| 1. |
- Birmpilis, Georgios, 1988, et al.
(author)
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Towards a methodology for the characterisation of the fabric of wet clays using x-ray scattering
- 2019
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 92
-
Conference paper (peer-reviewed)abstract
- X-ray scattering is a promising non-invasive technique to study evolving nano- and micro-mechanics in clays. This study discusses the experimental considerations and a successful method to enable X-ray scattering to study clay samples at two extreme stages of consolidation. It is shown that the proposed sample environment comprising flat capillaries with a hydrophobic coating can be used for a wide range of voids ratios ranging from a clay suspension to consolidated clay samples, that are cut from larger specimens of reconstituted or natural clay. The initial X-ray scattering results using a laboratory instrument indicate that valuable information on, in principal evolving, clay fabric can be measured. Features such as characteristic distance between structural units and particle orientations are obtained for a slurry and a consolidated sample of kaolinite. Combined with other promising measurement techniques from Materials Science the proposed method will help advance the contemporary understanding on the behaviour of dense colloidal systems of clay, as it does not require detrimental sample preparation.
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| 2. |
- Abadi, Imam, et al.
(author)
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Design of Adaptive Neuro-Fuzzy Inference Control Based One-Axis Solar Tracker on Battery Charging System
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; , s. 1-15
-
Conference paper (peer-reviewed)abstract
- The photovoltaic (PV) panel can produce electrical energy that is very environmentally friendly and easy to use. The use of PV panels is suitable for supplying peak loads or at night using batteries as energy storage. However, the battery needs to manage for control, and the battery can last long. The solution to battery management problems is through research about the battery charging system. The DC-DC converter used is the Single Ended Primary Inductance Converter (SEPIC) type. Voltage Control of the battery charging using Adaptive Neuro-Fuzzy Inference System (ANFIS). In the simulation of bright conditions, ANFIS controls can track the charging point set point and obtain a voltage response with a rise time of 0.0028 s, a maximum overshoot of 0.027 %, a peak time of 0.008 s, and a settling time of 0.0193 s. When charging a solar tracker, PV battery gets a 0.25 % increase compared to a fixed PV panel. PV solar tracker can follow the direction of the sun's position. The irradiation value and maximum temperature affect the input voltage and input current that enters the converter.
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| 3. |
- Abadi, Imam, et al.
(author)
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Performance Study of Maximum Power Point Tracking (MPPT) Based on Type-2 Fuzzy Logic Controller on Active Dual Axis Solar Tracker
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; , s. 1-16
-
Conference paper (peer-reviewed)abstract
- World energy consumption increases with time, so that occur an energy imbalance. Many breakthroughs have developed to utilize renewable energy. The photovoltaic system is one of the easy-to-use renewable energies. The power conversion from PV fixed is still low, so the PV system is designed using the active dual-axis solar tracker. The PV tracker position can be adjusted to change the sun position to get maximum efficiency. The active dual-axis solar tracker system is integrated with the maximum power point tracking (MPPT) algorithm to keep PV operating at a maximum power point even though input variations change. The active dual-axis solar tracker system integrated with the maximum power point tracking (MPPT) algorithm to keep PV operating at a maximum power point even though input variations change. Tracking test simulation had done by comparing the output power of a fixed PV system with the active dual-axis solar tracker. Type-2 fuzzy logic based MPPT successfully increased the average output power by 10.48 % with the highest increase of 17.48 % obtained at 15:00 West Indonesia Time (GMT+7). The difference in power from a fixed PV system with the active dual-axis solar tracker of 36.08 W is from the output power worth 206.3 to 242.4 W.
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| 4. |
- Abdul Hamid, Akram, et al.
(author)
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Impact of high residential density on the building technology, HVAC systems, and indoor environment in Swedish apartments
- 2020
-
In: E3S Web of Conferences. Volyme 172, 2020.. - : EDP Sciences. ; 172
-
Conference paper (peer-reviewed)abstract
- During the last few years, there has been an increased number of overcrowded apartments, due to increased migration but also housing shortage in general, particularly in the suburbs to major cities. The question is how the indoor environment in these apartments is affected by the high number of persons and how the problems related to high residential density can be overcome. This paper aims to specify the problem by investigating and analysing the technical parameters influenced by residential density in Swedish apartments built between 1965-1974. To map the situation, 11 interviews with employees at housing companies were conducted. Based on extreme conditions described in the interviews, simulations of the indoor climate and moisture risks at some vulnerable parts of constructions were made. Simulations were focused on moisture loads and CO2 concentrations as functions of residential density and ventilation rate. Finally, measures to combat problems associated to overcrowding are suggested. The aim is that the results should be used by authorities to formulate incentives and/or recommendations for housing companies to take actions to ensure a good indoor environment for all, irrespective of residential density conditions. © The Authors.
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| 5. |
- Abed, Salwan Ali, et al.
(author)
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Bioaccumulation and health risk assessment of severe metal pollution of street dust from various urban regions in Baghdad, Iraq
- 2020
-
In: E3S Web of Conferences. - France : EDP Sciences. - 2267-1242. ; 158:1, s. 1-6
-
Journal article (peer-reviewed)abstract
- This study sought to define the metals bioaccumulation from street dust in Baghdad, Iraq for the first time. The samples were collected that research the levels, sources, and health hazard model Cd, Cr, Zn and Cu. The geo accumulation Index (Igeo) found that the contamination level for Cd was moderately to strongly polluted in Karada, Jihad and Kinidi streets. Hence, it is important to measure the level of cadmium in the local environment. The relative bioaccumulation of chromium was high in Jadriyah Street (87.2%). The PCA showed two major sources of these minerals in Baghdad road dust that Cd, Zn are likely to originate from tire wear, brake wear and vehicular emissions as well as the fact that Cr and Cu originate from metal-processing industries. Assessing hazard to human health utilized measure population show suggested both non-carcinogenic and carcinogenic hazards minerals Baghdad road dust harmless to human environment.
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| 6. |
- Abugabbara, Marwan, et al.
(author)
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A Novel Method for Designing Fifth-Generation District Heating and Cooling Systems
- 2021
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In: The 10th Cold Climate HVAC & Energy Conference 2021. - : EDP Sciences. - 2555-0403. ; 246
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Conference paper (peer-reviewed)abstract
- District heating and cooling systems have been undergoing continuous development and have now reached the fifth-generation. In this innovative technology, connected buildings share local excess energy that otherwise would be wasted, which consequently reduces primary energy demands and carbon emissions. To date, the issue of implementing fifth-generation district systems on existing buildings has received scant attention, and our research addresses this challenging gap by proposing a novel method for designing these systems. We first explain the possible thermal interactions between connected buildings, and then present an analytical solution for the network energy balance, pipe design, and the prediction of fluid temperature under a fixed temperature difference control strategy. The analytical solution was validated against numerical simulations performed on 11 existing buildings located in Lund, Sweden using Modelica models. A diversity index metric between heating and cooling demands was also included in these models to assess the efficiency of the district system in the building cluster. The results from the analytical and numerical solutions were in complete agreement since Modelica is an equation-based modelling language. The developed models pave the way towards future investigations of different temperature control strategies and new business models that arise from the shift to the fifth-generation.
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| 7. |
- Airaksinen, Miimu, et al.
(author)
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Highly insulated crawl spaces with controlled minimal ventilation - Proof of concept by field measurements
- 2020
-
In: E3S Web of Conferences. Volyme 172, 2020.. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- In current practices crawl spaces are typically ventilated with outdoor air. This leads very often to high relative humidity especially in the beginning of the summer, which can be problematic if the excess humidity cannot be ventilated efficiently enough. This paper introduces a crawl space concept where the crawl space is highly insulated and traditional ventilation openings are replaced by minimal mechanical exhaust ventilation set by pressure difference with the aim to prevent potential pollutants to penetrate indoors through the base floor. The concept that has been developed based on the simulation study is tested in this study with field measurements in four single family houses. Continuous measurements of relative humidity and temperature in crawl spaces and outdoor air were running more than one year in each building. The results revealed that all the crawl spaces had very low relative humidity, mostly below 75% and for very short periods close to 80% even though some of the buildings were new and construction phase moisture was drying out. The results revealed that the crawl space concept studied provided an ultimate moisture safety and can be recommended for all buildings with wooden floor. © The Authors
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| 8. |
- Al Sam, Ali, et al.
(author)
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Evaluation of sub grid scale and local wall models in Large-eddy simulations of separated flow
- 2015
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In: 2nd Symposium on OpenFOAM® in Wind Energy. - : EDP Sciences. ; 5
-
Conference paper (peer-reviewed)abstract
- The performance of the Sub Grid Scale models is studied by simulating a separated flow over a wavy channel. The first and second order statistical moments of the resolved velocities obtained by using Large-Eddy simulations at different mesh resolutions are compared with Direct Numerical Simulations data. The effectiveness of modeling the wall stresses by using local log-law is then tested on a relatively coarse grid. The results exhibit a good agreement between highly-resolved Large Eddy Simulations and Direct Numerical Simulations data regardless the Sub Grid Scale models. However, the agreement is less satisfactory with relatively coarse grid without using any wall models and the differences between Sub Grid Scale models are distinguishable. Using local wall model returned the basic flow topology and reduced significantly the differences between the coarse meshed Large-Eddy Simulations and Direct Numerical Simulations data. The results show that the ability of local wall model to predict the separation zone depends strongly on its implementation way.
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| 9. |
- Arghand, Taha, 1982, et al.
(author)
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Some aspects of controlling radiant and convective cooling systems
- 2019
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 111
-
Conference paper (peer-reviewed)abstract
- This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 Designing appropriate control systems for radiant heating and cooling terminals entails an understanding of their dynamic behaviour. This study experimentally investigates the dynamic response of a room with convective and radiant cooling systems. The experiments were performed in a 12.6 m2 large test room outfitted as a single-office room. The main cooling system was radiant ceiling panels which covered 70% of the ceiling area. The thermal performance of the radiant system was compared to that of a fan-coil unit (FCU). The results from the step response test showed that the time constant of the room for the radiant system was shorter than for the convective one, indicating faster changes in room temperature by the radiant system. Furthermore, controlling the FCU with similar control system tuned for ceiling panels increased the hysteresis gap in the room air temperature from 0.4 K to 0.8 K. This indicates that control systems for low-mass radiant systems and convective systems might be applied to each other, but on-site tuning is required to omit the offset (persistent error). In this study, controlling room temperature with ceiling panels did not benefit from using an operative temperature sensor to provide feedback signal to the control system. However, the pump energy use was moderately decreased by 14%.
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| 10. |
- Azizi, Shoaib, et al.
(author)
-
Application of occupancy and booking information to optimize space and energy use in higher education institutions
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; 172
-
Journal article (peer-reviewed)abstract
- Building in higher education institutions (HEIs) are characterized as energy intensive Experience from practice showing large discrepancies between predicted and actual energy performance. The deviation can sometimes reach 100%. Explanations often originate from occupant’s behaviour along with building operation. IoT-based smart tools can provide extensive information about building usage to improve the building management, often associates with opportunities, for significant energy saving. The analysis in this study investigate space use based on occupancy and booking information in eight different lecture rooms at Umeå University. The results suggest interventions for significant saving potentials, such as modification of access permission and closing down redundant lecture rooms.
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| 11. |
- Baumann, Henrikke, 1964, et al.
(author)
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Switching the focus from product function to business profit: Introducing Business Model LCA (BM-LCA)
- 2022
-
In: Proceedings of LCM 2021. - : EDP Sciences. ; 349
-
Conference paper (peer-reviewed)abstract
- Recent years have seen much interest in business models as vehicles towards sustainability, cf. [1]. Conventional LCA, however, fails to properly capture the environmental impacts of a business model. Here, we introduce the background and the principles of Business Model LCA, a new LCA methodology for the assessment of environmental performance of business models. Methodological innovations are based on an understanding of the difference and relatedness between product and business. The key innovation is that BM-LCA centres its analysis on the ’business model’ instead of the ’product function’ as in conventional LCA. This requires the functional unit to represent the business (e.g., as ‘profit per time unit’) and the need to couple the monetary flows of the business to the material and energy flows of the product system via a set of ’coupling’ equations. BM-LCA contributes to environmental business analysis and could open up a new avenue of research where LCA and business analysts collaborate on business model innovation for sustainability.
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| 12. |
- Beltran, Francisco, et al.
(author)
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Solar Heat Pumps and Self-Consumption Can (and should) electricity suppliers encourage thermal storage?
- 2022
-
In: 2022 BuildSim Nordic, BSN 2022. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Heat pumps and water tanks can be used to increase PV self-consumption in buildings without any additional equipment, but there is sometimes a lack of economic incentives to maximize it that limits economic gains. Therefore, pricing conditions need to change in order to make self-consumption strategies more interesting for prosumers. This study aims at determining what, if any, unsubsidized market conditions could lead to economically motivated self-consumption control strategies with solar heat pumps. A sensitivity analysis is used on multiple pricing models based on current market conditions for a solar PV and ground source heat pump system for a single-family house in Norrköping, Sweden. The results show that control strategies aimed at maximizing self-consumption have very little impact on net costs, regardless of pricing model or variation in price. Feed-in-bonus is the most important aspect when comparing different pricing schemes, and no other sensitivity comes close.
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| 13. |
- Björk, Folke, et al.
(author)
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Electroosmosis - A method applied for handling of moisture in foundations
- 2020
-
In: E3S Web of Conferences. Volyme 172, 2020. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Electroosmosis is an electrokinetic phenomena which is applied in some technical fields. It is also applied large scale for transport of moisture out of basements. We see the method of electroosmosis as an opportunity for solving moisture problems in basements. However, there is a need to develop both the technology for the method and the understanding about what to expect out of it. Better methods are needed to predict whether the method will work in a particular case. © The Authors.
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| 14. |
- Bok, Gunilla, et al.
(author)
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Microbial growth behind tiles in bathrooms
- 2020
-
In: E3S Web of Conferences. Vollyme 172, 2020.. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Studies investigating microbial diversity in buildings have been performed mainly through the study of dust collected from e. g. floors and door frames and on moisture damaged building materials. A great diversity of mould fungi has been found and the fungus flora is dominated by the genera Aspergillus and Penicillium. The building materials targeted in this specific study were sampled on the back of ceramic tiles from bathroom walls and floors. Furthermore, two different analyses were used to investigate to which degree this specific environment was supportive of microbial growth. Microbial findings were detected in 48 % of the specimens from the spots exposed to liquid water in the bathrooms. To our knowledge, the microbial occurrence in this type of environment has not previously been investigated.. © The Authors.
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| 15. |
- Bose, A., et al.
(author)
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Hybrid renewable power systems for generation of own power by small and medium-scale enterprises
- 2018
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242.
-
Conference paper (peer-reviewed)abstract
- Decentralized power generation, from renewables, is an attractive option for the future energy transition. Through a case study, the techno-economic feasibility to produce own power from distributed renewable to de-carbonize the operations of the Small and Medium Scale Enterprises (SMEs) was critically analysed. The case study was performed on one of the leading printing outfits of Sri Lanka. Solar photovoltaic (PV) and biomass gasification systems are the most cost-efficient and easy to operate technologies for grid-connected, small-scale power generation, at present, for the context. Grid integration has been found as a major challenge, in both technical and economic parameters of the project. The low capacity factor of solar PV and complexity of the supply chain for biomass power systems are critical to the respective technologies. A hybrid Solar PV-Biomass gasification power plant would have superior techno-economic performances with lower environmental impact than stand-alone systems. An equal share of the net power capacity between the technologies was obtained as the most suitable combination for the proposed hybrid power plant. A net carbon dioxide reduction of more than eighty percent of the operations of the SMEs is feasible. Socio-political factors also have a high impact on overall viability of such small-scale systems.
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| 16. |
- Brunklaus, Birgit, 1970-, et al.
(author)
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Green and circular procurement in public organizations – from single use to reuse and prolonged lifetime in the City of Malmö
- 2022
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; 349
-
Journal article (peer-reviewed)abstract
- The procurement in public organisations has traditionally been performed in a linear way. Using circular solutions could help public organisations to save resources and tackle climate change. The Swedish City of Malmö strives to include circular solutions and become a circular municipality. The goal of the study was to explore activities for increased reuse and visualise how circular material flows can reduce environmental impacts. The goal was also to develop a method for mapping material flows that can be used in the City of Malmö and other public organisations. The studied activities included in this study are the reuse of furniture and replacement of single use plastic with reuse alternatives, as well as prolonged lifetime of IT products and textiles. Life cycle analysis (LCA) based methods were used to estimate the reduction in environmental impact from the studied activities. The perception of circular activities within the City of Malmö was analysed with a survey. The results showed that the purchasing agreements with increased lifetime for clothing and IT products, lead to reduced environmental impacts. The results also showed that most employees are interested in using a digital sharing platform. Additionally, the results pointed out the need for a circular manager.
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| 17. |
- Brunklaus, Birgit, 1970-, et al.
(author)
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The connected, sustainable and inclusive society : IoT implementation in a Swedish municipality
- 2022
-
In: E3S Web of Conferences. - : EDP Sciences. ; 349
-
Conference paper (peer-reviewed)abstract
- The Internet of Things (IoT) is expected to transform the way we live, work, and learn. Using IoT could thus be a game-changer for municipalities towards sustainability. The Swedish municipality of Södertälje strives to develop IoT concepts and use open data for a sustainable and inclusive society. The goal of this study was to explore how IoT can enable route optimization and placement planning for increased operational efficiency. The goal was also to enhance the knowledge of the environmental and social benefits of IoT systems in the waste collection system in Södertälje. The analysis is based on Life Cycle Assessment (LCA) and interviews. The results show a minor climate change impact for the IoT solutions in the overall smart waste collection system. The major climate impact contributor was instead associated with the trash bags used. Additionally, the study showed that the performance of the system relies on smart planning of the operations and the transportations.
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| 18. |
- Brunklaus, Birgit, 1970-, et al.
(author)
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The use of green roofs to improve wooden buildings for a future bioeconomy
- 2022
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In: Proceedings of LCM 2021: 10<sup>th</sup> International Conference on Life Cycle Management. - : EDP Sciences. ; 349, s. 04014-04014
-
Conference paper (peer-reviewed)abstract
- Bioeconomy helps to move towards a renewable, fossil-free future. The environmental impact is significantly reduced when replacing fossil-based products with bio-based alternatives. In a bioeconomy, all products are made from renewable and biogenic resources. In the building sector examples for biogenic sources are traditionally wooden building structures, while green roofs are becoming more popular. The goal of the present project was to assess the amount of biogenic carbon stored in green roofs and wooden buildings overall. The question is whether green roofs are improving the biogenic carbon usage of buildings and find out how that can be improved. The methods used are based on construction modelling, life cycle assessment and standardised environmental product declaration (EPD). The results indicate that wooden building structures are not enough for a complete biogenic building to move to a renewable, fossil-free future. Furthermore, the green roofs do add more biogenic carbon to the building than conventional roofs, while seen over the whole building these benefits are negligible. The results are presented as renewable and nonrenewable energy as well as biogenic carbon and greenhouse gas emissions. These are compared with conventional roofing based on non-renewable standard roofs in Sweden.
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| 19. |
- Brunklaus, Birgit, 1970-, et al.
(author)
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User centred design and energy efficient packaging collection infrastructure supporting circular future lifestyles
- 2022
-
In: E3S Web Conf.. - : EDP Sciences. - 2267-1242.
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Conference paper (other academic/artistic)abstract
- The collection and recycling of packaging and life cycle assessments have traditionally been developed from a technical perspective, not including the actors in the chain. How recycling should be done depends on who you ask, and whether you look at the issue from an energy, material, legal or user perspective. FTI, the Packaging and Newspaper Collection organization is responsible for better circularity and collecting these fractions in Sweden’s municipalities. When recyclable materials end up in the wrong place, it causes problems leading to increased energy use in the life cycle. The ongoing project Tjårven, aims to reduce energy use in connection with packaging collection, as well as potential energy gains in the second stage of the packaging life cycle, by redesigning packaging collection from a user centred perspective. To do this, design interventions are developed based on observed and self-reported user behaviour, a literature review of state-of-the-art collection infrastructure and an understanding of the system developed using actor-based LCA methodology. The latter methodology is used to show the energy use in the lifecycle, including the actions of the actors in the chain. The interventions developed will be tested through a case study that will be evaluated to see if it helps to achieve more energy efficient collection infrastructure, allowing for better circularity and therefore more sustainable future lifestyles. The present article presents the first part of the project, summarizing the results from the user centred observations, literature review and initial actor-based LCA model.
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| 20. |
- Burke, Stephen, et al.
(author)
-
Mapping of domestic hot water circulation losses in buildings – results from 134 measurements
- 2020
-
In: 12th Nordic Symposium on Building Physics (NSB 2020). - : EDP Sciences. ; 172
-
Conference paper (peer-reviewed)abstract
- The hot water circulation system in a building is a system which helps prevent Legionella problems whilst ensuring that tenants have access to hot water quickly. Poorly designed or implemented systems not only increase the risk to people’s health and thermal comfort, but even result in an increase in the energy needed for this system to function properly. Results from previous studies showed that the total hot water circulation system loss can be as high as 25 kWh/m2 heated floor area per year. The purpose of this project is to measure the total energy use per year of the hot water circulation system in about 200 multifamily dwellings of different ages to verify that a system loss of 4 kWh/m2, year is a realistic assumption for both newer and older/retrofitted buildings. The preliminary results from the first 134 measurements showed that the assumption of 4 kWh/m2, year is rarely fulfilled. An average energy use of more than three times this is more common, even in newer buildings. Whilst some of the total energy lost is used to heat the buildings, it is not desirable because it is an uncontrolled energy flow.
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| 21. |
- Bäcklund, Katarina, 1982-, et al.
(author)
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Showcasing the First Steps Towards a Digital Twin for Campus Environments
- 2022
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In: 2022 BuildSim Nordic. - : EDP Sciences.
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Conference paper (peer-reviewed)abstract
- This paper presents a path towards the implementation of a Digital Twin for campus environments. The main purpose of the Digital Twin is to accomplish an advanced analytical tool, which supports building owners, building operators and building users to reach an improved performance of the building. Digital Twins is new to the building and the real estate industry, hence research within this field is scarce. This paper contributes to the research by providing a methodology to implement a Digital Twin of an existing building stock of campus areas in Sweden. The main results obtained so far are presented. They indicate that the potential of a Digital Twin expands beyond the aspects of a navigational digital 3D model, including a state-of-the-art app that is developed from the Digital Twin platform.
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| 22. |
- Cabovska, Blanka, 1990, et al.
(author)
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A study on the relationship between energy performance and IEQ parameters in school buildings
- 2021
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 246
-
Conference paper (peer-reviewed)abstract
- Over the last decades, strong focus has been placed on the energy efficiency of buildings; not least school buildings. Energy performance (EP) of buildings is nowadays in principle described by one single indicator based on purchased energy in kWh/year.m2. Another important building performance aspect is the indoor environmental quality. This study's overarching goal is to identify school buildings with a good balance between energy performance and indoor environment. Thus, this paper investigates possible correlations between information given in energy performance certificates (EPCs/e.g. energy use, year of construction, type of ventilation) and measured indoor environmental parameters. The work comprises investigation of approximately 20 school buildings with different ventilation systems in Gothenburg. In-situ investigations of the buildings' properties and ventilation systems were conducted. Indoor environmental parameters were recorded during one week in each classroom. In this paper, indoor temperature, absolute humidity added indoors and CO2 concentration data are compared with the corresponding school's energy performance data and ventilation type. Results suggest that mechanically ventilated buildings have clearer relationships between energy performance, building indicators and measured indoor environment. For buildings such as naturally ventilated, the relationships are usually weak, and the values spread over much wider ranges.
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| 23. |
- Chai, Jiale, et al.
(author)
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Climate change impact on energy balance of net-zero energy buildings in typical climate regions of China
- 2019
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; 111
-
Journal article (peer-reviewed)abstract
- Net-zero energy building (NZEB) is widely considered as a promising solution to the current energy and environmental problems. The existing NZEBs are designed using the historical weather data (e.g. typical meteorological year-TMY). Nevertheless, due to climate change, the actual weather data during a NZEB’s lifecycle may differ considerably from the historical weather data. Consequently, the designed NZEBs using the historical weather data may not achieve the desired performance in their lifecycles. Therefore, this study investigates the climate change impacts on NZEB’s energy balance in different climate regions, and also evaluates different measures’ effectiveness in mitigating the associated impacts of climate change. In the study, the multi-year future weather data in different climate regions are firstly generated using the morphing method. Then, using the generated future weather data, the energy balance of the NZEBs, designed using the TMY data, are assessed. Next, to mitigate the climate change impacts, different measures are adopted and their effectiveness is evaluated. The study results can improve the understanding of climate change impacts on NZEB’s energy balance in different climate regions. They can also help select proper measures to mitigate the climate change impacts in the associated climate regions.
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| 24. |
- Claesson, Johan, et al.
(author)
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Benefits of Investigating the Thermal Component for Moisture Safety in Ventilated Attics
- 2020
-
In: 12th Nordic Symposium on Building Physics (NSB 2020). - : EDP Sciences. - 2555-0403. ; 172
-
Conference paper (peer-reviewed)abstract
- Cold ventilated attics often have mould problems in Sweden. This is valid both for old and sometimes newly built attics. Increased insulation on the attic floor is assumed to increase the problem. To investigate this, numerical 1D models like WUFI or WUFI+ are typically used. These models give results but the physical processes are not so transparent for the user due to the complex numerical techniques involved and takes a long time to simulate. The problem is mainly related to the temperature in the attic, the ventilation rate and possible of leaks from the living space. All exposed surfaces in the attic will buffer moisture variations. But if this buffering is neglected and the leakage is treated as a constant the moisture content in the attic is only dependent on the ventilation with outside air and the assumed leakage. This would make a pure thermal investigation meaningful. An analytical model for the thermal problem was developed that took into account radiation between the interior surfaces and the different boundary conditions at the outside and inside surfaces. Using this model a parameter study of exterior roofing insulation was done using a moisture transport model that only took into account convection exchange. The results were compared with WUFI Pro and WUFI+ simulations which included the moisture exchange between air and internal surfaces. The comparison showed that the pure thermal model gave, as expected, larger variations in relative humidity, but that the results were qualitatively very similar. This indicates that analytical solutions of thermal problems can be used as a base in qualitative investigations of certain combined heat and moisture problems.
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| 25. |
- Dabaieh, Marwa, et al.
(author)
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The Z free home from conceptual design to simulation results
- 2022
-
In: E3S Web of Conferences. - France : Web of Conferences. - 2267-1242. ; 362
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Journal article (peer-reviewed)abstract
- The need for affordable housing requires more compact living. With the increasing frequency and impact of climate change incidents, a new way of thinking is needed to live in a more resilient and climate responsive way. The idea of a Z free home began by considering these two needs. As a tiny mobile house equipped with passive and eco-cycle systems, it achieves 9 zero targets. This paper evaluates the design concept, building modelling, and building simulation for the Z free home design. The project is ongoing and aims to model a full physical prototype as a proof of concept for the 9 zero targets in an urban living lab context in Lund Sweden.
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| 26. |
- Dervishaj, Arlind, et al.
(author)
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New computational methods with Sunlight, Daylight, and Quality Views for Regenerative Design
- 2022
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In: 2nd International Nordic Conference on Building Simulation. - Copenhagen, Denmark : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- This paper investigates novel computational methods for Regenerative Design by developing further on the European Daylight Standard EN 17037, to make it useful at both urban and architectural scales. Case studies are evaluated for sunlight, daylight and quality views. A computational method, compliant with EN 17037, is introduced for the evaluation of sunlight. An assessment of daylight metrics, for an office building in Helsinki, with a 300 lux target, demonstrates a 12% difference between spatial Daylight Autonomy (sDA; occupied hours) and Illuminance levels (EN 17037 method 2; daylight hours), 37% between sDA and Daylight Factor (EN 17037 method 1), and 25% between methods 1 and 2. A new computational method for evaluating ‘views’ on the floorplan is proposed that considers ‘view content’ (EN 17037 View Out layers), ‘view access’, the potential viewpoint-based ‘outside distance’, and can be extended to add the ‘quality of environmental information’. Further research directions and use of spatial metrics are discussed for sunlight, daylight, and view quality.
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| 27. |
- Dijkstra, Jelke, 1980, et al.
(author)
-
Grain kinematics during stress relaxation in sand: Not a problem for x-ray imaging
- 2019
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 92
-
Conference paper (peer-reviewed)abstract
- X-ray tomography is a very valuable tool for studying the full-field 3D deformation of granular materials. The requirement to stop loading and scan a given state (assumed to be stationary) used in most approaches implies unavoidable stress relaxation during scanning. Since scanning times on laboratory tomographs are normally in the order of 1 hour, the strength of the assumption of a stationary state cannot be tested, which introduces some potential weakness in the interpretation of the rich micro-mechanics observed. This paper presents the kinematics of relaxation of a dry natural sand in a typical oedometric cell used for X-ray scanning, using a synchrotron X-ray source to provide scanning times of around 3 minutes, at two different magnifications. This allows the relaxation of the cell & sand system for the first time to be quantified. Advanced image correlation tools are used to quantify the rearrangements of the soil skeleton during loading and the subsequent relaxation. The results indicate that the magnitude of grain displacements during relaxation, associated to ≈4% reduction in externally measured axial stress under oedometric loading, falls below 0.01 D50. It can, therefore, be concluded that the relaxation step required prior to an X-ray scan during an in-situ geomechanical experiment on dry sand does not lead to appreciable uncertainties.
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| 28. |
- Domhagen, Fredrik, 1987, et al.
(author)
-
Pressure distribution around the thermal envelope - a parametric study of the impact from wind and temperature on contaminant transport within a building
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 173:11004
-
Conference paper (peer-reviewed)abstract
- Several school buildings in Sweden have indoor air quality problems. The contaminant source is often assumed to come from within the construction, for example from the crawl space or attic space. Contaminants, in these cases, are transported by air leaking between compartments in the building. Here, the driving force for the air leakage is difference in pressure and, therefore, determining pressure also determines the direction of contaminant transport. In many cases, measures to improve the air quality are taken without a thorough understanding of how it might affect the pressure distribution in the building. In this paper a numerical model is used to examine how different climate scenarios and different building configurations affect the leakage and contaminant transport in a building with a crawl space. Results show that for leaky buildings the ventilation rate increases with increased wind and therefore the contaminant concentration decreases. The worst scenario in terms of high contaminant concentration is mild days with little wind. Also, when installing an exhaust fan in the crawl space with the purpose to prevent air from leaking from the crawl space to the classroom it is advisable to also consider the airtightness and the climate, not only the pressure difference across the floor.
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| 29. |
- Ekberg, Olle, et al.
(author)
-
Investigating the presence of mold in wood treated with chlorophenol
- 2020
-
In: 12th Nordic Symposium on Building Physics (NSB 2020). - : EDP Sciences. - 2555-0403. ; 172
-
Conference paper (peer-reviewed)abstract
- A common moisture-related problem in Sweden and other countries, is mold odor indoors. The general perception is that mold odor indicates hazardous hidden mold. However, some grey literature studies indicate that the source of mold odor might not be substantial amounts of mold, but rather chloroanisoles (CAs) which are biomethylated from chlorophenols (CPs) in moist conditions. Products containing CPs were commonly used world-wide as wood preservatives in the 1960-70s and problems with indoor mold odor have been reported in buildings where such products have been used. In Sweden, one of the main uses of CPs in buildings was in wooden constructions exposed to big moisture loads, such as sill plates and crawl space ceilings. Here we aimed to determine the potential presence and level of mold growth on wood treated with CPs in one school building with reported odor problems built in the stated time period. Odorous wooden samples were taken and analyzed for mold growth. No mold was detected by the naked eye, but some growth was seen using a microscope. We presently investigate more schools and samples, but so far our results question that mold odor depends on substantial amounts of mold.
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| 30. |
- Ekström, Tomas, et al.
(author)
-
Proposed Method for Probabilistic Risk Analysis using Building Performance Simulations and Stochastic Parameters
- 2020
-
In: 12th Nordic Symposium on Building Physics (NSB 2020). - : EDP Sciences. ; 172
-
Conference paper (peer-reviewed)abstract
- As parts of the world continue the work of mitigating the impact of climate change, many countries strive for continued reductions in energy demand from buildings by implementing more stringent building regulations. Consequently, the importance of accurate and efficient building performance simulations to predict the energy use of a building design increases. As observed in earlier studies, there are performance gaps between the predicted annual energy demand from building energy performance simulations based on deterministic methods compared to the monitored annual energy use of a building. This paper presents a preliminary method developed using probabilistic methods for risk analysis and building performance simulations to predict the energy performance of buildings using stochastic parameters. The method is used to calculate the probability for the energy performance of a building design to fulfil the energy requirements. The consequences are quantified using an example of energy performance contracting to evaluate the inherent risk of a building’s design. The method was demonstrated in a case study and validated by comparing the results in energy performance and probability of failure against measured data from 26 single-family houses.
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| 31. |
- Fasci, Maria Letizia
(author)
-
Air-, ground-and dual-source heat pumps : a comparison between energy-efficient systems for a Swedish dwelling
- 2022
-
In: 2022 BuildSim Nordic, BSN 2022. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Air-source heat pumps (ASHPs) and ground-source heat pumps (GSHPs) are the most spread heat pumps nowadays. However, they suffer from drawbacks that could be mostly overcome coupling the two heat sources, i.e., using dual-source heat pumps (DSHPs). In this study, we compared the techno-economic performance of ASHPs and GSHPs for a small Swedish single-family house. We also calculated the performance improvements achieved using dual-source heat pumps, and evaluated the economic conditions necessary to make the dual-source heat pumps economically competitive with the more traditional systems. We found that the GSHPs were more efficient than the ASHP during the first year of installation, but their performance decreased-sometimes dramatically-during their lifetime. However, investing in either systems was always beneficial and no significant differences tended to exist between the investments. The dual-source heat pumps had-sometimes significantly-higher performance than the conventional systems but they might not be economically competitive with the more conventional systems.
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| 32. |
- Filcenco-Olteanu, Antoneta, et al.
(author)
-
Physical chemical characterization of historical mining waste and ARD prediction tests
- 2017
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; 18:4
-
Journal article (peer-reviewed)abstract
- There are thousands of historical mine tailings and metallurgical residues present on inactive metal mining sites which have been abandoned. However, the potential release of dissolved metals, acidity, or suspended particulates from mine-waste dumps can be a serious and long-lasting problem. A variety of environmental impacts may occur at this abandoned mine sites and leading the list is acid generation, which is one of the main problems from metal mining. The objective of the present study was to characterize and evaluate the Romanian historical tailing of Sasar-Red Valley, near Baia Mare. This involved physical and chemical characterization of the materials and its acid generating potential. Sasar tailing impoundment contains 8.5 million m3 of tailings and occupies an area of 32.5 hectares. Tailings samples were collected from different depths in three sampling points, and characterized by grain size, chemical elements concentration, elements distribution of elements in depth, paste pH, acid-base account and net acid generation tests. Acid base accounting (ABA) tests in conjunction with net acid generation (NAG) tests classified the samples into the category of 'potentially acid generating'. This paper presents a synthesis of works performed in the Improve Resource Efficiency and Minimize Environmental Footprint (REMinE) project.
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| 33. |
- Finnveden, Göran, et al.
(author)
-
Six areas of methodological debate on attributional life cycle assessment
- 2022
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242 .- 2555-0403. ; 349, s. 03007-03007
-
Journal article (peer-reviewed)abstract
- There is a general agreement in the LCA community that there are two types of LCAs: attributional and consequential. There have been numerous discussions about the pros and cons of the two approaches and on differences in methodology, in particular about methods that can be used in consequential LCA.There are, however, methodological aspects of attributional LCA and how it can be used that need further attention. This article discusses six areas of debate and potential misunderstandings concerning attributional LCA. These are:1) LCA results of all the products in the world should add up to the total environmental impact of the world, sometimes referred to as the 100 % rule.2) Attributional LCA is less relevant than consequential LCA.3) System expansion, and/or substitution, cannot be used in attributional LCA.4) Attributional LCA leads to more truncation errors than consequential LCA does.5) There is a clear connection between the goal and questions of an LCA and the choice of attributional or consequential LCA.6) There is a clear boundary between attributional and consequential LCA. In the article, these statements are discussed, and it is argued that they are either misunderstandings or sometimes incorrect.
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| 34. |
- Gkoutzamanis, V. G., et al.
(author)
-
Thermal energy storage in combined cycle power plants : Comparing finite volume to finite element methods
- 2019
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242.
-
Conference paper (peer-reviewed)abstract
- The research in thermal energy storage (TES) systems has a long track record. However, there are several technical challenges that need to be overcome, to become omnipresent and reach their full potential. These include performance, physical size, weight and dynamic response. In many cases, it is also necessary to be able to achieve the foregoing at greater and greater scale, in terms of power and energy. One of the applications in which these challenges prevail is in the integration of a thermal energy storage with the gas turbine (GT) compressor inlet conditioning system in a combined cycle power plant. The system is intended to provide either GT cooling or heating, based on the operational strategy of the plant. As a contribution to tackle the preceding, this article describes a series of 3-dimensional (3D) numerical simulations, employing different Computational Fluid Dynamics (CFD) methods, to study the transient effects of inlet temperature and flow rate variation on the performance of an encapsulated TES with phase change materials (PCM). A sensitivity analysis is performed where the heat transfer fluid (HTF) temperature varies from -7°C to 20°C depending on the operating mode of the TES (charging or discharging). The flow rate ranges from 50% to 200% of the nominal inflow rate. Results show that all examined cases lead to instant thermal power above 100kWth. Moreover, increasing the flow rate leads to faster solidification and melting. The increment in each process depends on the driving temperature difference between the encapsulated PCM and the HTF inlet temperature. Lastly, the effect of the inlet temperature has a larger effect as compared to the mass flow rate on the efficiency of the heat transfer of the system.
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| 35. |
- Glodic, Nenad, et al.
(author)
-
Blade oscillation mechanism for aerodynamic damping measurements at high reduced frequencies
- 2022
-
In: E3S Web Conf.Volume 345, 2022XXV Biennial Symposium on Measuring Techniques in Turbomachinery (MTT 2020). - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Accurate prediction of aerodynamic damping is essential for flutter and forced response analysis of turbomachinery components. Reaching a high level of confidence in numerical simulations requires that the models have been validated against the experiments. Even though a number of test cases have been established over the past decades, there is still a lack of suitable detailed test data that can be used for validation purposes in particular when it comes to aero damping at high reduced frequencies which is more relevant in the context of forced response analysis. A new transonic cascade test rig, currently undergoing commissioning at KTH, has been designed with the goal to provide detailed blade surface unsteady pressure data for compressor blades profiles oscillating at high reduced frequencies. The paper provides an overview of the blade actuation system employed in the test rig and presents the result of a series of bench tests characterizing the blade vibration amplitudes achieved with this actuation system.
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| 36. |
- Goto, Yutaka, 1984, et al.
(author)
-
Numerical and real-life assessment of the moisture safety of CLT structure with PIR insulation composite under the Swedish climate
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 172
-
Conference paper (peer-reviewed)abstract
- The building industry is a major contributor of CO2 emission. Wood construction is a good option for carbon storage among various construction alternatives. Considering the growing market of multi-story wooden building in Sweden, CLT (cross laminated timber) structure with an alternative insulation composite with PIR insulation and MgO board was proposed. In order to prove the applicability of this construction for moisture safety, the hygrothermal performance of the wall was measured in real life at HSB Living Lab (Gothenburg, Sweden) throughout 2019. Furthermore, a numerical model to analyse its performance by transient heat and moisture transfer analysis was created to predict the performance of the wall system. After the successful validation of the numerical model, a parameter study was carried out to investigate the moisture risk of the wall system in the case of extensive wetting of the CLT panel and in various areas in Sweden (Gothenburg, Stockholm, Lund, Karlstad and Lule). The study showed a low mould growth risk either in the test at the living lab or in the feasibility study. The development of the technology should further focus on the cost-effectiveness and design of all the construction details for the future market application.
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| 37. |
- Gramegna, Liliana, et al.
(author)
-
A constitutive framework for the chemo-mechanical behaviour of unsaturated non-expansive clays
- 2023
-
In: E3S Web of Conferences. - 2555-0403 .- 2267-1242. ; 382
-
Conference paper (peer-reviewed)abstract
- Both osmotic and matric suction changes have a significant influence on the mechanical behaviour of clays. Despite the different types of interactions at the microstructural level, both suctions havea relevant effect on the fabric of non-expansive clays. Starting from experimental observations at the laboratory scale, it is possible to identify some common features characterizing the mechanical response of non-expansive clays to salinity and degree of saturation changes. This paper presents an elastoplasticframework to reproduce the behaviour of unsaturated clayey soils upon changes in the salt concentration of the pore fluid. In particular, it presents a strategy to include osmotic suction induced by pore fluid salinity in BBM-like models [1]. The model was implemented in the Thebes code and it was calibrated on experimental data performed on Boom clay [2] and remoulded loess [3].
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| 38. |
- Gupta, Abhishek, et al.
(author)
-
Implementation and validation of pressure-dependent gas permeability model for bentonite in FEM code Thebes
- 2023
-
In: E3S Web of Conferences. - 2555-0403 .- 2267-1242. ; 382
-
Conference paper (peer-reviewed)abstract
- In an Engineered Barrier System of a nuclear waste repository, gas migrates through: a) diffusion/advection of dissolved gases, b) two-phase continuum flow, c) dilatant pathway flow and d) single-phase gas flow through macro-fractures in the soil. The gas production rate and the corresponding gas pressure accumulation affect the clay material behaviour and its properties such as air entry value. For the safe design of the EBS system, computational models need to account for the identified transport mechanisms. This study presents an enhancement in the finite element code Thebes [1, 2] that replicates the observed increase in permeability at higher gas pressures, e.g. due to pore dilatancy and gas fracture as proposed by Xu et al. [3]. The formulation links permeability to gas pressure and threshold/critical pressure. For model validation, the study utilizes a gas injection experiment carried out in IfG (Institute for Rock Mechanics, Germany) on Opalinus Clay [4]. The results show a good fit against the measurements while giving insight into gas flow through clays.
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| 39. |
- Hagentoft, Carl-Eric, 1958
(author)
-
Water vapor transport to a semi-infinite material with simultaneous varying surface relative humidity and temperature
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 172
-
Conference paper (peer-reviewed)abstract
- The water vapor transfer between the indoor air and hygroscopic finishing materials is of importance for the moisture balance of the room. Most protocols for determining the effect are based on isothermal conditions and cycling relative humidity in the form of square wave or sinusoidal functions. A new analytical solution for a material exposed to a both time varying surface relative humidity and temperature is presented in the paper. The time varying temperature inside the material is assumed to follow the surface temperature throughout the material layer since the reaction time for temperature changes in a reasonable thin surface material is rather short compared with the one for moisture changes. The semi-infinite approach is justified by the fact that the penetration depth for moisture variations are very limited for diurnal variations. The analytical approach and solution are presented in the paper.
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| 40. |
- Hagos, Dejene Assefa, 1981, et al.
(author)
-
Economic performance evaluation of natural gas vehicles and their fuel infrastructures
- 2018
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 51
-
Conference paper (peer-reviewed)abstract
- The transition from high carbon-intensity to low carbon-intensity transport fuels entails the development of energy efficient and cost-effective decarbonisation pathways. In this paper, 14 potential natural and renewable gas supply pathways and natural gas vehicles (NGVs) have been selected and evaluated with regards to well-to-tank (WTT) fuel production costs and break-even vehicle added investment costs. NGVs are evaluated for both road- and maritime transport applications with three types of gas engines; dedicated, dual fuel, and high pressure direct injection (HPDI) engines. The results indicate that owing to the alternate gas distribution mechanisms and filling stations configuration there exist a substantial fuel production cost differences between the selected gas pathways. Despite its long-distance shipping and distribution, imported LNG showed significant production cost advantage over compressed natural gas (CNG) and liquefied renewable natural gas (LRNG) pathways. Evaluating the current economic performances, all NGVs are found to be competitive corresponding to gasoline cars, but not compared to diesel cars due to the lower price gap between CNG and diesel. In the heavy-duty vehicle and passenger vessel segments, however, owing to the high price gap between LNG and diesel/marine gas oil (MGO), all NGVs and LNG passenger vessels showed high competitiveness compared to their conventional counterparts.
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| 41. |
- Hansen, Thor, et al.
(author)
-
Investigation of the Mould Resistance Design (MRD) model for mould growth in attics
- 2020
-
In: 12th Nordic Symposium on Building Physics (NSB 2020). - : EDP Sciences. - 2555-0403. ; 172
-
Conference paper (peer-reviewed)abstract
- Based on measurements of mould in 17 attics in the north of Sweden, 3 were chosen as a tentative validation of the MRD-model (Mould Resistance Design) for long periods of time (1961-2012). Comparing the measurements and the results from the simulations showed great differences regarding the mould growth depending on the simplifications used in the model. How the leakage was simulated and where the moisture from the leakage was placed in the construction were the most important factors. The study could not validate the MRD model as such, but it was clear that the simulations with relatively small adjustments could give realistic data.
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| 42. |
- Huang, Pei, et al.
(author)
-
A systematic comparison of various electric vehicle charging approaches
- 2022
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242.
-
Conference paper (peer-reviewed)abstract
- The use of electric vehicles (EVs) has been on the rise. Most of the existing EV smart charging controls can be categorized into three approaches according to their optimization principles: individual, bottom-up and top-down. Until now, systematic comparison and analysis of the different approaches are still lacking. It is still unknown whether a control approach performs better than others and, if yes, why is it so. This study aims to fill in such knowledge gaps by conducting a systematic comparison of these three different control approaches and analyzing their performances in depth. A representative control algorithm will be selected from each control approach, then the selected algorithms will be applied for optimizing EV charging loads in a building community in Sweden. Their power regulation performances will be comparatively investigated. This study will help pave the way for the developments of more sophisticated control algorithms for EV smart charging. © 2022 The Authors, published by EDP Sciences.
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| 43. |
- Jalilzadehazhari, Elaheh, et al.
(author)
-
Drivers and barrios in using augmented reality in renovation projects - literature review
- 2022
-
In: E3S Web Conf. Volume 362, 2022. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Reducing the emissions of greenhouse gases is of utter importance for the mitigation of climate change mitigation. In Sweden, the building and service sector is responsible for 21% of total greenhouse gas. Renovating existing buildings, more specifically those which were constructed before 1980, can significantly contribute to the reduction in energy consumption and emissions of greenhouse gases. Because the majority of these buildings are in need for renovation. But the energy renovation and energy efficiency-related maintenance rate in Sweden is very low due to lack of technical drawings and documentation of information about material specifications and structure systems. Adoption of augmented reality technologies can be beneficial as these technologies present digital information in the context of the physical environment. However, the level of adoption of these technologies in renovation and maintenance projects is still very low. This paper expands the technology acceptance model to evaluate determinants of users’ acceptance of augmented reality technologies in renovation and maintenance projects.
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| 44. |
- Jangsten, Maria, 1989, et al.
(author)
-
Field test of active night cooling supplied by district cooling in three commercial buildings
- 2021
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 246
-
Conference paper (peer-reviewed)abstract
- Several previous studies have investigated active night cooling strategies to reduce the peak cooling load in buildings, primarily by precooling the building by the ventilation air during the night. In this study, active night cooling is supplied by the use of district cooling, mainly for cooling buildings by hydronic cooling systems, such as chilled beam or fan coil systems, but potentially also to cool the ventilation air if the outdoor air temperature is above the supply air temperature setpoint. A field test with active night cooling by district cooling was conducted during the summer of 2020 in three commercial buildings located in Gothenburg, Sweden. The active night cooling strategy was implemented by changing the time schedule operation of the buildings’ chilled beam systems to twenty-four hours per day for the first half of the summer and changing back to regular time schedules for the second half. The results showed that active night cooling failed to reduce the hourly maximum cooling power. However, the peak cooling load, corresponding to the 100 hours with the highest cooling power, was reduced with 6.5% for one of the buildings. Active night cooling also reduced the daytime energy usage between 0.7 and 4.6%. The field test demonstrated that some buildings and associated cooling systems are more compatible for active night cooling than others. The test also showed it was possible to achieve some cooling power and energy reductions with simple measures. However, providing active night cooling supplied by district cooling will cause additional costs for the building owners unless it is incentivized by the district cooling provider.
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| 45. |
- Javanroodi, Kavan, 1988, et al.
(author)
-
Optimization of building form and its fenestration in response to microclimate conditions of an urban area
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 172
-
Conference paper (peer-reviewed)abstract
- Designing building form in urban areas is a complicated process that demands considering a high number of influencing parameters. On the other hand, there has been an increasing trend to design highly fenestrated building envelopes for office buildings to induce higher levels of natural lighting into the workspace. This paper presents a novel optimization framework to design high-performance building form and fenestration configuration considering the impacts of urban microclimate in typical and extreme weather conditions during a thirty-year period of climate data (2010-2039). In this regard, based on the introduced technique and algorithm, the annual energy demand and thermal comfort of over 8008 eligible form combinations with eight different fenestration configurations and seven different building orientation angels were analysed in a detailed urban area to find optimal design solutions in response to microclimate conditions. Results showed that adopting the framework, annual heating, and cooling demand can be reduced by 21% and 38% while maintaining thermal comfort by taking design-based decisions at the early stages of design.
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| 46. |
- Johansson, Pär, 1986, et al.
(author)
-
Deterioration in brick buildings: hygrothermal performance and measures to save them
- 2020
-
In: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 172
-
Conference paper (peer-reviewed)abstract
- Many former industrial building sites in Sweden have been abandoned and left to deteriorate. Nowadays, there is a large interest to refurbish and retrofit these buildings for other purposes. Commercial and housing developers are attracted to these areas which are often in the outskirts of the city centers. There are several challenges facing architects and engineers to preserve these buildings, also connected to cultural heritage demands. The aim of this study is to propose measures to preserve cultural heritage buildings. A brick building in Gothenburg, on the Swedish west coast, is used as a case study. The building was used for paper production until 2005. After that, it deteriorated quickly after the heating was turned off. The rapid decay affected the hygrothermal performance as well as the load-bearing capacity of the structure. Small scale laboratory investigations of the building materials show a high degree of decay. Measurements of temperature and relative humidity is used to monitor the hygrothermal performance. Observations show that the brick masonry has heavy salt efflorescence and is in need of further protective measures.
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| 47. |
- Johansson, Pernilla, et al.
(author)
-
Predicting mould growth on building materials- the PJ-model
- 2020
-
In: E3S Web of Conferences. Volyme 172, 2020.. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Mould growth in buildings is a complex process, affected by moisture and temperature, the properties of the building material as well as characteristics of the mould fungi. The complexity poses challenges when assessing the risk of mould growth in buildings. Mathematical models are often used to predict whether mould will grow in a part of building with expected RH and temperature conditions. The models can be described as static or dynamic. In a previous round-robin study, comparing results from models with observations from field studies, the outcome of the dynamic models evaluated depended on the user of the model. Also, the models often underestimated the risk of mould growth. A better agreement was found for static models, especially for the PJ-model. It is a part of a standardised technical specification (SIS-TS 41:2014) and has not previously been described as a model. The critical moisture level (RHcrit), determined by tests according to the method, is used as input. Thus, the subjectivity in the predictions is reduced. RHcrit is the lowest moisture level at which mould can grow and is temperature-dependent. The PJ-model provides an equation to estimate RHcrit at typical temperatures in buildings. If RH in a building section exceeds the limit values at the current temperature, growth is predicted. This paper describes the PJ-model version 1.0, some of the extensive work performed during the development and validation of the model and the ongoing work to refine the model to include considering transient conditions and measurement uncertainties. © The Authors
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| 48. |
- Johansson, Pernilla, et al.
(author)
-
Threshold values for mould growth : Critical moisture level of 21 different building materials
- 2020
-
In: E3S Web of Conferences. Volume 172, 2020. - : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- The susceptibility for mould growth varies among different building materials. One way to describe the susceptibility is the lowest RH at which mould can grow on a specific material, the critical moisture level (RHcrit). Determining RHcrit for materials provide the basis for material choice in designs where moisture and temperature conditions are known. In this study, RHcrit of 21different products were determined according to SIS-TS 41:2014/SPMet 4927. This test method is developed based on the results of a variety of laboratory studies and validated by field studies. Test specimens were inoculated with a suspension containing spores from six different mould fungi and were then incubated in moisture chambers at four levels of RH at 22 °C. After 12 weeks specimens were analysed for mould growth. RHcrit was determined based on the lowest RH at which mould grew on the specimens. RHcrit varied among different products, even between product belonging to a similar group of material, for example, calcium silicate boards or gypsum boards. The results show, and confirm, previous findings that it is not possible to estimate RHcrit for a specific product based on material group. Instead, each product must be tested. © The Authors
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| 49. |
- Kabanshi, Alan, et al.
(author)
-
Plenum airflow distribution and its influence on the performance of a diffuse ceiling ventilation
- 2022
-
In: E3S Web Conf. Volume 356, 2022 The 16<sup>th</sup> ROOMVENT Conference (ROOMVENT 2022). - Xian : EDP Sciences.
-
Conference paper (peer-reviewed)abstract
- Implementation of diffuse ceiling ventilation (DCV) is slowly gaining momentum and applications in building ventilation have taken off with countries like Denmark, Finland and Netherlands taking the lead in Europe. However, DCV is yet to gain a foothold in Sweden and so not many installations are known, and their performance in relation to Swedish building practice is not yet established. A school in southern Sweden was subsequently renovated and two classrooms were equipped with a sound-absorbent suspended ceiling compatible with DCV. DCV has possible benefits for educational environments including improved thermal comfort as well as lower costs and noise levels. However, it is currently still unknown how supply conditions in the plenum affect the diffusion of air and resulting conditions within the room. To assess airflow characteristics and whether these influence flow conditions in the classroom, we investigated and compared the performance of DCV with two different supply conditions in the plenum. Air speeds and temperature distribution measurements in the plenum and classroom were performed with constant temperature anemometers and thermocouples respectively. The general observation from this study and the system setup herein is that airflow and temperature characteristics in the classroom were independent of the airflow conditions in the plenum. Further investigations in a controlled climate chamber are recommended to investigate and optimise system performance in accordance with Swedish building practice.
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| 50. |
- Karasev, Andrey, et al.
(author)
-
Characterization of non-metallic inclusions in corrosion -resistance nickel - Based EP718 and 718 alloys by using electrolytic extraction method
- 2019
-
In: E3S Web of Conferences. - : EDP Sciences. - 2267-1242.
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Conference paper (peer-reviewed)abstract
- It is known that non-metallic inclusions (NMI) that are formed during steel production and heat treatment can significantly affect the properties of final steel products. Therefore, it is very important to be able to determine the content of harmful NMI in steels. Nickel-based alloys are widely used in the oil and gas recovery industry, due to a good combination of strength and corrosion properties. Earlier studies have shown that the corrosion properties in immersion test and electrochemical tests for Ni-based EP718 alloys are slightly lower than that for 718 alloys. The focus in this study was the influence of different NMI on the corrosion resistance of these alloys. The characteristics of inclusions (such as size, morphology, and chemical composition) were analysed by using the electrolytic extraction method followed by three-dimensional investigations using SEM in combination with EDS. It was found that some non-metallic inclusions in EP718 alloys significantly reduce its corrosion resistance. It was also shown that a primary dissolution of the metal matrix occurs around certain inclusions during electrolytic extraction. Based on obtained results, the corrosion active non-metallic inclusions can be determined in these Nickel-base alloys and some recommendations for optimization of their production technology can be formulated.
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