| 1. |
- Allard Stolterman, Ingrid, 1986-
(författare)
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Regulating energy performance of residential buildings in cold climate : a study of indicators, criteria, and evaluation methods
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Building energy performance has been important in Fennoscandia ever since the early vernacular houses, to combat the cold climate. Due to EU directive 2010/31/EU on the energy performance of buildings (EPBD recast), building energy performance has become even more relevant in northern Europe the last decade. Objectives for improving building energy performance may include reducing cost and CO2-emissions, increasing energy independency, and improving the indoor climate. Different indicators, criteria, and evaluations methods may be used to reach these objectives. This dissertation addresses indicators, criteria, and evaluation methods used to regulate energy performance of residential buildings in Sweden, Norway, Finland, and Russia. Four research objectives are covered: (RO1) comparing criteria and evaluation methods used to regulate energy performance of residential buildings in Sweden, Norway, and Finland, (RO2) studying the perspective of professionals with experience in building energy performance evaluation on (a) methods for evaluating envelope air leakage of residential buildings in Sweden and Finland and (b) potential energy performance indicators in the Swedish procurement process of multi-family buildings, (RO3) developing an approach for analysing the performance gap between design predictions and measurements that can be used to verify compliance with requirements on building energy use in practice, and (RO4) comparing the stringency of the energy performance criteria for residential buildings between the Swedish, Norwegian, Finnish, and Russian national building code. Many differences were found between how energy performance of residential buildings was regulated in the four countries. In Sweden, measurements were used more for evaluating building energy performance than in the other countries. As of 1st January 2020, the Finnish building code was characterized by its focus on the building heat loss and stringent energy performance criteria compared to the other countries. The Norwegian building code was characterized by a relatively narrow system perspective on energy performance, with no regulation of the energy production efficiency or energy source. The Russian building code also had a narrow system perspective but was also characterized by its focus on the form factor – the relationship between building volume and enclosing area. The practitioners wanted to minimize the influence from building operation and user behaviour on energy performance evaluations in the Swedish building procurement process of multi-family buildings. Hence, they preferred component-focused indicators or indicators with a narrow system boundary. An approach has been developed for analyzing the performance gap between design phase predictions and measurements. The approach can be used to verify the finished building’s energy performance, with minimal influence from occupant behavior and building operation.
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| 2. |
- Azizi, Shoaib, 1989-
(författare)
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A multi-method assessment to support energy efficiency decisions in existing residential and academic buildings
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rapid decarbonization of building stock is essential for the energy transition required to mitigate climate change and limit the global temperature rise below 1.5 °C. The decision-making for the adoption of energy efficiency measures (EEMs) is often complex and involves lasting consequences and risks. The strategy to direct and support the decision makers can significantly increase the adoption rate of EEMs in buildings. This Ph.D. project focuses on facilitating sustainability improvement in buildings by supporting the decision makers who are accountable for the consequences of adopting the EEMs. Energy efficiency improvement is decided and managed differently in various types of buildings and contexts and encounters different challenges and opportunities. Accordingly, it is required to understand the needs to select adequate strategies and to devise effective supporting interventions for energy efficiency improvement.The owners of single-family houses are often the occupants who are in charge of the most decisions to improve energy efficiency in their dwellings. The situation is rather different in multi-family buildings and academic buildings in which organizational management adds more complexity and the decisions affect various stakeholders. The studies in this project are based on qualitative and quantitative data collected from single-family houses, multi-family buildings, and university buildings in northern Sweden. Surveys were used to elicit the decision makers' perceptions of different types of buildings. Moreover, sensor data from university buildings were used in the case studies to develop informative metrics for space use efficiency and to analyze the effect of sensor positioning on monitored data.The initial work involved understanding the opportunities and challenges of improving energy efficiency in buildings and the tradeoffs between the perceived benefits and barriers. This part of the thesis provided the foundation and inspiration for the rest of the project, including investigating how to bundle several measures and use information and communication technologies (ICT) for building sustainability. The findings show lack of information and evidence that could justify the beneficial outcomes of EEMs is a major barrier for effective decision-making. Clear information on potential improvements allows sharing the responsibilities among different stakeholders and increases the management capacity to handle projects and adopt EEMs. Using feedback tools (for example, space use and/or energy use visualizations) might be an effective strategy to influence decision makers.Various studies incorporated in this multidisciplinary Ph.D. thesis develop and investigate strategies to support decision makers to improve energy efficiency in buildings. The findings provide insights to policymakers and businesses to devise intervention strategies for energy efficiency in buildings.
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| 3. |
- Brembilla, Christian, 1983-
(författare)
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Efficiency factors for space heating system in buildings
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis focuses on the efficiency of the space heating system. In particular, the efficiency factors measure the efficiency of thermal zone. The efficiency factors measures how the energy is used in a space heating. Efficiency factors relatively close to one mean that the energy is used "efficiently'', by contrast, efficiency factors close to the zero mean that the majority of the energy is lost to the outdoor environment. This method for the appraisal of space heating performance reads as if it is apparently simple and intuitive. In reality, the efficiency factor method has several pitfalls.The thesis provides tools, insights and remarks on how to apply the efficiency factor method to space heating systems equipped with hydronic panel radiator and floor heating respectively. Models of the latter heaters together with the multilayer wall were developed and validated to understand the reliability of their predictions. The hypothesis is that the heat stored in the building thermal mass and heaters plays a role in defining the building thermal performance and as a result in the appraisal of the efficiency factors. The validation is based on the sensitivity bands of the models' predictions. The heaters were tested in in a thermostatic booth simulator. Benefits and drawbacks of each model were highlighted to increase awareness of their use in the engineering fields. The results showed how the models accounting for the heat stored performed the charging phase. In addition, results of how the multilayer wall delayed and damped down the heat wave coming from the outdoor environment were presented with the appraisal of the decrement factor and time delay of the indoor temperature. The results of the efficiency factors analysis reveal how the weather affects the efficiency of each locality situated in cold climates. Lastly how different control strategies impact on the efficiency factors of space heating and its distribution system. To conclude, this study highlights the paradoxes around the efficiency factor method. The thesis proposes how such factors have to be interpreted by researchers and scientists tackling the lack of information around this topic.
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| 4. |
- Feng, Kailun, 1991-
(författare)
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Environmentally Friendly Construction Processes Under Uncertainty : Assessment, Optimisation and Robust Decision-Making
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The construction processes of building and civil infrastructure are broadly recognised as large contributors to the environmental degradation, which cause environmental impacts directly and indirectly by massive energy use, intensive greenhouse emissions, and significant resources consumption. The report from Royal Swedish Academy of Engineering Sciences (IVA) and the Swedish Construction Federation (Byggföretagen) shows that the total carbon dioxide equivalents emitted per year from construction processes are the same size as emissions from all of the cars in Sweden, and more than that is generated by all lorries and busses. Under the current scenario of practices and technologies, 35-60% of the remaining carbon budget of Paris Agreement in next 30 years would be taken by construction processes. To follow the fossil free Sweden initiative, Swedish construction and civil engineering sector has set the roadmap to reduce the greenhouse gas emissions of construction processes by 50% from 2015 to 2030 and reach net-zero emissions by 2045.Construction processes are usually carried out in contexts full of uncertainty, which causes significant challenges to achieve the target of environmentally friendly construction. The reasons can be summarised as three aspects. Firstly, most of related environmental impact assessment methods still base on static data, which lack the ability to capture the influence of uncertainty in an environmental assessment. Secondly, the uncertainty in construction processes leads to high level of computational loads, which results in that current studies present limitations on effectively providing real-time environmental optimisation. Thirdly, the robust decision-making has been proposed as an enabling method to yield decisions with robust performances with relatively less influences by uncertainty. However, current robust decision-making methods sometimes are not applicable for construction environmentally friendly decisions because the knowledge of uncertainty such as prior probability distributions are partly unknown due to characteristics of construction.The overall purpose of this thesis, therefore, was to formulate a holistic approach to assess, optimise and provide robust decision-making for environmentally friendly construction under the uncertain contexts. The developed environmental impact assessment method integrates discrete-event simulation (DES) and process-based life-cycle assessment (pLCA). It takes advantage of discrete-event simulation to reinforce the uncertainty analysis ability of conventional environmental assessment methods. The optimisation method achieves real-time environmental optimisation by introducing machine learning (ML) technology into simulation-based optimisation. It significantly reduces the computational loads of optimisation by the ML’s real-time feedback ability during uncertainty quantification. The developed robust decision-making method combines discrete-event simulation (DES) and data mining (DM) technologies to address the uncertain contexts of construction. It utilities construction performance dataset, i.e. a data-driven method, to quantify the robustness and identify the vulnerability of environmentally friendly decisions in the situation of partly unknown probability distributions.To achieve research purpose, the research is designed as an explorative procedure in a loop of (1) problem identification, (2) method development, and (3) method examination. In the first step, the requirements of environmentally friendly construction in real practices are identified, the current limitations and knowledge gaps that block the environmentally friendly construction are revealed. In the second step, to solve the identified problems, the holistic approach is designed. The theoretical methods that base on relevant theories are established, and prototypes that base on relevant technologies are developed. In the last step, the holistic approach is implemented into real construction cases. The procedure will be loop to solve identified problems until the research purpose has been fully achieved.The research provides a systematic tool to handle uncertainty and to support environmentally friendly construction practices for project decision-makers. Firstly, developed approach enables to assess the environmental impacts of construction processes involving uncertainty, which help to better understand the influences of uncertainty and develop construction planning that can improve the environmental performance. And the optimisation section enables the real-time decision support of an environmental optimisation by considering multi-objective and in a great deal of construction alternatives, which helps to efficiently narrow down numerous construction alternatives and provide practical environmentally optimal planning. Finally, it provides the decision-makers with robust environmentally friendly decisions on the construction planning that are least affected by uncertainty, and provides vulnerable scenarios of uncertain factors for an informed uncertainty management in the progress of construction.
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| 5. |
- Lidberg, Tina, 1982-
(författare)
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Building Energy Efficiency Measures in District Heating Systems
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Improving energy performance of existing buildings is an important part in decreasing energy use and in turn reducing greenhouse gas emissions and primary energy use. To be able to evaluate how energy refurbishment influences greenhouse gas emissions and primary energy use a wider system perspective is needed which puts the building in its context. This thesis deals with energy efficiency refurbishment performed on multi-family buildings within district heated areas and how greenhouse gas emissions and primary energy use is influenced. Both energy demand and temperature levels are considered.A simulated building is used to evaluate energy refurbishment packages. The results are used as input data for models of district heating systems to cost optimize district heating production. One district heating system model is also used to evaluate the impact of lowered district heating supply temperatures. The results from the cost optimizations are used to evaluate the impact on greenhouse gas emissions and primary energy use.The results show that all refurbishment packages decreases greenhouse gas emissions and primary energy use, but to a different extent. Depending on the fuel types used and to which extent electricity is co-produced in the district heating system, the results of implementing the refurbishment packages vary. The largest reduction of greenhouse gas emissions and primary energy use occurs in a district heating system with a high share of biofuel and no electricity production. Another result is that the temperature levels of a building’s heating system can be reduced when refurbished which promotes low-temperature district heating. The results also indicates that greenhouse gas emissions and primary energy use can be decreased from a short- and medium term perspective if the supply temperature of a district heating system is lowered. From a long term perspective primary energy use is still decreased while greenhouse gas emissions are increased.
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| 6. |
- Nydahl, Helena, 1990-
(författare)
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Communication of life cycle assessment results : life cycle key performance indicators
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The global warming that we are on track for will result in a severe loss of natural capital leading to significant losses in economic capital when urban infrastructure is destroyed, agricultural productivity declines and poverty spread among other disasters. Climate change due to emissions does not only affect the polluter, the hazardous effects becomes evident on a global level. An essential tool to enable decision‑making with concern to the welfare of the global commons is life cycle assessment (LCA). LCA compile and evaluate the inputs, outputs, and potential environmental impacts of a product system throughout its life cycle. The reviewed literature frames a gap regarding interpretation of LCA-results and inquire for guidelines that address a wide range of stakeholders to enable informed decision-making with regard to the welfare of the global commons. Some studies even argue that an apparent weakness of LCA-result communication is the understanding of what the results mean for the economic key performance indicators (KPIs) of the stakeholder. Thus, this thesis aims to contribute to the development of guidelines for interpretation of LCA-results by introducing an approach for communicating LCA-results that is compatible with the economically driven nature of stakeholders. The specific research questions (RQ) of this thesis are: (RQ1) How can well-established economic KPIs be utilised to quantify environmental impact? and (RQ2) How does incorporation of monetary valuation of environmental impacts and related environmental aspects affect the LCA-result and communication of results?These research questions have led to life cycle key performance indicators (LC‑KPIs) that quantify life cycle economic and environmental impacts in a way that take after the traditional economic KPIs of the stakeholders, which is outlined as essential to improve the understanding of LCA-results. The LC‑KPIs utilize the traditional economic KPIs of return on investment (ROI) and annual yield (AY). Additionally, to manage the large amount of non-commensurate units of holistic life cycle sustainability assessment, monetary valuation has been applied. Hence, contributing to the research area of monetary valuation in LCA by introducing and testing new approaches.The introduced LC-KPIs have been specified for building LCA and exemplified by applying them to a number of Swedish case buildings. The result show that the climate-economic assessment of building refurbishment differs compared to the traditional economic assessment when monetary valuation is utilized in LCA with the LC-KPI of ROIEconomy+. However, in the comparative assessment of building refurbishment and new construction, the LCA‑result does not change compared to the traditional economic assessment when monetary valuation is utilized in LCA with the LC-KPI of ELCCA. This is explained by the high costs associated with the investment and energy use of buildings and may not be the case if products with lower investment and energy use costs and high life cycle greenhouse-gas emissions would be studied. Still, if a purely environmental assessment of a product is wished for, the LC-KPI should only include monetary valuation of environmental impact factors and exclude traditional economic performance. Thus, the case study result defines further scope for research on the subject of monetary valuation in LCA and inquire for a wider spectrum of LC-KPIs that utilizes monetary valuation.The introduced approach of this thesis contribute to the development of guidelines for interpretation of LCA-results. Nevertheless, there are still challenges that needs to be addressed in the development of robust LCA-result interpretation. Still, the LC‑KPIs used in this thesis address the “cognitive logics” of a wide range of stakeholders and provide an approach for communication of LCA-results which improve the understanding of LCA-results.
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| 7. |
- Syrjänen, Elmeri, 1976-
(författare)
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The effects of valenced odors on facial perception
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We use our senses to navigate in the world. An important property of olfaction, the sense of smell, is to enable us to approach beneficial things, and to avoid what might be toxic or otherwise harmful in our environment. Other peoples’ behaviors are also paramount for our survival. Thus, we use our vision to decode their internal states from their facial expressions. For many modalities, multiple senses are integrated to enhance sensory percepts. In this thesis, I investigated how valenced odors affect the perception of facial expressions. Specifically, using a multi-method approach, I studied the integration of unpleasant and pleasant odor contexts on odor-congruent and incongruent facial expressions, disgusted, and happy faces.The effects I am interested in are those that valenced odors have on face perception, attention to faces, and the cortical processing of faces. To answer these questions, I used questionnaires, ratings, EEG, and behavioral measures such as reaction times. Across studies, ratings of face valence are affected in the direction of the odor valence (e.g., faces are rated more negatively in the context of an unpleasant odor). Also, overall, the results in my studies indicate that faces are perceived as more arousing in valenced odor contexts; however, these effects occur regardless of facial expression.In study 1, I found that valenced odors and facial expressions are integrated at an earlier time-frame than previously thought. Specifically, I found that the N170 event-related potential component (ERP) to disgusted facial expressions was lower in amplitude in the unpleasant odor condition than in the pleasant odor condition. This effect was not present for happy faces in the N170 component. An unpleasant odor might thus facilitate the processing of threat-related information.In study 2, I found evidence that odors, in general, did not affect the recognition speed of facial expressions that changed from neutral to disgusted or happy over 3 seconds. Also, I found robust evidence against congruency effects in facial expression recognition reaction times (RTs). The results indicated that faces overall were recognized faster in the unpleasant odor condition. Further, these results were not qualified by individual differences in body odor disgust. Thus, unpleasant odors might facilitate the recognition of facial expressions regardless of trait body odor disgust.In study 3, I studied whether valenced odors directed spatial attention toward odor-congruent facial expressions in a “dot-probe” task. I found decisive evidence that odors do not affect attention towards disgusted and happy facial expressions, casting doubt on the dot-probe experiment. However, I found that probes were detected faster as a function of time-on-task in the unpleasant odor condition. I hypothesized that this effect might be due to maintained vigilance in the presence of an unpleasant odor and task fluency effects.In summary, the results indicate that valenced odors affect facial perception. Generally, faces are perceived as more valenced and arousing in odor contexts. Further, an unpleasant odor may decrease RTs; however, this effect seems to be irrespective of the target type. Also, odor face integration may happen earlier than thought; yet, evidence in the literature is mixed, and more research is needed. The methods I have used may increase transparency and robustness of published results, and help accelerate knowledge development in this field of research.
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| 8. |
- Danielski, Itai, 1973-
(författare)
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Energy efficiency of new residential buildings in sweden : Design and Modelling Aspects
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Energy security and climate change mitigation have been discussed in Sweden since the oil crisis in the 1970s. Sweden has since then increased its share of renewable energy resources to reach the highest level among the EU member states, but is still among the countries with the highest primary energy use per capita. Not least because of that, increasing energy efficiency is important and it is part of the Swedish long term environmental objectives. Large potential for improving energy efficiency can be found in the building sector, mainly in the existing building stock but also in newly constructed buildingsIn this thesis, criteria for energy efficiency in new residential buildings are studied, several design aspects of residential buildings are examined, and possible further analysis from an energy system perspective discussed. Three case studies of existing residential buildings were analysed, including one detached house and multi-storey apartment buildings. The analysis was based on both energy simulations and measurements in residential buildings.The results show that the calculated specific final energy demand of residential buildings, before they are built, is too rough an indicator to explicitly steer society toward lower final energy use in the building sector. One of the reasons is assumptions made during calculation before the buildings is built. Another reason is the interior building design. A design that includes relatively large areas of heated corridors, service and storage rooms will lower the specific final energy demand without improving the building energy efficiency, which might increase both the total final energy demand and the use of construction materials in the building sector.Efficient thermal envelopes are essential in construction of energy efficient buildings, which include the thermal resistance and also the shape of the building. The shape factor of buildings was found to be an important variable for heat demand in buildings located in temperate and colder climates, particularly if they are exposed to strong winds.From a system perspective, energy efficiency measures and the performance of the end use heating technology in buildings should be evaluated together with the energy supply system, including the dynamic interaction between them.
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| 9. |
- Dannefjord, Per, 1964-
(författare)
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Organisationspraktiker och målförändring : Exemplet svensk socialdemokrati
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis emanates from a comparison between three points of time in the history of the Swedish social democratic party (SAP); 1889, 1905 and 1933. The comparison is partly about the political and organizational situation of the party, and partly about the goals the party expressed. The problem that I study, based on this comparison, is the identified changes of the party’s hierarchy of goals.I argue that goal change should be viewed as a process, not as a decision. There is no simple rationality in goal formulations or in the relation between goals and practices where the practices are shaped by the goals.My case shows the importance of the opposite causal direction where the practices reshape the goals. The organization formulates goals and intermediate goals. These are connected to practices directed towards the intermediate goals. The more resources the organization attach to these practices, the more difficult it is to change them and the higher status in the organizational activity they will get. The primary goals can still be important as justification, but their role will be reduced to a ritual rhetoric without practical significance. They will have to be reinterpreted and reformulated in correspondence to the practices in order to regain a practical significance in the activity of the organization. Thereby we have a practical goal change, which shouldn’t be confused with at rhetoric goal change. The rhetoric of the organization can remain unchanged even though no practices are directed towards the rhetorically important goals.One implication of this is that goals cannot be understood by their formulations only. The importance and meaning of the formulations will change over time and should therefore be related to the context and the organization’s position in the organizational field. When we study an organization over time it will be hard to understand it adequately if we don’t relate the organizational changes to the context.
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| 10. |
- Jassim, Hassanean S.H, 1978-
(författare)
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Assessing Energy Use and Carbon Emissions to Support Planning of Environmentally Sustainable Earthmoving Operations
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Road and infrastructure projects have significant environmental impacts due to their high energy consumption and CO2 emissions. Among it, earthmoving operations contribute disproportionately to these impacts because of their intensive use of heavy machinery. However, little is known about how different equipment configurations and/or operational management strategies affect the environmental impact of earthmoving operations. Specifically, there is• a lack of tools that enables stakeholders to understand and assess environment impacts of per unit volume of earth handled,• a lack of integrated method taking into account both environmental and economic impacts in the planning of earthmoving operations.This work aims to facilitate the adoption of sustainable earthmoving practices in construction by providing methods for selecting environmentally costeffective equipment configurations for earthmoving operations. Based on these considerations, three research questions were formulated:• How can planners and construction managers of earthmoving projects estimate the energy use and carbon emissions of earthmoving machines per functional unit of material handled? • Which factors relating to earthworks operations have the greatest impact on energy use and carbon emissions?• How can stakeholders optimize equipment configurations with respect to the trade-off between the carbon emissions, time, and cost of earthwork operations?To answer these questions, an exploratory research approach involving multiple case studies was adopted. This resulted in the generation of a large body of experimental data and made it possible to test new methods for predicting and minimizing emissions due to earthmoving operations during the planning phases of construction projects. Throughout, the work was guided by the results of comprehensive literature reviews. Key findings of the work presented here include:• The combination of Discrete Event Simulations (DES) and mass haul optimization (MHO) can be used to assess environmental impacts during project planning stage. Artificial Neural Networks (ANNs) provides an effective approach to model the relationships between input variables relating to the earthmoving equipment and project conditions and output variables relating to energy use and CO2 emissions per unit volume of hauled materials,• The environmental performance of an item of equipment during earthmoving operations can be expressed as a function of the equipment’s operational characteristics and the job-site conditions such as digging depth, density of hauled materials and/or the topography of haulage surface. These factors all have important effects on the environmental impacts of earthmoving operations and the efficiency of the work,• As expected, improving equipment utilization rates and/or cycle times significantly reduces energy use and CO2 emissions per unit volume of material handled. This also increases the equipment’s usage efficiency in terms of fuel consumption per unit volume of material hauled. A high usage efficiency (evaluated in terms of utilization rates and/or cycle times) thus minimizes both the emissions and the costs of earthmoving operations.• Planning tools that account for costs and durations when assessing the carbon emissions of earthmoving operations make it possible to select optimal earthmoving equipment configurations that minimize emissions and costs (or at least do not increases costs).In summary, this thesis identifies key factors that facilitate the assessment and reduction of energy consumption and carbon emissions in earthmoving projects. The developed approaches allow construction managers to benchmark the emissions of different equipment configurations during project planning.The most important outcome of this work is the development of new methods for assessing energy use and CO2 emissions per unit volume of materials handled based on equipment characteristics and project conditions. These methods can be used to compare equipment configurations during the early stages of projects, and also for benchmarking/monitoring purposes during the construction stage. In particular, their use in the planning stages could help planners and construction managers to identify optimal equipment configurations that will minimize the environmental and economic impacts simultaneously.
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| 11. |
- Linde, Erika, 1992-
(författare)
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New Reactivity in Diaryliodonium Salt Chemistry
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diaryliodonium salts (Ar2IX) have emerged as versatile multi-purpose reagents with desirable properties such as easy accessibility, low toxicity and applicability under mild and metal-free reaction conditions. Despite displaying broad utility in arylations of both carbon and heteroatom nucleophiles, the overall sustainability of these protocols is compromised by featuring poor atom economy due to the formation of stochiometric iodoarene byproducts. In this thesis, this imperative drawback was addressed by development of a novel class of diaryliodonium salts with unprecedented reactivity that prevents the formation of iodoarene waste by incorporating both aryl groups as well as the iodine-component into the final products. The first project concerns the development and design of ortho-fluorinated iodonium salts, where updated synthetic protocols were established to attain extensive salt scopes with diverse functionalities. The unique design of these reagents unveiled a cascade reaction whereby heteroatom-diarylated products were formed through concomitant nucleophilic aromatic substitution and intramolecular aryl transfer. The second project focuses on the applications of the ortho-fluorinated salts in diarylations of aliphatic amines, anilines, ammonia and water to attain industrially important diaryl- and triaryl amines as well as diaryl ethers (>100 examples). This atom-efficient methodology allows for transfer of two different aryl groups in a single step under mild and metal-free conditions, giving structurally diverse multi-arene products that would otherwise require expensive and time-consuming multi-step synthesis. The third project explores the potent combination of the diarylation strategy with the structural diversification of secondary aliphatic amines in the preparation of densely functionalized diarylamines. Cyclic amines constitute essential cornerstones in drug discovery and incorporation of such valuable moieties in Ar2IX reagents is of considerable interest. By further exploiting the SNAr reactivity of the ortho-fluorinated diaryliodonium salts, a previously inaccessible class of amino-functionalized Ar2IX were prepared by reactions with cyclic amines. These N-functionalized reagents were utilized in a one-pot sequential arylation/ring opening pathway, where intramolecular arylation afforded diarylammonium salts in situ, which upon reaction with external nucleophiles underwent deconstructive C-N functionalizations. The methodology enables atom- and step-economical access to value-added diarylamines with versatile functionalities at both the C- and N- terminal. The final project emphasizes the applicability of the diarylated products as versatile building blocks in various downstream functionalizations. The retention of the iodine-component enables diversification by a range of transition metal-catalysed cross-couplings, delivering products with increased structural complexity. The significance of the diarylation methodology was further demonstrated in the three-step synthesis of the drug molecule NMP-7. Two protocols were developed for transformation of the ortho-iododiaryl ethers into oxygen-bridged cyclic diaryliodonium salts and acyclic aryloxy salts. The synthetic utility of these unexplored Ar2IX reagents was demonstrated in metal-free, chemoselective functionalizations of common nucleophiles.
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| 12. |
- Pasichnyi, Oleksii, 1986-
(författare)
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Advancing urban analytics for energy transitions : Data-driven strategic planning for citywide building retrofitting
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Decarbonisation of the building stock is essential for energy transitions towards climate-neutral cities in Sweden, Europe and globally. Meeting 1.5°C scenarios is only possible through collaborative efforts by all relevant stakeholders — building owners, housing associations, energy installation companies, city authorities, energy utilities and, ultimately, citizens. These stakeholders are driven by different interests and goals. Many win-win solutions are not implemented due to lack of information, transparency and trust about current building energy performance and available interventions, ranging from city-wide policies to single building energy service contracts. The emergence of big data in the building and energy sectors allows this challenge to be addressed through new types of analytical services based on enriched data, urban energy models, machine learning algorithms and interactive visualisations as important enablers for decision-makers on different levels.The overall aim of this thesis was to advance urban analytics in the building energy domain. Specific objectives were to: (1) develop and demonstrate an urban building energy modelling framework for strategic planning of large-scale building energy retrofitting; (2) investigate the interconnection between quality and applications of urban building energy data; and (3) explore how urban analytics can be integrated into decision-making for energy transitions in cities. Objectives 1 and 2 were pursued within a single case study based on continuous collaboration with local stakeholders in the city of Stockholm, Sweden. Objective 3 was addressed within a multiple case study on participatory modelling for strategic energy planning in two cities, Niš, Serbia, and Stockholm. A transdisciplinary research strategy was applied throughout.A new urban building energy modelling framework was developed and demonstrated for the case of Stockholm. This framework utilises high-resolution building energy data to identify buildings and retrofitting measures with the highest potential, assess the change in total energy demand from large-scale retrofitting and explore its impact on the supply side. Growing use of energy performance certificate (EPC) data and increasing requirements on data quality were identified in a systematic mapping of EPC applications combined with assessment of EPC data quality for Stockholm. Continuity of data collaborations and interactivity of new analytical tools were identified as important factors for better integration of urban analytics into decision-making on energy transitions in cities.
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| 13. |
- Ramirez Villegas, Ricardo, 1981-
(författare)
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Energy efficient renovation in a life cycle perspective : A case study of a Swedish multifamily-building
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Energy use in the European Union is increasing. At the same time, it is estimated that by the year 2050 most of the EU population will be living in currently existing buildings. Some of these buildings are or will be in need of renovation, and they have identified a target to reduce overall energy use. The urgency of climate change also makes it highly relevant and important to improve buildings resource and energy efficiency. This thesis aims to explain how different proposed energy efficient renovation strategies affect the energy use at different system levels, the potential environmental impacts of these alternatives, how they are connected to economic impacts and the implications of using a commercial LCA software to answer these questions from a research perspective.In order to answer the questions above, the effect of different renovation strategies were studied by combining building energy simulations, energy system simulations, a building environmental assessment tool, life cycle assessment and life cycle cost calculations. These tools are used in order to provide an overview of how the different renovation strategies affect the production of district heating, greenhouse gas (GHG) emissions and the environmental and economic performance of the building.The results show that the selected renovation strategies reduce energy use by decreasing transmission losses, while reducing the total amount of purchased energy by using solar energy or by changing energy carriers. These different approaches have the potential to reduce the environmental impact, mainly by reducing global warming potential, acidification potential and eutrophication potential and to some extent abiotic depletion potential. However, when changing energy carriers there is a burden shift to radioactive waste disposed. When the economic aspects are analyzed, it is shown that there is no simple correlation between financial and environmental impacts.To analyze a building from a life cycle perspective can help to identify the advantages and disadvantages of energy efficient renovation from the building owner’s perspective as well as from a societal perspective. Applying a life cycle perspective is therefore important for building owners, building companies and practitioners as well for policy makers to avoid suboptimisation.
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| 14. |
- Stenberg, Henrik
(författare)
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Att bli konstnär : Om identitet, subjektivitet och konstnärskap i det senmoderna samhället
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation explore young peoples will to become artists. A group of artstudents have been interviewed and severel questions are raised. How do the students perceive their artistry and their role as artists? In what way is artistic creation meaningful to them? What does the relationship between the individual project of becoming an artist and their societal participation look like? As artists they examine different phenomena subjectively and they sometimes exceed personal and social boundaries. What may this look like and how may it be understod? In order to understand and interpret the art students’ work and reasons to become artists sociologically, I use Anthony Giddens analysis of the late-modern society and and the late-modern identity. Giddens creates a sociological understanding of the individual in society rather than an understanding of specific social groups. An understanding, which is well suited to highlight, the frequently individual life projects, created by the art students. However, Giddens theory is broad and opens for critisism. The art students, give their views of society and of themselves, which are not always in agreement with Giddens’ theory and therefore create different thoughts about the late-modern identity. When I develop Giddens’ theory, it is through an interaction between Giddens, the artstudents and other theories, between which I create a dialogue about identity, the exceedeing of social boundaries and the role of subjecticity in the late modern society.
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| 15. |
- Vesterberg, Jimmy, 1976-
(författare)
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Improved building energy simulations and verifications by regression
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is common with significant differences between calculated and actual energy use in the building sector. These calculations are often performed with whole building energy simulation (BES) programs. In this process the analyst must make several assumptions about the studied building and its users. These calculations are often verified with measured data through the EUI benchmark indicator which is calculated by normalizing the annual energy use (from the grid) with the floor area. Due to the highly aggregated nature of the EUI indicator it is problematic to use this indicator to deduce erroneous assumptions in the calculations. Consequently, the learning process is often troublesome.Against this background, the main aim of this thesis has been to develop methods that can provide feedback (key building performance parameters) from measured data which can be used to increase simulation accuracy and verify building performance. For the latter, regression models have been widely used in the past for verifying energy use. This thesis has the focus on the use of regression analysis for accurate parameter identification to be used to increase the agreement between BES predictions and actual outcome. For this, a BES calibration method based on input from regressed parameters has been developed which has shown promising features in terms of accurate predictions and user friendliness. The calibration method is based on input from regressed estimations of air-to-air-transmission losses, including air leakage (heat loss factor) and ground heat loss. Since it is known that bias models still can give accurate predictions, these parameters have been evaluated in terms of robustness and agreement with independent calculations. In addition, a method has been developed to suppress the bias introduced in the regression due to solar gain. Finally, the importance of calibrated simulations was investigated.The regressed parameters were found to be robust with yearly variations in the heat loss factor of less than 2%. The regressed estimates of ground heat loss were also in good agreement with independent calculations. The robustness of the heat loss factor based on data from periods of substantial solar gain was also found to be high, with an average absolute deviation of 4.0%. The benefit with calibrated models was mainly found to be increased accuracy in predictions and parameters in absolute terms. With increased access to measured data and the promising results in this thesis it is believed that the presented regression models will have their place in future energy quantification methods for accessing energy performance of buildings.
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| 16. |
- Allard, Ingrid
(författare)
-
Achieving building energy performance : requirements and evaluation methods for residential buildings in Sweden, Norway, and Finland
- 2015
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Building energy performance has always been important in the cold climate of Sweden, Norway and Finland. To meet the goal that all new buildings should be nearly zero-energy buildings by 2020, set in the EU directive 2010/31/EU [1] on the energy performance of buildings (EPBD recast), the building sector in Europe now faces a transition towards buildings with improved energy performance. In such a transition, a discussion is needed about the objective of the improvement – why, or to what end, the building energy performance should be improved. The objective of improving building energy performance is often a political decision, but scientific research can contribute with knowledge on how the objectives can be achieved.This thesis addresses how the indicators used in the requirements used to achieve building energy performance in Sweden, Norway, and Finland, and the methods used to evaluate these requirements, reflect building energy performance. It also addresses difficulties in achieving comparable and verifiable indicators in evaluations of building energy performance. The research objective has two parts: to review, compare, and discuss (i) requirements and (ii) evaluation methods used to achieve energy performance of residential buildings in Sweden, Norway and Finland. The work in this thesis includes reviews of the requirements used in national building codes and passive house criteria to achieve building energy performance, of methods used to evaluate compliance with such requirements, and of methods used specifically to evaluate the indicator Envelope Air Tightness. The results show that different sets of indicators are used to achieve building energy performance in the studied building codes and passive house criteria. The methods used to evaluate compliance with requirements used to achieve building energy performance are also different, but calculation methods are generally more often used than measurement methods. The calculation- and measurement methods used are often simple. A methodology to analyze the deviation between predictions- and measurements of building energy performance (the performance gap) was developed, to investigate the effects of different evaluation methods on different indicators used to achieve building energy performance. The methodology was tested in a case-study. This study indicated that the choice of method affects which parts of the performance gap reflected in the indicators Supplied Energy (see Terminology), Net Energy (see Terminology), and Overall U-value. Among the reviewed methods to evaluate air tightness, the Fan/Blower Door Pressurization is well known and preferred by professionals in the field. The results in this thesis may be useful when choosing indicators and evaluation methods to achieve different objectives of improving building energy performance and in the quest towards comparable and verifiable indicators used to achieve building energy performance.
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| 17. |
- Brembilla, Christian, 1983-
(författare)
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Modelling and simulation of building components : thermal interaction between multilayer wall and hydronic radiator
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and Scope: The scope of this thesis is to investigate the thermal behaviour of building components as hydronic radiator and multilayer walls subjected to dynamic conditions. The modelling and simulation of these building components provide information on how these components thermally interact among each other. The thermal interaction is fundamental to know how the energy is used in buildings. In particular, the thermal energy used in rooms can be expressed as the efficiencies for emission in a space heating system. This thesis analyzes the efficiencies for emission of a space heating system equipped with hydronic radiator for Swedish buildings by providing a comprehensive and detailed approach on this topic.Methodology: The methods used in this thesis are: experiment, modelling of multilayer wall and hydronic radiator, the dynamic simulation of the building and the efficiencies for emission of a space heating system. Here, the experiment, known as step response test, shows the heating up process of a hydronic radiator. The observation of the qualitative measurements suggests the most suitable technique of modelling the radiator known as transient modelling with multiple storage elements. The multilayer wall has been discretized both in space and time variable with a Finite Difference Method. Dynamic simulation of the building provides the efficiencies for emission of a space heating system.Findings: The experimental results show how the radiator performs the charging phase. The performance of the transient model is compared with lumped steady state models in terms of temperature of exhaust flow and total heat emitted. Results of the dynamic simulation show how buildings located in a Northern climate use the energy in a better way than Southern climates in Sweden. Heavy active thermal mass provides higher efficiencies for emission than light thermal mass. Radiators with connection pipes located on the same side react faster at the thermodynamic changing of the mass flow rate by providing higher efficiencies for emission than radiators with connection pipes located on the opposite side.Conclusion and Outlook: This thesis increases the knowledge about the modelling and simulation of hydronic radiators and multilayer walls. More research is needed on this topic to encompass modelling details of building components often ignored. The modelling and simulation of building components are the key to understand how building components thermally interact with each other. The thermal interaction among building components is a fundamental parameter for the assessment of efficiencies of emission of the space heating system. In the near future, the concept of efficiencies of emission can be implemented in National Building Code, therefore, this study provides guidelines on how to assess these efficiencies.
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| 18. |
- Feng, Kailun, et al.
(författare)
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Energy-efficient retrofitting with incomplete building information : a data-driven approach
- 2022
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Ingår i: E3S web of conferences. - : EDP Sciences.
-
Konferensbidrag (refereegranskat)abstract
- The high-performance insulations and energy-efficient HVAC have been widely employed as energy-efficient retrofitting for building renovation. Building performance simulation (BPS) based on physical models is a popular method to estimate expected energy savings for building retrofitting. However, many buildings, especially the older building constructed several decades ago, do not have full access to complete information for a BPS method. To address this challenge, this paper proposes a data-driven approach to support the decision-making of building retrofitting under incomplete information. The data-driven approach is constructed by integrating backpropagation neural networks (BRBNN), fuzzy C-means clustering (FCM), principal component analysis (PCA), and trimmed scores regression (TSR). It is motivated by the available big data sources from real-life building performance datasets to directly model the retrofitting performances without generally missing information, and simultaneously impute the case-specific incomplete information. This empirical study is conducted on real-life buildings in Sweden. The result indicates that the approach can model the performance ranges of energy-efficient retrofitting for family houses with more than 90% confidence. The developed approach provides a tool to predict the performance of individual buildings from different retrofitting measures, enabling supportive decision-making for building owners with inaccessible complete building information, to compare alternative retrofitting measures.
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| 19. |
- Ghorbani, Morteza, et al.
(författare)
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Unravelling the Acoustic and Thermal Responses of Perfluorocarbon Liquid Droplets Stabilized with Cellulose Nanofibers
- 2019
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Ingår i: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 35:40, s. 13090-13099
-
Tidskriftsartikel (refereegranskat)abstract
- The attractive colloidal and physicochemical properties of cellulose nanofibers (CNFs) at interfaces have recently been exploited in the facile production of a number of environmentally benign materials, e.g. foams, emulsions, and capsules. Herein, these unique properties are exploited in a new type of CNF-stabilized perfluoropentane droplets produced via a straightforward and simple mixing protocol. Droplets with a comparatively narrow size distribution (ca. 1-5 μm in diameter) were fabricated, and their potential in the acoustic droplet vaporization process was evaluated. For this, the particle-stabilized droplets were assessed in three independent experimental examinations, namely temperature, acoustic, and ultrasonic standing wave tests. During the acoustic droplet vaporization (ADV) process, droplets were converted to gas-filled microbubbles, offering enhanced visualization by ultrasound. The acoustic pressure threshold of about 0.62 MPa was identified for the cellulose-stabilized droplets. A phase transition temperature of about 22 °C was observed, at which a significant fraction of larger droplets (above ca. 3 μm in diameter) were converted into bubbles, whereas a large part of the population of smaller droplets were stable up to higher temperatures (temperatures up to 45 °C tested). Moreover, under ultrasound standing wave conditions, droplets were relocated to antinodes demonstrating the behavior associated with the negative contrast particles. The combined results make the CNF-stabilized droplets interesting in cell-droplet interaction experiments and ultrasound imaging.
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| 20. |
- Hu, Siying, et al.
(författare)
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A data-driven exploration of the relations between occupant behaviors and comfort performances of energy-efficient measures
- 2023
-
Ingår i: ICCREM 2023. - : American Society of Civil Engineers (ASCE). - 9780784485217 ; , s. 592-604
-
Konferensbidrag (refereegranskat)abstract
- Energy-efficient building retrofitting plays a crucial role in reducing energy consumption and carbon emissions within the building sector. Energy-efficient retrofitting brings about changes in the built environment and it could influence the occupant behaviors. Additionally, occupant behaviors, in turn, alter the indoor environment, thereby affecting the comfort performance of the building after retrofitting. To explore this intricate relation between occupant behaviors and comfort performances of energy-efficient measures, this paper employs a data-driven approach to compile a comprehensive dataset encompassing occupant behaviors, energy-efficient measures, and associated indoor comfort of an office building in Umeå University, Sweden. Multiple binary logistic regression is applied to quantify the relationship between occupant behaviors and comfort performances of energy-efficient measures. The findings of this study hold significant value, providing guidance for occupants in adapting to energy-efficient measures while also informing future retrofitting implementation.
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| 21. |
- Kadefors, Anna, Professor, 1962-, et al.
(författare)
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Innovation processes and dissemination of research-based knowledge in Swedish rock engineering : Experiences in the trust geoinfra project
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Innovation in the project-based construction industry is generally perceived to be complex and poorly understood on a system level. This report describes and discusses the innovation system in Swedish underground construction based on a study of knowledge dissemination and implementation in relation to the large collaborative R&D program TRUST, Transparent Underground Structures.The study is primarily based on interviews performed with representatives of clients, contractors, consultants, researchers and funding bodies within the TRUST program. There are two main focus areas: the innovation system level and the TRUST project. The innovation system level describes drivers, organization and processes for engaging in R&D and implementing results within the Swedish Transport Administration (STA), contractor companies and consultancy firms, but also interviewee opinions about the innovation culture in Swedish rock engineering and construction more generally. The section covering the TRUST project describes the background, performance and experiences from the TRUST collaboration as well as innovation processes within some of the sub-projects.Underground construction is a part of the construction sector where comparatively much research is carried out and university-industry collaboration is lively. Still, our results confirm many of the observations made by previous researchers on innovation in construction in general: the small resources within companies devoted to research and innovation, the importance of champions at the project level and the difficulties to disseminate knowledge and implement company level initiatives. The contractor interviews illustrate how sensitive their innovation processes are to chance factors such as timing of new relevant business projects and the experiences and knowledge of the individuals that happen to be assigned to a specific project. In this respect, the client is more in control. However, the interviewed client representatives from STA express the same kind of difficulties in driving innovation more strategically on the organizational level and convince their project managers to open up for R&D tests and new knowledge in their business projects.Previous research has also shown that there are many drivers for firms to engage in R&D collaborations with public funding. R&D collaboration provides access to knowledge networks by enabling participation in reference groups and communities. Important such networks in Swedish underground construction were BeFo and SBUF. Another driver for R&D collaboration was to support M Sc and PhD education for future recruitment. Thus, the individuals themselves were often the most important research output. Implementation of results was not a primary motivation although a more strategic approach was emerging among both public organizations and private companies, who put more emphasis than they used to on application in practice of research results. One consultancy company was especially active in developing their R&D strategy to support a business model based on premium services. In general, however, knowledge development for underground construction was still mainly driven by individual specialists based on their contacts in business projects. Organizations had developed centrally defined R&D strategies, but these did not deal explicitly with technical disciplines but tended to focus on general goals such as sustainability, or on participation in high profile research collaborations.Most specialists within academia as well as industry were involved in several networks and perceived these to provide useful interaction platforms. Research funding was governed by BeFo and SBUF, and these peer networks thus strongly influenced research strategy on a national level. The number of PhDs in industry had increased over the last years, and important informal networks developed over time between these individuals and their former university departments. Such relationships formed the basis for gaining research funding, which is often dependent on industry co-funding.When establishing TRUST, the assumption was that a large coordinated R&D project would be better for communicating with industry and implementing results than several smaller projects. However, it turned out to be more or less the other way around. The existing system could handle innovation in construction projects, but not innovation on the organizational level. This became apparent when trying to find a joint test site. In smaller research projects, access to business projects is provided by individuals on the client or supplier side, often with an R&D background, who use their personal contacts to provide access to researcher to perform measurements in ongoing construction projects. This often requires that site work is going well and that measurements are found not to cause too much disturbance. Large programs for site measurements involving numerous actors, such as TRUST, call for planning and upfront commitment. The failure to arrange fieldwork in TRUST illustrate the difficulties to take the step from a bottom up, ad-hoc, individual based regime to an organizational strategy with national level anchoring and implications. Thus, the TRUST program appeared to be an ideal partner for the Swedish Transport Administration, but in practice the size of the project turned out to be a major disadvantage.In general, the internal innovation capabilities of companies and client authorities need to be developed in order for organizations to benefit from the collaborative research programs and act upon the knowledge developed. One aspect is that measures should be taken to more explicitly involve business project managers in both R&D and implementation. Innovation capability development is needed especially on the client side, since long term strategies in supplier organizations will not develop if the strategies of the dominant clients is not clear. However, assuming that the geo area in general is largely an open innovation environment, it also seems useful to explore if different actors could perform complementary activities in an industry innovation system. For example, specialist networks both within organizations and on the industry level may be more formally mobilized in external monitoring, strategy development and evaluation. In the future, top management, technically oriented specialists and researchers need to develop a joint understanding of how the innovation system works, including the regulatory and contractual environment.There is also a need to invest also in research that is relatively far from application. Thus, evaluation processes and output measurement systems should be adapted to how close to implementation the research project is and also assess the need to build capabilities on the receiver side.
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| 22. |
- Kadefors, Anna, Professor, 1962-, et al.
(författare)
-
University-industry collaboration and innovation in a project-based engineering context
- 2017
-
Konferensbidrag (refereegranskat)abstract
- The construction industry plays a key role in society but innovation in this project-based context is perceived as slow and poorly understood. Interorganizational collaboration is important in both business projects and R&D. Based on a study of a large collaborative R&D programme to develop knowledge and new engineering methods for Swedish underground construction, we discuss and analyse the innovation system in this area with a focus on implementation of research-based knowledge. To sketch the institutional context, we summarize key findings in research on innovation in construction. Innovation in this sector is project-based and dependent on individual champions, and the large underground research program exposed system weaknesses originating in a lack of organizational absorptive capacity especially within the dominant client organization. An important finding is that absorptive capacities within organizations shape system level innovation capabilities and potential roles of industry network. It is therefore essential to understand the actor level in suggesting measures to increase implementation. The paper develops knowledge to support collaborative strategy formulation in this complex area.
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| 23. |
- Knief, Ulrich, et al.
(författare)
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Highly pathogenic avian influenza causes mass mortality in Sandwich Tern Thalasseus sandvicensis breeding colonies across north-western Europe
- 2024
-
Ingår i: Bird conservation international. - : Cambridge University Press. - 0959-2709 .- 1474-0001. ; 34
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Tidskriftsartikel (refereegranskat)abstract
- In 2022, highly pathogenic avian influenza (HPAI) A(H5N1) virus clade 2.3.4.4b became enzootic and caused mass mortality in Sandwich TernThalasseus sandvicensis and other seabird species across north-western Europe. We present data on the characteristics of the spread of the virus between and within breeding colonies and the number of dead adult Sandwich Terns recorded at breeding sites throughout north-western Europe. Within two months of the first reported mortalities, 20,531 adult Sandwich Terns were found dead, which is >17% of the total north-western European breeding population. This is probably an under-representation of total mortality, as many carcasses are likely to have gone unnoticed and unreported. Within affected colonies, almost all chicks died. After the peak of the outbreak, in a colony established by late breeders, 25.7% of tested adults showed immunity to HPAI subtype H5. Removal of carcasses was associated with lower levels of mortality at affected colonies. More research on the sources and modes of transmission, incubation times, effective containment, and immunity is urgently needed to combat this major threat for colonial seabirds.
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| 24. |
- Lane, Anna-Lena
(författare)
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Building-related renewable electricity production with storage and energy-efficient buildings : Exploring barriers, drivers and quality assurance
- 2020
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a need to reduce unsustainable use of fossil fuels. Increased usage of renewable energy by combined use of photovoltaic solar panels (PV) with battery storage is one way. Another way is to increase awareness of energy usage and reduce the energy performance gap by building energy-efficient buildings. Buildings have a long lifetime and high energy usage will have an impact for a long time.Barriers, drivers and non-energy benefits (NEBs) for investments in battery storage in photovoltaic systems (PV) in the context of farmers in Sweden with PV systems was investigated by a questionnaire study. The questionnaire was sent to farmers in Sweden who already have photovoltaics installed and about 100 persons answered, a response rate of 59%.Among the drivers for investments in battery storage in PV systems in agriculture it was found that the highest-ranked driver, i.e., to use a larger part of the electricity produced oneself, turns out to be the highest priority for grid owners seeking to reduce the need for extensive investments in the grid. The primary NEBs found were the possibility to become more independent of grid electricity.A method for the building process, called ByggaE, which aims to reduce the energy performance gap, has been developed and described. The method is based on two main processes with activities. Documents that support the activities can be found and stored in the energy documentation, a digital map structure. The two main processes are:The client’s activity to formulate requirements and ways to verify these requirements.The main process for other actors is to identify, handle and follow up risks or critical parts.An overall relation between the energy efficiency gap and the energy performance gap has been identified. Realistic assumptions and follow-up related to the assumptions are found to be important to reduce both the energy efficiency gap and the energy performance gap.
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| 25. |
- Lidberg, Tina, 1982-
(författare)
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Influences from Building Energy Efficiency Refurbishment on a Regional District Heating System
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Improving energy performance of existing buildings is an important part in decreasing energy use and in turn reduce the greenhouse gas emissions caused by human activity and the primary energy use.To be able to evaluate how energy refurbishment influences the greenhouse gas emissions and the primary energy use a wider system perspective is needed that puts the building in its context. This thesis deals with energy refurbishment packages performed on multi-family buildings within district heated areas and how they influence greenhouse gas emissions and primary energy use when the district heating use is altered.A simulated building is used to evaluate several energy refurbishment packages. The results are used as input data for models of district heating systems to cost optimize the district heating production. The results from the cost optimization are used to evaluate the impact on greenhouse gas emissions and primary energy use.The results show a difference between measures that saves district heating without increasing the use of electricity and measures that increases the use of electricity while district heating is saved. For example, a building refurbishment package including only building envelope improvements saves the same amount of district heating as a package including only mechanical ventilation with heat recovery. Despite this, the emissions of greenhouse gases and the use of primary energy is to a greater extent reduced in the first package because the use of electricity remains unchanged.Comparing energy refurbishment packages performed on the same building, but within different district heating systems, show the importance of the design of the district heating system. Depending on the fuel types used and to which extent electricity is co-produced in the district heating system, the results of implementing the energy refurbishment packages vary. The largest reduction of greenhouse gases and primary energy use occurs when a refurbishment package is performed on a building in a district heating system with high share of biofuel and no electricity production.
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| 26. |
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| 27. |
- Liu, Bokai, et al.
(författare)
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Data-driven quantitative analysis of an integrated open digital ecosystems platform for user-centric energy retrofits : A case study in northern Sweden
- 2023
-
Ingår i: Technology in society. - : Elsevier. - 0160-791X .- 1879-3274. ; 75
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an open digital ecosystem based on a web-framework with a functional back-end server for user-centric energy retrofits. This data-driven web framework is proposed for building energy renovation benchmarking as part of an energy advisory service development for the Västerbotten region, Sweden. A 4-tier architecture is developed and programmed to achieve users’ interactive design and visualization via a web browser. Six data-driven methods are integrated into this framework as backend server functions. Based on these functions, users can be supported by this decision-making system when they want to know if a renovation is needed or not. Meanwhile, influential factors (input values) from the database that affect energy usage in buildings are to be analyzed via quantitative analysis, i.e., sensitivity analysis. The contributions to this open ecosystem platform in energy renovation are: 1) A systematic framework that can be applied to energy efficiency with data-driven approaches, 2) A user-friendly web-based platform that is easy and flexible to use, and 3) integrated quantitative analysis into the framework to obtain the importance among all the relevant factors. This computational framework is designed for stakeholders who would like to get preliminary information in energy advisory. The improved energy advisor service enabled by the developed platform can significantly reduce the cost of decision-making, enabling decision-makers to participate in such professional knowledge-required decisions in a deliberate and efficient manner. This work is funded by the AURORAL project, which integrates an open and interoperable digital platform, demonstrated through regional large-scale pilots in different countries of Europe by interdisciplinary applications.
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| 28. |
- Liu, Bokai, et al.
(författare)
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Multi-scale modeling in thermal conductivity of polyurethane incorporated with phase change materials using physics-informed neural networks
- 2023
-
Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 220
-
Tidskriftsartikel (refereegranskat)abstract
- Polyurethane (PU) possesses excellent thermal properties, making it an ideal material for thermal insulation. Incorporating Phase Change Materials (PCMs) capsules into Polyurethane has proven to be an effective strategy for enhancing building envelopes. This innovative design substantially enhances indoor thermal stability and minimizes fluctuations in indoor air temperature. To investigate the thermal conductivity of the Polyurethane-Phase Change Materials foam composite, we propose a hierarchical multi-scale model utilizing Physics-Informed Neural Networks (PINNs). This model allows accurate prediction and analysis of the material’s thermal conductivity at both the meso-scale and macro-scale. By leveraging the integration of physics-based knowledge and data-driven learning offered by Physics-Informed Neural Networks, we effectively tackle inverse problems and address complex multi-scale phenomena. Furthermore, the obtained thermal conductivity data facilitates the optimization of material design. To fully consider the occupants’ thermal comfort within a building envelope, we conduct a case study evaluating the performance of this optimized material in a detached house. Simultaneously, we predict the energy consumption associated with this scenario. All outcomes demonstrate the promising nature of this design, enabling passive building energy design and significantly improving occupants’ comfort. The successful development of this Physics-Informed Neural Networks-based multi-scale model holds immense potential for advancing our understanding of Polyurethane-Phase Change Material’s thermal properties. It can contribute to the design and optimization of materials for various practical applications, including thermal energy storage systems and insulation design in advanced building envelopes.
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| 29. |
- Liu, Bokai, et al.
(författare)
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Multiscale modeling of Heat transfer in Polyurethane - Phase Change Materials composites
- 2023
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Ingår i: Yound investigators symposium Umeå 2023. - Umeå : Umeå University. ; , s. 29-29
-
Konferensbidrag (refereegranskat)abstract
- Polyurethane (PU) exhibits exceptional thermal properties, making it an ideal material for thermal insulation. Incorporating Phase Change Materials (PCMs) capsules into Polyurethane (PU) has proven to be highly effective in enhancing building envelopes. This innovative design greatly enhances the stability of indoor thermal environments and reduces fluctuations in indoor air temperature. To investigate the thermal conductivity of this composite material, we have developed a comprehensive multiscale model of a PU-PCM foam composite. By obtaining thermal conductivity data, we can optimize the material's design for maximum effectiveness. To fully assess the thermal comfort of occupants within a building envelope, we have conducted a case study based on the performance of this optimized material. Specifically, we focused on a single room where PU-PCM composites were applied. Simultaneously, we predicted the energy consumption associated with this scenario. The results of our study clearly demonstrate the promising nature of this design, as it enables passive building energy design and significantly improves the comfort experienced by occupants.
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| 30. |
- Liu, Bokai, et al.
(författare)
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Multiscale modeling of thermal properties in Polyurethane incorporated with phase change materials composites : a case study
- 2023
-
Ingår i: Healthy buildings Europe 2023. - Red Hook, NY : Curran Associates, Inc.. - 9781713877158 ; , s. 923-929
-
Konferensbidrag (refereegranskat)abstract
- Polyurethane (PU) is an ideal thermal insulation material due to its excellent thermal properties. The incorporation of Phase Change Materials (PCMs) capsules into Polyurethane (PU) has been shown to be effective in building envelopes. This design can significantly increase the stability of the indoor thermal environment and reduce the fluctuation of indoor air temperature. We develop a multiscale model of a PU-PCM foam composite and study the thermal conductivity of this material. Later, the design of materials can be optimized by obtaining thermal conductivity. We conduct a case study based on the performance of this optimized material to fully consider the thermal comfort of the occupants of a building envelope with the application of PU-PCMs composites in a single room. At the same time, we also predict the energy consumption of this case. All the outcomes show that this design is promising, enabling the passive design of building energy and significantly improving occupants' comfort.
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| 31. |
- Liu, Bokai, et al.
(författare)
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Stochastic interpretable machine learning based multiscale modeling in thermal conductivity of Polymeric graphene-enhanced composites
- 2024
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Ingår i: Composite structures. - : Elsevier. - 0263-8223 .- 1879-1085. ; 327
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Tidskriftsartikel (refereegranskat)abstract
- We introduce an interpretable stochastic integrated machine learning based multiscale approach for the prediction of the macroscopic thermal conductivity in Polymeric graphene-enhanced composites (PGECs). This method encompasses the propagation of uncertain input parameters from the meso to macro scale, implemented through a foundational bottom-up multi-scale framework. In this context, Representative Volume Elements in Finite Element Modeling (RVE-FEM) are employed to derive the homogenized thermal conductivity. Besides, we employ two sets of techniques: Regression-tree-based methods (Random Forest and Gradient Boosting Machine) and Neural networks-based approaches (Artificial Neural Networks and Deep Neural Networks). To ascertain the relative influence of factors on output estimations, the SHapley Additive exPlanations (SHAP) algorithm is integrated. This interpretable machine learning methodology demonstrates strong alignment with published experimental data. It holds promise as an efficient and versatile tool for designing new composite materials tailored to applications involving thermal management.
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| 32. |
- Man, Qingpeng, et al.
(författare)
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Transfer of building retrofitting evaluations for data-scarce conditions : an empirical study for Sweden to China
- 2024
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 310
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Tidskriftsartikel (refereegranskat)abstract
- Evaluating and comparing the performances of different strategies is critical for energy-efficient building retrofitting. Data-driven modelling based on large building performance datasets is an effective method for such evaluations. However, it could be challenging to apply this approach to buildings from data-scarce areas where local building performance datasets have not been well-established, which means the data falls short of the high demand for building retrofitting on a global level. To address this, a transfer learning approach is proposed in this study that can evaluate the performance of buildings without local well-established building performance datasets. The proposed approach is applied in the Swedish-Chinese empirical study that relies on the Swedish dataset to transfer and predict the building performance in China without well-established datasets. It was achieved by applying fuzzy C-means clustering and a neural network (FCM-BRBNN) to pre-train the evaluation model based on the Swedish dataset. Then, the proposed approach collects a small sample of Chinese buildings in the data-scarce area and transfers the model to local building performance prediction. The results show that the transfer learning approach can reliably predict the performance of building retrofitting in data-scarce areas with only hundreds of local building samples. As such, this study provides a novel methodology that can support the evaluation and comparison of retrofitting strategies in data-scarce regions and countries with only limited local data. It could efficiently assist designers in optimizing energy-efficient designs in the pre-retrofit stage. Crucially, the methodology enables the transfer of knowledge regarding building performance across different countries and regions, being pivotal for the international collaboration required to stimulate the global energy-efficiency transformation.
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| 33. |
- Olofsson, Gunnar, professor, 1942-, et al.
(författare)
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Gavra : I istoria enos ellinikou choriou kai ton katikon tou
- 2020. - 1
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This is a Greek translation of the following work:Gunnar Olofsson och Thomas Thomnell: "Gavra - historien om en grekisk by och dess invånare" published by Arkiv förlag 2012Se dokumentation i DIVA avseende den svenska utgåvan. Det forskningsprojekt som boken summerar är FAS 2003-0556 (Vägen från Gavra)
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| 34. |
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| 35. |
- Penaka, Santhan Reddy, et al.
(författare)
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A data-driven framework for building energy benchmarking and renovation decision-making support in Sweden
- 2023
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Ingår i: SBE23-Thessaloniki. - : Institute of Physics (IOP).
-
Konferensbidrag (refereegranskat)abstract
- In Europe, the buildings sector is responsible for 40% of energy use and more than 30% of buildings are older than 50 years. Due to ageing, a large number of houses require energy-efficient renovation to meet building energy performance standards and the national energy efficiency target. Although Swedish house owners are willing to improve energy efficiency, there is a need for a dedicated platform providing decision-making knowledge for house owners to benchmark their buildings. This paper proposes a data-driven framework for building energy renovation benchmarking as part of an energy advisory service development for the Vasterbotten region, Sweden. This benchmark model facilitates regional homeowners to benchmark their building energy performance relative to the national target and similar neighbourhood buildings. Specifically, based on user input data such as energy use, location, construction year, floor area, etc., this model benchmarks the user's building performance using two benchmark references i.e., 1) Sweden's target to reduce buildings by 50% energy use intensity (EUI) by 50% by 2050 compared to the average EUI in 1995, 2) comparing user building with the most relevant peer group of buildings, using energy performance certificates (EPC) big data. Several building groups will be classified based on influential factors that affect building energy use. Hence, this benchmark provides decision-making supportive knowledge to homeowners e.g., whether they need to perform an energy-efficient renovation. In the future, this methodology will be extended and implemented in the digital platform to provide helpful insights to decide on suitable EEMs. This work is an integral part of project AURORAL aims to deliver an interoperable, open, and integrated digital platform, demonstrated by cross-domain applications through large-scale pilots in 8 regions in Europe, including Vasterbotten.
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| 36. |
- Penaka, Santhan Reddy, et al.
(författare)
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Improved energy retrofit decision making through enhanced bottom-up building stock modelling
- 2024
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 318
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Tidskriftsartikel (refereegranskat)abstract
- Modelling the performance of building stocks is crucial in facilitating the renovation at the building stock level. Bottom-up building stock modelling begins by detailing individual buildings and then aggregates them into stock level. Its primary advantage lies in capturing the inherent heterogeneity among distinct buildings, which enables tailored retrofitting. Naturally, this approach requires a comprehensive dataset with detailed building information such as geometry and envelope thermal properties. However, a common challenge is the incompleteness of available data in individual datasets. To address this, previous bottom-up studies have filled the missing data with representative or statistical data. Such practice could lead to homogeneous modelling of distinct buildings within the same statistical group. This limits the utilization of key ability of bottom-up building stock modelling in capturing heterogeneity, such as tailored retrofitting to explore potential retrofitting areas and strategies. To address this challenge of homogeneous modelling, we utilize data fusion framework for bottom-up building stock modelling, employing probabilistic record linkage and inverse modelling techniques to integrate multiple incomplete building performance datasets. This framework fills the missing data in one dataset with information from another, thus capturing inherent heterogeneity in the building stock. An empirical study was conducted in Umeå, Sweden, to investigate the framework's effectiveness by modelling building stock with various retrofitting strategies. This study contribution lies in enhancing bottom-up building stock modelling by capturing inherent heterogeneity, to provide tailored retrofitting solutions.
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| 37. |
- Puttige, Anjan Rao, 1990-, et al.
(författare)
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Are radiators ready for the challenges of the future : a review of advancements in radiators
- 2022
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Ingår i: E3S Web of Conferences. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- Radiators play an important role in providing a comfortable and safe indoor environment while maintaining high-energy efficiency. In the perspective of future climate change with expected larger temperature fluctuations and the rapidly changing heat supply and demand, it is required that the current radiator technology is adaptable. The heat supply is changing towards a lower supply temperature to enable an increase in energy efficiency and an increase in the share of renewable energy. Simultaneously, both the heat supply and demand are expected to have more variations in the future. An additional concern that has come into more focus after the experience with the COVID 19 pandemic is the prevention of the spread of infection in indoor environments. Researchers have extensively studied several innovations in radiator technologies and their deployment that addresses these challenges. Some of the solutions available in the literature include floor heating, ceiling heating, ventilation radiator, stratum ventilation. Researchers have used advanced modeling and experimental techniques to understand how to deploy different types of radiator technologies. This review summarizes solutions in the literature that address these challenges and identifies knowledge gaps that need to be addressed. In particular, this study explores the gaps in knowledge of practical issues, such as the position of furniture and the position of people, which have received less attention in the literature. Research that addresses the effect of radiators on ventilation and a healthy indoor environment is also of particular interest in this review.
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| 38. |
- Puttige, Anjan Rao, 1990-
(författare)
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Utilization of a GSHP System in a DHC Network : modeling and optimization
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ground source heat pumps (GSHPs) of customers connected to the district heating and cooling (DHC) network can benefit both the customer and the energy company. However, operating the GSHP to minimize the cost of providing heating and cooling to the customer while ensuring the long-term stability of the ground temperature is a challenge. This thesis addresses the challenge by developing accurate models of GSHP and optimizing the operation of the GSHP system using these models.The models presented in this thesis use field measurements to develop accurate models with low computational time. The main components of a GSHP system are the heat pump and the borehole heat exchanger (BHE). This thesis presents two approaches to use measured data to improve the accuracy of analytical models for BHE. The first approach is the calibration of the model parameters using this measured data. The second approach combines the analytical model with an artificial neural network model resulting in a hybrid model. The calibration approach reduced the relative RMSE of the analytical model from 21.9% to 13.9% in the testing period. The relative RMSE of the hybrid model for the testing period was 6.3%.We compared different data-driven models for heat pumps and determined that artificial neural network models have an advantage over traditional regression models when field measurements are available. The artificial neural network model was refined to better utilize the measured data. The refined models of heat pumps had a relative RMSE of less than 5%.The hybrid BHE model and an artificial neural network model for the heat pumps were used to model the GSHP system. The model was validated using four years of field measurements. The relative MAE for the compressor power and BHE power were 7.3% and 19.1% respectively.The validated model was used to optimize the operation of the GSHP system. In optimal operation, the cost of providing heating and cooling to the area was minimized from the perspective of the energy company while maintaining a stable temperature in the ground. In optimal operation, the annual cost of operation was shown to reduce by 64 t€ and the annual CO2 emission was shown to reduce by 92 tons.
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| 39. |
- Risberg, Daniel
(författare)
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CFD simulation of indoor climate in low energy buildings
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis computational fluid dynamics (CFD) was used for simulation of the indoor climate of low-energy buildings in cold climate. The heat consumption in newly built houses was reduced drastically. Along with the different classification systems for low-energy buildings the demand for the indoor climate has increased, which causes a need to investigate buildings even before they are built. Than CFD is of importance in studies of different heating systems and how new construction solutions can affect the indoor environment. The work focus was on investigating the computational setup, such as grid size and boundary conditions in order to solve the indoor climate problems in an accurate way and compare different heating systems. A limited number of grid elements and knowledge of boundary settings is therefore essential in order to obtain reasonable calculation time.The models show that radiation between building surfaces has a large impact on the temperature field inside the building, with the largest differences at the floor level. An accurate grid edge size of around 0.1 m was enough to predict the climate. Different turbulence models were compared with only small differences in the indoor air velocities and temperatures. To explore the viability of this approach, the indoor climate in a building was studied considering three different heating systems: an underfloor heating system, air heating through the ventilation system and an air heat pump installation. The underfloor heating system provided the most uniform operative temperature distribution and was the only heating system that fully satisfies the recommendations to achieve tolerable indoor climate set by the Swedish authorities. On the contrary, air heating and the air heat pump created a relatively uneven distribution of air velocities and temperatures, and none of them fulfils the specified recommendations. From an economic point of view, the air heat pump system is cheaper to be installed but produces a less pleasant indoor environment then distributed heating systems. The most widely used turbulence model for indoor CFD simulations, the k-ε model, has exhibited problems with treating natural convective heat transfer, while other turbulence models have shown to be too computationally demanding. One paper therefore studies how to deal with natural convective heat transfer for a radiator in order to simplify the simulations, reduce the numbers of cells and the simulation time. By adding user-defined wall functions, to the k-ε model the number of cells can be reduced considerably compared with the k-ω SST turbulence model. The user-defined wall function proposed can also be used with a correction factor for different radiator types without the need to resolve the radiator surface in detail. Compared to manufacturer data the error was less than 0.2% for the investigated radiator height and temperature.
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| 40. |
- Saini, Puneet Kumar
(författare)
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Solar integrated heating systems: Applications in buildings and industries
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- “Heat is half” of the global final energy consumption, and the decarbonization of the heating sector is critical to achieving climate goals. This thesis employs a system modelling approach to evaluate renewable heating systems. The overarching goal is to reduce fossil fuel reliance by integrating renewable energy technologies, such as solar thermal, photovoltaics, photovoltaic thermal, heat pump, and thermal energy storage in different system concepts. Two primary sectors are addressed: buildings, with a focus on utilizing solar collectors and heat pumps for heating systems in multifamily houses by recovery of waste heat; and industries, utilizing solar collectors for steam generation below 200 °C. The work is centred around five primary research questions, addressing the technical and economic feasibility of the mentioned technologies and their roles in decarbonization.Two system arrangements were simulated to address the heating demands of buildings: a) Centralized heat pump that utilizes ventilation air as a heat source, serving three multifamily buildings, and b) A fifth generation district heating system that utilizes industrial waste heat as its source. The techno-economic performance of these systems was evaluated. The results suggest that the economic viability of such arrangements largely depends on critical factors that include the costs of heat pump sub-stations, prevailing electricity prices, and the cost of waste heat. Incorporating solar air heating collectors and optimizing flow controls enhance both component and system energy efficiency. Moreover, integrating photovoltaic systems, up to a specific capacity, is advantageous as it offers reductions in heating costs.For industrial steam generation, the importance of the solar fraction in technological comparisons is highlighted. Parabolic trough collector and heat pump for steam generation are compared for 34 locations in the European Union, using solar fraction as an indicator. The results highlight the economic competitiveness of both technologies for a wide range of boundary conditions. However, heating costs from solar thermal collectors increase at higher solar fractions, primarily due to the storage costs. This trend sets an economic limit on the maximum feasible solar fraction. As a result, hybrid systems combining solar thermal collectors with steam heat pumps offer a promising combination to achieve a high renewable fraction for industrial applications.Concerns about CO2 emissions from the electricity grid, and its reliability in many countries, necessitate the exploration of alternative system concepts to meet a higher fraction of heating demand. One such novel energy system combines a parabolic trough collector, photovoltaic, and thermal energy storage (using water and sand as storage media) to reach a combined solar fraction of 90 %, while remaining cost-competitive with fossil fuels. The techno-economic performance of solar thermal collectors is system dependent, largely influenced by their integration within industrial systems. Two novel indicators are introduced to quantify the integration incompatibilities, offering insights into the dynamics for specific integration point. Using this method for a case study resulted in an optimized configuration, improving the overall system performance.Collectively, the results are expected to be leveraged by relevant stakeholders to advance the cause of heating decarbonization in buildings and industries.
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| 41. |
- Shadram, Farshid, 1987-
(författare)
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Assessment and optimization of life cycle enrgy use in buildings
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Buildings account for 40% of all energy use in European countries. The European Union (EU) therefore encourages member states to adopt Energy Efficiency Measures (EEMs) and implement energy-efficient practices during building design to minimize the energy use of buildings. However, recent studies have shown that energy-efficient buildings may not always outperform conventional buildings in terms of Life Cycle Energy (LCE) use. This is mainly due to the trade-off between embodied and operational energy, and a reliance on EEMs that reduce operational energy while sometimes increasing embodied energy and LCE use. To improve buildings’ environmental performance, the impact of different EEMs on buildings’ energy use needs to be assessed from a lifecycle perspective, and methods for identifying optimal combinations of EEMs that minimize LCE use should be developed. Ideally, these methods should be integrated with building information modelling (BIM) to enable seamless data exchange and to help Architecture, Engineering and Construction (AEC) practitioners make optimal design decisions relating to EEMs. The work presented in this thesis had two overall objectives: (1) to explore the scope for developing BIM-supported method(s) for assessing and optimizing the impact of EEMs on buildings’ LCE use during the design process, and (2) use the BIM-supported method(s) for exploring the impact of various EEMs that are implemented and modified during the building design process on the buildings’ LCE use.The work presented in this thesis is based on an exploratory research design involving iterative cycles of (1) problem identification, (2) method development, (3) method examination, and (4) theory suggestion. In step 1, problems were identified by conducting literature studies and workshops with AEC practitioners, and analyzing archival data. In step 2, prototyping was used to develop methods to overcome the identified problems. In step 3, the applicability of these methods (or prototypes) was tested in case studies on actual and hypothetical building projects. Three case studies were conducted – one dealing with a low energy dwelling located in Kiruna, Sweden; another dealing with a multifamily residential building in Uppsala, Sweden; and a third dealing with a hypothetical multifamily residential building in Stockholm, Sweden. In step 4, the results were compared to existing theories to strengthen existing knowledge and identify previously unrecognized findings.In relation to the first objective, the results obtained show that the factors and activities required to develop BIM-supported method(s) for assessing and optimizing the impact of EEMs on a building’s LCE use during the design phase are:• A database that stores external and building project data (e.g. BIM data) and links it to be used for assessment and optimization, providing access to the data whenever needed.• The development of interfaces using middleware applications to ensure interoperability and seamless automated exchange of information between BIM and other systems.• Predefined objects (i.e. building part and component recipes) that are stored in a database and linked to inventories and Environmental Product Declarations (EPDs) for the relevant materials, enabling assessment of the buildings’ embodied energy and LCE use.• The application of multi-objective optimization techniques (e.g. Pareto-based genetic algorithms) to identify optimal solution(s) for EEMs that minimize (optimize) the building’s LCE use.In relation to the second objective of the thesis, the results obtained indicate that:• EEMs that are implemented and modified during the detailed design phase have much less influence on the building’s LCE use than those implemented in the early design phase. Highly influential EEMs related to the early design phase which were tested herein were the building’s shape, orientation, Window to Wall Ratio (WWR), and the selection of materials used in the building envelope.• Generally, thickening roof insulation has a strong beneficial effect on LCE use for buildings in Sweden.• For buildings using energy sources with high primary energy factors, the most effective way to reduce LCE use may be to implement many EEMs that reduce operational energy use. However, this approach may be less helpful for buildings using greener energy sources because in such cases the embodied energy may have a greater effect on the final LCE use.• The embodied energies of materials in the same class can vary significantly between suppliers. Such differences in embodied energy can be identified by considering the suppliers’ EPDs, the energetic contributions due to their mode of transportation from the site of production, and the distance between the site of production and the construction site.• If the developed optimization approach is used to identify optimal combinations of EEMs in the early design phase, designers can freely choose from a wide range of building shapes without greatly affecting LCE use. However, without early phase optimization, designs that use different building shapes may exhibit significantly different LCE use values.The results provide both theoretical and practical contributions that may be useful to researchers and AEC practitioners seeking to develop BIM-supported design processes and to reduce buildings’ LCE use by adopting appropriate EEMs. The results also show that embodied energy can be a major component of a building’s LCE use if the building’s design relies heavily on EEMs designed solely to reduce operational energy use. Policy makers and governmental bodies are thus advised to update regulations and building codes to reflect the importance of embodied energy so as to minimize the LCE use of new and retrofitting building projects.
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| 42. |
- Thomell, Thomas, 1939-
(författare)
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Från tobaksfältet till pappersbruket : grekiska arbetare i Lessebo 1970
- 2002
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Ingår i: Arkiv för studier i arbetarrörelsens historia. - Lund : Arkiv förlag & tidskrift. - 0345-0333. ; :85, s. 1-55
-
Tidskriftsartikel (refereegranskat)abstract
- Detta är en redigerad version av Thomas Thomells uppsats från 1972. Två tidskriftsartiklar byggde på detta arbete.Thomell, Thomas. 1972a. ”Grekiska arbetare i Lessebo.” Zenit, vol. 29, nr. 3, s. 7–22.Thomell, Thomas. 1972b. ”Grekiska arbetare. Två perspektiv på grekisk utvandring.” Sociologisk forskning, vol. 9, nr. 3, s. 170–184
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| 43. |
- Vesterberg, Jimmy, 1976-
(författare)
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A regression approach for assessment of building energy performance
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reliable evaluation methods is needed to ensure that investments in energy conservation measures (ECMs) and the construction of new energy efficient buildings lives up to the promised and expected performance.This thesis presents and evaluates a regression method for estimation of influential building parameters: transmission losses above ground (including air leakage), ground heat loss, and overall heat loss coefficient.The analysis is conducted with separately metered electricity, heating and weather data using linear regression models based on the simplified steady-state power balance for a whole building.The evaluation consists of analyzing the robustness of the extracted parameters, their suitability to be used as input values to building energy simulations (BES) tools. In addition, differences between uncalibrated and calibrated BES models are analyzed when they are used to calculate energy savings. Finally the suitability of using a buildings overall heat loss coefficient as a performance verification tool is studied.The presented regression method exhibits high robustness and good agreement with theory. Knowledge of these parameters also proved beneficial in BES calibration procedures as well as in performance verifications. Thus, the presented method shows promising features for reliable energy performance assessments of buildings.
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| 44. |
- Yu, Haitao, et al.
(författare)
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Data-driven modelling of building retrofitting with incomplete physics : a generative design and machine learning approach
- 2023
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 2654
-
Tidskriftsartikel (refereegranskat)abstract
- Building performance simulation (BPS) based on physical models is a popular method for estimating the expected energy savings from energy-efficient building retrofitting. However, for many buildings, especially older buildings, built several decades ago, an operator do not have full access to the complete information for the BPS method. Incomplete information comes from the lack of detailed building physics, such as the thermal transmittance of some building components due to the deterioration of components over time. To address this challenge, this paper proposed a data-driven approach to support the decision-making of building retrofitting selections under incomplete information conditions. The data-driven approach integrates the backpropagation neural networks (BRBNN), fuzzy C-means clustering (FCM), and generative design (GD). It generates the required big database of building performance through generative design, which can overcome the problem of incomplete information during building performance simulation and energy-efficient retrofitting. The case study is based on old residential buildings in severe cold regions of China, using the proposed approach to predict energy-efficient retrofitting performance. The results indicated that the proposed approach can model the performance of residential buildings with more than 90% confidence, and show the variation of results. The core contribution of the proposed approach is to provide a way of performance prediction of individual buildings resulting from different retrofitting measures under the incomplete physics condition.
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