<p dir="ltr">Vapor Compression Systems (VCS) are the most common air conditioning technology. However, the VCS process is energy inefficient due to overcooling and reheating. Liquid Desiccant air conditioning (LDAC) is a potentially more energy-efficient air conditioning technology. LDAC removes vapor in the air using the liquid desiccant’s high-water affinity and controls temperature using an additional cooling device. Additionally, LDAC typically requires heating to regenerate the diluted Liquid Desiccant (LD) for repeated use after absorbing moisture.</p><p dir="ltr">Earlier types of the LDAC systems operated at a relative high concentration and temperature during the dehumidification process, resulting in an increased heat source temperatures required for regeneration, which substantially diminished the energy efficiency advantages of LDAC systems. In the past two decades, researchers have explored a new LDAC system configuration that integrates an LDAC system with a heat pump (HP). The HP can deliver sensible cooling to lower the LD operating temperature and cool the process air. Simultaneously, it provides heating at the condenser side to facilitate the regeneration process. Subsequently, membrane-based dehumidifiers were introduced to separate the LD and airflow using a membrane that permits the passage of water vapor. This approach prevents direct contact, which otherwise would result in LD droplet carryover, addressing concerns related to health and the corrosion of air ducts. An internally cooled membrane-based dehumidifier with enhanced performance garners significant attention, as it essentially functions as a three-stream heat exchanger that facilitates both heat and mass transfer processes. Because of the intricate characteristics of the three-stream heat and mass exchanger, the finite difference models used to analyze the internally cooled membrane dehumidifier is highly detailed and comprehensive. These models are well-suited for assisting in the device’s design but are not suitable for system-level simulations. The lack of simple models for internally cooled membrane-based dehumidifiers limits the evaluation of energy performance at the system level. The limitation becomes particularly pronounced when a HP is integrated, as the model hinders our comprehension of the interactions between the HP and LDAC under the transient operating conditions.</p><p dir="ltr">The thesis research aims to bridge the gaps related to system configuration design, limitations of existing dehumidifier models, and the analysis and assessment of transient system level performance. A model of the internally cooled membrane-based dehumidifier, based on artificial neural networks, was created using data generated through the utilization of a published and detailed finite element dehumidifier model. The resulting model was validated by testing it with out-of-sample data and comparing its results with the validated finite difference model. An LDAC system setup using the internally cooled dehumidifier was established in Modelica using the artificial neural network model created. Furthermore, models of a VCS and an LDAC based on adiabatic dehumidifier were also developed to facilitate performance comparison. The different systems underwent simulation for an entire cooling season spanning from May to September. The internally cooled dehumidifier-based system exhibited superior energy performance, achieving seasonal energy performance levels up to 104% and 34% higher than the VCS and adiabatic dehumidifier systems, respectively. The improved performance in comparison to the VCS is due to the higher temperature operation of the HP. The improvement in comparison to the adiabatic dehumidifier system is due to the improved capacity of the internally cooled dehumidifier to deal with the absorption heat released during dehumidification. Depending on the geographical location, the internally cooled dehumidifier system displayed enhanced performance in the applications characterized by moderate sensible cooling, while its efficiency was relatively lower in arid and hot regions. Additionally, the results demonstrated that the adiabatic system performed similarly to the internally cooled dehumidifier system in locations with high sensible and latent cooling loads.</p><p dir="ltr">This work introduces a pioneering data-driven model for internally cooled membrane liquid desiccant dehumidifiers, representing a significant advancement in the field. The model's computational efficiency and accuracy address the challenges posed by sophisticated and computationally expensive physical models, providing a valuable tool for simulating such devices. The creation of the simple ANN-based dehumidifier model opens the possibility for simulation of internally cooled devices as part of dehumidification systems, whereas as of today its study has been mostly limited to single devices simulations. In the study, a model-based comparison of system performance between an HP-coupled internally cooled dehumidifier-liquid desiccant air conditioning system and HP-coupled adiabatic LDAC, as well as Vapor Compression Systems, elucidates the optimal operational configuration and rationale. Furthermore, a climate sensitivity analysis of system simulations guides researchers toward focusing on the development of HP-coupled internally cooled/heated liquid desiccant systems, particularly in climates that offer the greatest potential for energy savings compared to commonly used vapor compression systems. This comprehensive exploration enhances our understanding and paves the way for more efficient and effective developments in liquid desiccant-based dehumidification technologies.</p>

Energianvändningen har ökat markant globalt sedan 1971, vilket har påverkat klimatet och orsakat global uppvärmning. För att minska energiförbrukningen och dess påverkan på klimatet har Sverige fastställt energi- och klimatmål fram till år 2030. Sektorn för bygg- och fastigheter har en stor roll att spela i att minska utsläppen av växthusgaser eftersom den stod för 15,9 miljoner ton koldioxidekvivalenter år 2020. Syftet med denna studie är att undersöka möjliga alternativa lösningar och åtgärder som kan minska både energiförbrukningen och kostnaderna samtidigt som klimatpåverkan från byggnader minskas. Fokus ligger på att tillämpa dessa åtgärder på ett småhus i Markaryd. I studien användes litteraturstudier, intervjuer och beräkningsprogram som Bidcon, energiberäkning.se och pay off-metoden. Resultaten visar att renoveringsåtgärder, såsom fönster- och dörrbyte, tilläggsisolering av vinden och installation av ett mekaniskt ventilationssystem, minskade energiförbrukningen och var ekonomiskt fördelaktiga när de kombinerades med andra åtgärder. Undersökningen visar att trä och cellulosa hade lägre klimatpåverkan än aluminium och glasull i skedena A1-A5. Renoveringsåtgärder, med rätt val av material, kan således minska energiförbrukningen och klimatpåverkan samtidigt som de är ekonomiskt fördelaktiga, vilket leder till positiva effekter för både miljön och ekonomin. / Studies indicate that renovation projects have significantly lower environmental impact compared to new constructions, with emissions reduced by up to 50 % due to the reuse of existing materials. The purpose of this study is to explore alternative solutions and strategies that can effectively reduce both energy consumption and costs, while mitigating the climate impact of buildings. The focus is specifically on applying these measures to a small house in Markaryd. The research methodology involved a combination of literature reviews, interviews, and the utilization of calculation tools such as Bidcon, energiberäkning.se, and the pay-off method. The results demonstrate that renovation measures such as window and door replacement, additional insulation in the attic, and the installation of a mechanical ventilation system effectively reduced energy consumption and proved economically viable. The investigation also revealed that wood and cellulose materials had lower climate impact compared to aluminum and glass wool in stages A1-A5. Therefore, renovating buildings with careful material selection can simultaneously achieve reduced energy consumption and climate impact, while also offering economic benefits, thereby contributing positively to both the environment and the economy.

Increased energy efficiency is of major importance for Sweden to reduce their carbon emissions and to reach self-sufficiency in Europe on energy, which is important both from an economic standpoint and also to lower Russia's political influence over the EU. This thesis explores how the Swedish policy mix regarding buildings' energy efficiency is developed and which logic dominates in policy-making. To understand this, all key policies regarding building energy efficiency have been analyzed, and put into contrast with the policy goals. Through this viewpoint, it’s been evident that Sweden is heavily reliant on packaging for new policies, which is abandoning old policies and goals when formulating new ones. However, there has also been identified evidence of layering, which is when new policies are being added on top of old ones. / Den här uppsatsen behandlar hur byggnaders energieffektivitet regleras med hjälp av policies (rekommendationer, lagar, mm.). Detta är viktigt för att minska mängden utsläpp men även för att uppnå självförsörjning av energi inom Europa, vilket är viktigt både från ett ekonomiskt perspektiv men också för att minska Rysslands inflytande över den svenska politiken. Syftet med rapporten är att studera hur Sveriges policy mix har utvecklats, där policy mix syftar till alla policys utvecklade emot områden. Studien finner mönster för att Sverige karaktäriseras av både paketering och skiktning i dess utveckling av policys. Det är också tydligt att Sverige använder en stor andel information i sin policy mix, vilket skiljer sig tydligt från Finland och Storbritannien. Metodmässigt så har de olika policys sorterats utifrån ett ramverk som är uppsatt från tidigare forskning, vilket tydligt visar skillnaden för Sverige gentemot Finland och Storbritannien som tidigare har studerats.

The concept of future sustainability is driving efforts toward the efficient improvement of energy systems. District heating systems play a key role in balancing the energy system by improving performance and flexibility. As system efficiency increases, fuel consumption decreases, resulting in reduced greenhouse gas emissions and mitigating potential climate impacts, especially when using fossil fuels. In Sweden, district heating has shown significant growth, with a 75 % increase in total heat production over the last 30 years. Furthermore, carbon dioxide emissions have been reduced by approximately 50 % for each delivered kWh in the past 20 years, while renewable energy sources have doubled in the district heating sector. This thesis focuses on optimizing the cooling process to achieve lower return temperatures and higher system efficiency. It also emphasizes the importance of implementing an efficient heat consumption strategy to reduce peak loads and improve overall system efficiency. This approach involves managing demand to minimize peak heat requirements and distribute the load evenly throughout the day, leading to a more resource-effective and efficient system. The case study examines district heating supplied by VB Energy to Ludvikahem AB buildings, using data from Dec 2022 to Jan 2023. Quantitative data from district heating substations and the district heating plant are collected and analyzed to generate qualitative insights. The study proposes theoretical optimization measures based on the findings. The evaluation of substation performance reveals 20 poorly performing substations with various issues. Eight of these substations have technical problems related to substation components, while another eight experience management issues not aligned with specific activity profiles. The load shifting simulation demonstrates a 3% reduction in heat rate peak levels, resulting in approximately 7 kW of subscribed heat rate savings. Energy usage savings reach approximately 0.9%, leading to an increase in energy usage effectiveness. The cost savings amounted to about 3000 SEK over two months for a single building. This research emphasizes the importance of routine control, inspection, and documentation of substation performance to ensure optimal efficiency. Furthermore, indicates that the poorly performing substations that contribute to inefficiencies in the district heating network. Additionally, real-time regulation and load-shifting strategies are vital for optimizing customer consumption and maintaining an efficient district heating system, benefiting both suppliers and consumers.

Hållbarhet är en förutsättning för att både nuvarande och kommande generationer ska kunna tillgodose sina behov. I fastighetsbranschen omfattas hållbarhet av många ämnesområden, dock är energieffektiviseringar ett återkommande ämne. Det befintliga fastighetsbeståndet behöver renoveras för att uppfylla energidirektiv och andra krav som ställs på fastighetssektorn. Däremot finns det motstridiga intressen hos olika aktörer, specifikt vid bostadsrenoveringar. Energiförbrukningen är hög i flerbostadshus med belägenhet i socioekonomiskt utsatta områden. Det finns problem som hyreshöjningar, stigmatisering och segregation i bostadsområdena.  Syftet med studien är att undersöka privata bostadsföretags förhållningssätt till hållbara renoveringar i flerbostadshus, belägna i socioekonomiskt utsatta områden i Malmö. Undersökningen genomfördes via intervjuer med respondenter från fyra privata fastighetsföretag och deras senaste årsredovisningar. Det empiriska materialet har analyserats och utvärderats utifrån det teoretiska ramverket. Slutsatsen visade att privata bostadsföretag har flera utmaningar för att genomföra hållbara renoveringar i socioekonomiskt utsatta områden. Det finns utmaningar med att inkludera hyresgästerna som berör renoveringen, eftersom det finns särskiljande intressen. Bostadsföretagen har utmaningar med att genomföra renoveringar som gynnar de sociala, miljömässiga och ekonomiska hållbarhetsaspekterna, eftersom det missgynnar företagens intressenter som hyresgäster och samhället. / Sustainability is a condition to the present and future generations to meet their needs. Sustainability enclose many subject fields related to the real estate sector, but energy efficiency is a recurrent subject. The existing real estate stock is in need of renovations in order to achieve the energy directive and other demands in the real estate sector. However, there are contrarious interests of different actors, especially in housing renovations. The energy consumption is high in multi-dwellings located in socio-economic vulnerable areas. There are problems that involve rent increases, stigmatization and segregation in these areas.  The purpose of this study is to investigate the private housing companies approach to sustainability considering renovations of multi-dwelling buildings, located in socio-economic vulnerable areas in Malmö.  The research was conducted through interviewees with four private housing companies and their latest versions of annual reports. The empirical results have been analysed and evaluated in terms of the theoretical framework. The conclusion of this study showed that there are multiple challenges for private housing companies to perform sustainable housing renovations in socio-economic vulnerable areas. There are challenges to include the tenants that concern renovations, since there are different interests. The housing companies challenges to perform renovations that support the social, environmental and economic aspects of sustainability, because it disfavors the stakeholders of the companies as tenants and the society.

[pt] Nos últimos anos foi registrado crescimento no consumo energético dos edifícios residenciais, fato marcado pela aceleração gradual do aquecimento global e pelo declínio econômico e ambiental. A eficiência energética vem se apresentando como um vetor estratégico para a sustentabilidade e economia. As tecnologias e a dependência da energia cresceram exponencialmente nos últimos anos, por isso, o tema foi ganhando mais força e atraindo mais consumidores, pois a dependência da população era cada vez maior e não estava sendo acompanhada economicamente. Portanto, essa dissertação tem o objetivo de fomentar através de uma revisão bibliográfica, o progresso da introdução de ações de sustentabilidade na construção. Na presente dissertação são estudadas algumas medidas para ser implementar em um condomínio já existente, localizados no bairro da Tijuca, em Rio de Janeiro, de forma a reduzir consumos energéticos nas áreas comuns dos dois prédios. Foi apresentada uma solução para a produção de energia elétrica a partir de um sistema solar fotovoltaico do tipo On-Grid, analisando o custo de implantação deste sistema, bem como o tempo de retorno do investimento, para finalmente, chegarmos à conclusão sobre a viabilidade da implantação. / [en] Sustainability in the construction sector has gained significant attention in recent years, as the industry recognizes the need for greener and more socially responsible practices. This paradigm shift stems from the understanding that construction activities have a substantial impact on the environment, consuming large amounts of energy, water and raw materials, while generating significant amounts of waste and carbon emissions. To meet these challenges, sustainable construction aims to minimize negative environmental and social impacts throughout a building s life cycle. Incorporating sustainability principles into the construction sector involves several key elements, such as energy efficiency, which plays a key role in sustainable construction. Photovoltaic solar energy aims to minimize dependence on non-renewable energy and reduce greenhouse gas emissions. In conclusion, sustainability in the construction sector involves integrating environmentally responsible practices into all stages of a building s life cycle. The energy performance of buildings has become a concern in Brazil, increasingly focused on sustainability and renewable energy, this concept refers to the measurement of a building s energy efficiency. With energy consumption and greenhouse gas emissions on the rise, it is imperative to assess and improve a building s energy performance in order to mitigate the negative consequences of climate change and reduce the building s energy bills. Several international standards and certifications, such as LEED (Leadership in Energy and Environmental Design) or BREEAM (Building Research Establishment Environmental Assessment Method), provide frameworks for assessing and certifying the energy performance of buildings. These programs emphasize sustainable design, energy efficiency and the reduction of environmental impact, improving the energy and environmental sustainability aspects of buildings. In conclusion, the energy performance of buildings is a critical aspect of achieving sustainability goals and mitigating climate change. Implementing energy-saving measures and adhering to international standards and certifications can lead to improved energy performance and reduced environmental impact.

This study focuses on assessing the greenhouse gas emissions and energy efficiency of 40-tonne haulage trucks in fuel production and manufacturing in a Swedish context. The aim was to provide accurate greenhouse gas accounting and evaluate the contribution to mitigating climate change. Four scenarios were analysed: hydrogen from steam reforming, hydrogen from electrolysis, biomethane from biogas, and electricity in battery-electric vehicles. A comprehensive methodology involving literature review, data collection, and CO2 emissions calculations was employed. The manufacturing stage had higher CO2 emissions than fuel production for all scenarios. Hydrogen from steam reforming had the lowest emissions during manufacturing, while LBM from organic waste had the lowest emissions during fuel production. Sensitivity analysis highlighted the importance of lifespan, fuel consumption, and electricity generation in emissions. This research provides insights into renewable technologies and underscores the need for optimization to achieve climate goals. The study supports EU and Swedish climate laws and emphasizes the significance of considering the full life cycle of fuels to accurately assess their environmental impact.

Hard carbon is now a popular choice for the anode material in sodium-ion batteries. Converting biochar to produce hard carbon is considered carbon neutral and of great interest since it reduces the environmental impacts of biomass waste. This procedure requires high temperatures, and induction heating provides several advantages over other heating methods and is, therefore, widely used. In this thesis, a thermochemical reactor based on the principle of induction heating is designed, and CFD simulations of fluid-thermal coupling are performed. According to the simulation results, the total energy use efficiency of the induction heating reactor is calculated and compared with that of the thermal conduction heating reactor, which is found to be much higher than that of the thermal conduction heating reactor. Furthermore, the temperature of the tube wall of the reactor and the power losses of the inlet and outlet are observed, and design improvements are suggested. Simulation results indicate that adding a layer of protector to the exterior of the workpiece effectively reduces the wall temperature and the effect would be greater as the thickness of the protector increases. Meanwhile, the change in efficiency and energy losses are essentially negligible. / Hårt kol är nu ett populärt val för anodmaterialet i natriumjonbatterier. Att omvandla biokol till att producera hårt kol anses vara kolneutralt och av stort intresse eftersom det minskar miljöpåverkan från biomassaavfall. Denna procedur kräver höga temperaturer och induktionsuppvärmning ger flera fördelar jämfört med andra uppvärmningsmetoder och är därför allmänt använd. I detta examensarbete designas en termokemisk reaktor baserad på principen om induktionsvärme, och CFD-simuleringar av fluid-termisk koppling utförs. Enligt simuleringsresultaten beräknas den totala energianvändningseffektiviteten för induktionsvärmereaktorn och jämförs med den för värmeledningsvärmereaktorn, som visar sig vara mycket högre än den för värmeledningsvärmereaktorn. Vidare observeras temperaturen på reaktorns rörvägg och effektförlusterna i inloppet och utloppet, och designförbättringar föreslås. Simuleringsresultat indikerar att att lägga till ett lager av skydd på utsidan av arbetsstycket effektivt minskar väggtemperaturen och effekten skulle bli större när tjockleken på skyddet ökar. Samtidigt är förändringen i effektivitet och energiförluster i stort sett försumbara.

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