In Sweden, 90% of multifamily buildings utilize district heat and a large portion is in need of renovation. The aim is to analyze the impact of renovating a multifamily building stock in a district heating and cooling system, in terms of primary energy savings, peak power demands, electricity demand and production, and greenhouse gas emissions on local and global levels. The study analyzes scenarios regarding measures on the building envelope, ventilation, and substitution from district heat to ground source heat pump. The results indicate improved energy performance for all scenarios, ranging from 11% to 56%. Moreover, the scenarios present a reduction of fossil fuel use and reduced peak power demand in the district heating and cooling system ranging from 1 MW to 13 MW, corresponding to 4–48 W/m2 heated building area. However, the study concludes that scenarios including a ground source heat pump generate significantly higher global greenhouse gas emissions relative to scenarios including district heating. Furthermore, in a future fossil-free district heating and cooling system, a reduction in primary energy use will lead to a local reduction of emissions along with a positive effect on global greenhouse gas emissions, outperforming measures with a ground source heat pump.
A hydronic pavement system (HPS) is an alternative method to clear snow and ice, which avoids the use of salt, sand, and fossil fuel in conventional snow clearance, and minimizes the risk of accidents. The aim is to analyze the performance of different control strategies for a 35,000 m2 HPS utilizing heat from a district heating and cooling (DHC) system. The key performance indicators are (1) energy performance of the HPS, and (2) primary energy use, (3) electricity production and (4) greenhouse gas (GHG) emissions from the DHC system. The methodology uses a simulation model of the HPS and an optimization model of the DHC system. Three operational strategies are analyzed: A reference scenario based on the current control strategy, and scenarios where the HPS is shut down at temperatures below −10 °C and −5 °C. The study shows that the DHC return temperature is suitable for use. By operational strategies, use during peak demand in the DHC system can be avoided, resulting in reduced use of fossil fuel. Moreover, the energy use of the HPS could be reduced by 10% and the local GHG emissions by 25%. The study emphasizes that the HPS may have positive effects on global GHG emissions, as it enables electricity production from renewable resources.
The outline of the thesis is presented below and is intended to provide an introductory outlook on how the research and the two appended papers are presented. Chapter 1-Introduction, introduces the research field of the thesis and how the appended papers are associated. The aim and research question are presented. The first chapter also gives an overview of the appended papers and a co-author statement. Finally, the research project from where this research is sprung from is presented. Chapter 2-Background and related research, presents an introductory background and related research of key subjects being; the sustainable development goals, district heating and cooling, residential and service sector, and hydronic pavement system. Chapter 3-Research design and methodological approach, presents the research design and methodology of this research. The research utilizes a cross-disciplinary approach and an approach of system perspective, which is then incorporated in a scenario analysis. Moreover, the software tools used in this research are presented. Chapter 4-The DHC system and scenarios of energy end-use measures, presents the optimization model of the DHC system and the simulation models used in the two studies in this thesis. Moreover, the scenarios regarding the energy end-use measures in the two studies are presented. Chapter 5-Results and analyses, presents and analyze selected results from the appended papers that are related to the research questions. Additionally, an analysis of how the results relate to the national targets and SDGs are presented. Chapter 6-Concluding remarks, concludes the research questions. The chapter ends with an overview of suggested areas for further research.
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