a system perspective, because of the increased use of primary energy resources.

    There is many parameters that affects the performance of a CHP plant but the most crucial is the operation time. To have a continuous operation over a major part of the year has a great impact on the economic performance. The low electric efficiency means that the major part of the savings gets on the heat production. This means that the CHP plant should be dimensioned to replace primarily the heat requirement.

  • 66.
    Lignell, Moa
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Föroreningsmängder och koncentrationer i dagvattendammars sediment: påverkan från omgivande markanvändning, en studie i Gävle2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis addresses how human activities in the catchment area could influence the contaminant concentrations and amounts of contaminants in the sediments of stormwater ponds. Sediment sampling was done in April 2019. The storm water ponds had different land uses: industrial, residential (detached area) and two land uses of traffic with different intensities; “traffic by Hamnleden” (7000 cars/day) and “traffic by Västerbacken” (2000 cars/day). Samples were taken with a Russian corer and sediment depth was measured to quantify sediment volume. Samples were sent to laboratory for analysis of metals, phosphorus, aliphatics, aromatics and polycyclic aromatic hydrocarbons [PAH].

    The stormwater pond with industry as land use had the highest concentration of contaminants in the sediment, followed by residential area – traffic by Hamnleden – traffic by Västerbacken. The results of this study showed that the land use concentrations of contaminants were all similar, and the patterns of concentration in the graphic figures were similar. The results could be explained by the narrow geographic area in which the three storm water ponds are situated. They could be affected by the same atmospheric downfall which could even out the concentrations. It was not expected that the residential area would have one of the highest concentrations in the sediment. This could be explained by the high content of organic matter, as some contaminants create strong chemical bonding with organic matter.

    Bigger differences were seen for the amounts of contaminants in the sediments and the comparative figure “fixated amount of contaminant per year”. The land use industry had the highest amount of contaminants followed by traffic by Hamnleden – traffic by Västerbacken – residential area. This is probably due to differences in particle quota in the storm water coming from the land uses.

    Calculations were done for the amount of transported contaminants in stormwater, via the watershed management tool and model StormTac. The calculated transportation of contaminants resulted in total amounts of contaminants, meaning both dissolved and particulate fractions. The calculations from StormTac were compared with the comparative figure “fixated amount of contaminant per year” for the land use residential area, and the amounts were significantly higher for the calculated transportation. This could partly be explained by comparing total amounts with particulate amounts.

    A conclusion of this report is that land use affects the amounts of contaminants and sediment volume in the studied storm water ponds, rather than the concentrations.

  • 67.
    Lilja, Grace
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Appelgren, Victoria
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Strategiskt arbete med att minska invasiva växtarters spridningsrisker: Klimatförändringar och trädgårdsavfallets inverkan på spridning2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Invasive species are an increasing problem worldwide, threatening indigenous communities and species. In a world where people travel and trade a lot in a global market, many organisms are transported to new parts of the world where they have never existed before. Most do not survive in the new environment but die, but some thrive and thrive. When such species are established and multiply in places outside their natural range, it can be followed by negative consequences for species that have existed there for a long time - so-called indigenous species. Then the new species are often called alien invasive species. An example of this is the beautiful and colourful plant flower lupin (Lupinus polyphyllus)that people on their travels brought with them from North America, among other things, Europe. Global warming and increased trade between countries is the main reason why foreign species are introduced to new ecosystems while climate change means that habitats can change to become more suitable for an invasive alien species. The invasive species currently causes major economic losses worldwide. Lupins, park slides, and giant sheds are examples of invasive plants that have been introduced in European gardens because they are beautiful and easy to care for. They are also invasive, spread aggressively and are detrimental to our nature because they penetrate our native species. To stop these invasive plants and from damaging Europe's nature, the EU countries have decided to take action against certain species. On January 1, 2015, the EU adopted a regulation on invasive alien species and how to combat it within the Union. On February 5, 2016, the Swedish Environmental Protection Agency submitted the Authority's proposal to the Swedish Government on new rules and measures on how to stop invasive harmful species. Already today, great resources are being devoted to combating invading plants such in our nature reserves. However, an early preventive or direct targeted intervention is much more cost effective than a continuous control of unwanted, invasive species with well-established populations. In order to succeed in this, we need an increased awareness of the problem of alien, invasive species among the public and decision makers, but also a sharp global analysis. Only with knowledge and continuous monitoring can we put in early action against future, aggressive invaders.

  • 68.
    Lindqvist, Simon
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energikartläggning och förbättringsförslag för lättbetonghus i Mellansverige2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Energy efficiency in dwellings is crucial in reaching goals set within the European Union, but homeowners won’t invest in energy-efficient measures unless it is cost-effective. This study is going to investigate the energy savings and cost-effectiveness of different renovating measurements for a light-concreate house in Söderhamn. The aim is to investigate the building’s energy balance and how renovating measurements affect the energy use, the indoor climate and the operating cost.

    An energy audit was performed on the building for the purpose of investigating the various measurements. The audit was achieved with IDA Indoor Climate and Energy simulation tool, which was used to construct a reference model that included data from the studied building. Previous research in the field were used for selecting the renovating measurements used in this study. The results of the simulations were then used to carry out a cost analysis with the equivalent annual cost method to evaluate the annual cost saving for each measurement. The carbon dioxide level was measured in the beginning of the project to investigate the indoor air quality in the building and if it needed to be addressed.

    The primary energy use of the building was 148 kWh/(m2·year), which was 43 % more than Building regulations energy requirements for single-family households. The heat demand was 18 209 kWh/year and could be reduced by 42,7 % when installing a created renovation package and resulting in the primary energy use of 109 kWh/(m2·year).  The three most energy efficient measures were adding extra insulation on external walls, insulating the roof and decreasing the indoor temperature level. The most cost-effective measure was to insulate the roof if the upstairs area were heated and insulate the basement walls was the least cost-effective of the energy efficient measures. The ventilation problem was fixed with installation of an FTX system that switched to an air flow of 0,35 l/(s·m2) to 0,1 l/(s·m2) during unoccupancy. Complementing the heat demand with a heat pump was a cost-effective measure but did increase the primary energy use. It is recommended to finish isolating the roof if the family is interested in using the unoccupied space.

  • 69.
    Lundström, Lukas
    et al.
    Mälardalens högskola, Framtidens energi, Västerås, Sweden; Eskilstuna Kommunfastighet AB, Eskilstuna, Sweden.
    Akander, Jan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Zambrano, Jesus
    Mälardalens högskola, Framtidens energi, Västerås, Sweden.
    Development of a space heating model suitable for the automated model generation of existing multifamily buildings: a case study in Nordic climate2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 3, article id 485Article in journal (Refereed)
    Abstract [en]

    Building energy performance modeling is essential for energy planning, management, and efficiency. This paper presents a space heating model suitable for auto-generating baseline models of existing multifamily buildings. Required data and parameter input are kept within such a level of detail that baseline models can be auto-generated from, and calibrated by, publicly accessible data sources. The proposed modeling framework consists of a thermal network, a typical hydronic radiator heating system, a simulation procedure, and data handling procedures. The thermal network is a lumped and simplified version of the ISO 52016-1:2017 standard. The data handling consists of procedures to acquire and make use of satellite-based solar radiation data, meteorological reanalysis data (air temperature, ground temperature, wind, albedo, and thermal radiation), and pre-processing procedures of boundary conditions to account for impact from shading objects, window blinds, wind- and stack-driven air leakage, and variable exterior surface heat transfer coefficients. The proposed model was compared with simulations conducted with the detailed building energy simulation software IDA ICE. The results show that the proposed model is able to accurately reproduce hourly energy use for space heating, indoor temperature, and operative temperature patterns obtained from the IDA ICE simulations. Thus, the proposed model can be expected to be able to model space heating, provided by hydronic heating systems, of existing buildings to a similar degree of confidence as established simulation software. Compared to IDA ICE, the developed model required one-thousandth of computation time for a full-year simulation of building model consisting of a single thermal zone. The fast computation time enables the use of the developed model for computation time sensitive applications, such as Monte-Carlo-based calibration methods. 

  • 70.
    Ma, Ding
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Omer, Itzhak
    Tel-Aviv University, Tel-Aviv, Israel.
    Osaragi, Toshihiro
    Tokyo Institute of Technology, Tokyo, Japan.
    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.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Why Topology Matters in Predicting Human Activities2019In: Environment and Planning B: Urban Analytics and City Science, ISSN 2399-8083, Vol. 46, no 7, p. 1297-1313Article in journal (Refereed)
    Abstract [en]

    Geographic space is best understood through the topological relationship of the underlying streets (note: entire streets rather than street segments), which enabales us to see scaling or fractal or living structure of far more less-connected streets than well-connected ones. It is this underlying scaling structure that makes human activities or urban traffic predictable, albeit in the sense of collective rather than individual human moving behavior. This power of topological analysis has not yet received its deserved attention in the literature, as many researchers continue to rely on segment analysis for predicting urban traffic. The segment-analysis-based methods are essentially geometric, with a focus on geometric details such as locations, lengths, and directions, and are unable to reveal the scaling property, which means they cannot be used for human activities prediction. We conducted a series of case studies using London streets and tweet location data, based on related concepts such as natural streets, and natural street segments (or street segments for short), axial lines, and axial line segments (or line segments for short). We found that natural streets are the best representation in terms of traffic prediction, followed by axial lines, and that neither street segments nor line segments bear a good correlation between network parameters and tweet locations. These findings point to the fact that the reason why axial lines-based space syntax, or the kind of topological analysis in general, works has little to do with individual human travel behavior or ways that human conceptualize distances or spaces. Instead, it is the underlying scaling hierarchy of streets – numerous least-connected, a very few most-connected, and some in between the least- and most-connected – that makes human activities or urban traffic predictable.

  • 71.
    MacCutcheon, Douglas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Hurtig, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Pausch, Florian
    Aachen University, Aachen, Germany.
    Hygge, Staffan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Fels, Janina
    Aachen University, Aachen, Germany.
    Ljung, Robert
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Second language vocabulary level is related to benefits for second language listening comprehension under lower reverberation time conditions2019In: Journal of Cognitive Psychology, ISSN 2044-5911, E-ISSN 2044-592X, Vol. 31, no 2, p. 175-185Article in journal (Refereed)
    Abstract [en]

    The acoustic qualities of a room can have a deleterious effect on the quality of speech signals. The acoustic measurement of reverberation time (RT) has shown to impact second language (L2) speech comprehension positively when lower due to release from spectral and temporal masking effects as well as top-down processing factors. This auralization experiment investigated the benefits of better L2 vocabulary and executive function (updating) skills during L2 listening comprehension tests under shorter versus longer RT conditions (0.3 and 0.9 s). 57 bilingual university students undertook L2 vocabulary, number updating and L2 listening comprehension tests. After splitting groups into high/low vocabulary and updating groups, a mixed ANOVA was conducted. The high number updating group showed no significant differences or interactions in L2 listening comprehension than the lower number updating group across RT conditions. The high vocabulary group had 22% better L2 listening comprehension than the low vocabulary group in long RT, and 9% better in short RT. A significant benefit in L2 listening comprehension due to release from reverberation was only evident in the high vocabulary group. Results indicate that the benefit of good room acoustics for listening comprehension is greatest for those with better language (vocabulary) ability.

  • 72.
    Magnusson, Peter
    et al.
    Centre for Research and Development, Uppsala University/Region Gävleborg, Gävle, Sweden; Cardiology Research Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
    Kihlström, Gabriella
    Centre for Research and Development, Uppsala University/Region Gävleborg, Gävle, Sweden.
    Wallhagen, Marita
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Rambaree, Komalsingh
    University of Gävle, Faculty of Health and Occupational Studies, Department of Social Work and Criminology, Social Work.
    Life‐threatening peripartum cardiomyopathy — not expected when expecting2019In: Clinical Case Reports, E-ISSN 2050-0904, Vol. 7, no 6, p. 1127-1132Article in journal (Refereed)
    Abstract [en]

    Peripartum cardiomyopathy is challenging to diagnose as it mimics symptoms present in normal pregnancy. The clinical course and prognosis are various. In selected cases, a cardioverter implantable defibrillator with/without cardiac resynchronization therapy, mechanical ventricular assist device treatment, and transplantation is indicated.

  • 73.
    Marois, Alexandre
    et al.
    Université Laval, Québec, Canada.
    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, United Kingdom.
    Vachon, François
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Université Laval, Québec, Canada.
    Is auditory distraction by changing-state and deviant sounds underpinned by the same mechanism?: Evidence from pupillometry2019In: Biological Psychology, ISSN 0301-0511, E-ISSN 1873-6246, Vol. 141, p. 64-74Article in journal (Refereed)
    Abstract [en]

    The mere presence of task-irrelevant auditory stimuli is known to interfere with cognitive functioning. Disruption can be caused by changing auditory distractors (the changing-state effect) or by a sound that deviates from the auditory background (the deviation effect). The unitary account of auditory distraction explains both phenomena in terms of attentional capture whereas the duplex-mechanism account posits that they reflect two fundamentally different forms of distraction in which only the deviation effect is caused by attentional capture. To test these predictions, we exploited a physiological index of attention orienting: the pupillary dilation response (PDR). Participants performed visual serial recall while ignoring sequences of spoken letters. These sequences either comprised repeated or changing letters, and one letter could sometimes be replaced by pink noise (the deviant). Recall was poorer in both changing-state and deviant trials. Interestingly, the PDR was elicited by deviant sounds but not changing-state sounds, while a tonic increase in pupil size was found throughout changing-state trials. This physiological dissociation of the changing-state and the deviation effects suggests they are subtended by distinct mechanisms thereby procuring support for the duplex-mechanism account over the unitary account. 

  • 74.
    Marsh, John E.
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. School of Psychology, University of Central Lancashire, Preston, UK.
    Campbell, Tom A.
    Faculty of Information Technology and Communication Sciences, Tampere UniversityTampereFinland.
    Vachon, François
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Université Laval, Quebec City, Canada.
    Taylor, Paul J.
    School of Psychology, University of Central Lancashire, Preston, UK.
    Hughes, Robert W.
    Department of Psychology, Royal Holloway, University of London, Egham, UK.
    How the deployment of visual attention modulates auditory distraction2019In: Attention, Perception & Psychophysics, ISSN 1943-3921, E-ISSN 1943-393XArticle in journal (Refereed)
    Abstract [en]

    Classically, attentional selectivity has been conceptualized as a passive by-product of capacity-limits on stimulus-processing. Here, we examine the role of more active cognitive control processes in attentional selectivity, focusing on how distraction from task-irrelevant sound is modulated by levels of task-engagement in a visually-presented short-term memory task. Task-engagement was varied by manipulating the load involved in the encoding of the (visually-presented) to-be-remembered items. Using a list of Navon letters (where a large letter is composed of smaller, different-identity, letters), participants were oriented to attend and serially recall the list of large letters (low encoding-load) or to attend and serially recall the list of small letters (high encoding-load). Attentional capture by a single deviant noise burst within a task-irrelevant tone sequence (the deviation effect) was eliminated under high encoding-load (Experiment 1). However, distraction from a continuously changing sequence of tones (the changing-state effect) was immune to the influence of load (Experiment 2). This dissociation in the amenability of the deviation effect and the changing-state effect to cognitive control supports a duplex- over a unitary-mechanism account of auditory distraction in which the deviation effect is due to attentional capture while the changing-state effect reflects direct interference between the processing of the sound and processes involved in the focal task. That the changing-state effect survives high encoding-load also goes against an alternative explanation of the attenuation of the deviation effect under high load in terms of the depletion of a limited perceptual resource that would result in diminished auditory processing.

  • 75.
    Marsh, John E.
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. School of Psychology, University of Central Lancashire, Preston, United Kingdom.
    Hansson, Patrik
    Department of Psychology, Umeå University, Umeå, Sweden.
    Eriksson Sörman, Daniel
    Department of Psychology, Umeå University, Umeå, Sweden.
    Körning Ljungberg, Jessica
    Department of Psychology, Umeå University, Umeå, Sweden; Division of Human Work Science, Luleå University of Technology, Luleå, Sweden.
    Executive Processes Underpin the Bilingual Advantage on Phonemic Fluency: Evidence from Analyses of Switching and Clustering2019In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 10, article id 1355Article in journal (Refereed)
    Abstract [en]

    Bilinguals often show a disadvantage in lexical access on verbal fluency tasks wherein the criteria require the production of words from semantic categories. However, the pattern is more heterogeneous for letter (phonemic) fluency wherein the task is to produce words beginning with a given letter. Here, bilinguals often outperform monolinguals. One explanation for this is that phonemic fluency, as compared with semantic fluency, is more greatly underpinned by executive processes and that bilinguals exhibit better performance on phonemic fluency due to better executive functions. In this study, we re-analyzed phonemic fluency data from the Betula study, scoring outputs according to two measures that purportedly reflect executive processes: clustering and switching. Consistent with the notion that bilinguals have superior executive processes and that these can be used to offset a bilingual disadvantage in verbal fluency, bilinguals (35-65 years at baseline) demonstrated greater switching and clustering throughout the 15-year study period.

  • 76.
    Martinez, Pablo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Quenching a steel plate by water - impinging jets and different simultaneous flow rates2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Regarding the great importance of fast cooling in steel industry for the production processes, a deep understanding of heat transfer and fluid dynamics must be held. A steel plate is heated up until a maximum temperature of 700 ⁰ C to be the n cooled down seconds later by a configuration of multi ple impinging water jets. Different flow rates are used simultaneously by different adjacent jets to perform quenching over the sample, so different hardness is obtained in the material over a small area . Temperature drop in time i s measured and monitored by embedded thermocouples and LabVIEW program. To achieve greater understanding of the quenching performance with different flow rates , several parameters are selected to be varied in order to achieve the best working conditions. Jet diameter takes values between 4 and 10 mm, initial temperature of quenching varies from 400 to 700 ⁰ C , subcooling temperature is tested for 65 and 75 K, and jet velocity varies between 1.9 and 3.9 m/s. The result of total number of 9 expe riments shown that v ariation of jet diam eter does not influence substantially on the cooling rate if flow rate is kept constant. High initial quenching temperature (600 - 700 ⁰ C ) led to slightly higher cooling rate in the stagnation region of water jets. The peak value of heat transfer rate in the upwash flow zone was more highlighted for initial quenching temperature 600 ⁰ C and below it. High er values of subcooling and jet velocity produce better cooling rates. The result shown higher jet velocity at one column of water jets changes position of upw ash flow slightly toward the adjacent column of jets with lower jet velocity. In general, the result shown that all the studied parameters did not have negative effect on obtaining various cooling rates over the steel plate.

  • 77.
    Milić, Vlatko
    et al.
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Ekelöw, Klas
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Andersson, Maria
    Division of Energy Systems, Department of Management and Engineering, 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.
    Evaluation of energy renovation strategies for 12 historic building types using LCC optimization2019In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 197, p. 156-170Article in journal (Refereed)
    Abstract [en]

    The life cycle cost (LCC)optimization is a vital method when performing building energy renovation. The present paper provides an evaluation of cost-optimal energy renovation strategies for historic buildings using LCC optimization software OPERA-MILP. The evaluation is performed based on preset targets depending on LCC (LCC optimum)and energy use (decrease by 50%), where the environmental performance is also addressed. Twelve building types, which are typical of the historic building stock in Visby, Sweden, are used as the study object. The results show possible decreases of 12–38% in LCC when targeting LCC optimum. When targeting a 50% decrease in energy use, the LCC is decreased in 21 of 26 cases compared to before energy renovation. Cost-efficient EEMs on the building envelope are characterized by low renovation costs and additional insulation of building components with poor thermal properties. Furthermore, the environmental performance from the energy renovations is highly dependent on the chosen energy system boundary. 

  • 78.
    Monjurul Hasan, A. S. M.
    et al.
    Department of Electrical and Electronic Engineering, Bangladesh Army International University of Science and Technology, Cumilla, Bangladesh.
    Rokonuzzaman, M.
    Institute for Intelligent Systems Research and Innovation, Deakin University, Victoria, Australia.
    Tuhin, R. A.
    Department of Computer Science and Engineering, East West University, Dhaka, Bangladesh.
    Salimullah, S. Md.
    Department of Electrical and Electronic Engineering, Bangladesh Army International University of Science and Technology, Cumilla, Bangladesh.
    Ullah, M.
    Department of Electrical and Electronic Engineering, Bangladesh Army International University of Science and Technology, Cumilla, Bangladesh.
    Sakib, T. H.
    Department of Electrical and Electronic Engineering, Bangladesh Army International University of Science and Technology, Cumilla, Bangladesh.
    Thollander, Patrik
    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.
    Drivers and barriers to industrial energy efficiency in textile industries of Bangladesh2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 9, article id 1775Article in journal (Refereed)
    Abstract [en]

    Bangladesh faced a substantial growth in primary energy demand in the last few years. According to several studies, energy generation is not the only means to address energy demand; efficient energy management practices are also very critical. A pertinent contribution in the energy management at the industrial sector ensures the proper utilization of energy. Energy management and its efficiency in the textile industries of Bangladesh are studied in this paper. The outcomes demonstrate several barriers to energy management practices which are inadequate technical cost-effective measures, inadequate capital expenditure, and poor research and development. However, this study also demonstrates that the risk of high energy prices in the future, assistance from energy professionals, and an energy management scheme constitute the important drivers for the implementation of energy efficiency measures in the studied textile mills. The studied textile industries seem unaccustomed to the dedicated energy service company concept, and insufficient information regarding energy service companies (ESCOs) and the shortage of trained professionals in energy management seem to be the reasons behind this. This paper likewise finds that 3–4% energy efficiency improvements can be gained with the help of energy management practices in these industries. 

  • 79.
    Norell, Pontus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Prospects for biodiesel in Gävleborg County: Feedstocks and production2019Report (Other academic)
    Abstract [en]

    The increasing emissions from the transport sector have become a global concern as these emissions contribute to climate change. One way to reduce carbon dioxide (CO2) emissions from the transport sector is to replace fossil fuels with biofuels. The diesel engine is important for transports in society, especially since it is more efficient and more powerful compared with the gasoline engine. Therefore, replacing fossil diesel with biodiesel is one feasible option for achieving short and long-term emission targets. Fatty acid methyl esters (FAME) and hydrotreated vegetable oils (HVO) are the two kinds of biodiesel being used in Sweden. The raw materials are vegetable and animal oils and fats and the production method is esterification for FAME and hydrotreatment for HVO. HVO is more similar to fossil diesel and higher blends can be used in existing diesel engines if the vehicle manufacturer has approved it whereas FAME requires vehicle modifications when used in higher blends. Both HVO and FAME can be used as drop-in fuel with fossil diesel, but only up to 7% for FAME according to regulations. The Swedish consumption of HVO has increased rapidly in recent years. In 2017 it was more than 20% of the total globally produced HVO that year. Furthermore, the dependence on imported raw materials is heavy. Only 3% of the raw materials for FAME and only 5% of the raw materials for HVO sold in Sweden were of Swedish origin in 2017.

    Since the feedstocks used for biodiesel production are of limited availability and have competing uses, it is important to increase the knowledge of local resources. The County of Gävleborg has many large forest-related industries. The actors at different levels of the supply chain have important roles in the challenges to reduce fossil fuel dependence. The overall aim of this report is to investigate the current status and future prospects of biodiesel feedstocks and production technologies for FAME and HVO from a regional perspective. This is achieved by two separate approaches. First, a literature review is done through which potential feedstocks and production processes are described. The feedstocks are categorized into different generations. Second, ongoing and upcoming activities related to biodiesel production in Gävleborg County are explored through interviews with regional actors. The interviewees are representatives from companies with activities in Gävleborg County: Setra, BillerudKorsnäs, Iggesund, Rottneros and Colabitoil.

    Raw materials belonging to the first generation compete with food production. For biodiesel these raw materials are different types of vegetable oils. The main ones worldwide are palm oil, soybean oil, rapeseed oil and sunflower oil. These raw materials can be used as feedstock for both FAME and HVO. In Sweden the agricultural activity is relatively low and even lower in Gävleborg County. The extensive use of land and competition with food production makes these type of raw materials for biodiesel production questionable. But arguments can be made that the vegetable oils have good traceability and this can lead to better control to ensure a sustainable biodiesel value chain.

    Second-generation raw materials are non-food based. There are a variety of different types. Some are already being used and some are potential biodiesel feedstocks for the future. The ones presented in this report are animal fats, fish oils, waste cooking oils (WCO), pyrolysis oil, lignin and crude tall oil (CTO). Animal fats and fish oils can also be considered first-generation raw materials since they might be edible. There are strict health regulations for human food and the fats and oils that do not live up to the regulations can be used for other purposes. Animal fats and fish oils can also be used as animal feed and production of different chemicals. It is not obvious which use is best, but generally it seems that biodiesel and other energy uses are regarded as the least valuable in comparison. An important issue to consider is that the availability of animal fats and fish oils depends on the demand for meat.

    WCO is a feedstock for biodiesel which is currently used by Colabitoil in their pilot plant for HVO. It seems that the profitability of using WCO is dependent on the production capacity of the WCO producers and the distance between them since these two factors affect the fuel consumption during collection. It is optimal to have one big WCO producer in order to minimize the collection costs. In theory, there could be a situation in which there are so many small producers that more fuel is required for collection than is gained in biodiesel production.

    Pyrolysis oil from biomass is an interesting future source for biodiesel. It is a heterogeneous mixture of compounds and contains a lot of oxygen. Pyrolysis oil is definitely a raw material that needs catalytic hydrotreatment for upgrading. It is therefore considered an HVO feedstock and not feasible for FAME. This study did not clarify how much pyrolysis oil will end up as diesel fuel and how much will end up as gasoline or other products. A pyrolysis plant for production of pyrolysis oil from sawdust might be built at Setra’s sawmill Kastet in Gävle. The pyrolysis oil will then be used as a feedstock for diesel and gasoline fuels in Preem’s refinery.

    Lignin is one of the main components of wood. In the production of pulp by the sulfate process lignin is separated from the pulp as a component in the black liquor. The lignin is then primarily burned for energy purposes in the recovery boiler. The three pulp mills within Gävleborg County all use the sulfate process. At the pulp mill owned by Rottneros in Vallvik a plant for extraction of lignin and a plant for conversion into a lignin oil might be built. This pulp mill has a surplus of energy and therefore a potential to extract some of the lignin. The lignin will be processed together with a bio-based carrier oil to the lignin oil. This lignin oil will then be used as a feedstock for gasoline and diesel fuel in Preem’s refinery. It was not clarified in this study what the source of the bio-based carrier oil will be. Additionally, the composition of the lignin oil was not revealed and therefore it could not be determined what share of it can be used for biodiesel production. Lignin oil is very interesting as a feedstock due to the large amount of lignin that is available in the forests. However, the interviews with the two other pulp mills (i.e., Iggesund and BillerudKorsnäs) showed that the availability is limited by other factors. These two pulp mills are integrated with production of paper products and therefore they have no surplus of energy. If lignin is extracted the energy has to be replaced by other sources. An eventual extraction of lignin is associated with reconstruction of different parts of the plant and thereby large investment costs.

    CTO is a by-product from pulp mills that use the sulfate process. It is of limited availability and consists mainly of fatty acids and rosin acids. The fatty acids can be converted to biodiesel. One way to utilize the components of CTO is to fractionate it into different product streams through distillation. These product streams include one stream with fatty acids, one stream with rosin acids and one stream called pitch. The pitch can be seen as a residue. There are two main refineries to which the three pulp mills in Gävleborg County deliver their CTO: Sunpine in Piteå and Kraton in Sandarne. Sunpine produces tall oil diesel and other products from the CTO, and the tall oil diesel is used for HVO production by Preem. Kraton produces different chemicals from the CTO. For all three pulp mills an important factor is to get tall oil pitch back from Sunpine and Kraton to be used for energy purposes.

    A potential source of lipids for biodiesel production was mentioned in the interview with Colabitoil. This was the conversion of lignocellulosic material into lipids by microbes. A particularly suitable feedstock for the microbes would be waste fibers from pulp and paper industries. This still appears to be at the research stage, but it will be interesting to follow the development since it has promising opportunities if it can be achieved at a commercial scale.

    Third-generation feedstocks for biodiesel are oils obtained from microalgae. Microalgae are potentially superior to the other raw materials. Biodiesel from microalgae is not commercially available so it is up to the future to determine its destiny. Due to the cold climate of Gävleborg County it is questionable if it is a good place for large-scale cultivation of microalgae.

    The optimal feedstock for FAME are triglycerides. Therefore, first-generation raw materials are wanted. Catalytic hydrotreatment can handle more complex raw materials and the feedstock range can thereby be increased to second-generation feedstocks. There is no producer of FAME in Gävleborg County, but there is a company (Colabitoil) that distributes HVO produced by Neste. Colabitoil also has a pilot plant for HVO production and might build a large-scale production plant in the future. The activities in Norrsundet, which Colabitoil is part of, has a potential to provide synergy effects if different companies settle there. There can then be knowledge-sharing and utilization of different by-products between the companies.

    There are two aspects about the limitations of the report that should be mentioned. First, the environmental performance of the different raw materials and production technologies is not considered. This is an important issue since the main purpose of biofuels is to reduce the environmental impact of fossil fuels. Second, it cannot be ruled out that there could have been intentional or unintentional bias in the interviews, even though there is no reason to suspect this. Additionally, it is very tricky to assess the certainty behind different statements from different persons since they have different backgrounds and different expectations about the future. Apart from this, the aim of the report was met to a large extent by shedding light on the future prospects of biodiesel through the challenges, uncertainties and success factors related to projects that the different actors described in the interviews. The challenges are technical and financial. The uncertainties are related to political stability but also to the environmental permit and future availability of raw materials. The success factors are the high demand for transport fuels and cooperation with other companies.

  • 80.
    Olausson, Jesper
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energy efficiency in a renovated modern office with activity-based work style2019Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During renovation Ljusåret 2 was converted to a modern office with an activity based work style (ABW) with a Demand Controlled Volume (DCV) ventilation system connected to a closed-loop duct. Cooling is provided through air handling units and active water based beams, the underfloor heating system was kept.

    Written instruction and specification have been studied for the two different control systems Schneider EcoStructure and Lindinspect. Both control systems have been analyzed according to time schedule, set-point and process value by using different functions in software.

    To be able to perform a energy audit and look at indoor climate for Ljusåret 2 there have been studies according to underfloor heating, constructions of ventilation system, diversity factor for DCV, closed-loop-ducts, heat losses from ducts, cooling demand and energy certification.

    According to this audit, energy performance is calculated to 89.1 kWh/m2 according to building energy, activity energy is not audited or calculated. During design phase, an energy calculation was made by an energy consultant with the result of 81.3 kWh/m2. The estimated performance is a 9.6 % increase. This building is designed for Miljöbyggnad certification of level silver and should be ≤ 109 kWh/m2,year. According to audit and calculation for energy performance this level is possible to keep.

    The estimated energy performance have been calculated with only 4 month of statistics from January until April 2019 because Ljusåret 2 have just been renovated. District heating has been estimated through the energy signature by data from energy meter. Electrical components for the building have been measured and energy usage calculated. Energy produced by compression chiller have been estimated with calculated performance from design phase and adding heat transfer between rooms and supply ducts. Energy between rooms and supply ducts were not included in energy calculation during the design phase.

    According to the control system for the DCV system there have been some issues with high temperature in supply ducts even when they are supplied with 15 ºC from air- handling unit. There have been measurement to the ventilation system 5701-5704 that is connected to a close-loop duct with a result of temperatures between 15.2 ºC up to 21.4 ºC and the velocity has varied between 0.05-2.1 m/s in different measurement spots. This is an increase of 6.4 ºC.

    A heat transfer calculation have been made in Paroc Calculus to estimate heat transfer between room and supply ducts. The results of this calculation indicates the same level of temperature increases as when the system was measured. With no thermal insulation cooling capacity is lost to half after less than 5 m with a velocity of 0.2 m/s, after 15 m with a velocity of 1 m/s and 30 m with a velocity of 2 m/s . This should be compared with supply duct with 20 mm of thermal insulation that has lost its cooling capacity after less than 13 m with a velocity of 0.2 m/s, after 63 m with a velocity of 1 m/s and is increase with 4 ºC after 100 m with a velocity of 2 m/s.

    Using closed-loop ducts with velocity below 2.0 m/s and without thermal insulation combined with under tempered supply air is not a good combination. Even short length with low velocity and lack of thermal insulation is devastating because of heat transfer according to logarithmical temperature difference between room and supply ducts.

    A closed-loop duct is often designed as a pressure chamber and recommended when using DCV and/or VAV ventilation to avoid problems with noise and to be able to reduce the need of dampers. Problems with temperature increasing according to velocity in ducts must be taken in consideration.

    For Ljusåret 2 this will affect district heating usage where ducts are placed because underfloor heating must compensate heat transfer. Chilled water must be provided an extra time for rooms with both DCV and chilled beams and rooms with only DCV is less comfortable which they could been with a correct installation.

  • 81.
    Panicker, Suresh Ambu
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Student.
    Investigation of the energy performance and renovation opportunities in a historic building.: using questionaire and assessment scale for decision making and improving energy performance.2019Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    On a global scale it is estimated that the building sector accounts for about 35% of the final energy use. The building sector accounts for nearly 40% of energy demand in European union (EU) and in Sweden too it is almost the same percentage demand. It is also known that more than 40% of the residential buildings in Europé were built before 1960 when the energy performance regulations for buildings were not so strict in view of the climate change objectives.

    Compared to other countries in the EU, Sweden has a large number of listed or historic buildings as almost 15% of multi-family buildings and 27% of all single-family houses in Sweden were built before 1945. However it also stated that research on listed buildings energy efficiency potential and indoor environment is very scarce in Sweden.

    Due to climate change and the need to reduce greenhouse gas emission

    (mainly CO2) associated with reduction in energy use in buildings is very evident. Some buildings are of heritage significance due to their historical, architectural or cultural values. The Swedish standard SS-EN 16883:2017 refers to them as listed or historic buildings. This standard does not presuppose that all historic buildings need energy performance improvements. The use of this standard is not limited to historic building with heritage values however it can also be applied to historic buildings of all ages and types.

    This study presents an assessment of a historic building built around 1945 where both the building owners energy use data and the building tenants or users indoor environment perceptions includes their expectations on daylight needs, illumination, temperature control or heating and ventilation are evaluated by the assessment scale methodology recommended in the Swedish Standard SS-EN 16883:2017.

    The results obtained have been presented on an assessment scale as per SS-EN 16883:2017 also considering the building users perceptions of the indoor work environment. This could be a basis for future decision making for the building owner considering the planned investments on prioritized and feasible energy effective measures. Thus this study is based on quantitative approach. This assessment scale decision making model can be a basis for future builing investigations and investments iii

    plans in building refurbishments leading to improvements in energy performance of this historic building.

    Keywords:

    english

    Listed building, Energy performance, Energy efficient measures, historic buildings, Energy use, Indoor environment, Building survey and accessment, Energy efficient measures.

    swedish

    Byggnadsminne, Energiprestanda, förbättring av energiförbrukning, historiska byggnader, energianvändning, inomhusmiljö, byggundersökning och bedömning, energieffektiva åtgärder.

  • 82.
    Petrovic, Bojana
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science. Department of Energy and Construction Technology, Dalarna University, Falun, Sweden.
    Myhren, Jonn Are
    Department of Energy and Construction Technology, Dalarna University, Falun, Sweden.
    Zhang, Xingxing
    Department of Energy and Construction Technology, Dalarna University, Falun, Sweden.
    Wallhagen, Marita
    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.
    Life cycle assessment of a wooden single-family house in Sweden2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 251, article id 113253Article in journal (Refereed)
    Abstract [en]

    To understand the reasons behind the large environmental impact from buildings the whole life cycle needs to be considered. Therefore, this study evaluates the carbon dioxide emissions in all stages of a single-family house in Sweden from the production of building materials, followed by construction and user stages until the end-of-life of the building in a life cycle assessment (LCA). The methodology applied is attributional life cycle assessment (LCA) based on ‘One Click LCA’ tool and a calculated life span of 100 years. Global warming potential (GWP) and primary energy (PE) are calculated by using specific data from the case study, furthermore the data regarding building materials are based on Environmental Product Declarations (EPDs). The results show that the selection of wood-based materials has a significantly lower impact on the carbon dioxide emissions in comparison with non-wood based materials. The total emissions for this single-family house in Sweden are 6 kg CO 2 e/m 2 /year. The production stage of building materials, including building systems and installations represent 30% of the total carbon dioxide equivalent emissions, while the maintenance and replacement part represents 37%. However, energy use during the in-use stage of the house recorded lower environmental impact (21%) due to the Swedish electricity mix that is mostly based on energy sources with low carbon dioxide emissions. The water consumption, construction and the end-of-life stages have shown minor contribution to the buildings total greenhouse gas (GHG) emissions (12%). The primary energy indicator shows the largest share in the operational phase of the house. © 2019

  • 83.
    Prado, Ana
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Comparing the performance of a combined confluent jets, windows façade supply device and active chilled beam air distribution systems in an office2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As temperatures rise around the world and people work more hours throughout the day, the necessity for a comfortable work environment and better thermal comfort has increased. Ventilation systems might have an impact on workers’ health in relation to providing suitable levels of indoor air quality and thermal comfort. Thereby, the purpose of this research was to test different existing installations in an office by taking measures and carrying out a questionnaire to the office staff, so the performance of the systems and the thermal comfort provided could be evaluated. The investigated systems were: wall confluent jets supply device, windows façade supply device and active chilled beams.

    The results show that the mean room temperature from both confluent jets ventilation (CJV) and façade-integrated displacement ventilation (FIDV) is higher than with the mixing ventilation with active chilled beams. Also the maximum temperature difference between neck level and ankle level was lower with the active chilled beams (ACB) system. Nevertheless, the draught rate was higher for the chilled beams. In addition to the fact that the mixing ventilation (MV) systems have the drawback of mixing contaminated air with the fresh air supplied, which can lead to lower performance and diseases for the occupants.

    For the office studied, results confirm that the CJV provides better overall ventilation performance than the mixing and displacement supply devices used in this study, as it combines the positive effects of both mixing and stratification principles.

  • 84.
    Ramirez Villegas, Ricardo
    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. School of Technology and Business Studies, Dalarna University, Falun, Sweden.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Olofsson, Thomas
    Department of Applied Physics and Electronics, Umeå University, 90187 Umeå, Sweden.
    Life Cycle Assessment of Building Renovation Measures: Trade-off between Building Materials and Energy2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 3, article id 344Article in journal (Refereed)
    Abstract [en]

    The scope of this study is to assess how different energy efficient renovation strategies affect the environmental impacts of a multi-family house in a Nordic climate within district heating systems. The European Union has set ambitious targets to reduce energy use and greenhouse gas emissions by the year 2030. There is special attention on reducing the life cycle emissions in the buildings sector. However, the focus has often been on new buildings, although existing buildings represent great potential within the building stock in Europe. In this study, four different renovation scenarios were analyzed with the commercially available life cycle assessment software that follows the European Committee for Standardization (CEN) standard. This study covers all life cycle steps from the cradle to the grave for a residential building in Borlange, Sweden, where renewable energy dominates. The four scenarios included reduced indoor temperature, improved thermal properties of building material components and heat recovery for the ventilation system. One finding is that changing installations gives an environmental impact comparable to renovations that include both ventilation and building facilities. In addition, the life cycle steps that have the greatest environmental impact in all scenarios are the operational energy use and the building and installation processes. Renovation measures had a major impact on energy use due to the cold climate and low solar irradiation in the heating season. An interesting aspect, however, is that the building materials and the construction processes gave a significant amount of environmental impact.

  • 85.
    Ramírez-Villegas, Ricardo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. School of Technology and Business Studies, Dalarna University, Falun, Sweden.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Olofsson, Thomas
    Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Combined Environmental and Economic Assessment of Energy Efficiency Measures in a Multi-Dwelling Building2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 13, article id 2484Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to assess how different renovation scenarios affect the environmental and economic impacts of a multi-dwelling building in a Nordic climate, how these aspects are correlated and how different energy carriers affect different environmental impact categories. In order to reduce greenhouse gas emissions, the European Union has set an agenda in order to reduce energy use in buildings. New buildings on the European market have a low replacement rate, which makes building renovation an important factor for achieving the European Union goals. In this study, eight renovation strategies were analyzed following the European Committee for Standardization standards for life cycle assessment and life cycle costs of buildings. This study covers all life cycle steps from cradle to grave. The renovation scenarios include combinations of photovoltaics, geothermal heat pumps, heat recovery ventilation and improved building envelopes. Results show that, depending on the energy carrier, reductions in global warming potential can be achieved at the expense of an increased nuclear waste disposal. It also shows that for the investigated renovation strategies in Sweden there is no correlation between the economic and the environmental performance of the building. Changing energy carriers in Sweden in order to reduce greenhouse gas emissions can be a good alternative, but it makes the system more dependent on nuclear power.

  • 86.
    Röjerås, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Projektering av takkonstruktioner med förindustriella träförband: beräkning och provning av hophuggningar2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In earlier wood constructions, the method of joining the parts was by the carpenter joint. There are many different kinds of carpenter joints. The kind of carpenter joint that was used was partly due to the type of building, but also to local variations in building tradition. 

    The industrialization at the end of the 19thcentury led to new construction technology with new types of joints. It gradually became more difficult for the craftsmen to compete with mass-produced standard joints with screws and nails.

    During the latter half of the 20thcentury, it once again began to become popular with the carpenter joint. New technology in the wood industry began to make carpenter joints competitive. 

    Modern technology with modeling of geometries has made it possible to analyze and optimize structures and joints in a new way. Verification through tests has also led to increased understanding of wood joints. 

    Calculation of the load bearing capacity in carpenter joints is possible by applying calculation rules in Eurocode.  

    The purpose with this study is to verify strength calculations for a traditional carpenter joint. 

    An analysis of an imagined timber frame and roof truss was made in a calculation program to assess in a rough manner what section forces the structure was subjected to.  

    A dovetail joint in the roof truss shown in fig. 1 was chosen for further analysis. 

    Manual calculation of the load bearing capacity in the dovetail joint was made. Verification of the calculations was then done through strength tests in a lab.  

    The study shows that it is possible to calculate the load bearing capacity in a dovetail joint and that account must be taken to eccentricities in the joint and varying wood quality. 

  • 87.
    Samuelsson, Karl
    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. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Colding, Johan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, 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.
    Urban resilience at eye level: spatial analysis of empirically defined experiential landscapes2019In: Landscape and Urban Planning, ISSN 0169-2046, E-ISSN 1872-6062, Vol. 187, p. 70-80Article in journal (Refereed)
    Abstract [en]

    An unresolved issue in creating resilient cities is how to obtain sustainability benefits from densification while not eroding the capacity of social-ecological systems to generate wellbeing for urban dwellers. To understand how different relationships between urban form and wellbeing together play out, we analysed geocoded experiential data (1460 experiences from 780 respondents) together with variables of the physical environment. Through statistical and spatial analysis, we operationalised resilience principles to assess what urban environments provide “resilience at eye level” – a diversity of experiences and a level of connectivity between them that limit adverse outcomes. We found 8 typologies of experiential landscapes – distinct compositions of 11 categories of experiences. Our analysis shows that typologies with experiences supportive of wellbeing are diverse and exist in environments that balance residents and workplaces, avoid extreme spatial integration and/or density and have accessible nature. Typologies with many experiences hindering wellbeing fail in one or several of these respects. Our findings suggest that resilience principles can act as a guiding heuristic for urban densification that does not compromise human wellbeing.

  • 88.
    Sandberg, Mats
    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.
    Kabanshi, Alan
    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.
    Is building ventilation a process of diluting contaminants or delivering clean air?2019In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to discuss the performance of air distribution systems intended for dilution of contaminants (e.g. mixing ventilation) and those intended for delivery of clean air to local regions within rooms (e.g. personalized ventilation). We first start by distinguishing the systems by their visiting frequency behaviour. Then, the performance of the systems with respect to their possibility to influence contaminant concentration in the room or regions within the room is dealt with. Dilution capacity concept for mixing systems is discussed, and delivery capacity concept for systems intended to deliver clean air locally is introduced. Various ways for supply of clean air to regions within the room are presented and their pros and cons are discussed. In delivery capacity systems, the most important single parameter is the entrainment of ambient air into the primary supply flow. Therefore, methods of determining entrainment in these systems need to be defined and the results should be included when describing the performance of the air terminal devices.

  • 89.
    Soam, Shveta
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Hillman, Karl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Factors influencing the environmental sustainability and growth of hydrotreated vegetable oil (HVO) in Sweden2019In: Bioresource Technology Reports, ISSN 2589-014X, Vol. 7, article id 100244Article in journal (Other academic)
    Abstract [en]

    The study analyzes the factors influencing the environmental sustainability and growth of hydrotreated vegetableoil (HVO) in Sweden. The major feedstocks identified in the HVO supply chain are palm oil, rapeseed oil,PFAD, tallow and tall oil. LCA studies reveal that feedstock grown on-purpose have larger life cycle GHGemissions than residual feedstock. However, due to the limited supply of residual feedstock there is a need to bemore dependent on domestic sustainable resources. The complexity of feedstock, origin, processing technologies,allocation approach, land use changes (LUC) and selection of environmental categories could result in variationsof the LCA results. To achieve national emissions target, policy instruments such as reduction obligations and taxincentives favor the market for HVO. However, to see more comprehensive results of the HVO development,research is needed to integrate the technological perspective from pilot scale to the commercialized market atlocal, regional and global level.

  • 90.
    Starrin, Susanne
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Simulering och dimensionering av ett solcellssystem på en skola i Mellansverige: En fallstudie med fokus på kostnadsoptimal anläggningsstorlek2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The advancement of photovoltaic systems is growing exponentially both in Sweden and internationally. Reasons for this include decreasing prices, more efficient techniques, reduction in taxes as well as the increasing interest. In many cases, financial incentives like tax reductions or investment incentives are still necessary for photovoltaic systems to become profitable. In this case study, the possibility of installing a photovoltaic system at Västerberg folkhögskola in Storvik is examined. The properties are owned by Region Gävleborg. Bionär Närvärme AB, which is a subsidiary of Gävle Energi AB, provides the properties with heat through a pellet boiler system. In the summer however, electricity is used for the boiler when the heating requirement is less demanding, and there is an interest in producing electricity using solar cells. Since there is only one electricity subscription the PV-system is dimensioned with regards to the whole of the school’s electricity use including heating. The main purpose was to first identify suitable rooftops and then find the most costeffective size of a photovoltaic system for the school. Then, a simulation was performed to find out the annual electricity production and with the help of these results, an economic calculation could be determined. Suitable rooftops were selected with respect to orientation, angle, size and placement of distribution boxes. Quantitative data regarding the properties and electricity use were collected from Region Gävleborg. Subsequently, different photovoltaic system sizes were tested in Winsun to find the system size that yielded the shortest straight repayment time. Next, simulation of the selected system size was performed in PVsyst, where annual electricity exchange was presented as a result. An economic analysis could be carried out with the help of the values of electricity usage, solar-produced electricity, self-used electricity, over-produced electricity (which is sold to the power grid). The result shows that the system size that gives the shortest repayment time is just under 100 kWp. After simulation of selected rooftops in PVsyst, a peak power of 94.6 kWp was achieved. This gave a payback period of 7,8 years.

  • 91.
    Svedman, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Förhindrande av frostbildning i plattvärmeväxlare via variabel förvärmd uteluft2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study has analysed if preheating of air is a good method to prevent frost formation in a counter flow plate heat exchanger used in Air Handling Units. Frosting in heat exchangers used in AHU-systems is a problem in cold climates and lowers the energy recovery when its potential is the highest.  

    Previous research has been done to 1) Define safe operating conditions without frost formation in heat exchangers with laminar flow. 2) Compare different frost control strategies. 3) Analyse frost formation properties and its effects on heat exchangers in AHU-systems. That the research is not unambiguous for which frost control method is the best highlights the importance of this work.

    Empirical heat transfer coefficients are quantified in this study and are used in the creation of an analytical model of a counter flow heat exchanger that predicts the energy use for heating the air at different operating modes. The heat transfer coefficients are produced by measurements in an AHU-systems located in an apartment building. The AHU has an installed air heater before the heat exchanger which heats the outdoor inlet air to constant temperature.  

    The manufacturer of the AHU-system proclaims turbulent flow in the heat exchanger. Change of airflow has greater impact on the heat transfer coefficients during turbulent flow compared to laminar flow conditions. This is also derived from the results of the measurements. The effectiveness of the current control system is analyzed, and flaws are discovered. A new control system is therefore proposed for frost free operation and higher energy efficiency. The proposed control system is compared to a frequently used frost control system which uses bypass-dampers to redirect the inlet air to the reheater, to let the warm air stream melt formed frost on the warm air side. This comparison is accomplished by analyzing the usage of the bypass-dampers during different outdoor temperatures in a comparable AHU-system that have the mentioned frost control method. The results show that preheating of inlet air for frost free operation uses less energy than usage of the bypass-dampers to melt formed frost on the warm air side.

    The proposed control system needs the bypass-dampers to be used when the preheater is on full operation to prevent frost formation at extreme outdoor temperatures when the preheating may not be enough. The proposed control system is regulated by the dewpoint and the temperatures of the exhaust air stream and the supply air stream.

    The derived heat transfer coefficient that is used to predict the plate-temperature take no account for condensation on the warm air side during humid conditions when the dew point is above the freezing point. Future studies can derive the heat transfer coefficient during condensation which will improve the prediction of the plate-temperature. This would make the system more energy efficient during humid air conditions. This can be done by measurements in an AHU-system with high temperature efficiency placed in a humid environment.

  • 92.
    Sörqvist, Patrik
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Langeborg, Linda
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Psychology.
    Hurting the world you love2019In: New scientist (1971), ISSN 0262-4079, Vol. 241, no 3221, p. 24-25Article in journal (Other academic)
  • 93.
    Sörqvist, Patrik
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Langeborg, Linda
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Psychology.
    Why People Harm the Environment Although They Try to Treat It Well: An Evolutionary-Cognitive Perspective on Climate Compensation2019In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 10, article id 348Article in journal (Refereed)
    Abstract [en]

    Climate changes stress the importance of understanding why people harm the environment despite their attempts to behave in climate friendly ways. This paper argues that one reason behind why people do this is that people apply heuristics, originally shaped to handle social exchange, on the issues of environmental impact. Reciprocity and balance in social relations have been fundamental to social cooperation, and thus to survival, and therefore the human brain has become specialized by natural selection to compute and seek this balance. When the same reasoning is applied to environment-related behaviors, people tend to think in terms of a balance between ‘environmentally friendly’ and ‘harmful’ behaviors, and to morally account for the average of these components rather than the sum. This balancing heuristic leads to compensatory green beliefs and negative footprint illusions—the misconceptions that ‘green’ choices can compensate for unsustainable ones. ‘Eco-guilt’ from imbalance in the moral environmental account may promote pro-environmental acts, but also acts that are seemingly pro-environmental but in reality more harmful than doing nothing at all. The current paper suggests strategies for handling this cognitive insufficiency.

  • 94.
    Threadgold, Emma
    et al.
    School of Psychology, University of Central Lancashire, Preston, UK.
    Marsh, John E.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science. School of Psychology, University of Central Lancashire, Preston, UK.
    McLatchie, Neil
    Department of Psychology, Lancaster University, Lancaster, UK.
    Ball, Linden J.
    School of Psychology, University of Central Lancashire, Preston, UK.
    Background music stints creativity: evidence from compound remote associate tasks2019In: Applied Cognitive Psychology, ISSN 0888-4080, E-ISSN 1099-0720Article in journal (Refereed)
    Abstract [en]

    Summary Background music has been claimed to enhance people's creativity. In three experiments, we investigated the impact of background music on performance of Compound Remote Associate Tasks (CRATs), which are widely thought to tap creativity. Background music with foreign (unfamiliar) lyrics (Experiment 1), instrumental music without lyrics (Experiment 2), and music with familiar lyrics (Experiment 3) all significantly impaired CRAT performance in comparison with quiet background conditions. Furthermore, Experiment 3 demonstrated that background music impaired CRAT performance regardless of whether the music induced a positive mood or whether participants typically studied in the presence of music. The findings challenge the view that background music enhances creativity and are discussed in terms of an auditory distraction account (interference-by-process) and the processing disfluency account.

  • 95.
    Torre, Andoni
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energy analysis of a house and proposals for improvements2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 96.
    Tsivras, Sotirios-Ilias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Load Demand Forecasting: A case study for Greece2019Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    It is more than a fact that electrical energy is a main production factor of every economic activity. Since electrical power is not easy to store, it needs to be consumed as it is generated in order to keep a constant balance between supply and demand. As a result, for developing an efficient energy market it is significant to create a method for accurately forecasting the electricity consumption.

    This thesis describes a method for analyzing data provided by the ENTSO-E transparency platform. The ENTSO-E (European Network of Transmission System Operators) is a network of electricity operators from 36 countries across Europe. Its main objective is to provide transparency concerning data of electricity generation and consumption in Europe in order to promote the development of efficient and competitive electricity markets.

    By using the method described in this thesis, one may use historical data provided by ENTSO-E to forecast the electricity consumption of an EU country for the years to come. As an example, data of electricity consumption in Greece during the years 2015-2018 have been used in order to calculate the average load demand of a weekday during the year 2030.

    On the other hand, in order to correctly predict the electricity demand of a specific region over the next decade, one should take into account some crucial parameters that may influence not only the evolution of the load demand, but also the fuel mix that will be used in order to cover our future electricity needs. Advances in power generation technologies, evolution of fuel prices, expansion of electricity grid and economic growth are a subset of parameters that should be taken into account for an accurate forecast of the electricity consumption in the long run.

    Particularly for Greece, a set of parameters that may affect the electricity consumption are being computationally analyzed in order to evaluate their contribution to the load demand curve by the year 2030. These include the interconnection of Greek islands to the mainland, the development of Hellinikon Project and the increase of the share of electric vehicles.

    The author of this thesis has developed code in Python programming language that can be found in the Appendix. These scripts and functions that implement most of the calculations described in the following chapters can also be used for forecasting the load demand of other EU countries that are included in the ENTSO-E catalogue. The datasets used as input to these algorithms may also be used from the readers to identify more patterns for predicting the load demand for a specific region and time.

    A sustainable energy system is based on consumers with environmental awareness. As a result, citizens living inside the European Union should become a member of a community that promotes energy saving measures, investments in renewable energy sources and smart metering applications.

  • 97.
    Wallberg, Ellinor
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Nyberg, Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Klimatförändringarnas påverkan pågrundvattnet: En effektstudie över den framtida grundvattensituationen iHedesundaåsen, med fokus på vattenkvantitet2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Climate change may affect the hydrological cycle on a global scale. The changes will most clearly be noticed on the surface, with increasing precipitation amounts, in-creased evaporation and a reduced snow cover. What happens at the surface has a great impact on what happens to the groundwater, and varies greatly between the different water storages, the prevailing climate and land use. The European Environ-ment Agency has therefore sought to investigate future groundwater conditions at local levels. The Hedesunda esker was chosen for this study because it is used as a water source without human modification of its inflow. No similar studies have pre-viously been performed on the Hedesunda esker. It is an esker in Gävleborg County, which supplies drinking water to the population in Hedesunda. The purpose of this study has been to present how the groundwater in the Hedesunda esker may be af-fected in a future climate.

    The hydrological model HBV-light was calibrated for the time period 2000-2009 us-ing meteorological measurements from SMHI, and validated against the time period 2011-2017. Simulations were performed for the time periods 2022-2050 and 2072-2100. In the simulations, two widely different future scenarios were used to cover a large range of possible future scenarios. The simulations in the study consistently showed trends with increasing groundwater levels and recharge, regardless of the scenario. Depending on the chosen scenario, the groundwater level according to the simulations may increase by between 6.3–11.5 % and the groundwater recharge by between 4.8–13.6 % for the period 2072-2100. A similar study, previously con-ducted in a nearby area, showed an increase in groundwater recharge by up to 15 % at the end of the century. A comparison of the results between the studies makes it likely that the results from the Hedesunda esker may well be correct.

    It is clear after this study that climate change will affect the groundwater in Hede-sunda in the future. The uncertainties about the details are many, as the future sce-narios are only an estimate of how precipitation, temperature etc. will be affected in a future climate. The uncertainty is based on the fact that these factors are used as a forecast in a hydrological model, which also contains uncertainties from the mathe-matical model and the future scenarios. Despite the many uncertainties, the simula-tions can give an indication of how climate change may affect the groundwater in the future, and can be used to prepare society for possible future consequences of the groundwater's changed quantity and, in the long run, also the water quality.

  • 98.
    Wallhagen, Marita
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Holmgren, Mattias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Andersson, Hanna
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Environmental Science.
    Brister i vårt logiska tänkande ett hinder för klimatkloka beslut2019In: Husbyggaren, ISSN 0018-7968, no 1, p. 23-25Article in journal (Other (popular science, discussion, etc.))
  • 99.
    Wang, Chengju
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Energy use and energy saving in buildings and asthma, allergy and sick building syndrome (SBS): a literature review2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Energy use in buildings is an important contribution to global CO2 emissions and contributes to global warming. In recent years, there has been concern about creating energy efficiency buildings, green buildings and healthy buildings but this development needs guidance by multidisciplinary scientists and experts. Since energy saving can influence the indoor environment in different ways, epidemiological research is needed in different climate zones to evaluate the health consequences of making the buildings more energy efficient. Epidemiological studies and modelling studies are available on health effects and indoor effects of energy conversation, improved thermal insulation, increased air tightness and creating green buildings. The health-related literature on this issue was reviewed, by searching scientific articles in the medical Database PubMed and in the general database Web of Science as well as Nature database. In this literature review, 53 relevant peer reviewed articles on health effects of energy use and energy saving were found. Most of the studies had investigated residential buildings. One main conclusion from the review is that combined energy efficiency improvements in buildings can be associated with improvement of general health, such as less asthma, allergies, sick building syndrome (SBS) symptoms, respiratory symptoms, and reduced cold-related and heat-related mortality. Moreover, combined energy efficiency improvements can improve indoor air quality, increase productivity and satisfaction and reduce work leave and school absence. Effective heating of buildings can reduce respiratory symptoms and reduce work leave and school absence. However, some potential health problems can occur if increased energy efficiency will reduce ventilation flow. Energy saving by increasing air tightness or reducing ventilation is associated with impaired indoor air quality and negative health effects. In contrast, improved ventilation may reduce SBS, respiratory symptoms and increase indoor air quality. Installation of mechanical ventilation can solve the negative effects of making the building construction in dwellings more air tight. In future research, more studies are needed on health impacts of single energy efficiency improvement methods. Existing studies have mostly used a combination of improvement methods. In addition, modelling software programs should more often be used, since they can take into account effects of different energy efficiency improvement methods on indoor air quality in different types of buildings and in different climates.

  • 100.
    Wennberg, Tim
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Fjärrvärme och frånluftsvärmepump: Systemets lönsamhet och primärenergitalets inverkan2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The combination of district heating and exhaust air heat pump (EAHP) has become increasingly common in Sweden. This combined heating system is well suited for reducing energy use in existing buildings with mechanical exhaust air ventilation that lacks heat recovery. However, an EAHP installation can lead to higher return temperatures in the district heating network. In order to promote district heating use during the summer, the district heating supplier use seasonal varying price models in which the district heating price varies during some of the year. By shutting down EAHP in summer and only using district heating, there is a potential cost saving as the district heating price is at its lowest. This cost saving is investigated based on various types of district heating tariffs, electricity grid charges and electricity prices. It is also examined how Boverket's rules for calculating primary energy affects this type of heating system. Typical price models for district heating have been investigated. The energy use for six fictitious multi-dwelling buildings around the country has also been made. For each building, the energy use was calculated from three cases. For the reference case, Case 1, only district heating is used, for Case 2 EAHP is used for both heating and domestic hot water and Case 3 is as Case 2 fixed EAHP does not cover domestic hot water requirements and is switched off during the summer period. The energy consumption is calculated over a year and the energy cost is compared between the cases. In Case 2 and Case 3, the total energy costs for the buildings are between 61–75% and 67–78% of the energy costs in Case 1, respectively. However, between Case 2- and 3, there is no clear saving trend despite all the locations having a seasonally varying district heating price. The fact that no saving trend arises shows that the cost of each heat unit delivered from FVP in the summer is about the same as each heating unit of district heating. This is because a high COP (coefficient of performance) is used, which makes it very cost-effective to buy electricity. With a lower COP, shutdown of EAHP benefits summer time. Based on the calculated energy use, the primary energy and the specific energy use are calculated for all buildings. In most cases, the primary energy number is larger than the specific energy use, as the electricity consumption is going to be larger with primary energy. In Luleå, on the other hand, the energy-area ratio is greater than the primary energy number, even when using an EAHP.

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