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  • 1.
    Khadra, Alaa
    et al.
    Högskolan Dalarna.
    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.
    Myhren, Jonn Are
    Högskolan Dalarna.
    Greenhouse Gas Payback Time of Different HVAC Systems in the Renovation of Nordic District-Heated Multifamily Buildings Considering Future Energy Production Scenarios2024In: Buildings, E-ISSN 2075-5309, Vol. 14, no 2, article id 413Article in journal (Refereed)
    Abstract [en]

    The European Union (EU) has implemented several policies to enhance energy efficiency. Among these policies is the objective of achieving energy-efficient renovations in at least 3% of EU buildings annually. The primary aim of this study was to offer a precise environmental comparison among four similar district-heated multifamily buildings that have undergone identical energy efficiency measures. The key distinguishing factor among them lies in the HVAC systems installed. The chosen systems were as follows: (1) exhaust ventilation with air pressure control; (2) mechanical ventilation with heat recovery; (3) exhaust ventilation with an exhaust air heat pump; and (4) exhaust ventilation with an exhaust air heat pump with a Photovoltaic (PV) panel. This study involved a life cycle assessment that relied on actual material data from the housing company and energy consumption measurements. This study covered a period of 50 years for thorough analysis. A sensitivity analysis was also conducted to account for various future scenarios of energy production. The findings revealed that the building with an exhaust air heat pump exhibited the lowest greenhouse gas emissions and the shortest carbon payback period (GBPT), needing only around 7 years. In contrast, the building with exhaust ventilation without heat recovery showed the highest emissions and the longest carbon payback period (GBPT), requiring approximately 11 years. Notably, the results were significantly influenced by future scenarios of energy production, emphasizing the crucial role of emission factors in determining the environmental performance of distinct renovation scenarios.

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  • 2.
    Khadra, Alaa
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Hugosson, Mårten
    Inland Norway University of Applied Sciences.
    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.
    Myhren, Jonn Are
    Högskolan Dalarna, Akademin Industri och samhälle, Byggteknik.
    Development of a Weight Factor Method for Sustainability Decisions in Building Renovation: Case Study Using Renobuild2020In: Sustainability, E-ISSN 2071-1050, Vol. 12, no 17, article id 7194Article in journal (Refereed)
    Abstract [en]

    Energy efficiency investments have become strategically important for the European Union. In particular, energy efficient renovation and investment in the existing building stock have become major challenges. Renovation of a building should involve a holistic and integrated design process, which considers all aspects of sustainability. The aim of this work is to suggest a mathematical model that weighs economic, social and ecological aspects into a measure that supports housing owners/decision makers to find the optimal renovation alternative from their perspective, taking factors such as budget, energy consumption, etc. into consideration. Multi-criteria decision-making (MCDM) concerns structuring and solving multiple-criteria decision problems. MCDM has become popular in energy planning as it enables the decision maker to pay attention to all the criteria available and make the appropriate decision as per the priority of the criteria. In this study, the concept is introduced based on economic, social and ecological aspects assessed during a renovation project. A pedagogical example illustrates the suggested numerical system for comparing different renovation alternatives. The suggested method will facilitate decision-making processes in renovation projects and will allow decision makers to choose the best renovation alternatives that are in line with their business ideas and principles.

  • 3.
    Khadra, Alaa
    et al.
    Högskolan Dalarna.
    Hugosson, Mårten
    Inland Norway University of Applied Sciences.
    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.
    Myhren, Jonn Are
    Högskolan Dalarna.
    Economic performance assessment of three renovated multi-family buildings with different HVAC systems2020In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 224, article id 110275Article, review/survey (Refereed)
    Abstract [en]

    The EU has adopted several policies to improve energy efficiency. One of these policies aims to achieve energy efficient renovations in at least 3% annually of buildings in EU. The aim of this study was to provide an accurate economic comparison between three similar multi-family buildings that have undergone the same energy efficiency measures, with essential differences regarding the installed ventilation systems. The selected ventilation systems were: 1) balanced mechanical ventilation with heat recovery; 2) exhaust ventilation with air pressure control; and 3) exhaust ventilation with an exhaust air heat pump. In the latter two cases, radiators pre-heat supply air. Life cycle cost analysis were conducted using real investment and operational costs for the three buildings. Sensitivity analysis was also made for different discount rates and energy price escalation patterns. It was found that the building with exhaust ventilation has the lowest life cycle cost. At 2% inflation rate, 3% real discount rate and 1% real energy price escalation, the building with exhaust air heat pump and the building with mechanical ventilation with heat recovery has 13% and 29% higher life cycle cost than the building with exhaust ventilation, respectively. The sensitivity analysis further showed that a lower discount rate gives higher future costs and gives more profitability of systems with heat recovery with lower future costs. Energy price assumptions have a crucial impact on the results and change the profitability of studied renovation packages.

  • 4.
    Lidberg, Tina
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Högskolan Dalarna.
    Gustafsson, Marcus
    Högskolan Dalarna; KTH.
    Myhren, Jonn Are
    Högskolan Dalarna.
    Olofsson, Thomas
    Högskolan Dalarna; Umeå universitet.
    Ödlund, L.
    Linköpings universitet.
    Environmental impact of energy refurbishment of buildings within different district heating systems2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, p. 231-238Article in journal (Refereed)
    Abstract [en]

    The refurbishment of existing buildings is often considered a way to reduce energy use and CO2 emissions in the building stock. This study analyses the primary energy and CO2 impact of refurbishing a multi-family house with different refurbishment packages, given various district heating systems. Four models of typical district heating systems were defined to represent the Swedish district heating sector. The refurbishment packages were chosen to represent typical, yet innovative ways to improve the energy efficiency and indoor climate of a multi-family house. The study was made from a system perspective, including the valuation of changes in electricity use on the margin. The results show a significant difference in primary energy use for the different refurbishment packages, depending on both the package itself as well as the type of district heating system. While the packages with heat pumps had the lowest final energy use per m2 of floor area, air heat recovery proved to reduce primary energy use and emissions of CO2-equivalents more, independent of the type of district heating system, as it leads to a smaller increase in electricity use.

  • 5.
    Lidberg, Tina
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Högskolan Dalarna.
    Swing Gustafsson, Moa
    Högskolan Dalarna; KTH.
    Myhren, Jonn Are
    Högskolan Dalarna.
    Olofsson, Thomas
    Högskolan Dalarna; Umeå universitet.
    Trygg, Louise
    Linköpings universitet.
    Comparing different building energy efficiency refurbishment packages performed within different district heating systems2017In: Energy Procedia, ISSN 1876-6102, Vol. 105, p. 1719-1724Article in journal (Refereed)
    Abstract [en]

    This study analyses the differences in primary energy (PE) use of a multi-family building refurbished with different refurbishment packages situated in different district heating systems (DHS). Four models of typical DHS are defined to represent the Swedish DH sector. The refurbishment packages are chosen to represent typical, yet innovative ways to improve the energy efficiency of a representative multi-family building in Sweden. The study was made from a broad system perspective, including valuation of changes in electricity use on the margin. The results show a significant difference in PE savings for the different refurbishment packages, depending on both the package itself as well as the type of DHS. Also, the package giving the lowest specific energy use per m2 was not the one which saved the most PE. © 2017 The Authors.

  • 6.
    Swing Gustafsson, Moa
    et al.
    Högskolan Dalarna, Energiteknik; Mälardalen University.
    Gustafsson, Marcus
    Högskolan Dalarna, Energiteknik; KTH.
    Myhren, Jonn Are
    Högskolan Dalarna, Byggteknik.
    Dotzauer, Erik
    Mälardalen University.
    Primary energy use in buildings in a Swedish perspective2016In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 130, p. 202-209Article in journal (Refereed)
    Abstract [en]

    The building sector accounts for a large part of the energy use in Europe and is a sector where the energy efficiency needs to improve in order to reach the EU energy and climate goals. The energy efficiency goal is set in terms of primary energy even though there are different opinions on how to calculate primary energy. When determining the primary energy use in a building several assumptions are made regarding allocation and the value of different energy sources. In order to analyze the difference in primary energy when different methods are used, this study use 16 combinations of different assumptions to calculate the primary energy use for three simulated heating and ventilations systems in a building. The system with the lowest primary energy use differs depending on the method used. Comparing a system with district heating and mechanical exhaust ventilation with a system with district heating, mechanical exhaust ventilation and exhaust air heat pump, the former has a 40% higher primary energy use in one scenario while the other has a 320% higher in another scenario. This illustrates the difficulty in determining which system makes the largest contribution to fulfilling the EU energy and climate goals.

  • 7.
    Swing Gustafsson, Moa
    et al.
    Högskolan Dalarna, Energiteknik.
    Myhren, Jonn Are
    Högskolan Dalarna, Byggteknik.
    Dotzauer, Erik
    Mälardalen University.
    Assessment of the potential for district heating to lower the peak electricity consumption in a medium size municipality in SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    Sweden faces several challenges when more intermittent renewable power is integrated into the energy system. One of the challenges is to have enough electrical power available in periods with low production from intermittent sources. A solution to the problem could be to reduce the electricity peak demand and at the same time produce more electricity during peak hours. One way of doing this is to convert electricity based heating in buildings to district heating (DH) based on combined heat and power (CHP).

    The study analyzes how much a medium sized Swedish municipality can contribute to lower the electricity peak demand. This is done by quantifying the potential to reduce the peak demand for six different scenarios of the future heat market volume and heat market shares regarding electricity based heating and DH in 2050.

    The main finding is that electricity consumption will be reduced by 35-70 % during the peak hour (and 20-40 % on a yearly basis) for all the six scenarios studied compared with the current situation. If the aim is to lower the electricity peak demand in the future, the choice of heating system is more important than reducing the heat demand itself. For the scenario with a large share of DH, it is possible to cover the electricity peak demand in the municipality by using CHP.

  • 8.
    Swing Gustafsson, Moa
    et al.
    Högskolan Dalarna, Energiteknik; Mälardalen University.
    Myhren, Jonn Are
    Högskolan Dalarna, Byggteknik.
    Dotzauer, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Life cycle cost of heat supply to areas with detached houses: a comparison of district heating and heat pumps from an energy system perspective2018In: Energies, E-ISSN 1996-1073, Vol. 11, no 12, article id 3266Article in journal (Refereed)
    Abstract [en]

    There are different views on whether district heating (DH) or heat pumps (HPs) is or are the best heating solution in order to reach a 100% renewable energy system. This article investigates the economic perspective, by calculating and comparing the energy system life cycle cost (LCC) for the two solutions in areas with detached houses. The LCC is calculated using Monte Carlo simulation, where all input data is varied according to predefined probability distributions. In addition to the parameter variations, 16 different scenarios are evaluated regarding the main fuel for the DH, the percentage of combined heat and power (CHP), the DH temperature level, and the type of electrical backup power. Although HP is the case with the lowest LCC for most of the scenarios, there are alternatives for each scenario in which either HP or DH has the lowest LCC. In alternative scenarios with additional electricity transmission costs, and a marginal cost perspective regarding the CHP investment, DH has the lowest LCC overall, taking into account all scenarios. The study concludes that the decision based on energy system economy on whether DH should expand into areas with detached houses must take local conditions into consideration.

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  • 9.
    Swing Gustafsson, Moa
    et al.
    Högskolan Dalarna, Energiteknik.
    Myhren, Jonn Are
    Högskolan Dalarna, Byggteknik.
    Dotzauer, Erik
    Mälardalen University.
    Mapping of heat and electricity consumption in a medium size municipality in Sweden2017In: Energy Procedia, ISSN 1876-6102, Vol. 105, p. 1434-1439Article in journal (Refereed)
    Abstract [en]

    The Nordic electricity system faces many challenges with an increased share of intermittent power from renewable sources. One such challenge is to have enough capacity installed to cover the peak demands. In Sweden these peaks appear during the winter since a lot of electricity is used for heating. In this paper a mapping of the heat and electricity consumption in a medium size municipality in Sweden is presented. The paper analyze the potential for a larger market share of district heating (DH) and how it can affect the electrical power balance in the case study. The current heat market (HM) and electricity consumption is presented and divided into different user categories. Heating in detached houses not connected to DH covers 25 % of the HM, and 30 % of the electricity consumption during the peak hours. Converting the detached houses not connected to DH in densely populated areas to DH could reduce the annual electricity consumption by 10 %, and the electricity consumption during the peak hours by 20 %.

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    FULLTEXT01
  • 10.
    Swing Gustafsson, Moa
    et al.
    Högskolan Dalarna, Energiteknik.
    Myhren, Jonn Are
    Högskolan Dalarna, Byggteknik.
    Dotzauer, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Primary energy reduction in buildings: Case study on a residential building in Falun, Sweden2014In: Proceedings from the 14th International Symposium on District Heating and Cooling / [ed] Anna Land, Swedish District Heating Association, 2014, p. 543-545Conference paper (Refereed)
    Abstract [en]

    Since a large share of the total European primary energy is consumed in the building sector, buildings have to become more energy efficient in order to reach the goals of the European energy efficiency directive. In Sweden, focus has been on lowering final energy consumption, not primary energy consumption. A relevant question today is whether a general understanding of the primary energy concept is needed to encourage selection of better energy efficiency measures from an environmental perspective. There are however uncertainties of how to calculate primary energy consumption since different primary energy factors (PEF) are used by different actors, especially for district heating (DH) and electricity (EL.).

    In this study total primary energy consumption was calculated for a residential building before and after several renovation measures were made. The major change after the renovation was that a large share of the DH was substituted by heat from an exhaust air heat pump and solar collectors. A range of commonly used PEFs were assessed.

    The evaluation showed that the energy efficiency measures reduced the total primary energy consumption for most combinations of PEFs. The most essential was how the DH was valued. A low PEF for DH in combination with most of the PEFs for electricity could even result in higher total primary energy consumption after the renovation.  

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