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  • 101.
    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.
    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.
    Non-energy benefits in energy audit and energy efficiency network policy programs for industrial SMEs2019In: Eceee 2019 Summer Study Proceedings, 2019, p. 225-233Conference paper (Refereed)
    Abstract [en]

    Improved energy efficiency is a key component towards sustainable and climate-neutral industrial energy systems. The potential for industrial energy efficiency varies between sectors and processes but is stated to be high. Implementation of energy efficiency measures and activities could also result in benefits in addition to energy cost savings, benefits that are more difficult to quantify in economic terms. Research shows that additional gains from investments are underestimated as non-energy benefits (NEBs) are often neglected when the financial attractiveness of energy efficiency investments are evaluated. In the literature, great attention has been given to realise industrial energy efficiency potential through industrial energy policies and programs, in order to promote investments and implementation of new, more efficient technologies and processes. The most internationally common industrial energy policies for industrial SMEs are energy audit programs, but energy efficiency networks have also received increased attention from policymakers. However, there is a scarcity of studies exploring NEBs in relation to industrial SME energy audits and energy efficiency network policy programs. The aim of this study was to identify and compare NEBs from two key energy efficiency policies: energy audit and energy efficiency network programs. Semi-structured interviews were conducted with executives at two groups of industrial companies: companies that participated in the regional Swedish energy efficiency network policy program, and participants from the national energy audit program, Swedish Energy Audit Program (SEAP). The overall most commonly mentioned NEBs were related to production, such as increased lifetime of equipment and more reliable production. However, while participants from the energy audit program related these NEBs mainly to technical installations, network participants also saw these types of NEBs from energy management practices. If NEBs were to be included in energy audit programs the benefit of the audits could be increased, but will then particularly affect the technical installations. NEBs in terms of network participation were shown to lead to an increase in the general benefits of the networks, and for network companies NEBs are also linked to measures related to operation and maintenance, i.e., energy management practices. One difference between the two groups was that NEB improved the company’s environmental image. Two of the companies participating in the network policy program had presented their participation on their public webpage perceiving this as a very important benefit, while respondents from the energy audit program could not relate their company image to their energy audit. One additional NEB that was found, not previously mentioned in the scientific literature on NEBs, was that among the network participants, establishing contacts with other companies in the region was considered of great importance, and further contacts that would not have been established outside of the network. Results even found new customer relationships as a result of the network. This finding is of a general nature, thus apart from the other commonly known NEBs, an additional NEB that primarily relates to participation in energy efficiency networks that this study found is establishing new relationships with other companies in the region.

  • 102.
    Johansson, Maria T.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköping University.
    Improved energy efficiency within the Swedish steel industry: the importance of energy management and networking2015In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 8, no 4, p. 713-744Article in journal (Refereed)
    Abstract [en]

    The iron and steel industry is an energy-intensive industry that consumes a significant portion of fossil fuel and electricity production. Climate change, the threat of an unsecure energy supply and rising energy prices have emphasised the issue of improved energy efficiency in the iron and steel industry. However, an energy-efficiency gap is well recognised, i.e. cost-efficient measures are not implemented in practice. This study will go deeper into why this gap occurs by investigating energy-management practices at 11 iron and steel companies in Sweden. Energy managers at the steel plants were interviewed about how they perceived their own and their companies’ efforts to improve energy efficiency and how networking among energy managers influenced the efforts to improve energy efficiency. Reported barriers to improved energy efficiency were, for example, too long payback period, lack of profitability, lack of personnel, risk of production disruption, lack of time and lack of commitment. Only three out of the eleven companies had assigned a person to work full time with energy management, and some of the energy managers were frustrated with not having enough time to work with energy issues. Generally, the respondents felt that they had support from senior management and that energy issues were prioritised, but only a few of the companies had made great efforts to involve employees in improving energy efficiency. Networking among Swedish steel companies was administered by the Swedish Steel Producers’ Association, and their networking meetings contributed to the exchange of knowledge and ideas. In conclusion, Swedish steel companies regard improved energy efficiency as important but have much work left to do in this area. For example, vast amounts of excess heat are not being recovered and more efforts could be put into engaging employees and introducing a culture of energy efficiency.

  • 103.
    Johansson, Maria T.
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköping University.
    Söderström, Mats
    Electricity generation from low-temperature industrial excess heat: an opportunity for the steel industry2014In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 7, no 2, p. 203-215Article in journal (Refereed)
    Abstract [en]

    Awareness of climate change and the threat of rising energy prices have resulted in increased attention being paid to energy issues and industry seeing a cost benefit in using more energy-efficient production processes. One energy-efficient measure is the recovery of industrial excess heat. However, this option has not been fully investigated and some of the technologies for recovery of excess heat are not yet commercially available. This paper proposes three technologies for the generation of electricity from low-temperature industrial excess heat. The technologies are thermoelectric generation, organic Rankine cycle and phase change material engine system. The technologies are evaluated in relation to each other, with regard to temperature range of the heat source, conversion efficiency, capacity and economy. Because the technologies use heat of different temperature ranges, there is potential for concurrent implementation of two or more of these technologies. Even if the conversion efficiency of a technology is low, it could be worthwhile to utilise if there is no other use for the excess heat. The iron and steel industry is energy intensive and its production processes are often conducted at high temperatures. As a consequence, large amounts of excess heat are generated. The potential electricity production from low-temperature excess heat at a steel plant was calculated together with the corresponding reduction in global CO2 emissions.

  • 104.
    Jonasson, Karl
    Environmental Systems Analysis, Chalmers University of Technology, Göteborg, Sweden.
    Consequential Environmental Assessment Including Socio-Technical Change2007In: 3rd International Conference on Life Cycle Management, Zurich, August 27-29, 2007: Program & Abstract Book, 2007, p. 95-Conference paper (Other academic)
    Abstract [en]

    There are various ways to perform environmental assessment of emerging technologies, to be used as a base for decision-making. For instance, direct effects of a technology investment can be assessed, as in consequential studies, or the environmental impact in a number of possible future scenarios can be calculated, using an attributional approach. Here, we propose a consequential approach that includes socio-technical change, to account for contributions of an investment to system change and the resulting improvements (or deterioration) in environmental performance. We have earlier performed a socio-technical analysis of the development of alternative transport fuels in Sweden, both in a historic perspective and with scenarios for the coming years. Our aim was to investigate how new technologies emerge and grow, and how investments in one technology affect the growth of others. The results show for instance that a research program on coal gasification in the 1970’s, or an investment in a few ethanol buses in the 1980’s, have far-reaching effects on the development of alternative fuels in general. New actors are involved and institutions are adjusted that are in favour of the technology concerned (and related ones), thus stimulating further investments in new (and improved) technologies. Accordingly, some of the resulting environmental improvements could be allocated to early investments, and we would like to pose the question of how this could be accounted for in environmental assessment of emerging technologies. To illustrate this issue by an actual example, we use published LCA data to calculate the environmental impact of the use of ethanol as a vehicle fuel in Sweden at three points in time: 1990, 2005 and 2020. First, for each year, this will give us the LCA results traditionally used as a base for decision-making. Then we look at the factors related to socio-technical change: How does the environmental impact change between the years, both per functional unit and when looking at the total use of petrol and diesel replaced? These changes are compared with the LCA results for the three years to highlight the proportions, and it is discussed how they could be taken into account when performing and using environmental assessment as a base for decision-making regarding strategic technology choice.

  • 105.
    Jonasson, Karl
    Chalmers University of Technology, Department of Environmental Systems Analysis.
    Environmental aspects of the use-phase for bearings in trains2003Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This master thesis was performed in co-operation with SKF Sverige AB and the Department of Environmental Systems Analysis at Chalmers. The purpose of the project is to investigate the environmental aspects of the use-phase for bearings in trains. A Life Cycle Assessment (LCA) has been made, and together with earlier results, it is intended to give a deeper understanding of the environmental performance for the whole life cycle of bearings.

    The environmental impact related to the use of wheel bearings in three generations of trains is studied, and comparisons are made between processes within the life cycle of the bearings, and between the bearings in the different generations of trains. The environmental aspects are related to friction losses when the bearings are in operation, and the use of electricity, water, detergents and oil products during maintenance.

    The results show that the largest emissions of the use-phase for the bearings are related to electricity use caused by friction losses when the bearings are in operation in the trains. The emissions relation between operation and maintenance varies with the way the electricity is produced, but the emissions from operation are up to 1 000 times higher.

    The electricity use related to the bearings is up to 30 percent higher for the heavy train with Spherical Roller Bearings (SRBs), compared to the lighter one with the same bearings and the heavier one with Taper Bearing Units (TBUs). When the mass of the trains is considered, the bearings in the train with TBUs show a 30-40 percent lower electricity use.

    The environmental impact related to the transport of the trains to a wheel axle dismounting site can be of the same size as that from trains bearings in operation, if a detour of about 500 km or more is needed.

    During maintenance, most electricity is used for heating of washing water and heating of SRBs for mounting. The emissions from naphtha production, oil and grease production and waste oil handling are noticeably lower for the maintenance of TBUs, due to lower grease use, and the use of water and detergent for washing, instead of naphtha.

    The study can be used as a motivation to perform more explicit investigations of the environmental impact of different construction, maintenance and transports alternatives, and of how to include the results in product development and everyday work.

  • 106.
    Jonasson, Karl
    Environmental Systems Analysis, Department of Energy and Environment, Chalmers University of Technology, Gothenburg, Sweden.
    Environmental Assessment of Emerging Technologies: The Case of Alternative Transport Fuels2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are several methods to evaluate the environmental performance of new technologies. The purpose of this thesis is to contribute to the methodological development of environmental assessments, with contributions from life-cycle assessment (LCA), theories on technical change and socio-technical scenarios. LCA, or ‘well-to-wheel studies’, is a widely used tool for evaluating the environmental performance of alternative transport fuels. However, the methodology is usually not adapted to answer questions regarding strategic technology choice. Suggestions are presented that could increase the usefulness of LCA in this respect. A ‘net output approach’ is used, where fuels are used for their own production and distribution. Background system changes and the size of byproduct markets are studied, and it is shown that these factors can have a large influence on the results. Studies of LCA type can be used to give information on which fuels that have a low environmental impact today, and which are promising in the long run. However, it is suggested that also dynamic processes of technical changed need to be taken into account in the selection of technologies. In a study of the history of alternative transport fuels in Sweden, we show that also short-term options can contribute to the development towards more promising long-term options. Investments in alternative fuels during the years have not only resulted in physical artefacts and new explicit knowledge, but have also created dedicated actors and changed tacit knowledge and normative rules. Positive feedback loops related to actors, knowledge and rules have created more actors and changed regulation, and an ability of alternatives to survive. At the same time, the growth of some alternatives has favoured others, due to overlaps in socio-technical systems. However, the growth of alternatives is still very much dependent on exogenous factors and policy. The balance between short-term and long-term options in the transition of the transport system is illustrated through the use of socio-technical scenarios. These show that there is a risk that any policy could result in a negative development for renewable alternatives, but they also suggest that there are opportunities for growth. Policy could balance the development in different parts of the system, and make use of short-term options to contribute to more radical changes in the transport system.

  • 107.
    Jonasson, Karl
    Institutionen för energi och miljö, Miljösystemanalys, Chalmers tekniska högskola, Göteborg ; Göteborgs miljövetenskapliga centrum (GMV).
    Well-to-Wheel Studies and Technical Change - 9 problems with WTW studies2007Conference paper (Other academic)
  • 108.
    Jonasson, Karl
    et al.
    Göteborgs miljövetenskapliga centrum (GMV) ; Institutionen för energi och miljö, Miljösystemanalys.
    Sandén, Björn A.
    Göteborgs miljövetenskapliga centrum (GMV) ; Institutionen för energi och miljö, Miljösystemanalys.
    Exploring technology paths: The development of alternative transport fuels in Sweden 2005-20202005In: 4th European Meeting on Applied Evolutionary Economics (EMAEE), 2005Conference paper (Other academic)
    Abstract [en]

    In this paper we use a socio-technical scenario approach to illustrate how the development of alternative transport fuels in Sweden can be influenced by different policy choices. With the present situation as a starting point, we introduce different feasible scenarios for the development of alternative transport fuels in Sweden from 2005-2020. The scenario policies differ mainly on two points: (i) the commitment and economic incentives aiming at a rapid introduction of existing alternative transport fuels and (ii) the economic resources allocated to R&D of new, more efficient alternatives. The main focus on the first point in our market-oriented scenario and on the second in our technology-oriented scenario has implications for the development of the stocks and structures of the socio-techno-environmental system (STE-system). A first phase in the development is seen between 2005 and 2010. In the market-oriented scenario, a domestic production and a relatively widespread use of alternative transport fuels create advocates for these alternatives among producers and users. Limited explicit knowledge is gained, but legitimacy for alternatives to petrol and diesel is created. Physical artefacts are adjusted to the present alternative fuels, which are more similar to petrol and diesel than to new alternatives. In the technology-oriented scenario authorities and researchers are key actors. A high technical competence is built up in connection with pilot production plants for new alternative fuels. Both petrol and diesel are questioned, while the early alternatives are criticised for being too costly and having limited potential. A second phase, between 2011 and 2020, begins with a bifurcation of both scenarios, where one path from each is characterised by stagnation and one from each is characterised by growth, with regard to the potential for large-scale introduction of biofuels or other renewable fuels in Sweden. Our four scenarios, ending in 2020, can be seen as somewhat extreme examples of feasible outcomes resulting from policy choices made today. Numerous stocks and structures within the STE-system are affected and interact, to determine further changes of the system. In the market-oriented scenario, we illustrate consequences of breaking the dominance of entrenched technologies and demonstrating a growing market potential for alternative fuels and vehicles, while we in the technology-oriented scenario point out the value of keeping variety among niches at the early stage of a transition. The latter may add to the capability to respond to exogenous shifts in a way that is beneficial for the transition.

  • 109.
    Jonasson, Karl
    et al.
    COMESA, Miljösystemanalys.
    Sandén, Björn A.
    COMESA, Miljösystemanalys.
    Time and Scale Aspects in Life Cycle Assessment of Emerging Technologies: Case Study on Alternative Transport Fuels2004Report (Other academic)
    Abstract [en]

    Life cycle assessments (LCAs, including well-to-wheel studies) that are to support decisions that strive to change large technical systems need to consider time- and scale-related factors that are given little attention in standard LCA procedures. We suggest that it is important to look beyond the current situation and study many possible future states, what we call “stylised states”, to explore general technology differences. We choose to address three issues in this report. Our case study deals with alternative fuels for transportation, and relates to a recent well-to-wheel study performed by CONCAWE, EUCAR and JRC. The methodological results, though, could be of equal importance when studying other major technologies. First, shifting time frame gives room for technical development that should affect not only the choice of performance data, but perhaps also the functional unit and the selection of technologies under study. Second, background systems such as heat and power production change over time, and we exemplify by using three different systems, mainly based on coal, natural gas and short rotation forestry, respectively. Increased production volumes may for some technologies also change the background system, which is of particular importance for technologies that are used in their own production processes. We show that for biofuels changes in background systems have consequences not only for greenhouse gas (GHG) emissions and agricultural land use for each fuel chain, but also for the ranking order of e.g. wheat ethanol and RME, in terms of GHG emissions. We use what we call a “net output approach”, which implies that a fraction of the produced biofuel is used for its own production. Accordingly, the functional unit used in this study is 1 MJ fuel available for other purposes than producing fuel. Finally, different types of feedstock are available in different quantities and different by-product markets vary in size. Allocation of environmental impact between product and by-products is here made through system expansion, and we study some possible markets for by-products. To give an example of by-product effects, current key markets for ethanol by-products in EU-15 correspond to an ethanol production that covers about 2 % of demand, and for RME about 3 %, that is, well below the 5.75 % EU biofuel target for 2010. Therefore, the GHG emissions and agricultural land use allocated to the fuels differ between a low and a high market penetration. Combining the results, we show that time and scale are important factors for the ranking of wheat ethanol, RME and wood methanol in terms of GHG emissions and agricultural land use, as the results are dependent on assumptions regarding background system and by-product markets. We indicate that agricultural land use results can be weighted in GHG terms in several ways, e.g. by using short rotation forestry or solar panels as a reference, an approach that would require further research.

  • 110.
    Jonasson, Karl
    et al.
    Göteborgs miljövetenskapliga centrum (GMV) ; Institutionen för energi och miljö, Miljösystemanalys.
    Sandén, Björn A.
    Göteborgs miljövetenskapliga centrum (GMV) ; Institutionen för energi och miljö, Miljösystemanalys.
    Time and Scale in LCA: Case Study on Biofuels2005In: LCM 2005 - Innovation by Life Cycle Management, LCM 2005 - Innovation by Life Cycle Management , 2005, Vol. 1, p. 501-505Conference paper (Other academic)
  • 111.
    Jonasson, Karl
    et al.
    Göteborgs miljövetenskapliga centrum (GMV) ; COMESA, Miljösystemanalys.
    Sandén, Björn A.
    Göteborgs miljövetenskapliga centrum (GMV) ; COMESA, Miljösystemanalys.
    Time and Scale in Life Cycle Assessment: The Case of Fuel Choice in the Transport Sector2004In: Vehicles Alternative Fuel Systems & Environmental Protection (VAFSEP 2004), Vehicles Alternative Fuel Systems & Environmental Protection (VAFSEP 2004) , 2004, p. 140-145Conference paper (Other academic)
  • 112.
    Jonsson, Daniel
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Ericsson, Victor
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Livscykelanalys av en flaska whisky2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis is to, in collaboration with Mackmyra Svensk Whisky, investigate the environmental impact of their whisky. In addition to this it is also investigated which sub-processes that cause the most environmental impact, and how the environmental impact can be reduced.

     

    Generally, large amounts of resources are used in the food industry, which can cause great impact on the environment. In this thesis the methodology Life Cycle Assessment is used to identify and estimate the environmental impact. An important step in the beginning of the LCA is to select one or more functional units for which the environmental impact is calculated. This study has two functional units. The first is a 70 cl bottle containing an average of the whisky that Mackmyra Svensk Whisky delivers to Systembolaget. Mackmyra also sells whole 30-liter whisky barrels to individuals, and the second functional unit is a bottle of 50 cl containing an average of this whiskey. The system under study begins with the production of raw materials such as barley and stops when the whisky is delivered to Systembolaget.

     

    Information about emissions and energy use was then collected. The data is primarily collected from companies that Mackmyra purchase raw materials and other resources from, if they had information available. When this was not possible, data from similar operations, databases or ultimately reasonable estimates were used.

     

    The environmental impact categories examined are global warming, acidification and eutrophication, and the results varies between these categories. Generally speaking, however, the production of barley, the manufacture of glass bottles and transports dominate the environmental impact. Mackmyra uses two kinds of malt, of which one is self-produced and makes use of a diesel-powered heater for drying. Compared with the purchased malt (which uses district heating primarily from waste and biomass), the environmental impact is significantly higher. Since the Mackmyra malt is used in small amounts per functional unit it does, however, not cause huge environmental impact.

     

    A study has been made to see what the effect would be if the diesel heater was replaced with heaters powered by electricity, which showed a reduction of the environmental impact. No comparison has been made of the difference in cost between the heat fans.

  • 113.
    Kabanshi, Alan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Experimental Evaluation of Intermittent Air Jet Ventilation Strategy : Cooling Effect Analysis2016In: IAVEQ 2016: 9th International Conference on Indoor Air Quality Ventilation & Energy Conservation In Buildings, Songdo, South Korea: IAQVEC Committe , 2016Conference paper (Other academic)
    Abstract [en]

    In the built environment climate control is the most energy intensive component and in trying to reduce energy use, occupant satisfaction is compromised.  Identifying strategies that balance the energy use and occupant satisfaction is important. One strategy is optimizing elevated air movements with intermittent air jet strategy (IAJS). The strategy enhances human convective and evaporative cooling resulting in good indoor climate and low energy use. Understanding the systems cooling capabilities is thus important to justify its practical implementation. In this paper, the potential cooling effect of the strategy is estimated with different calculation methods: thermal manikin measurements, measurements with thermal comfort data logger and estimation of the cooling effect with a web application tool (CBE thermal comfort tool). As shown in this study, the obtained cooling effect may differ by as much as 1 oC between estimation/calculation methods. This may have both implications on energy use and occupant satisfaction. 

  • 114.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ameen, Arman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Yang, Bin
    Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Cooling energy simulation and analysis of an intermittent ventilation strategy under different climates2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 156, p. 84-94Article in journal (Refereed)
    Abstract [en]

    Energy use on heating, ventilation and air conditioning (HVAC) accounts for about 50% of building energy use. To have a sustainable built environment, energy efficient ventilation systems that deliver good indoor environmental quality are needed. This study evaluates the cooling energy saving potential of a newly proposed ventilation system called Intermittent Air Jet Strategy (IAJS) and compares its performance against a mixing ventilation (MV) system in a classroom located in three cities with different climates, Singapore with ‘hot and humid’, Ahvaz with ‘hot and dry’ and Lisbon with “moderate” climate. The results show a significant reduction of cooling energy need and flexibility in control strategies with IAJS as a primary system in hot and humid climates like Singapore. Hot and dry climate with short cool periods like Ahvaz show possible application and considerable energy savings with IAJS as a primary system under optimized variable setpoints, but moderate climates have an increased risk of occupant discomfort likely due to increased draft especially during the cool season.  Thus, IAJS as a secondary system that operates only during cooling season may be conducive for moderate climates like Lisbon. Additionally, the results show that supply fan energy savings can also be realized if well implemented. 

  • 115.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Keus van de Poll, Marijke
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ljung, Robert
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology. Linnaeus Centre HEAD, Swedish Institute for Disability Research, Linköping University, Sweden.
    The effect of heat stress on writing performance in a classroom2014In: Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 2014, p. 183-188Conference paper (Refereed)
    Abstract [en]

    Studies have shown that heat stress impairs performance. This depends on the mental loading capacity of the task performed and the exposure time. This is a study of a common task in schools and offices: writing task. It also analyses the occupants’ perceived thermal comfort. The experiment was done in two heat conditions: 20 and 25 centigrade. The between participant design was used. ScriptLog was used to perform the writing task, while questionnaires and a Sudoku task were paper based tasks. The results show that the predicted mean vote (PMV) between conditions was significant (p<0.02) and participants perceived the 20 º C condition to be draughty. They however preferred a little more air movements in both conditions. Writing performance only showed a significant difference (p = 0.03) on deleted characters but the other variables considered did not show any significant differences but showed a strong tendency that with a long exposure time it would eventually be impaired.  This shows that writing despite being a complex task is not a high mental loading task and is not quickly impaired by heat stress.

  • 116.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Liu, Shichao
    University of California, Berkeley, USA.
    Schiavon, Stefano
    University of California, Berkeley, USA.
    Potential adaptive behaviour to counteract thermal discomfort in spaces with displacement ventilation or underfloor air distribution systems2016In: Proceedings of the 14th international conference of Indoor Air Quality and Climate, Ghent, 2016Conference paper (Refereed)
    Abstract [en]

    Building occupants behave in various adaptive ways to restore thermal comfort when in a state of thermal discomfort. These adaptive actions affect building energy use and indoor environmental quality. This paper reports part of a draft risk study, here we focus on potential adaptive behaviour to counteract discomfort in rooms with displacement ventilation (DV) and underfloor air distribution (UFAD) systems. The most likely adaptive behaviours to be taken are: adjust clothing, open/close windows, adjust thermostat and change workstation. No conclusive relationship was found on whether these behaviours are influenced by overall or ankle thermal sensation. Females stated more frequently than males that they would open/close windows, while more males expressed the intention to use heaters and complain to building managers.

  • 117.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Measurement of Entrainment into an Axisymmetric Jet using Temperature as a Tracer: A Pilot Study2018In: Excellent Indoor Climate and High Performing Ventilation / [ed] Risto Kosonen, Mervi Ahola and Jarkko Narvanne, 2018, p. 397-402Conference paper (Refereed)
    Abstract [en]

    The current extended abstract is a pilot study of an ongoing experimental and theoretical investigation of ambient entrainment of room air into an axisymmetric free jet using temperature as a tracer. The project aims to investigate, by revisiting the concepts and fundamentals of axisymmetric free Jets and entrainment in ventilation applications, particularly focusing on how to optimize performance of low mixing air distribution systems and to test methods of measuring entrainment in such systems. The study aims to explore a scalar field method using temperature as a tracer to estimate entrainment in axisymmetric free Jets. The results obtained show jet characteristics that slightly differ from what is reported in velocity field measurements and other scalar field studies. Thus, a call is made herein for further investigations to understand entrainment and appropriate methods to determine jet characteristics and its mixing effect. Additionally, more studies are needed to verify whether earlier results are representative of entrainment conditions for low mixing ventilation systems whose operation mode depend on near-filed characteristics of jets.

  • 118.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Center for the Built Environment, University of California, Berkeley, Berkeley CA, USA.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Experimental Evaluation of Intermittent Air Jet Ventilation Strategy: Cooling effect and the associated energy saving2016Conference paper (Refereed)
    Abstract [en]

    The potential to reduce building energy demand is high especially on building services like ventilation and air conditioning. This potential lies in identifying ventilation strategies that can provide both the required indoor climate and lower the energy use. One of the strategies is optimizing elevated air movements to enhance human convective and evaporative cooling which, as shown in literature, results in reduced energy use on cooling. This paper evaluates the cooling potential and the resulting energy saving of a novel air supply system called intermittent air jet strategy (IAJS). As shown in this study, IAJS with velocities of 0.4 m/s at the breathing height provides a cooling effect equivalent to reducing the ambient temperature in a mixing ventilation system by up to 1.5 oC to achieve a neutral sensation. This translates to a 13% reduction on the cooling demand. The strategy is also shown to have an energy saving potential of up to 50% on the supply fan. 

  • 119.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Center for the Built Environment, University of California, Berkeley, Berkeley CA, USA.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Keus van de Poll, Marijke
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Ljung, Robert
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    The influence of heat, air jet cooling and noise on performance in classrooms2015In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 14, no 3, p. 321-332Article in journal (Refereed)
    Abstract [en]

    The quality of indoor environments influences satisfaction, health, and work performance of the occupants. Additional understanding of the theoretical and practical value of individual indoor parameters in relation to health and performance aids indoor climate designers to obtain desired outcomes. This also results in expenditure savings and increased revenue: health care and improved productivity. Here, we report two experiments that investigated how heat, cooling strategy and background noise influence performance in a full-scale classroom mockup setting. The results show that heat and background noise are detrimental to logic-based tasks and to writing, whilst cooling manipulations can protect performance. Implications for indoor environment design are discussed.

  • 120.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ljung, Robert
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Sorqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology. Linnaeus Centre HEAD, Swedish Institute for Disability Research, Linköping University, Sweden.
    Perception of intermittent air velocities in classrooms2014In: Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 2014, p. 189-191Conference paper (Refereed)
    Abstract [en]

    Classrooms normally host a large number of people and the heat generated provides a challenge cool. Traditional cooling methods by increased low temperature supply airflow rate or use of heat sinks are expensive and mostly inefficient. The strategy of controlled air movements in the occupied zone may prove cheaper and desirable. This research investigates recirculation of room air to provide intermittent velocity cooling in classrooms. The objective of this experiment was to assess how occupants perceive the recirculated intermittent air velocity conditions in classrooms and when the variations should be introduced in the room for optimal results. This was done with a between participant design, accessing how they perceived indoor air quality (IAQ) and the thermal comfort in two velocity conditions: constant low air velocity condition (< 0.15 m/s) and intermittent air velocity condition (0.4 m/s). As shown here; intermittent air velocity has a positive effect on the perceived thermal comfort (p < 0.04) and perception of air quality: less draughty and improved humid perception. The participants perceived the conditions with intermittent velocity to give comfortable feelings and better air quality.  The variations also showed better performance if they were provided at the start of occupancy as opposed to during or after a temperature build up. This strategy can be used in environments where it is rather uneconomical to provide cooling like spaces hosting a group of people: movie theatres, auditoriums, classrooms and perhaps in restaurants.

  • 121.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ljung, Robert
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Experimental evaluation of an intermittent air supply system – Part 2: Occupant perception of thermal climate2016In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 108, p. 99-109Article in journal (Refereed)
    Abstract [en]

    A newly proposed intermittent air jet strategy (IAJS) provides satisfactory indoor climate while promising a substantial energy saving potential, as shown in technical (objective) measurements. The strategy creates non-uniform airflow and non-isothermal conditions critical for sedentary operations at elevated temperatures. The current study explored human perception of thermal environment under an IAJS. Assessment of thermal sensation, thermal comfort, and thermal acceptability were collected based on responses from 36 participants. Participants sat in a classroom setup and performed sedentary work. Their clothing had an insulation of 0.51 clo (T-shirt on upper body). Participants were exposed to homogeneous (v < 0.15 m/s) and nonhomogeneous (0.4 m/s < v < 0.8 m/s) velocity conditions across three temperature conditions: 22.5 °C, 25.5 °C and 28.5 °C. The participants found air speeds to be undesirable at lower temperatures, but reported an improved thermal sensation, comfort and acceptability at higher temperatures. As shown here, IAJS generated neutral operable conditions between 24.8 °C and 27.8 °C, within an air speed range of 0.4 m/s to 0.8 m/s. Additionally, air movements induced thermal alliethesia resulting in improved comfort and acceptance of the thermal climate even at lower air speeds in warm temperature conditions. Hence, the current study supports the energy saving potential with IAJS in view of the human perception of the indoor environment.

  • 122.
    Kabanshi, Alan
    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.
    Yang, Bin
    Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    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.
    Occupants’ perception of air movements and air quality in a simulated classroom with an intermittent air supply system2019In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 28, no 1, p. 63-76Article in journal (Refereed)
    Abstract [en]

    The study reported herein builds on occupant response to an intermittent air jet strategy (IAJS), which creates periodic airflow and non-isothermal conditions in the occupied zone.  Previous research has highlighted the benefits of IAJS on thermal climate and supports energy saving potential in view of human thermal perception of the indoor environment. In this study, the goal was to explore occupant acceptability of air movements and perceived indoor air quality, and to determine a way of assessing acceptable air movement conditions under IAJS. Thirty-six participants were exposed to twelve conditions: three room air temperatures (nominal: 22.5, 25.5 and 28.5 oC), each with varied air speeds (nominal: <0.15 m/s under mixing ventilation (MV), and 0.4, 0.6 and 0.8 m/s under IAJS) measured at the breathing height (1.1 m). The results show that participants preferred low air movements at lower temperatures and high air movements at higher temperatures. A model to predict percentage satisfied with intermittent air movements was developed, and predicts that about 87% of the occupants within a thermal sensation range of slightly cool (-0.5) to slightly warm (+0.5), in compliance with ASHRAE standard 55, will find intermittent air movements acceptable between 23.7 oC and 29.1 oC within a velocity range of 0.4 – 0.8 m/s.  IAJS also improved participants’ perception of air quality in conditions deemed poor under MV. The findings support the potential of IAJS as a primary ventilation system in high occupant spaces such as classrooms. 

  • 123.
    Kahandagamage, Gayan Asanka
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Royal Institute of Technology.
    Theoretical and Practical analysis of the effect of charge air temperature and humidity in the combustion process of diesel engines at Heladhanavi Power Plant, Puttalam, Sri Lanka2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heladhanavi 100MW Diesel Power Plant in Puttalam, Sri Lanka comprises of six 18V 46 Wartsila turbocharged air cooled engines. Fuel consumption of the engines varies with the ambient conditions. It has been seen in hotter days fuel consumption is higher comparatively to cooler days.

    This study was conducted as per the requirement to find out the reasons behind this variation of the fuel consumption and to quantify the effects on the efficiency with respect to the charge air properties in relation to temperature and humidity.

    In this study the effect of charge air temperature was analyzed performing two sets of experiments. A combustion analysis experiment (experiment 1) was performed to monitor what happens inside the combustion chamber during day and night times. This is to investigate the cause of efficiency variation and why and how it happens. Simultaneously a fuel consumption test was performed using the direct method with the fuel flow meter and energy dispatch readings taking in to the consideration. A humidity analysis inside the charge air receiver was carried out simultaneously to investigate the humidity effect on the combustion.

    A flue gas analysis test (experiment 2) was performed to determine the efficiency variation in day and night times through the indirect method. Along with this analysis the direct method was followed up to calculate fuel consumption to compare the results from the both tests. A humidity analysis inside the charge air receiver was carried out simultaneously to investigate the humidity effect on the combustion.

    For all the tests and analysis DG 02 at approximately Rhs: 55,000 was selected to conduct the measurements as 48,000 rhs major overhaul was completed recently. All the components in the fuel system such as pumping elements and injectors are in good condition. The cylinder head, liner and piston overhaul was also have been carried out. The experiments were planned so the lots other factors are not affecting the combustion efficiency during the process to isolate the ambient conditions.

    The experiments were also carried out during day and night times on the same day to minimize other factors such as fuel quality affecting the equations. Always the LHV of the incoming fuel was obtained for calculations to avoid further mistakes.

    The results are elaborated along with findings from the past studies in the Literature review.

    It was confirmed the fuel consumption is positively affected by the charge air temperature while the efficiency is negatively affected. From the literature review it was found out the humidity in charge air affects positively on the fuel consumption while efficiency is negatively affected. The charge air temperature affects the ignition delay period so that the peak pressure and then the combustion efficiency. The efficiency improvement is further confirmed by the flue gas analysis experiment as the loss in the flue gas reduces in night time comparatively to the day time.

    At Heladhanavi temperature and humidity in charged air behaves in completely opposite manner in day and night times. During day time temperature is high while humidity is low. For the night time case its vise versa. Finally it can be concluded that under the prevailing ambient conditions at the Heladhanavi Power Plant, Puttalam, Sri Lanka, the effect of charge air temperature is more prominent than the effect of humidity in the combustion process for the Wartsila 18 V 46 diesel engines, as a result the efficiency improves during the night time comparatively to the day time.

    Therefore, proper cleaning and maintaining of the charge air coolers are the most important factor to maintain the charge air temperature and relative humidity inside charge air receiver at a lowest value. Therefore to attain the best electrical efficiency and the fuel consumption for a certain fuel batch.

  • 124.
    Kamaldeen, Mohammed Rizwan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Royal Institute of KTH, Sweden.
    Sustainable Energy Source for Water Pumping at Puttalam Salt Limited2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cost of grid based electrical and diesel sea water pumping to salt fields is one of the major cost components out of the total production cost in Puttalam Salt Limited, situated in northern part of Sri Lanka. In order to explore ways and means to improve the energy efficiency and alternative resources to meet the energy requirement a feasibility study was conducted using power system simulation software, (HOMER) and also detailed technical, environmental and financial tools.

     

     This research study is conducted to evaluate the performances and applicability and propose the most suitable sustainable renewable energy source and methodology for water pumping to salt fields instead of currently utilized grid based and fossil fueled energy supply.

     

    Preliminary results obtained by simulation software shows that direct wind mill pumping and solar PV water pumping was found to be unfeasible due to its limited pumping capacity and high investment cost. More over solar PV does not seems much feasible due to its high cost of energy (0.234 US $/kWh) compared to wind powered rivals in this type of applications.

     

    Based on comparisons of the analysis it is seen that the wind/ grid combined configuration of 04 units of AOC15/50 model (50kW manufactured by AOC Renewable Energy - Canada) wind turbine units with 150kw inverter seems to be a logical supplement for water pumping energy requirement than using grid based electricity which costs 0.201 US $/ kWh. The solution in this research affords an attractive 60% annual average renewable fraction as well as an approximate 215.8 tCO2(eq) of annual Carbon Footprint saving. Also it assures a moderate Discounted Payback Period of 6 years and 5months with a 15% of Internal Rate of Return.   

  • 125.
    Karlberg, Anna
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Swedish hydropower: A literature study about Swedish hydropower, environmental impact and EU: s Water Framework Directive 2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden, EU: s Water Framework Directive led to an investigation that started in April 2012 by the Swedish government, called Vattenverksamhetsutredningen freely translated to "Water Activities Survey", with the purpose to investigate the Environmental Code’s rules concerning water activities and water plants. The survey is divided into 3 reports, two sub-reports and a final report. One of the sub-report is focused on Swedish hydropower and the investigators found that many hydropower plants have old permits. One suggestion in the survey was to reconsider old permits so they would become consistence with today’s Environmental Code. There have been discussions regarding whether Sweden will lose much of its electricity production from hydropower as an outcome if the survey’s suggestions becomes reality.

    The aim with this literature study is to investigate how the EU: s Water Framework Directive and the Water Activities Survey will affect Swedish hydropower and if there will be a decrease in electricity production as an outcome if the suggestions made in the survey becomes reality.

    The results in this literature study shows that there will probably be a decrease in production for Swedish hydropower, but with how much is hard to say because the Swedish government has not yet decided what they will do with the suggested actions in the Water Activities Survey. A comparison is done with Sweden’s import and export statistics between the years 2001-2014 with a predicted loss of 13 TWh per year, which is a number taken from a survey made by Vattenfall. A comparison with a loss of half of 13 TWh per year is also done. Between the years 2001 and 2014 Sweden imported electricity 6 out of 14 years and exported electricity 8 out of 14 years. If adding the predicted loss of 13 TWh per year to the import and export statistics, Sweden would have had to import electricity 12 years and export 2 years. If adding a loss of 6.5 TWh per year Sweden would have had to import electricity 8 years and export 6 years.

    The conclusions is that Sweden will have to import a lot more electricity if only looking at import and export statistic if the loss of electricity is between 6.5-13 TWh per year.

  • 126. Karlsson, Björn
    et al.
    Lundström, Lukas
    Eriksson, Ola
    Energivärdering av byggnader: Analys av regelstyrd energi- och miljövärdering av byggnader2016Report (Other academic)
  • 127.
    Kayumba, Epimaque
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Design of a Battery Charging System Using a Micro-Hydro Power for Rwandan Rural Area Electrification2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 128.
    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.

  • 129.
    Kobayashi, Tomo
    et al.
    Department of Architectural Engineering, Osaka University, Division of Global Architecture, Osaka, Japan.
    Sagara, Kazunobu
    Department of Architectural Engineering, Osaka University, Division of Global Architecture, Osaka, Japan.
    Yamanaka, Toshio
    Department of Architectural Engineering, Osaka University, Division of Global Architecture, Osaka, Japan.
    Kotani, Hisahi
    Department of Architectural Engineering, Osaka University, Division of Global Architecture, Osaka, Japan.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Power transportation inside stream tube of cross-ventilated simple shaped model and pitched roof house2009In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 44, no 7, p. 1440-1451Article in journal (Refereed)
    Abstract [en]

    The ultimate goal of this work is to establish a prediction method based on Power Balance Model for prediction of flow rate through cross-ventilated building. For the establishment of Power Balance Model, the lost power across stream tube sections must be determined in advance. However, the loss of power in the stream tube was not well studied by other researchers but this concerned critical step forms the focus of the present CFD study in which transported power in stream tubes formed at two selected models: (i) a suspended rectangular model, and (ii) a pitched roof single-storey house model standing on a flat ground surface, was documented. For the development of a new method applying to predict the lost power, decrease of the transported power across the stream tubes through both types of models will finally be shown in this paper.

  • 130.
    KUBWIMANA, Valens
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Evaluating sustainability of electricity access in Rwanda (2009 to 2013)2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sustainable energy supplies have been a key to economic development and the transition from agricultural economies to modern industrial and service-oriented societies. Energy as essential to improved social and economic welfare is a key for reducing poverty and raising living standards. However, still 1.2 billion people have no access to electricity [1] and providing sustainable energy access to these people is a real challenge. How Rwanda is performing in terms of providing sustainable electricity to its rural people? This thesis evaluates the relative performance of Rwanda from 2009 to 2013 in providing sustainable electricity access. The evaluation of sustainability of electricity access situation was undertaken using Principal Components Analysis technique (PCA) whereby a theoretical framework defining sustainability of electricity was constructed and a set of indicators has been selected basing on analytical soundness, measurability and ability to describe electricity sustainability phenomenon and also basing on the availability of data to define and determine the sustainability. The study shows that the sustainability for electricity access in Rwanda has been improved for the evaluated period of time (2009-2013). The results conclude that the sustainability of electricity access situation has gone up and this is due to the introduction of many programs that have been instigated and Government commitment to improve the electrification rate. Some strategies, commitments and laws such as electricity law, National energy policy and national energy strategic plan; economic development and Poverty Reduction Strategy as well as Renewable Energy Feed In –Tariffs and electricity access roll-out program that were executed in these period seems to be instrumental in achieving better performance in terms of electricity sustainability.

  • 131.
    Kumara, Thanura Padma
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Analysis of floating type water wheel for pico hydro systems in Sri Lanka 2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sri Lanka is an island in the Indian Ocean and water is freely available around the island. Most of the people from rural areas are farmers and they cultivate in large areas. But they do not have electricity for pumping water to their agricultural. Normally channels are used to convey water into land but most of the time agricultural lands are situated at higher positions than the channels which make it difficult to transport water. The kinematic energy of water flow in those channels could be converted into useful energy, which in turn could be used for pumping water to higher elevations. For this purpose a simple method such as water wheel could be easily employed to generate electricity.

    This study mainly focused on to carry out a feasible study based on the existing details of water wheel with related accessories and improves the overall working efficiency while developing a new system or modification of the present system and transfer the technology to the rural community.

    A theoretical analysis of the water wheel was done based on 6 blades straight type wheel. The performance testing of water wheels in open channel were carry out for three types of blades and two different numbers of blades( 6 and 12).Based on the results It shows that 5% deviation between theoretical and experimental values of power and 36% deviation between theoretical and experimental values of R.P.M.

    Also results obtained by testing of water wheels showed that experimental results of 12 blades water wheels were more powerful compared with 6 blades water wheels. It is approximately 2.5-3 times factor.

    Based on this results calculations were carried out for 6 blade water wheel and predictions were done for a twelve wheel inclined blade wheel type considering the factors that affect the performance of the wheel. According to the test results, the average power output of the 12 blade curved type water wheel was 9.5 W. Solid works software was used to carry out the simulation to determine the stability and properties of blade.

    According to analysis, floating type water wheel was found to be economical for rural areas because the cost of building a plant is US$ 340 and it is cheaper than other methods.

  • 132. Kärrman, Erik
    et al.
    Sörelius, Helene
    Eriksson, Ola
    Tegelberg, Linda
    Hantering av slam och organiska restprodukter i Gästrikeregionen: Förstudie2013Report (Other academic)
  • 133.
    Lajas, Sandra
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Viability of the electricity production comparing photovoltaic and wind power in three markets.2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To carry out the implementation of some type of renewable energy must do a viability study because the weather conditions at all sites are not the same and therefore the profitability of these technologies would not be good.

    In case of this project, it is taken into account two of the most important technologies which results are very good around of the world. They are photovoltaic and wind power energy.

    It will be analysed both kind of energy production from how to produce energy with photovoltaic system and with wind power till how much energy is produced by both ways in one year and whether is this ways to produce electricity is profitable in relation of the investment costs, maintenance, etc...

  • 134.
    Lane, Anna-Lena
    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. RISE Research Institutes of Sweden.
    Boork, Magdalena
    RISE Research Institutes of Sweden.
    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.
    Barriers, driving forces and non-energy benefits for battery storage in photovoltaic (PV) systems in modern agriculture2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 18, article id 3568Article in journal (Refereed)
    Abstract [en]

    Battery storage has been highlighted as one way to increase the share of renewables in energy systems. The use of local battery storage is also beneficial when reducing power variations in the grid, thereby contributing to more robust and cost-effective energy systems. The purpose of this paper is to investigate barriers, drivers and non-energy benefits (NEB) for investments in battery storage in photovoltaic systems (PV) in the context of farmers with PV systems in Sweden. The study is based on a questionnaire about barriers, driving forces and NEB for investment in battery storage connected to PV. The questionnaire was sent to farmers in Sweden who already have photovoltaics installed and about 100 persons answered, a response rate of 59%. The major barriers found are related to the technical and economic risks of investing in battery storage. One of the main conclusions is that the highest-ranked driver, i.e., to use a larger part of the produced electricity oneself, turns out to be the highest priority for the grid-owner seeking to reduce the need for extensive investments in the grid. The primary NEBs found were the possibility of becoming independent from grid electricity.

  • 135.
    Lane, Anna-Lena
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. SP Technical Research Institute of Sweden.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Gustavsson, Thorbjörn
    SP Technical Research Institute of Sweden.
    ByggaE – Method for Quality Assurance of Energy Efficient Buildings2017In: International Journal of Energy Production and Management, ISSN 2056-3272, E-ISSN 2056-3280, Vol. 2, no 2, p. 133-139Article in journal (Refereed)
    Abstract [en]

    Policies for energy efficiency requirements in buildings have become more stringent according to EU2020 goals. Despite policy regulations, requirements for energy efficiency are not met in many new buildings. Some of the reasons for this energy performance gap are related to the building process. The aim with this paper is to describe a purposed method for quality assurance of sustainable buildings according to energy efficiency. The proposed method is called ByggaE, where ‘Bygga’ is the Swedish word for ‘build’ and E is the first letter in ‘energy efficient’. It is a tool intended to lower the energy performance gap related to the building process by guiding the client and providers through the process to fulfill goals. The essence of ByggaE is the formulation of requirements by the client and the working process of identifying, handling and following up critical constructions and key issues. This working process involves all participants in the building project by using appropriate quality guidelines and checklists for documentation, communication and verification. ByggaE is a step forward ensuring that the building fulfills the defined functions and that conscious decisions are taken when goals have to be changed during the building project. The next steps are to ensure the usefulness of the method in practice by more testing and to spread knowledge about the method.

  • 136.
    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.

  • 137.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Linköpings universitet, Energisystem.
    On the performance of stratified ventilation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    People nowadays spend most of their time indoors, for example in their homes, cars, in trains, at work, etc. In Sweden, the energy demand in the built environment is a growing issue. The building sector accounts for 40% of total energy use and 15% of total CO2 emissions, and around one-third of the energy use in the world is related to providing a healthy and good comfort indoors. To achieve acceptable indoor climates new designs for the ventilation systems have been proposed in recent decades, among them stratified ventilation systems.

    Stratified ventilation is a concept that often allows good performance for both indoor air quality and thermal comfort. Stratified ventilation systems are effective in reducing cross contamination, since there is virtually no mixing in the space; the temperature and the pollutant concentration increase linearly from the heat source with the height of the occupied zone. There are many different ventilation supply devices using the stratified principle, such as displacement supply device (DSD), impinging jet supply device (IJSD) and wall confluent jet supply device (WCJSD).

    The main aim of this thesis is to analyze and compare different supply devices based on stratified ventilation, with different setups, related to thermal indoor climate, energy efficiency and ventilation efficiency. The ultimate goal is to contribute to an increased understanding of how ventilation systems with stratified supply devices perform.

    Two scientific methods have mainly been used in this thesis, i.e., experimental and numerical investigations. For numerical experiments the CFD (Computational Fluid Dynamics) code ANSYS and FIDAP have been used. Experimental studies have been performed with thermocouples, Hot-Wire Anemometry (HWA) and Hot-Sphere Anemometry, thermal comfort measurement equipment and tracer gas measurement equipment.

    This thesis mainly focuses on three research questions: Interaction between a supply device based on stratified ventilation and downdraft from windows; Flow behavior, energy performance and air change effectiveness for different supply devices based on stratified ventilation; and Thermal comfort for different supply devices based on stratified ventilation.

    Research question one showed that the arrangement of displacement supply device and window in cold climate has significant effect on the flow pattern below the window. Different supply airflow rates have an effect on both the velocity and the temperature of the downdraft. In this case the velocity decreased by approximately 9.5% and the temperature in the downdraft decreased 0.5°C when the flowrate from the supply device increased from 10 to 15 l/s.

    Research question two showed that airflow patterns between different air supply systems were essentially related to characteristics of air supply devices, such as the type, configuration and position, as well as air supply velocities and momentum. For WCJSD, IJSD and DSD, positions of heat sources (such as occupant, computers, lights and external heat sources) played an important role in formation of the room airflow pattern. One interesting observation is that the temperature in the occupied zone is lower and a more stratified temperature field implies a more efficient heat removal by a stratified air supply device. The results revealed that the lowest temperature in the occupied zone was achieved for DSD, but with IJSD and WCJSD slightly warmer, while the system with a mixing supply device (MSD) showed a much higher temperature. The results confirm that air change effectiveness (ACE) for the DSD, WCJSD and IJSD is close to each other. However, MSD shows lower ACE in all the present papers than IJSD, WCJSD and DSD.

    Research question three showed that ventilation systems with stratified supply devices in almost all of the studied cases showed an acceptable level for predicted percentage dissatisfied (PPD), predicted mean vote (PMV) and percentage dissatisfied due to draft (DR). If comparing ventilation systems, using IJSD, WCJSD or DSD with MSD always showed thermal comfort better or at the same level.

  • 138.
    Li, Ning
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Environmental Assessment of a Residential Building According to Miljöbyggnad2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Miljöbyggnad is a Swedish system for certifying building in regarding to energy, indoor climate and materials. Energy usage in built environment occupies more than a third of total energy consumption and greenhouse gas emissions in Sweden (SEA, 2008).

    Among fifteen indicators regulated by Miljöbyggnad, four indicators which consist of specific energy use, thermal climate winter, thermal climate summer and daylight have been analyzed in this report.

    There has two objectives for the project. The first objective is to make optimized approaches for the building according to baseline simulation model. And the second objective is to make assessment of the optimized model based on Miljöbyggnad environmental certification.

    As a conclusion, the implemented approaches helped to improve indoor thermal comfort and decrease demand of operational electricity for lighting. The four analyzed indicator of the optimized model have achieved GOLD level according to criteria regulated by Miljöbyggnad.

  • 139.
    Lidberg, Tina
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Högskolan Dalarna, Energiteknik.
    Ramírez Villegas, Ricardo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering. Högskolan Dalarna, Energiteknik.
    Olofsson, Thomas
    Högskolan Dalarna, Energiteknik.
    Eriksson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    An approach to illustrate strategies for improved energy efficiency at the municipal level2014In: Proceedings from the 14th International Symposium on District Heating and Cooling / [ed] Anna Land, Swedish District Heating Association, 2014, p. 50-55Conference paper (Refereed)
    Abstract [en]

    This work focuses on how implementation of wellknown refurbishment strategies, applied on multifamily buildings in a post-war housing complex in Sweden can affect the generation of district heating. Both the energy use and the power load were considered.

    The study was performed in Borlänge municipality, Sweden, where the municipality owns both the energy and the housing companies. The strategies for energy efficiency were simulated with IDA-ICE for the Tjärna Ängar area, a housing complex built between 1969- 1971, with access to documented information about the buildings and energy audit. The results of the building simulation were implemented in a simplified model of the local district heating system.

    The results indicate how different renovation strategies affect the demand of energy and power load within the district heating system and can be used to provide indicators for different scenarios. The larger goal of the research is how to maximize the economic and environmental efficiency of improvement strategies on a municipal level as well as how to find appropriate energy optimization methods that can be proposed by building contractors. The initial study presented here was conducted within the research program Reesbe.

  • 140.
    Lindberg, Joakim
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energikartläggning av Masurgårdens förskola: Åtgärder och dess potentiella energi- och kostnadsbesparing2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work aims to illustrate the use of energy in Masurgårdens förskola and verify that the property's energy is used optimally. The survey seeks to provide the landlord with decision support for future investment calculations and energy saving measures.A model of the building is created in the energy simulation program IDA ICE, the building envelope was recreated from the buildings blueprints, lighting and personal load was inventoried. The remaining input data were taken from previous studies or from standard values.Simulation results show that the building is not in need of significant investment in energy saving measures. But it is found that annual energy savings of 5308 kWh (5.6%) is possible by lowering the outdoor airflow during winter months and by replacing the radiator thermostats with new ones. The measures also leads to an improvement of indoor environment and is believed to reduce the problem with mucosal dryness on the buildings occupants during the winter months.

  • 141.
    Lopez Ramirez, Izar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Operating correction factor of PV system: Effects of temperature, angle of incidence and invertor in PV system performance2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this project, the correction factor of different solar panels of the laboratory of the University of Gävle, located in Sweden, is going to evaluated. The solar modules’working conditions are different from the ones used to test them in the laboratory. In the laboratory. the output energy of the modules is less than in working conditions,and therefore a correction factor is going to be calculated from the data collected, inorder to describe the factors that affect the performance of the solar modules.Also, the obtained correction factor validity for different PV systems it is going to be examined, determining which system has a better correction factor and the energy losses due to temperature, angle of incidence and micro invertor.

  • 142.
    Lu, Yinghao
    et al.
    University of Gävle, Department of Technology and Built Environment.
    Musunuri, Ravi Kiran
    University of Gävle, Department of Technology and Built Environment.
    Energy Survey and Energy Savings in an Office Building with Aid of Building Software2008Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Simulation is one of the best Analytical tools for Building Research .Energy Efficient Buildings are of great concern which is gaining importance steeply in this energy scarcity’s world.

    Selected for the thesis work is a small Office building (Mariannelund), located in Jönköping. The building is single-storied with 26 rooms. The study motive involves Energy Survey and to provide, investigate Energy conservation measures. The Energy simulation software used is the IDA indoor climate and energy 3.0. (ICE).Data included was from the provided (Specifications) and with the review of architectural drawings.

    Energy saving measures was analyzed, documented with respect to their feasibility and practical operational strategies. Measures concerning the modifications in the building envelope; retrofit insulation, shading devices and other improvements leading to savings of energy have been tested and are supplemented with results.

    The Proposed Model which is with the combined Energy saving measures yields annual energy savings of about 70% and also working efficiency is increased by 37% compared to the existing building’s Baseline model.Considering the economic aspects together with the thermal response of employees the analyzed energy saving measures are highly recommended.

  • 143.
    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. 

  • 144.
    Mandefro Bezie, Yalewayker
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Feasibility Study of Small Hydropower/PV/Wind Hybrid System for Off-Grid Electrification of Liben and MedaWoulabu Villages2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    According to the International Energy Agency 2016 statistics, Ethiopia is among the lowest countries in annual electricity consumption, 70 KWh/capita. Rural areas hold more than 80% of the country’s population and less than 30% of them have been electrified. Most of the population (the rural areas) still predominantly depend on traditional biomass energy sources for cooking and heating, and household lights are provided mainly by kerosene and biomass including this study area, Tadacha Rarasa, which consist of 4100 households with 6 members, totally 24,600 people[1, 2].

    The feasibility study of hybrid system consisting of small Hydro, PV, Wind and Battery is carried out using HOMER as a tool for optimization and sensitivity analysis. TURBNPRO software also assists for the optimization of the small hydropower which is suggested to utilize the 2.2 m3/s ecological flow of the Genale 3 multipurpose hydropower plant’s reservoir. The wind speed and solar radiation data of the site is collected from NASA. Then, the wind speed, solar radiation, electric load and hydro data is input to HOMER in their respective appropriate format for simulation and analysis of the proposed hybrid system.  Electric loads of the community is estimated bearing in mind the irrigation, fishery and other opportunities which will arise after the multipurpose project completion in addition to basic household demands. The daily average estimated residential consumption by each family is 9.118 kWh and the daily average total energy consumption per person is 1.872 kWh.  

    After optimization and sensitivity analysis using HOMER, several different feasible configurations of Hydro, PV, Wind and Battery hybrid system has been displayed with a range of 0.049 to 0.067 $/kWh cost of energy. The optimum configuration becomes Hydro/PV/Battery hybrid system with 0.049 $/kWh levelized COE which is closer to the national energy tariff, 0.032 USD/kWh. The optimum Hydro/PV/Battery hybrid system generates annually 18,647,372 kWh with 0.18% capacity shortage and 0.15% unmet load. The hydropower supports the base load and the PV supplies for the peak load demand in the daytime which shares 19% of the total electric production.

  • 145.
    Marco Estruc, Ignacio
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Investigation of how Insulation affects the pipe system in the soil for ice rinks2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden, ice rinks are one of the largest energy consumers in the public building sector, requiring, each ice rink, about 1050 MWh/year, from which approximately 42 % is used by the refrigeration system.

    The goals of this project is to study the cooling system in the floor of indoor ice rinks placed at Sweden and achieve a solution against the problem of permafrost in the soil, due to low temperatures, and against the problem of the large amount of energy lost through the ground, due to low efficiency.

    In order to success in this challenge, five different models performed with COMSOL Multiphysic 3.5 have been simulated and studied to observe the energy saving that can be obtained by changing different design parameters, such as property of the concrete, insulation layer or heating pipes layout.

    According to the results the following conclusions have been obtained.

    On one hand, regarding the thermal conductivity, models design with high thermal conductivity concrete, conducts heat in an easier way than the normal concrete, and it will enable higher and quicker amounts of heat transferred through the slab. The improved thermodynamic properties of Concrete layer allow using the refrigerant 5,4 ºC higher temperature to keep the ice at a desired temperature. So, it must be pointed out that in terms of heat transfer, the concrete layer that supports the cooling pipes is one of the most important parts of the structure.

    On the other hand, as far as the insulation layer is concerned, the best option is to place one below heating pipes, due to the energy losses are reduced from 9 W/m2   to 0,4 W/m2.

    Finally, regarding to the cooling pipes depth, it must be pointed out that when the pipes are raised up 50 mm, the refrigerant temperature required to maintain the desired ice surface properties has been increased from -16 ºC to -9 ºC.

    So it can be concluded that increasing thermal conductivity concrete, placing insulation layer below heating pipes and raising up the cooling pipes, it is possible to achieve an energy saving around 33,6 MWh/year, being 7,6 % of the total energy consumption.

  • 146.
    Maritz, Kerry-Leigh
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Feasibility Study of Chemical Energy Storage for an Energy Efficient Commercial Office Space2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Shifting the load demand of a commercial office space to utilise off peak tariffs would lead to cost savings as power is cheaper at this time. To achieve this shift, chemical energy storage was considered using Lead Acid batteries, Lithium-ion batteries and Advance Lead Acid batteries. The output of these storage types is electricity.

    Current costs of storage do not support the option of reducing peak demand by adding chemical storage, as electricity from the grid is cheaper over the storage project life. A levelised cost analysis was completed and lithium-ion batteries proved to be the outright best choice for chemical storage in commercial office spaces.

    Town buildings were analysed and assessed for energy savings in order to reduce overall load demand. Incorporating chemical storage as a viable option was assessed based on cost. Heating, Cooling and lighting proved to be the highest load demands in the buildings. Cost savings in buildings can be better met by increasing the efficiency in buildings, rather than by reducing the cost by shifting the purchase of electricity from peak to off-peak tariffs.

    More suitable options to chemical energy storage would be to replace standard lights with energy efficient variations, installing an air heat pump to heat the space and ice thermal storage to cool the space. The use of a solar thermosyphon will meet the demand for heated water.

    Solar energy generation was assessed as an alternative as off-peak electricity stored using chemical storage proved to be too costly. A 50kW system would be suitably sized when peak sun hours were above the local areas average. Net metering could be used to offset costs during the winter months, when the peak sun hours fall below the average.

  • 147.
    Mata González, Jaume
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Use of the waste heat from the chillers for the heating of Läkerol Arena in Gävle1992Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Every day, huge amounts of energy are used by all sectors of the economy. From transport to industries, energy constitutes the base of development and people’s way of living. Besides, the energetic demand of millions of individuals must be satisfied with resources that are in constant depletion while the consumption is growing at a 2% rate every year. The consequence of such increase is that in the last decade energy costs have risen extremely fast. Societies must now find a way of maintaining the actual social-economic growth whilst reducing the energy demand in order to ensure sustainable development.

    Ice hockey arenas in Sweden have an average energy consumption of more than 1000 MWh per year, and around 42% of the total is used by the refrigeration system to cool the rink surface. The core of these units is the chiller, a machine that removes heat from a cold refrigerant and as a product of this chilling process, waste heat is generated. This energy can be exhausted to the environment or recovered for heating purposes.

    The main aim of this study is to investigate the uses given to the waste heat in Läkerol Arena, in Gävle. Some alternatives have been proposed and analysed in order to diminish the amount of rejected heat. Other objectives set in this project are to examine the possibility of reducing the dependence on district heating and to determine the efficacy of insulating the ground below the heating pipes that prevent permafrost.

    Nowadays the heat recovery system is used to preheat tap water until 30ºC and then up to 60ºC, to warm the air sent to the main rink area and to prevent the creation of permafrost in the ground below the main arena. The unused energy is sent to ambient with six big fans placed on the roof.

    The first additional use for waste heat proposed in this study is to design a heating system just for the resurfacing water. The current method in Läkerol Arena is to mix hot tap water with cold water. The problem is that the first one is three times more expensive than the second, so installing a unit that warms only cold cheap water up to 30ºC would result into saving 18760 SEK per season. Although this solution does not reduce the waste heat sent to the environment, it does reduce the demand of the desuperheater and increases the demand in the glycol circuit by 7%.

    Another option is to build a pit to melt the snow generated in the ice rinks. This solution would increase the use of the waste heat by 26% and bring annual savings of 32198 SEK, since it would not be necessary to rent any transport service to remove this snow. Besides, the emissions of CO2 would be reduced by 43774 kg.

    The possibility of sending part of the produced heat to a nearby building has also been investigated. The suggestion made in this study is to use part of the waste heat to warm the air for the ventilation of the Gefle Tennisklubb, an indoor tennis facility located at 150 m of the ice hockey arena. It has been calculated that this ventilation unit has an average heating demand of 9,1 kW. Results showed that in average this would represent 2% of the total heating capacity of the chillers and annual savings of 39858 SEK and 6880 kg of CO2 sent to the environment.

    The option of installing a heat pump in the hockey facility has also resulted beneficial. The purpose of such equipment is to cover the demand of district heating from the arena, which is currently used for radiators, radiant floor and 4 small ventilation units. After analysing average consumptions and talking with an expert, it has been decided that the best option is to install a ground source heat pump with a heating capacity of 415 kW. The interesting aspect about the heat pump is its efficiency, being it over the 300% (COP of 3,26). Although it means an important economic investment, this technology would save the arena around 239264 SEK every year and reduce CO2 emissions by 58331 kg.

    Finally, the installation of an insulation layer below the heating pipes has been analysed. The purpose was to see if this measure would be energy efficient. A simulation has been done with the educational version of the software ANSYS 14.5, and the results show that with a 100 mm insulation layer placed under the heated sand below the tubes, the heating demand is reduced by 44 kW (–54,6%), while the cooling demand increases by 5 kW (+1,1%). At the end this alternative has been dismissed since the installation would be too expensive and more heat would be sent to the environment, which is counter-productive.

    To sum up, with all the measures being installed, the arena would reduce the waste heat sent to the environment by 175,5 kW. It would represent the 49% of the total capacity generated (currently it is around 85% of the total waste heat). Besides, the annual emission of CO2 would decrease by 109 tonnes, the equivalent to 22 American cars. Finally, in terms of money, all the measures would bring total savings of 68880 SEK per year.

    The study concludes with three suggestions to continue with further research. The ideas are to investigate the possibility of introducing a filtering system for the water obtained in the snow pit, the viability of installing renewable energy sources to supply the electricity for the heat pump and study the efficiency of reducing the condensing temperature of the chillers.

  • 148.
    Mohey, Gagandeep
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energy Efficiency Opportunities in a Pulp Drying Machine2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Global concerns about declining resources and climate change mean that industries must do their best to use energy as efficiently as possible. Energy is also an important component of a modern economy. The pulp and paper industry is one of the most energy-intensive industries round the world. In this study energy efficiency opportunities in pulp drying machines are identified and the saving potential is then quantified. The methodology followed was based on comparison of energy saving technologies and practices such as Turbo Vacuum blowers, Shoe Press, Heat pump, Use of low pressure steam etc. The data used for the calculations was taken from the mill data records. Six energy efficiency improvement projects were identified. The total proposed energy saving potential in the two Drying Machines studied in the thesis is 10511 MWh. Installation of the shoe press shows the highest saving potential followed by the turbo vacuum blowers. Although the accuracy of the results is heavily dependent upon the accuracy of the data records from the case study mill. The proposed savings would act as a reference point and depending upon the estimated savings potential, would help the mill to identify areas, projects that need more detailed measurements for further action.

  • 149.
    Monleon Jimenez, Alex
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Villas Roca, David
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Study of temperature raise in Gavleån river related to district cooling2010Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    This project is a preliminary study in order to build a small power plant, located beside to Gavleån River. It has been designed with the aim of cooling a district of Gävle city, Sweden. That big project is carried out by the international consulting engineering company SWECO. The mentioned plant contains a thermodynamic cycle that takes water from the river and afterwards, it is returned back warmer. It will attempt to study the temperature raise downstream along the river due to the spill of hot water. In addition, it will try to quantify and weight which may be the importance of the increment of temperature compared to the entire river. This work could be vital for an environmental impact study. The thermo and fluid dynamic problem is going to be solved using typical procedure for numerical simulations. To do this, it will be used Computer Aided Design (CAD) to model Gavleån River path and Computational Fluent Dynamics (CFD) to predict the distribution of temperatures. Finally the results of the simulations will be analyzed and discussed to draw conclusions about the final temperature raise in Gavleån River.

  • 150.
    Moreno Fernandez, Marcos
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Solar cooling of buildings in a Swedish climate: Analysis and design of solar cooling in Building 45 at Högskolan i Gävle.2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays Solar Energy is one of the engineering fields most exploited, due to the ongoing need to developing new technologies based on renewable energy or improving the existing ones. One particular application of this kind of energy is Solar Cooling, which consist in generating cold from the heat received from the Sun. A common installation of solar cooling requires solar collectors, an absorption/adsorption chiller, fan coils, piping, valves and pumps. It calls for a minimal preventive maintenance which should allow keeping operating conditions within certain limits.The aim of this work is to analyze the viability of the installation of a solar cooling system in a roof. It has been chosen the Building 45 of the University of Gävle (Hus 45) as a pattern design. It was built in 2008, thirteen years after Högskolan i Gävle was inaugurated. This building uses electric compression coolers for its cooling demand. According to their heating demand, this is solved by using District Heating.This work is focused on the determination of the cooling demand of this particular building and the proposal of a solar cooling system that could supply it. Calculating the cooling demand means applying most of the concepts learnt during the whole speciality of the degree, like thermal loads in buildings. This calculation has been possible by using IDA ICE, which is a software that allows the user to develop a new construction through defining all structure parameters. After having defined all the contour conditions, the simulation shows all kinds of parameters in detail, in particular, the cooling demand of the respective building. Moreover, creating a new solar cooling system for this building means reviewing all the concepts related to refrigeration cycles and solar energy that have been learnt during the intensification. To do it, it has been necessary to use POLYSUN, another program that let the user to create solar thermal systems, photovoltaic systems or any other installation for getting heating, cooling or hot water.In addition, another important point to discuss is the usage of a solar cooling system based on absorption/adsorption technology instead of using photovoltaic as a way of providing to the current cooling units.The simulation about the cooling demand of the building shows that for covering the 95,22% of the operation hours (within the study), it is required to solve a cooling peak demand of 100 kW, which is in terms of energy a value of 68437,6 kWh. Regarding the designs of the solar cooling systems, two variants have been analyzed. While the first one is based on using the absorption technology, the second one has two subdivided proposals: a stand-alone photovoltaic system and a net metering installation. The absorption system could cover the cooling demand with the exception of July. The viability of this installation is questioned because of the low operation hours of the absorption machine, which is not working as it was expected since it is the cooling tower who really carries out the cooling function. On the other hand, the stand-alone system allows the building to cover all of its cooling demand, but the system is oversized and no profitable within a period of 30 years although it supposes a reduction of 100% in CO2 emissions, which is obvious since this option considers an electrical consumption from the grid of 0 kWh. Finally, the net metering system is probably the best option for covering the cooling demand of this building, as it has the shorter pay-back (18 years), the less visual impact when the solar modules are installed on the roof and requires less maintenance.Since there are no advantages in using an absorption machine for a cooling system in a Swedish climate, the next step would be analysing a system like the one proposed into another climate, where the solar radiation has more influence, thus, the absorption machine could work because of the inlet water (coming from the solar loop) is hot enough.

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