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  • 1.
    Abd Nikooie Pour, Mina
    et al.
    Linköpings universitet.
    Algergawy, Alsayed
    University Jena, Germany.
    Amardeilh, Florence
    Elzeard.co, Paris, France.
    Amini, Reihaneh
    Data Semantics (DaSe) Laboratory, Kansas State University, United States.
    Fallatah, Omaima
    Information School, University Of Sheffield, Sheffield, United Kingdom.
    Faria, Daniel
    Faculdade De Cîencias, Universidade De Lisboa, Lasige, Portugal.
    Fundulaki, Irini
    Institute Of Computer Science-FORTH, Heraklion, Greece.
    Harrow, Ian
    Pistoia Alliance Inc., United States.
    Hertling, Sven
    University Of Mannheim, Germany.
    Hitzler, Pascal
    Data Semantics (DaSe) Laboratory, Kansas State University, United States.
    Huschka, Martin
    Fraunhofer Institute For High-Speed Dynamics, EMI, Germany.
    Ibanescu, Liliana
    AgroParisTech, Umr MIA-Paris/INRAE, France.
    Jiménez-Ruiz, Ernesto
    University Of London, City, United Kingdom; Department Of Informatics, University Of Oslo, Norway.
    Karam, Naouel
    Fraunhofer Fokus, Berlin, Germany; Institute For Applied Informatics (InfAI), University Of Leipzig, Germany.
    Laadhar, Amir
    Department Of Computer Science, Aalborg University, Denmark.
    Lambrix, Patrick
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Linköpings universitet.
    Li, Huanyu
    Linköpings universitet.
    Li, Ying
    Linköpings universitet.
    Michel, Franck
    University Ĉote d'Azur, CNRS, Inria, France.
    Nasr, Engy
    University Of Freiburg, Freiburg Galaxy Team, Germany.
    Paulheim, Heiko
    University Of Mannheim, Germany.
    Pesquita, Catia
    Faculdade De Cîencias, Universidade De Lisboa, Lasige, Portugal.
    Portisch, Jan
    University Of Mannheim, Germany.
    Roussey, Catherine
    Inrae Centre Clermont-ARA, Laboratoire Tscf, France.
    Saveta, Tzanina
    Institute Of Computer Science-FORTH, Heraklion, Greece.
    Shvaiko, Pavel
    Trentino Digitale SpA, Trento, Italy.
    Splendiani, Andrea
    Pistoia Alliance Inc., United States.
    Trojahn, Cássia
    Irit and Université Toulouse II, Toulouse, France.
    Vatascinová, Jana
    Prague University Of Economics And Business, Czech Republic.
    Yaman, Beyza
    Adapt Centre, Dublin City University, Ireland.
    Zamazal, Ondrej
    Prague University Of Economics And Business, Czech Republic.
    Zhou, Lu
    Data Semantics (DaSe) Laboratory, Kansas State University, United States.
    Results of the Ontology Alignment Evaluation Initiative 20212021Inngår i: Proceedings of the 16th International Workshop on Ontology Matching co-located with the 20th International Semantic Web Conference (ISWC 2021), Virtual conference, October 25, 2021 / [ed] Shvaiko P., Euzenat J., Jimenez-Ruiz E., Jimenez-Ruiz E., Hassanzadeh O., Trojahn C., CEUR-WS.org , 2021, s. 62-108Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Ontology Alignment Evaluation Initiative (OAEI) aims at comparing ontology matching systems on precisely defined test cases. These test cases can be based on ontologies of different levels of complexity and use different evaluation modalities (e.g., blind evaluation, open evaluation, or consensus).The OAEI 2021 campaign offered 13 tracks and was attended by 21 participants.This paper is an overall presentation of that campaign. 

  • 2.
    Abd Nikooie Pour, Mina
    et al.
    Linköping University.
    Li, Huanyu
    Linköping University.
    Armiento, Rickard
    Linköping University.
    Lambrix, Patrick
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Linköping University.
    A First Step Towards a Tool for Extending Ontologies2021Inngår i: Proceedings of the Sixth International Workshop on the Visualization and Interaction for Ontologies and Linked Data: co-located with the 20th International Semantic Web Conference (ISWC 2021) / [ed] Patrick Lambrix, Catia Pesquita, Vitalis Wiens, CEUR Workshop proceedings , 2021, s. 1-12Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Ontologies have been proposed as a means towards making data FAIR (Findable, Accessible, Interoperable, Reusable). This has attracted much interest in several communities and ontologies are being developed. However, to obtain good results when using ontologies in semantically-enabled applications, the ontologies need to be of high quality. One of the quality aspects is that the ontologies should be as complete as possible. In this paper we propose a first version of a tool that supports users in extending ontologies using a phrase-based approach.  To demonstrate the usefulness of our proposed tool, we exemplify the use by extending the Materials Design Ontology.

  • 3.
    Abdul Hakim, Faisal
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Said, Shazad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    En studie av småhusentreprenader: Varför går det fel?2021Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Syftet med denna studie är att kartlägga småhusentreprenader och vilka problem samt konflikter som uppstår mellan entreprenader och beställare. Vidare är det tänkt att denna studie skulle ge allmänheten en bättre uppfattning kring varför konflikter uppstår mellan beställare och entreprenörer samt hur husleverantörer jobbar för att motverka dessa problem.

    För att uppnå syftet och besvara forskningsfrågorna användes en kvalitativ forskningsmetod i form av semistrukturerade intervjuer. Anledningen till att denna intervjuteknik tillämpades var för att ge respondenterna frihet att prata öppet om sina upplevelser och synpunkter. Respondenterna som intervjuades var fyra representanter för husleverantörer, tre beställare, en byggnadsinspektör och en kontrollansvarig.

    Resultatet av intervjuerna visade att det fanns en gemensam uppfattning bland beställare och husleverantörer kring att det är för mycket pappersarbete och att totalentreprenad är den mest optimala entreprenadformen för den som inte vill ta på sigallt för mycket ansvar. Det fanns dock även åsikter som skiljde sig. Studien visade att beställare upplever uppförandet av småhus som en långsam och energikrävande process. Problemen som är vanligt förekommande inom småhusentreprenader är att det finns en skillnad i språk och kunskap mellan parterna. Detta resulterar i att det blir en bristande kommunikation som i sin tur kan leda till diverse konflikter.

    Husleverantörerna är medvetna om dessa problem och jobbar kontinuerligt för att ta fram lösningar. En sådan lösning är att lägga stor vikt på dokumentation och kontrakt eftersom det är de som är lagligt bindande. Slutsatsen för denna studie var att en god kommunikation resulterar i färre missförstånd och konflikter. Konflikter går däremot inte att undvika helt, utan kommer alltid kunna uppstå på grund av mänskliga faktorer. 

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  • 4.
    Abellán Guallarte, Alejandro
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy analysis between traditional hot water circulation system and an innovative pipe-in-pipe system2022Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    We are at a time when energy efficiency and the reduction in the use of non-renewable energy is an important objective in all aspects and will continue to be so, therefore it is necessary to try to reduce energy and heat losses in the systems used in homes and, in particular, in the domestic hot water (DHW) system. This study aims to find out the advantages and disadvantages of an innovative pipe-in-pipe (PIP) system for DHW circulation with respect to the conventional system of two separate pipes. Previous studies have shown that DHW circulation is indeed an important point of energy losses in the home and that it is possible to reduce these losses by using the innovative system under study. The properties and coefficients defining the heat transfer system have been obtained for both the traditional and innovative systems by using empirical equations and iterative processes, indicating a 32% reduction in heat losses in favour of the pipe-in-pipe system. However, this result has been obtained in a kind of case study, using some simplifying assumptions, needed to accomplish to work within limited time. So the result could vary if a somewhat different system is studied, which is why it is necessary to carry out further studies and research on this subject in order optimize DHW systems in buildings.

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  • 5.
    Afzali Gorouh, Hossein
    et al.
    Shahid Bahonar University of Kerman, Iran.
    Salmanzadeh, Mazyar
    Shahid Bahonar University of Kerman, Iran.
    Nasseriyan, Pouriya
    Shahid Bahonar University of Kerman, Iran.
    Hayati, Abolfazl
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cabral, Diogo
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Gomes, João
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karlsson, Björn
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Thermal modelling and experimental evaluation of a novel concentrating photovoltaic thermal collector (CPVT) with parabolic concentrator2022Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 181, s. 535-553Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, a zero-dimensional thermal model has been developed to analyze a novel low concentration photovoltaic-thermal (CPVT) collector. The model has been developed by driving heat transfer and energy balance equations for each part of the collector and then solving all the equations simultaneously. Moreover, a Monte-Carlo ray-tracing software has been used for optical stimulations of the parabolic trough solar collector. The novel CPVT collector has been experimentally tested at Gävle University (Sweden) and the model has been validated against the experimental results. The primary energy saving equivalent to the thermal-electrical power cogeneration of the CPVT collector has been determined. The effect of glass cover removal, heat transfer fluid (HTF) inlet temperature and mass flow rate on the collector performance has been investigated. The optimum HTF mass flow rates of the collector for maximum electrical yield and overall primary energy saving were determined under specified operating conditions by considering the pump consumption. The effect of mean fluid temperature on the thermal and electrical efficiencies has been studied and the characteristic equation of the thermal efficiency has been obtained. The thermal and electrical peak efficiencies of the collector have been found to be 69.6% and 6.1%, respectively.

    Fulltekst (pdf)
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  • 6.
    Ahmad, Afaq
    et al.
    Department of Civil Engineering, University of Engineering and Technology, Taxila, Rawalpindi 46600, Pakistan.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Alajarmeh, Omar
    Centre for Future Materials (CFM), School of Civil Engineering and Surveying, University of Southern Queensland, Toowoomba 4350, Australia.
    Chairman, Nida
    Department of Civil and Architectural Engineering, University of Westminster, London W1B 2HW, UK.
    Yaqub, Muhammad
    Department of Civil Engineering, University of Engineering and Technology, Taxila 47080, Pakistan.
    Investigation of Circular Hollow Concrete Columns Reinforced with GFRP Bars and Spirals2023Inngår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 4, artikkel-id 1056Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Glass fiber-reinforced polymer (GFRP) reinforcements are useful alternatives to traditional steel bars in concrete structures, particularly in vertical structural elements such as columns, as they are less prone to corrosion, and impart increasing strength and endurance of buildings. There is limited research on the finite element analysis (FEA) of the structural behavior of hollow glass fiber-reinforced polymer reinforced concrete (GFRPRC) columns. The hollow portion can be used for the service duct and for reducing the self-weight of the members. Numerical analysis of the compressive response of circular hollow concrete columns reinforced with GFRP bars and spirals is performed in this study. This article aims to investigate the axial behavior of hollow GFRP concrete columns and compare it with that of solid steel reinforced concrete (RC) columns as well as hollow steel RC columns. The Abaqus software is used to construct finite element models. After calibration of modeling using an experimental test result as a control model, a parametric study is conducted. The columns with the same geometry, loading, and boundary conditions are analyzed in the parametric study. It is resulted that the hollow GFRP concrete columns provide a greater confinement effect than the solid steel RC columns. The average variation in the ultimate axial load-carrying capacities of the experimental results, from that of the FEA values, is noted to be only 3.87%, while the average difference in the corresponding deformations is 7.08%. Moreover, the hollow GFRP concrete columns possess greater axial load and deformation capacities compared with the solid steel RC columns.

    Fulltekst (pdf)
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  • 7.
    Ahmed, Ali Mohamed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Rashid, Obaidullah
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Optimering av flervåningsbyggnadsstruktur genom att ersätta bärande väggar med pelare och balkar2023Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I takt med att den globala befolkningen fortsätter att växa, ökar efterfrågan på nya bostadsbyggnader avsevärt. Samtidigt har behovet av bostäder och byggande vuxit över hela världenunder de senaste decennierna, vilket har lett till en ökad efterfrågan på byggmaterial. Betong ärdet viktigaste byggmaterialet för flervåningsbyggnader pga. sin hållfasthet, men det bidrarbetydligt till utsläppen av växthusgaser. För att minska koldioxidavtrycket och främja hållbarhet är det avgörande att minimera materialanvändning med moderna byggmetoder.Syftet med denna studie är att optimera flervåningsbyggnadsstrukturer genom att ersättabärande väggar med pelare och balkar. Studien använder en referensbyggnad belägen iSandvikens kommun och verktyget StruSoft FEM-Design. Studien genomförs i två steg.I steg 1 utförs modellering, design och analys av referensbyggnaden med bärande väggar(byggnad 1). I steg 2 genomförs en förändring av byggnadsstrukturen genom att ersätta debärande väggarna med pelare och balkar av armerad betong (byggnad 2). Samma procedurersom i steg 1 upprepas för den omkonstruerade strukturen. Resultaten jämförs medreferensbyggnaden med hänsyn till utnyttjandegrad, deformation, spänningar, reaktioner, viktoch stabilitet.Ersättningen av bärande väggar med bärande pelare och balkar av armerad betong har variteffektiv. Båda strukturerna uppfyller de nödvändiga kraven. Baserat på resultaten ärdeformationen 9 mm för byggnad 1 och 7 mm för byggnad 2, vilket indikerar att skillnaden ideformation mellan de två strukturerna inte är signifikant.Byggnad 1 har en maximal utnyttjandegrad på 87%, medan byggnad 2 har en högre maximalutnyttjandegrad på 99%. Detta innebär att byggnad 2 kan utnyttjas i större utsträckning änbyggnad 1. Reaktionskrafterna är 563,6 respektive 476,4 kN i båda byggnaderna, vilketindikerar att reaktionskrafterna i byggnad 2 är 15% lägre än i byggnad 1. Båda strukturerna ärstabila, men det finns en skillnad i byggnadernas totala vikt. Vikterna på byggnaderna är 4169respektive 3 143 ton. Resultatet indikerar att byggnadens totala vikt minskar med ca 25% vidanvändning av betongpelare och betongbalkar.

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  • 8.
    Ahmed Waqas, Hafiz
    et al.
    Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi 23640, Pakistan.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Sahil, Mehran
    Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi 23640, Pakistan.
    Poshad Khan, Adil
    Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi 23640, Pakistan.
    Ejaz, Ali
    National University of Science and Technology, Risalpur 23200, Pakistan.
    Shafique, Taimoor
    Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi 23640, Pakistan.
    Tariq, Zain
    Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi 23640, Pakistan.
    Ahmad, Sajeel
    Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Swabi 23640, Pakistan.
    Onuralp Özkılıç, Yasin
    Necmettin Erbakan University, Konya, Turkey.
    Performance Prediction of Hybrid Bamboo-Reinforced Concrete Beams Using Gene Expression Programming for Sustainable Construction2023Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 16, nr 20, artikkel-id 6788Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The building and construction industry’s demand for steel reinforcement bars has increased with the rapid growth and development in the world. However, steel production contributes to harmful waste and emissions that cause environmental pollution and climate change-related problems. In light of sustainable construction practices, bamboo, a readily accessible and ecofriendly building material, is suggested as a viable replacement for steel rebars. Its cost-effectiveness, environmental sustainability, and considerable tensile strength make it a promising option. In this research, hybrid beams underwent analysis through the use of thoroughly validated finite element models (FEMs), wherein the replacement of steel rebars with bamboo was explored as an alternative reinforcement material. The standard-size beams were subjected to three-point loading using FEMs to study parameters such as the load–deflection response, energy absorption, maximum capacity, and failure patterns. Then, gene expression programming was integrated to aid in developing a more straightforward equation for predicting the flexural strength of bamboo-reinforced concrete beams. The results of this study support the conclusion that the replacement of a portion of flexural steel with bamboo in reinforced concrete beams does not have a detrimental impact on the overall load-bearing capacity and energy absorption of the structure. Furthermore, it may offer a cost-effective and feasible alternative. 

    Fulltekst (pdf)
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  • 9.
    Aksoylu, Ceyhun
    et al.
    Konya Technical University, Konya 42250, Turkey.
    Özkılıç, Yasin Onuralp
    Necmettin Erbakan University, Konya, Turkey.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yıldızel, Sadık Alper
    Karamanoglu Mehmetbey University, Karaman, Turkey.
    Hakeem, Ibrahim Y.
    Najran University, Najran, Saudi Arabia.
    Özdöner, Nebi
    Necmettin Erbakan University, Konya 42000, Turkey.
    Başaran, Boğaçhan
    Amasya University, Amasya 05100, Turkey.
    Karalar, Memduh
    Zonguldak Bulent Ecevit University, Zonguldak, Turkey.
    Application of waste ceramic powder as a cement replacement in reinforced concrete beams toward sustainable usage in construction2023Inngår i: Case Studies in Construction Materials, E-ISSN 2214-5095, Vol. 19, artikkel-id e02444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main purpose of this study was to investigate the flexural behavior of reinforced concrete beams (RCBs) containing waste ceramic powder (CP) as partial replacement of cement. For this purpose, flexural tests were carried out using various amounts of mixing ratios. By determining the amount of CP utilized in the optimum ratios, it was aimed both to make predictions for design engineers and to show its beneficial effect on the environment by recycling the waste material. For this purpose, twelve specimens were produced and verified to monitor the flexural behavior. The longitudinal reinforcements percentage (0.77%, 1.21%, and 1.74%) and CP percentage (0%, 10%, 20%, and 30%) were chosen as the parameters. CP could be effectively used up to 10% of cement as a replacement material. Increasing the CP percentage by more than 10% could considerably reduce the load-carrying capacity, ductility, and stiffness of RCBs, specifically when the longitudinal reinforcements percentage was high. In other words, as CP increased from 0% to 30%, the load-carrying capacity decreased between 0.4% and 27.5% compared with RCBs with the longitudinal tension reinforcements of 2ϕ8 without CP. However, reductions of 5.5–39.8% and 2.15–39.5% in the load-carrying capacity occurred respectively compared with RCBs with the longitudinal tension reinforcements of 2ϕ10 and 2ϕ12 without CP. The achieved longitudinal reinforcements percentage was close to the balanced ratio, while more than 10% CP cannot be used without any precautions for mixtures.

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  • 10.
    Alaneme, George U
    et al.
    Department of Agricultural Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, 440109, Abia, Nigeria; Department of Civil Engineering, Kampala International University, Kampala, Uganda.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Ibe Iro, Uzoma
    Department of Agricultural Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, 440109, Abia, Nigeria.
    Ganasen, Nakkeeran
    Department of Civil Engineering, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu, 603203, India.
    Otu, Obeten N
    Department of Civil Engineering, University of Cross River State, Calabar, Nigeria.
    Udeala, Richard C
    Department of Agricultural Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, 440109, Abia, Nigeria.
    Ifebude, Blessing O
    Department of Agricultural Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, 440109, Abia, Nigeria.
    Onwusereaka, Emmanuel A
    Department of Agricultural Engineering, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, 440109, Abia, Nigeria.
    Numerical Analysis and Parametric Study on Multiple Degrees-of-Freedom Frames2023Inngår i: Civil Engineering Journal, ISSN 2676-6957, Vol. 9, nr 7, s. 1709-1736Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The design of multiple degrees-of-freedom frames is critical in civil engineering, as these structures are commonly used in various applications such as buildings, bridges, and industrial structures. In this study, a six-degrees-of-freedom beam-column element stiffness matrix was formulated by superposition of beam and truss elements stiffness matrices and was adapted to statically analyze indeterminate frame structures. The development of a numerical model for the frame structures was achieved using the finite element method in the current study. Also, the investigation of the effects of various parameters such as frame geometries, material properties, and loading conditions was conducted on the internal forces developed in the frame structures. Three different parametric study cases that presented the frame structures with varying geometries and loading conditions were analyzed utilizing this matrix approach for the sake of emphasis and to evaluate the flexibility and adequacy of this formula to analyze the indeterminate frames using the MATLAB software. The analysis method comprised the derivation of the system displacements employing the relationships between the stiffness matrix and fixed end forces as the force vector and taking the attained displacements, which would be transformed to the local coordinates to obtain the member forces. The computed results from the element stiffness matrix approach were further statistically compared with the results achieved from the finite element software (SAP2000) applying the analysis of variance (ANOVA). The statistical results showed a P-value > 0.05, which indicated a good correlation between the compared results and adequate performance for the derived beam-column element matrix formula method. 

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  • 11.
    Al-Asadi, Bashar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energikartläggning av Montessoriskolan2022Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Energianvändning stiger kontinuerligt varje år. Detta beror på ekonomisk tillväxtoch ökad befolkning. Byggnadssektorn förbrukade 40 % av den totala energianvändningen i Sverige. Minskning av energibehovet inom byggsektorn är viktigt föratt Sverige ska uppnå energimål för minskad energianvändning i framtiden. Därförär energieffektivitetsåtgärder i byggnader idag, utgör ett av huvudmålen för energipolitiken mot 2020-mål. För att identifiera aktuell energianvändning för en byggnad är en energikartläggning först steg. Energikartläggningen utförds i Gefle Montessoriskola i Gävle.Byggnaden består av bottenplan och kälarenplan. Skolbyggnaden Uppfördes påsextitalet vilket gör deras energianvändning intressant. Skolbyggnadens energikartläggning baserad på energiberäkningar, insamlingsdata och energisimuleringar. Detfinns olika åtgärder för energieffektivitet som kan genomföras om energieffektiviseringsåtgärder är lönsamt. I detta arbete beskrivs olika åtgärder för energieffektivisering i Gefle Montessoriskola. Med hjälp av programvara IDA ICE skapades basmodellen för skolbyggnaden och läggs insamlingsdata in i IDA ICE som simulerades under ett år. Den totalaelanvändningen av skolbyggnaden var cirka 85 032 kWh/år medan var fjärrvärmen325 227 kWh/år. Resultatet visade en stor minskning av energianvändningar som kan utföras olikaenergieffektiviseringsåtgärder i skolbyggnaden såsom byte av fönster, byte av belysningar och tillägg isolering på ytterväggar. Enligt resultat var värmeförluster viafönster store 88 634 kWh/år och förbättringar på fönstren kan vara ett effektivt sättatt minska energiförlusterna. Genom att göra en beräkning efter förbättringar reducerar värmeförluster till 61 991 kWh/år.Att tillägga mer isolering på yttervägg för att reducera värmeförluster. Vid tilläggsisolering minskar energianvändningen till 395 699 kWh/år.LED installation för varje utrymmen i byggnaden är ett sätt att minska energianvändningen och LED belysningen ge bra effektiv än nuvarande belysning. Byte tillLED minskar energianvändningen till 405 983 kWh/år.ivResultatet av studien visade att skolbyggnaden kan minska deras energianvändningmed 10 % med hjälp av de samtliga åtgärder. Ekonomiska aspekter har beaktatsvilket visar samband mellan energibesparing och ekonomiska vinst

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  • 12.
    Albeman, William
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Lif, Emma
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Hur kan en gammal industribyggnad med kulturhistoriskt värde göras om till bostäder?: En fallstudie av lokstallarna i Bollnäs2022Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    In Sweden there is a shortage of housing whilst old, abandoned industrial buildingstake up space on desirable land. These buildings generally do not live up to today’s standards regarding comfort and energy efficiency and are therefore not used today. If these buildings were to be renovated into housing, they could help remedy the housing shortage. However, many of these buildings are protected from distortion by law which makes renovation and remodeling difficult. The purpose of this work has been to provide solutions for how an old industrialbuilding with cultural-historical values can be remodeled into housing. The solutions consist of floor plans and drawings modeled in Autodesk Revit. The possibilities and difficulties with this kind of project as well as solutions to expected problems are also presented in the report. This work was executed as a case study on one of the old locomotive depots in Bollnäs. Since the building for this project is an old locomotive depot, it is positioned close to the railroad. Noise and ground pollution are therefore important to consider and demand certain measures, for example retaining walls, noise barriers and excavation of polluted soil. An energy simulation of the building was made using BV2 to determine the energy usage of the building. The walls, roof and slab were additionally insulated for the purpose of meeting the demands of energy efficiency and comfort defined by BBR 29. The insulation had to be internally constructed in order to avoid distortion of the facade. Additionally, all windows and doors had to be made energy efficient while remaining aesthetically preserved. Internal insulation is generally problematic due to problems with moisture. The solution to this problem was to insulate the walls with polyurethane foam and the slab with cellular plastic. In order to make the building energy efficient, the building should be heated using district heating in combination with photovoltaic panels. This building is well suited for solar panels due to the large, black metal sheet roof and shadow free placement. The study shows the complexity of refurbishing this type of building. The renovation is extensive, and the floor plans are characterized by compromises. It is possible to renovate the building without distorting it. A better alternative would be to use the building for other functions such as a store, restaurant or bar. 

    Fulltekst (pdf)
    fulltext
  • 13.
    Albuquerque, Daniel P.
    et al.
    Universidade de Lisboa.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Linden, P. F.
    University of Cambridge.
    Carrilho da Graça, Guilherme
    Universidade de Lisboa.
    Experimental and numerical investigation of pumping ventilation on the leeward side of a cubic building2020Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 179, artikkel-id 106897Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unstable interaction between shear layers that form in the wake of an isolated building exposed to wind can drive natural pumping ventilation in windward and leeward facing rooms with two or more horizontally separated openings. This paper presents an experimental and numerical study of pumping ventilation in a three-story cubic building with two leeward openings in its middle floor. Reduced-scaled measurements were performed in the University of Gävle atmospheric-boundary-layer wind tunnel. The ventilation mechanism was investigated using smoke visualization, hot wire anemometry and particle image velocimetry. Effective ventilation rates were obtained using a tracer gas decay method. Experimental results confirmed that pumping ventilation is a 3D oscillatory unstable phenomenon with periodic behavior over several oscillation cycles. Measured flowrates show a linear relation between the effective ventilation rate and window separation. The numerical simulations used two turbulence modeling approaches: unsteady Reynolds-averaged Navier-Stokes (URANS) and large eddy simulation (LES). Both URANS and LES could predict vortex shedding frequency with an error below 5%. LES showed a good agreement with the measured ventilation rates, with an error below 10%, while URANS underestimated ventilation rates by at least 40%. The ventilation efficiency, obtained by LES, ranged between 0.60 and 0.75 (for the case with larger window separation). The results show that LES may be a suitable simulation approach for pumping ventilation. In contrast, URANS cannot simulate pumping ventilation.

  • 14.
    Albuquerque, Daniel
    et al.
    Universidade de Lisboa, Portugal.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Linden, Paul
    University of Cambridge, UK.
    da Graca, Guilherme Carrilho
    Universidade de Lisboa, Portugal.
    LES simulation of oscillating natural ventilation driven by vortex shedding in isolated buildings2020Inngår i: Proceedings of Building Simulation 2019: 16th Conference of IBPSA / [ed] Corrado et al., IBPSA , 2020, s. 644-649, artikkel-id 11456Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A recently published study presented a new type of natural ventilation (NV) flow, named pumping ventilation. The oscilatory mechanism of vortex shedding that occurs at the wake region of an isolated building drives this new type of ventilation in rooms with two (or more) openings facing the leeward or windward side of an isolated building. This paper presents a validated Large Eddy Simulation (LES) study of oscillating/pumping NV in an isolated building using three different separations (s') between its two windows. LES is validated using an experimental database from measurements performed at the University of Gavle boundary layer wind tunnel (WT). The measurements use a cubic model with 0.45m side representing a three-story building at a 1/20 scale that allows the use of bottom-hung windows. LES results show a good agreement with the measured non-dimensional ventilation rates. A dimensionless analysis shows the dominant frequencies of the pumping flow, are close to the Strouhal frequency.

  • 15.
    Alcoverro Colom, Pau
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    A new energy model for the Lakshadweep islands: Change from a diesel-based model to a hybrid model with renewable energy systems considering the ecological fragility of the islands2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    A new energy model for the Lakshadweep islands
  • 16.
    Alhajjaj, Eman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Sanchez, Marvin
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Effektivisering av byggprocessen med hjälp av lean: En fallstudie på ett företag med prefabricerat byggande2022Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The increasing housing shortage occurring in society has for a long time created a great need to build housing quickly and cost-effectively. This has led to more and more industrialization of its building process, where housing is manufactured in modular form in the factory. With industrial processes, companies can give freedom to workers to take responsibility for the process in which they participate, and thus contribute with improvements and standardization in the process. One concept that is very suitable for this is The Toyota Production system (TPS), also called Lean production. Today, there are studies where Lean has been combined with the building process. The purpose of this study is to investigate and study whether the building process for prefabricated houses can be streamlined using the Lean method and, if so, how. As an efficiency improvement is sought in this study, questions about the basic principles of Lean will be involved.

    A qualitative data collection is done, which is based on an interview study. The questions for these interviews have been formulated with the help of literature contained within the subject. The interview questions are structured by being open where the respondent is given the opportunity to speak freely and in detail about the topic.

    Two companies were selected for this study. One company is a Stockholm stationed company that deals with prefabricated construction. These do not use the Lean working method as standard in their work. The other company is a company that also deals with prefabricated construction on a larger scale and that they use the Lean working method throughout their organization.

    The theory behind the study is the actual implementation of Lean in an existing building process that does not use the working method. By introducing Lean's basic principles into a company that does not use it today, this study will describe what elements can be applied from Lean's perspective.

    Finally, improvement measures, based on Lean's principles, are being introduced to improve and streamline the construction process of prefabricated construction at the particular company where the study was conducted.

    The aim of the study is to describe and analyze the construction process for industrial companies, the obstacles that arise in the process and how can Lean streamline the construction process from the 14 principles.

    Key-word: Efficiency, Lean, Prefabricated, Modular house, Construction, Construction process, Elimination, The Toyota Way, Lean principle

    Fulltekst (pdf)
    Effektivisering av byggprocessen med hjälp av Lean
  • 17.
    Ali, Ali Talib
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Resilient cooling technologies: Simulation study to determine the cooling capacity in old residentialbuildings located in mid-Sweden2022Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Long-term changes in the climate conditions have increased the need foradequate thermal comfort systems. These alternations influence extremeevents, which their intensity and frequency have increased over the past years.Moreover, this study focuses on space cooling and parameters that the systemshould have to be considered as resilient. Literature study was done to presentthe concept of resilience as well as the different methods used to provide spacecooling. In addition, the cooling systems suggested in this study, which aredistrict cooling and absorption cooling, were presented and explained.Furthermore, the study focuses on cooling demand in a group of residentialbuildings based on different thermal characteristics, which were implementedbased on building regulations from late 1960s to early 1980s. The buildingthermal properties were used as input to obtain their cooling demand by usingbuilding energy simulation tool. Based on the acquired results, an evaluationhas been made for the cooling demand of those buildings. Further analysispresented a correlation between the cooling demand and thermal properties ofthe buildings and aided in the determination of the required cooling capacity.The selection of the capacities was based on the resilience criterion as the systemhas to be able to provide adequate performance and safety for the occupantsduring extreme events. Furthermore, an assessment was done to compare thesuggested system based on their capacities and the primary energy use.

    Fulltekst (pdf)
    Fulltext99
  • 18.
    Ali, Liaqat
    et al.
    Southern University of Science and Technology, Shenzhen, China.
    Isleem, Haytham F.
    Qujing Normal University, Qujing 655011, Yunnan, China.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Jha, Ishan
    Indian Institute of Technology-BHU, Varanasi, Uttar Pradesh, India.
    Zou, Guang
    Southern University of Science and Technology, Shenzhen, China.
    Kumar, Rakesh
    National Institute of Technology Patna, India.
    Sadeq, Abdellatif M.
    Qatar University, Doha, Qatar.
    Jahami, Ali
    University of Balamand, Tripoli P.O. Box 100, Lebanon.
    Integrated behavioural analysis of FRP-confined circular columns using FEM and machine learning2024Inngår i: Composites Part C: Open Access, ISSN 2666-6820, Vol. 13, artikkel-id 100444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the structural behaviour of double-skin columns, introducing novel double-skin double filled tubular (DSDFT) columns, which utilise double steel tubes and concrete to enhance the load-carrying capacity and ductility beyond conventional double-skin hollow tubular (DSHT) columns, employing a combination of finite element model (FEM) and machine learning (ML) techniques. A total of 48 columns (DSHT+DSDFT) were created to examine the impact of various parameters, such as double steel tube configurations, thickness of fibre-reinforced polymer (FRP) layer, type of FRP material, and steel tube diameter, on the load-carrying capacity and ductility of the columns. The results were validated against the experimental findings to ensure their accuracy. Key findings highlight the advantages of the DSDFT configuration. Compared to the DSHT columns, the DSDFT columns exhibited remarkable 19.54 % to 101.21 % increases in the load-carrying capacity, demonstrating improved ductility and load-bearing capabilities. Thicker FRP layers enhanced the load-carrying capacity up to 15 %, however at the expense of the reduced axial strain. It was also observed that glass FRP wrapping displayed 25 % superior ultimate axial strain than aramid FRP wrapping. Four different ML models were assessed to predict the axial load-carrying capacity of the columns, with long short-term memory (LSTM) and bidirectional LSTM models emerging as superior choices indicating exceptional predictive capabilities. This interdisciplinary approach offers valuable insights into designing and optimising confined column systems. It sheds light on both double-tube and single-tube configurations, propelling advancements in structural engineering practices for new constructions and retrofitting. Further, it lays out a blueprint for maximising the performance of the confined columns under the axial compression.

    Fulltekst (pdf)
    fulltext
  • 19.
    Ali, Remen
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Issa, Yaser
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Återanvändning av byggnadsmaterial: En fallstudie om Andersberg förskola i Gävle2021Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta arbete är grundad på byggnadsmaterialåterbruk. Syftet med arbetet är att reda ut vilka byggnadsmaterial och inventarier som kan återanvändas vid ombyggnation av Andersbergsgården förskola i Gävle, samt betrakta lönsamheten hos dessa byggnadsmaterial eller inventarier om de skulle selektivt rivas, lagras och sedan återanvändas. Genom en litteraturstudie i början av arbetet samt kontakt med de berörda företagen har både ny information (utöver litteraturen) och resultat formulerats. Litteraturstudien visar att 95% av byggnadsmaterial kan återvinnas. Denna procent överensstämmer om byggnaden inte innehåller farliga ämnen i konstruktionen och är i dåligt skick.I studien presenteras några av de hinder som föreligger för ett mer omfattande användande av återbrukade material. Exempel på detta är att säkerställa garantier och kvaliteter för materialen. Det har visat sig att kostnaden för den traditionella rivningen är generellt högre än den selektiva rivningen. Det som kan lagras och återanvändas är till exempel dörrar eftersom de är i bra skick.Till slut kan det sägas att alla konstruktionsmaterial i Andersbergsgården förskola går att återvinna förutom betong och värmeisolering, detta är på grund av att betongen har haft fuktproblem och isoleringen är för gammal för att återvinnas.

    Fulltekst (pdf)
    fulltext
  • 20.
    Ali, Sabir
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Building Information Modelling for Energy Analysis and Environmental Assessment: The comparison of LEED and Miljöbyggnad for two school buildings in Gävle, Sweden2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The building sector is one of the largest energy consumers and there are global efforts toward sustainable and energy-efficient new buildings and existing buildings retrofit. The application of Building Information Modelling (BIM) in environmental assessment was practiced and studied following the increasing number of projects adopting the BIM workflows and pursuing green building certifications. The interest of this thesis is to study the use of different Building Information Modelling tools used globally for energy and environmental assessment to examine their practical benefits and challenges. Case studies of two primary school buildings that achieved the Swedish Miljöbyggnad system were used to compare what could have been achieved with Leadership in Energy and Environmental Design (LEED) categories of energy and atmosphere and indoor environmental quality to what has been achieved in similar Miljöbyggnad areas. A review and summary of energy and atmosphere and indoor environmental categories in the LEED version 4 user’s guide is presented to evaluate the case study potential score in them.

    The early adoption of modeling in the evaluation from the conceptual design is the best approach to achieve better performance. It will improve the way of working and result in a more efficient and sustainable building.

    The Building Information Modelling software can be used directly in assessment using the integrated modules within the popular authoring tools such as Revit’s lighting and Insight the cloud base service or by transferring the model data to a stand-alone tool like IDA-ICE. The energy plug-ins of the authoring tools such as Revit are still lacking full control over the analytical model and the limited input options.

    The identified and discussed advantages of Building Information Modelling implementation are collaboration, accuracy, time, and cost saving. Data exchange issues, knowledge, and the differences in assessment tools were discussed as implementation barriers.

    Although the full comparison of certification systems is difficult, the comparison between the potential LEED score and achieved Miljöbyggnad rating showed some differences and similarities in the rating systems. The comparison requires rearranging the rating system indicators into unified categories. The framework that compares the scope, structure, content, and aggregation, would give a meaningful comparison. The way that the LEED and Miljöbyggnad are rewarding the indicators and the aggregation of aspects towards the final rating is totally different.

    Fulltekst (pdf)
    fulltext
  • 21.
    Ali, Shara
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Khatibi, Farida
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Påbyggnad av våningsplan ovanför befintligt höghus: En fallstudie inom förtätning av storstäder2022Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I hela landet expanderas städerna alltmer till följd av ökad befolkningsmängd. Utvecklingen gerupphov till bostadsbrist och kräver större och modernare infrastruktur i städerna. Markytan behöverdå utnyttjas för etablering av ny infrastruktur och nya bostäder. Då markytan redan är begränsaduppstår ett dilemma i detta sammanhang. Vad ska prioriteras, produktionen av bostäder ellerutveckling av infrastruktur?

    Ett förslag på lösning till det avsedda problemet är att bostadsbristen kan täckas av ett specifiktkoncept där bostadsproduktionen inte kräver arbete på den begränsade markytan. Lösningen kallaspåbyggnad och innebär byggnation ovanför en befintlig byggnad. Man utnyttjar det fria utrymmetovanför byggnaden istället för att bygga i sidled - tillbyggnad - dvs. byggnation på marken.

    Detta examensarbete utgör en fallstudie om förtätning av befintliga höghus mha. påbyggnad. Specifiktprojekteringsskedet i byggprocessen för påbyggnad behandlas. I projekteringsskedet utreds bl.a.ämnena geoteknik, stadsplanering, arkitektur, miljö och konstruktionsteknik. Dessa ämnen studeras idenna fallstudie. Avsikten med forskningen är att mha. dessa utredda ämnen, klargöra varförpåbyggnad kan lösa urbana omständigheter som rådande bostadsbrist.Denna fallstudie är baserad på kvalitativ forskning. Insamling av vetenskapligt stoff har skett genombåde litteratursökning och webbaserad sökning.

    Fulltekst (pdf)
    fulltext
  • 22.
    Al-Obaidi, Mudhar A.
    et al.
    Technical Institute of Baquba, Middle Technical University, Baquba 32001, Iraq;Technical Instructor Training Institute, Middle Technical University, Baghdad 10074, Iraq.
    Rashid, Farhan Lafta
    Petroleum Engineering Department, College of Engineering, University of Kerbala, Karbala 56001, Iraq.
    Ameen, Arman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Kadhom, Mohammed
    Department of Environmental Science, College of Energy and Environmental Science, Al-Karkh University of Science, Baghdad 10081, Iraq.
    Mujtaba, Iqbal M.
    Department of Chemical Engineering, Faculty of Engineering and Informatics, University of Bradford, Bradford BD7 1DP, UK.
    Optimizing Reverse Osmosis Feed Spacer Design for Enhanced Dimethylphenol Removal from Wastewater: A Study of Hydrodynamics and Performance Indicators2024Inngår i: Water, E-ISSN 2073-4441, Vol. 16, nr 6, artikkel-id 895Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.

    Fulltekst (pdf)
    fulltext
  • 23.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    El Tayara, Khaled
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy Performance Evaluation of Historical Building2022Inngår i: Buildings, E-ISSN 2075-5309, Vol. 12, nr 10, artikkel-id 1667Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Retrofitting measures in old buildings aimed at reducing energy usage have become important procedures meant to counteract the effects of climate change and greenhouse gas emissions. The aim of this study is to evaluate energy usage, thermal comfort, and CO2 emissions of an old building by changing parameters such as building orientation, shading systems, location, low energy film application, and alternative energy supply in the form of a geothermal heat pump. When evaluating the buildings in terms of geographical location with or without applying the low energy film, the results show that the city of Gävle in Sweden requires the most heating energy, 150.3 kWh/m2∙year (B0) compared to Jakarta (L0), which requires 23.8 kWh/m2∙year. When examining the thermal comfort, cases B4 and L4 demonstrate the best results in their respective categories (B0–B4 are cases without low energy film and L0–L4 are cases with applied low energy film). The results for the CO2 emissions levels for B0–B4 and L0–L4 indicate that B4 has the highest value, 400 kg CO2 eq/year higher than B0, and L1 has the lowest value, 731 kg CO2 eq/year lower than B0. The economic feasibility study illustrates that the installation of a geothermal heat pump with at least a coefficient of performance of 4.0 leads to a shorter payback period than solely applying LEF.

    Fulltekst (pdf)
    fulltext
  • 24.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Elousa Ansa, Ibai
    Assessment of Thermal Comfort and Indoor Air Quality in Library Group Study Rooms2023Inngår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 5, artikkel-id 1145Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human performance and health are among the most relevant topics in the modern society, especially at young ages, when academic performance is indispensable. Thus, as humans spend most of their lifetime inside a building, thermal comfort and indoor air quality are an essential aspect of a room. The aim of the current study is to numerically evaluate the main thermal comfort parameters such as PMV and PPD as well as indoor air quality, i.e., CO2 concentration, in library group study rooms at the University of Gävle in Sweden. Rotroninc Measurement Solutions CL11 sensors were utilized for temperature measurements. Simulation models were created and validated based of building data as well as temperature measurements. Several simulations were conducted throughout a year, covering different periods. The results show that even though the ventilation system, with only temperature control, works as intended for maintaining the thermal comfort, the CO2 concentration rises above 1000 ppm when more than one student occupy the rooms, which is not recommended by different thermal comfort ruling institutions. Consequently, a modification to the ventilation system control is recommended, changing it from temperature control to CO2 and temperature control.

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    fulltext
  • 25.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Reducing energy usage in multi-family housing2019Inngår i: 2019 9th International Conference on Future Environment and Energy 9–11 January 2019, Osaka, Japan, Institute of Physics Publishing (IOPP), 2019, Vol. 257, artikkel-id 012030Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The energy usage in residential sector have been around 22% of the total energy use in the world and increasing due to the population growth and higher living standards. The energy sources for this are made up primarily of non-renewable energy resources which generates a large amount of global greenhouse gases. A lot of countries have implemented various regulations and rules to reduce the energy usage in buildings and promoting the use of renewable energy technologies. This paper presents a parametric study of a typical multi-family building in its pre-design stage. The climate location used is Sweden (Gothenburg) and Japan (Osaka). The aim of the study is to compare various configurations and to examine how they affect the energy use. The most interesting configurations are the use of heat pump and solar cells. Other configurations that are examined are infiltration levels, pressure coefficients, wind impact, ventilation with heat recovery, ventilation scheduling, building orientation and finally changing U-values in the building material. Results of this study show that the energy saving, by utilizing a heat pump and solar panels, can reduce the total energy use by 34.9% for Gothenburg and 32% for Osaka. The results also show that the difference in total energy use between the two cities reduce substantially (3% difference) when utilizing a heat pump in combination with solar panels.

    Fulltekst (pdf)
    fulltext
  • 26.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Numerical investigation of indoor thermal comfort and air quality for an office equipped with corner impinging jet ventilation2023Inngår i: Advances in Building Energy Research, ISSN 1751-2549, E-ISSN 1756-2201, Vol. 17, nr 5, s. 578-604Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the feasibility of using only corner impinging jet ventilation (CIJV) for heating and cooling a medium-sized office space with two occupants while maintaining adequate indoor thermal comfort and air quality compared to traditional mixing ventilation systems. This study examines what impact various outdoor temperatures, ranging from −15°C to 25°C, have on an office environment in terms of indoor thermal comfort and air quality. Three different workspace positions were evaluated. The results show that the CIJV system meets the ASHRAE thermal comfort standards for all three positions. In terms of indoor air quality, CIJV performs better than traditional mixing systems, with improved mean age of air and ACE values. This study concludes that CIJV can be used both close and far away from the supply inlets and still provide adequate indoor thermal comfort and air quality during both cooling and heating season.

    Fulltekst (pdf)
    fulltext
  • 27.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment: Heating Mode2019Inngår i: Energies, E-ISSN 1996-1073, Vol. 12, nr 10, artikkel-id 1835Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

    Fulltekst (pdf)
    fulltext
  • 28.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode2019Inngår i: Energies, E-ISSN 1996-1073, Vol. 12, nr 7, artikkel-id 1354Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

  • 29.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yamasawa, Haruna
    Kyushu University, Fukuoka, Japan.
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan.
    Numerical investigation of the flow behavior of an isothermal corner impinging jet for building ventilation2022Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 223, artikkel-id 109486Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The corner impinging jet concept has been proposed as a new air distribution system for use in office environments. The present paper reports the mean flow field behavior of an isothermal corner-based turbulent impinging jet in a room. A detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed using three turbulence models. RNG k−ε model was chosen for this study. This study investigates the influence different configuration parameters such as jet discharge height, diffuser geometry (shape and size) and supply airflow rate have on the flow field. The results show that the diffuser geometries used in this study had in general a minor effect on the velocity developments along the centerline of the floor, maximum velocity decay and jet spreading rate except for some specific cases. When evaluating the triangle geometry cases, the results show that all the cases with volume flow <20 L/s are able to meet Boverket's building regulations velocity requirement both for summer and winter. The applicability evaluation show that the results can be considered for room sizes between ≈25 and 100 m2. In addition, the wall confinement effect (90° vs. 180°) is having a significant impact on the maximum velocity decay for corner impinging jet ventilation. In the regression analysis the results shows that the distance along the diagonal centerline of the room has the most impact on the evaluation of maximum velocity decay and jet spreading rate.

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  • 30.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yamasawa, Haruna
    Osaka University, Japan..
    Kobayashi, Tomohiro
    Osaka University, Japan..
    Karimipanah, Taghi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy saving, indoor thermal comfort and indoor air quality evaluation of an office environment using corner impinging jet ventilation2023Inngår i: Developments in the Built Environment, ISSN 2666-1659, Vol. 15, artikkel-id 100179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of a corner based impinging jet ventilation system (CIJV) in an office environment was evaluated numerically. The evaluation was done both in terms of the local thermal comfort and the local indoor air quality. Three different inlet configurations were tested for a range of outdoor temperatures that included both winter and summer conditions. In terms of indoor air quality, the results showed that CIJV performed better than a traditional mixing system. The study also revealed that CIJV creates a stronger temperature stratification in summertime compared to wintertime. When evaluating the energy saving potential the results showed a possible reduction of 7% for the ventilation flowrate when the outdoor temperatures were between -15 °C and -5 °C, 8 % when the outdoor temperatures were between 0 °C and 10 °C and 9 % when the outdoor temperatures were between 15 °C and 25 °C.

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    fulltext
  • 31.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Choonya, Gasper
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment2019Inngår i: Buildings, E-ISSN 2075-5309, Vol. 9, nr 7, artikkel-id 169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.

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    fulltext
  • 32.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Boström, Hanna
    Lindelöw, Hanna
    Assessment of Thermal Comfort and Air Quality in Office Rooms of a Historic Building: A Case Study in Springtime in Continental Climate2023Inngår i: Buildings, E-ISSN 2075-5309, Vol. 13, nr 1, artikkel-id 156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the most important aspects of working in an office environment is ensuring that the space has optimal thermal comfort and an indoor environment. The aim of this research is to investigate the thermal comfort and indoor climate in three office rooms located at one of the campus buildings at the University of Gävle, Sweden. The evaluated period is in the month of April during springtime. During this period, parameters such as temperature, relative humidity, CO2, supply air flow rate, and room air velocities are measured on site. The results of the measurement show that the indoor temperature is on average lower in the rooms facing north, at 21–23.5 °C, compared to the rooms facing south, which reach high temperatures during sunny days, up to 26 °C. The results also show that the ventilation air supply rate is lower than the requirement for offices in two of the office rooms. The ACH rate is also low, at ≈ 1 h−1 for all the rooms, compared to the required levels of 2–4 h−1. The CO2 levels are within the recommended values; on average, the highest is in one of the south-facing rooms, with 768 ppm, and the maximum measured value is also in the same room, with 1273 ppm for a short period of time.

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    fulltext
  • 33.
    Ameen, Arman
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Yamasawa, Haruna
    Kyushu University, Fukuoka, Japan..
    Kobayashi, Tomohiro
    Osaka University, Osaka, Japan..
    Numerical Evaluation of the Flow Field of An Isothermal Dual-Corner Impinging Jet for Building Ventilation2022Inngår i: Buildings, E-ISSN 2075-5309, Vol. 12, nr 10, artikkel-id 1767Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The corner impinging jet ventilation is a new air distribution system for use in office environments. This study reports the mean flow field behavior of dual isothermal corner-placed inlets based on an impinging jet in a square-shaped room with the size of 7.2 m × 7.2 m. A detailed numerical study is carried out to evaluate the influence the different configuration parameters, such as the inlet placement, same side or opposite side, and supply airflow rate, have on the flow field. The results show that the highest velocity peak for all cases is obtained at x = 0.5 m and the lowest at x = 3.5 m. The velocity profiles development remains similar when increasing the flow rate. For the zone evaluation, the results show that Case 1 and 2 (V = 20 L/s) meet the requirement of not exceeding 0.15 m/s during the heating season in the occupied zone according the BBR standard both for same-side and opposite-side configurations. For Case 4, the optimal placement of the inlets is opposite to each other when V = 30 L/s for the BBR requirements. Case 1, 2, 3, 4, 5, and 7 all meet the requirement of not exceeding 0.25 m/s during the cooling season both for the same-side and opposite-side configurations. For Case 8, the optimal placement of the inlets is opposite to each other when V = 50 L/s.

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    fulltext
  • 34.
    Andersson, Emelie
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Aziz, Shniar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    En jämförelse mellan gröna-, metall- och gråa tak för ett oisolerat parkeringshus utifrån dess olika temperaturer och dagvattenhantering2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Since climate change increases and changes constantly, it contributes to higher average temperatures, ice melting and has a great impact on our ecosystem. This will then lead to a warmer climate, which means increased precipitation and milder winters. One of the reasons to climate change is urbanization, meaning people moving to the cities. To succeed in changing the climate, international cooperation and common goals are required. At the northern part of Brynäs, in the municipality of Gävle, work is currently in progress around the area where the factory of Läkerol was once standing. The area continues to be rebuilt and the outcome will eventually be called Godisfabriken. There, amongst other, a car park will be built for the newly built homes. The aim of this study is to compare metal roofs, grey concrete roofs and green roofs within the two aspects of stormwater management and temperature. Then analyse which alternative of these three roofs would be most advantageous for the car park of Godisfabriken.

     

    The focused roofs are green, metal and concrete. A green roof is when it's completely or partly covered by a layer of vegetation and metal roofs are different sheet roofs with steel and aluminium-zinc. Grey roofs are made of concrete which works as both floor and ceiling. A building's roof affects which air temperature the surroundings has with its slope, vegetation and surrounding buildings. Another problem with urbanization and a warmer climate is stormwater management, which means rain and melted snow from roofs, parking areas and other hard surfaces.

     

    The method includes a literature study and calculations. The literature study gave research on temperature for all roofs as well as stormwater management for green roofs. Calculations were made for stormwater management and temperature with its flow, absorption, reflectance and heat transfer.

     

    The literature study and the calculations showed that green roofs have a high SRI value of 80 while the remaining roof is at around 40. The higher SRI, the lower surface temperatures on the material. This is proven in both methods when green roofs according to the literature study received a maximum surface temperature of 38 °C and 48 °C. According to the literature study green roofs can preserve more than 50 % of the rainwater. They also had a water flow rate of 1.97 l/s, which is less than half of what the metal roof got in the calculations. Since green roofs had both low air and surface temperatures, as well as longer drainage times and most absorbed water, green roofs are a more suitable choice than metal and grey concrete.

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  • 35.
    Andersson, Harald
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    An Investigation Concerning Optimal Design of Confluent Jet Ventilation with Variable Air VolumeManuskript (preprint) (Annet vitenskapelig)
  • 36.
    Andersson, Harald
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Numerical and experimental study of confluent jets supply device with variable airflow2019Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent years, application of confluent jets for design of ventilation supply devices has been studied. Similarly, numerus studies have been made on the potential and application of variable air volume (VAV) in order to reduce the energy demand of ventilation systems. This study investigates the combination of supply devices based on confluent jets and VAV, both in terms of the nearfield flow behavior of the device and the impact on thermal comfort, indoor air quality and energy efficiency on a classroom-level space when the airflow rate is varied.

    The method used in this study is an experimental field study where the confluent jets-based supply devices were compared to the previously installed displacement ventilation. The field study evaluated the energy efficiency, thermal comfort and indoor air quality of the two systems. In the case of the confluent jets supply devices, airflow rate was varied in order to see what impact the variation had on the performance of the system for each airflow rate. Furthermore, the confluent jets supply devices were investigated both experimentally and numerically in a well insulated test room to get high resolution data on the particular flow characteristics for this type of supply device when the airflow rate is varied. The results from the field study show nearly uniform distribution of the local mean age of air in the occupied zone, even in the cases of relatively low airflow rates. The airflow rates have no significant effect on the degree of mixing. The thermal comfort in the classroom was increased when the airflow rate was adapted to the heat load compared to the displacement system. The results lead to the conclusion that the combination of supply devices based on confluent jets can reduce energy usage in the school while maintaining indoor air quality and increasing the thermal comfort in the occupied zone.

    The results from the experimental and numerical study show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for different airflow rates.

    The results from both studies show that the airflow rate does not affect the distribution of the airflow on both near-field and room level. The distribution of air is nearly uniform in the case of the near-field results and the room-level measurement shows a completely uniform degree of mixing and air quality in the occupied zone for each airflow rate. This means that there is potential for combining these two schemes for designing air distribution systems with high energy efficiency and high thermal comfort and indoor air quality.

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  • 37.
    Andersson, Harald
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Optimization of confluent jets ventilation with variable airflow2022Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent years, applications of confluent jets for design of ventilation supply devices have been widely studied. Similarly, numerous studies have been made on the potential and application of variable air volume (VAV) in order to reduce the energy demand of ventilation systems. This study investigates the combination of confluent jets ventilation (CJV) and VAV, both in terms of the near-field flow behavior of the device and the impact on thermal comfort, indoor air quality and energy efficiency in conference room and classroom environments when the airflow rate is varied. For the investigation of CJV with VAV in a classroom environment two experimental studies were performed. One was a field study in a school classroom with a constant supply temperature and four cases with varying heat loads and airflow rates. The other took place in a laboratory environment with five cases, all with varying heat loads, supply temperatures and airflow rates. The two experimental studies measured mean age of air, air speeds and temperatures in the occupied zone. Both studies showed that CJV had higher energy efficiency and indoor air quality than conventional mixing ventilation. The main effects of lower supply temperatures were higher velocities in the occupied zone as well as lower temperatures due to higher energy efficiency . CJV produces mixing ventilation conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. The thermal comfort was similar to that of conventional mixing ventilation and had very small temperature gradients compared to displacement ventilation. For the investigation of CJV with VAV in a conference room environment three combined experimental and numerical studies were performed. One focused on the jet velocity profiles from the CJV supply device, the results of which were used as boundary conditions for the two other studies. The second study measured the conditions in the confluent jet development area and the occupied zone experimentally for six cases with different supply temperatures, airflow rates and nozzle matrix configurations. The results were used for validating the numerical model which was used in the last paper. The final paper was a parametric numerical study which used the response surface method to investigate the impact of four design variables: heat load, number of nozzles, airflow rate and supply temperature on energy efficiency, indoor air quality and thermal comfort. The results show that indoor air quality is increased with higher airflow rates. The energy efficiency has a negative correlation to the heat load but a positive correlation to the airflow rate which results in relatively stable heat removal effectiveness of 110% as heat load is increased and the VAV system compensates with higher airflow rates. The results also show that in a VAV system which aims at providing  uniform temperatures in the occupied zone, the thermal comfort is mostly dependent on a combination of the CLO value and the range of the airflow rates. At low CLO values the range of the airflow rate needs to be increased to create a satisfactory thermal climate.

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  • 38.
    Andersson, Harald
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Linköpings universitet.
    A numerical and experimental investigation of a confluent jets ventilation supply device in a conference room2022Inngår i: Energies, E-ISSN 1996-1073, Vol. 15, nr 5, artikkel-id 1630Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, confluent jets ventilation (CJV) supply devices with three different nozzle arrays (1 × 19, 2 × 19, 3 × 19) were investigated both numerically and experimentally at two different airflow and supply air temperature set-ups. The performance of the CJV supply devices was investigated concerning thermal comfort, indoor air quality (IAQ), and heat removal effectiveness in a conference room environment. A comparison between the experimental and numerical results showed that the v2−f model had the best agreement out of the investigated turbulence models. The numerical results showed that the size of the array had a great impact both on near-field development and on the conditions in the occupied zone. A larger array with multiple rows and a lower momentum conserved the inlet temperature and the mean age of the air better than a single-row array with a higher momentum. A larger array with multiple rows had a higher IAQ and a greater heat removal effectiveness in the occupied zone because the larger array conserved the mean age of air better and the buoyancy driven flow was slightly better at removing the heat. Because of the lower inlet velocities, they also had lower velocities at ankle level, which decreased the risk of draft and thermal discomfort.

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  • 39.
    Andersson, Harald
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Linköping Universitet.
    An Investigation Concerning Optimal Design of Confluent Jets Ventilation with Variable Air Volume2023Inngår i: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This  parametric study aims to predict the  performance of confluent jets ventilation (CJV) with variable air  volume (VAV) from four  CJV  design parameters. A  combination of  computational fluid dynamics (CFD), and response surface method (RSM) has  been used to  predict the  energy efficiency, thermal comfort and  IAQ  for  the  four  expected vital  design variables, i.e.,  heat load (XH),  number of  nozzles (XN),  airflow rate  (XQ) and  supply temperature (XTS).  The  RSM was  used to  generate a  quad-ratic  equation for  the  response variables exhaust temperature (TE),  sup-ply  temperature (TP),  PMV, DR, eT and  ACE. The  RSM  shows that  the  TE, TP and PMV were independent of the number of nozzles. The proposed equations were used to  generate setpoints optimized for  thermal com-fort  (PMV) for  summer, spring and  winter cases with different CLO  fac-tors  and  different TS under a  scenario where the  heat load varied between 10-30W/m2.  TE was  used as  setpoint to  regulate the  airflow rate  to  keep the  PMV values close to  zero. The  results show that  by adapting the TS to the CLO factor both thermal comfort and the energy efficiency can  be  improved. Further energy reduction can  be  gained by downregulating the airflow rate to keep the TP at a fixed setpoint when the  heat load is  decreased. This  means that  a  CJV  can  effectively be combined with VAV  to  improve environmental performance with good thermal comfort (-0.5<PMV <0.5,  DR <20%), above average IAQ (ACE = 106%) and  with a  higher heat removal efficiency (eT = 110%) than conventional mixing ventilation

  • 40.
    Andersson, Harald
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Kabanshi, Alan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik. Linköpings universitet.
    On the ventilation performance of low momentum confluent jets supply device in a classroom2020Inngår i: Energies, E-ISSN 1996-1073, Vol. 13, nr 20, artikkel-id 5415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of three different confluent jets ventilation (CJV) supply devices was evaluated in a classroom environment concerning thermal comfort, indoor air quality (IAQ) and energy efficiency. The CJV supply devices have the acronyms: high-momentum confluent jets (HMCJ), low-momentum confluent jets (LMCJ) and low-momentum confluent jets modified by varying airflow direction (LMCJ-M). A mixing ventilation (MV) slot jet (SJ) supply device was used as a benchmark. Comparisons were made with identical set-up conditions in five cases with different supply temperatures (TS) (16–18 °C), airflow rates (2.2–6.3 ACH) and heat loads (17–47 W/m2). Performances were evaluated based on DR (draft rating), PMV (predicted mean vote), ACE (air change effectiveness) and heat removal effectiveness (HRE). The results show that CJV had higher HRE and IAQ than MV and LMCJ/LMCJ-M had higher ACE than HMCJ. The main effects of lower Ts were higher velocities, DR (HMCJ particularly) and HRE in the occupied zone as well as lower temperatures and PMV-values. HMCJ and LMCJ produce MV conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. LMCJ-M had 7% higher HRE than the other CJV supply devices and produced non-uniform conditions at lower airflow rates (<3.3 ACH). The non-uniform conditions resulted in LMCJ-M having the highest energy efficiency of all devices.

    Fulltekst (pdf)
    fulltext
  • 41.
    Andersson, Martin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Jonsson, Andreas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Nyström, Niklas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Insvällning av olimmade och limmade trädymlingar2019Independent thesis Basic level (degree of Bachelor), 180 hpOppgave
    Abstract [sv]

    Trä är ett förnybart material till skillnad mot många andra byggnadsmaterial. Andelen trä inom byggnadsindustrin kan ökas genom att använda trädymlingsförband som ett substitut till skruvar och spikar. Skruvar och spikar tillverkas av metaller, vilka inte är förnybara material. Tillverkningsprocessen av metallbaserade material är mer energikrävande än den för trämaterial och har därför en större inverkan på vår miljö.Syftet med studien var att undersöka vidhäftningskapaciteten hos trädymlingsförband, olimmade och limmade av träslagen bok och furu. Fastsättningen av de olimmade trädymlingarna gjordes med insvällning. Insvällning innebar i studien att trädymlingarna först torkades, vartefter de placerades i en regel i inomhusklimat. Trädymlingarna strävade därefter att uppnå fuktkvotsjämvikt vilket medförde svällning. Vidhäftningskapaciteten för trädymlingsförband bör kunna konkurrera med utdragskapaciteten för till exempel spik för att vara praktiskt användbart.Trycktester har genomförts i laborationssalen i hus 45 på Högskolan i Gävle för att fastställa trädymlingarnas kraftupptagningsförmåga. Trycktesterna genomfördes i en drag- och tryckmaskin av modellen Shimadzu AG-X. Resultaten av testerna har sedan jämförts med den teoretiska utdragskapaciteten för spik. Karakteristiska hållfasthetsvärden har beräknats utifrån trycktestsresultaten.Resultatet av studien visar att endast de limmade trädymlingarna kan konkurrera med utdragskapaciteten hos spik. Limmade trädymlingar kan därför vara ett substitut till spik. Karakteristiska hållfasthetsvärden för limmad bok och limmad furu är 5,2 kN respektive 4,3 kN.

    Fulltekst (pdf)
    Insvällning av olimmade och limmade trädymlinga r
  • 42.
    Andersson, Michael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Jonsson, Axel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Strorheter vid bedömning av energieffektivitet för byggnader: En fallstudie för indikator 1 och 3, Miljöbyggnad 3.12021Independent thesis Basic level (university diploma), 180 hpOppgave
    Abstract [en]

    Sweden uses a large amount of energy within the housing and services sector and there is a greatneed to reduce the energy usage & heat demand of buildings. Using environmental certifications it ispossible to reward buildings that are dimensioned for lower energy usage and low heat demand fromrequirements demanded by the Swedish National Board of Housing, Building and Planning(Boverket). Miljöbyggnad 3.1 (Swedish Green Building Council) Indicator 1 Heat demand is todayassessed in relation to the inside enclosing area of the building, W/m2,Aoms, while Indicator 3 Energyusage is assessed in relation to heated floor area, kWh/m2,Atemp. Previous research indicates that thesequantities do not take into account how well the building is used but only how well it is dimensionedin terms of construction technology. Therefore it might be appropriate to introduce a quantity thattakes into account how well the building is used.

    The purpose of this case study is to raise a discussion if Boverket and Miljöbyggnad 3.1 today usessuitable quantities when it comes to grade energy efficient building and how different quantities cancome and affect a grading.

    This research presents a case study where an elementary- and a preschool using IDA ICE-modelsevaluates based on simulations for energy usage and heat demand. The results from the simulationsare compiled in diagrams to be able to see how different cases affect the grading based on whichquantities are being used. The quantities that are being used in this study is based on previousresearch and the different cases have been made to see which parameters affect the quantities.

    The study shows that depending on what is considered to be an energy efficient building, differentquantities may be applied for the assessment. The quantities used today in Miljöbyggnad 3.1 forIndicator 1 Heat demand and Indicator 3 Energy usage favors different types of buildings.kWh/m2,Aoms favors buildings with higher floor heights while kWh/m2,Atemp favors buildings withlower floor heights.

    Fulltekst (pdf)
    fulltext
  • 43.
    Andersson, Nils
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Lindberg, Samuel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Dynamisk energieffektivisering med hjälp av elektrokroma fönster i ett svenskt klimat: En fallstudie av en simulerad kontorslokal med geografisk variabilitet.2022Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Det används stora mängder energi inom kontorslandskap för att reglera inomhusklimatet. Intresset har ökat för energisparande åtgärder både politiskt och privat. För kontorsbyggnader är fönster en stor andel av klimatskärmen vilket har en stor påverkan på värme- och kylvärmeenergin som tillförs in i kontorsbyggnaden.

    Elektrokroma fönster kan, genom att skicka en spänning till ett av fönstrets skikt, aktivt förändra sina egenskaper för att steglöst begränsa solinstrålning i en byggnad.   

    Denna fallstudie är framtagen för att undersöka var och hur elektrokroma fönster kan användas för att effektivisera inomhusklimatet, med betoning på kylbehov, i Sverige.

    Undersökningen gjordes genom att göra flertal simuleringar på en kontorslokal i IDA ICE där lokalen simuleras på olika orter. Orter varieras från norr till söder och från kust till inland. Fönsterfasaden simulerades även i olika väderstreck.

    Resultaten visar att användning av tekniken sänker inkommande värmeenergi genom fönster med runt 60 procent oavsett på omgivande medeltemperatur. Därför motiveras användandet bäst på sydliga fasader och vid orter nära kust eller stora vatten där solvärmelasten är som störst.

     

    Fulltekst (pdf)
    fulltext
  • 44.
    Arana, Eneko
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Energy improvement options for a small-scale brewery: a literature study2022Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    In the age of technology and development in which we live nowadays, it is inevitable to realise that this so-called progress is translated into pollution, damage to the environment and abuse of energy and fossil fuels. The companies and factories that produce the goods we need, use a lot of energy and pollute in massive ways, posing dilemmas such as how to make these companies more energetically and environmentally efficient, with the aim of decreasing the emissions and energy use. This literature review proposes a compilation and update of suggestions made to microbreweries after undergoing an energy audit, in an attempt to make these companies more energy-efficient, competitive, economical and sustainable. The information has been obtained by searching peer-reviewed articles in different databases and re-arranged in this article into sections on energy efficiency measures, waste treatment options and environmental impact. Several studies have been carried out on improving efficiency and trying to decrease the environmental impact of beer production processes. The main issues found during the process are energy efficiency and the generated wastewater. Both problems could be solved either by using an internal boiler that would generate less waste, applying renewable energies or by treating the residues in bioreactors, a field that needs further study. The choice of packaging material will be influenced by customer preferences and material recycling, being glass bottles and aluminium cans the most popular choices. 

    Fulltekst (pdf)
    fulltext
  • 45.
    Archakis, Viktor
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    The Design of a Passive House2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    About 25 % of the total buildings in the European Union have been categorized as ”old buildings”. Followed the recent strickt rules for carbon emissions reduction, each house has to approximetely cut 20 % of CO2 by 2020. Countries like England, have taken the issue very seriously and planning to reduce the carbon emissions by 30 % until the end of 2020 and by an extra 80 % by 2050 (Francis Moran, 2014). The aim of the report is to present how a traditional house can be retroffited into a passive house and also to identify the key points that every passive house should have. For the purpose of the project an avtual house, based in Gävle, was provided and all the simulations are based on actual data. The initial design of the house which was used for the simulation and the 3D design, was provided by the house owner. The building was built in 1953, information regarding the current insulation of the house was provided by the owner as well. For the simulations and the 3D design a software know as IDA ICE was used, license and access to the software were given by the University of Gävle. The report simulates the current house and compares the results with two possible scenarios that are reducing the energy demand of the house. Furthermore, the possible ways and tools that could be used to reduce the energy demand of the house and cost estimation for the retrofitting is available in the paper.The first simulations were occured on the actual house, the first retrofitting package introduces new simulations based on new insulation materials, like wood and cement, that are placed mainly on the roof and on the outer walls. Also, the thickness have changed, thus the new insulations are thicker.Moreover, the second and final retrofitting package, introduces an HVAC system, which is a standard system. The aim is to achieve further energy demand reductions and prove that simple and basic changes can improve the quality of living and reduce CO2 emissions.After the completition of the first analysis, a reduction equal to 60 % and after the addition of the HVAC a further 20 % reduction achieved.

    Fulltekst (pdf)
    fulltext
  • 46.
    Arnal Estelles, Paloma
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Hand drying in public places: Paper towel vs warm air blower, which is best from an energy and environmental point of view.2023Independent thesis Advanced level (degree of Master (Two Years)), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 47.
    Attia, Shady
    et al.
    Université de Liège, Belgium.
    Benzidane, Caroline
    Grenoble INP University of Grenoble Alpes, France.
    Rahif, Ramin
    Université de Liège, Belgium.
    Amaripadath, Deepak
    Université de Liège, Belgium.
    Hamdy, Mohamed
    Norwegian University of Science and Technology (NTNU), Norway.
    Holzer, Peter
    Institute of Building Research & Innovation, Vienna, Austria.
    Koch, Annekatrin
    Darmstadt University of Technology, Germany.
    Maas, Anton
    University of Kassel, Germany.
    Moosberger, Sven
    Equa Solutions AG, Switzerland.
    Petersen, Steffen
    Aarhus University, Denmark.
    Mavrogianni, Anna
    University College London, United Kingdom.
    Maria Hidalgo-Betanzos, Juan
    University of the Basque Country UPV/EHU, Spain.
    Almeida, Manuela
    University of Minho Department of Civil Engineering, Portugal.
    Akander, Jan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Khosravi Bakhtiari, Hossein
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Kinnane, Olivier
    University College Dublin, Dublin, Ireland.
    Kosonen, Risto
    Aalto University, Finland.
    Carlucci, Salvatore
    Overheating calculation methods, criteria, and indicators in European regulation for residential buildings2023Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 292, artikkel-id 113170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the ongoing significance of overheating calculations in the residential building sector, building codes such as the European Energy Performance of Building Directive (EPBD) are essential for harmonizing the indicators and performance thresholds. This paper investigates Europe's overheating calculation methods, indicators, and thresholds and evaluates their ability to address climate change and heat events. e study aims to identify the suitability of existing overheating calculation methods and propose recommendations for the EPBD. The study results provide a cross-sectional overview of twenty-six European countries. The most influential overheating calculation criteria are listed the best approaches are ranked. The paper provides a thorough comparative assessment and recommendations to align current calculations with climate-sensitive metrics. The results suggest a framework and key performance indicators that are comfort-based, multi-zonal, and time-integrated to calculate overheating and modify the EU's next building energy efficiency regulations. The results can help policymakers and building professionals to develop the next overheating calculation framework and approach for the future development of climate-proof and resilient residential buildings.

  • 48.
    Awn, Rim Fares
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Corona, Jaqueline
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Hur mogen är marknaden för klimatsmart betong och dess aktörer?2020Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Carbon dioxide emissions have long proven to be one of the greenhouse gases that affect our planet's climate and environment. With the upcoming EU targets and Sweden's own net zero targets, the construction and real estate sector is required to work with climate-smart materials to construct the buildings of the future. The net zero target for year 2045 requires a joint pool of power from all companies to find innovative solutions to reduce carbon dioxide emissions.

    The purpose of this study was to investigate how conscious and active the construction and real estate sector is for climate-smart concrete through a survey and comparison of different typ of concretes EPDs. The work aims to investigate how far the development has taken place and to investigate how the market has adopted the new products that are available. The purpose was also to investigate which alternative additives are most common and the advantages and disadvantages of the climate-smart concrete. Climate smart is a term for concrete that contains a lower percentage of Portland cement clinker than the traditional concrete.

    A questionnaire was created to answer the purpose of the study. The survey sent out involved questions about how companies view the new environmental target for year 2045. As well as investigating how the construction and real estate sector works together to achieve the goal of reducing carbon dioxide emissions by 85% less than in year 1990. A comparison was made between three different EPDs of climate-smart concrete and two reference concrete with ordinary Portland cement clinker. Reference concrete one is a standard value derived from previous studies made and reference concrete two is an EPD value. This was done to investigate the amount of carbon dioxide they emit at the production stage. A reference building was used to calculate the amount of concrete. The result shows that the comparison between reference concrete one with the standard value and the three climate-smart concrete from Svensk Betong, Betongindustrin and Swerock gives a carbon dioxide reduction of 29.3%. And the comparison with reference concrete two with the associated EPD value received a percent climate reduction of only 2.8%.

    The future will require the construction and real estate industry to invest time and training to work with climate-smart concrete. More in-depth work could be explored and mapped as to which are the major obstacles in construction projects. How companies can work to get the entire value chain to work together for a climate-smart thinking and primarily to get the developer to invest in improved concrete with less climate impact.

    Fulltekst (pdf)
    A. Rim & C. Jaqueline - Klimatsmart betong
  • 49.
    Awoyera, Paul O.
    et al.
    Covenant University, Ota, Nigeria.
    Akin-Adeniyi, Ayomide
    Covenant University, Ota, Nigeria.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Bendezu Romero, Lenin M.
    Universidad Cesar Vallejo, SJL, Lima, Peru.
    Structural performance of fire-damaged concrete beams retrofitted using bamboo fiber laminates2024Inngår i: Results in Engineering (RINENG), ISSN 2590-1230, Vol. 21, artikkel-id 101821Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fire-induced damage is a serious threat to the structural integrity of reinforced concrete (RC) beams, necessitating an effective retrofitting strategy to restore and improve their performance. This study investigates the structural performance of fire-damaged RC beams retrofitted with bamboo fiber laminates. A comprehensive analysis was performed, incorporating degradation rules to quantify the effect of temperature on both the load-carrying capacity and ultimate deflection of the RC beams. Eight conventionally designed and reinforced RC beams were tested, with two serving as controls. The remaining six beams were tested in pairs at three different temperatures (400 C, 600 C, and 800 C) for 2-h exposure, with one beam featuring the bamboo fiber laminates in each pair. The bamboo fiber laminates enhanced the load-carrying capacity and deflection of the fire-damaged beams when subjected to incremental loading until failure. The deflection was improved by 48.78% at 400 C, restoring the load-carrying capacity to control levels. The load-carrying capacity was increased by 29.5% at 600 C, while the deflection was restored by 39.37%. The load-carrying capacity was enhanced by 37% at 800 C, while the deflection was improved by 4.83%. According to the findings, bamboo fiber laminate is a viable alternative to synthetic fibers for retrofitting fire-damaged beams.

    Fulltekst (pdf)
    fulltext
  • 50.
    Awoyera, Paul O.
    et al.
    Covenant University, Ota, Nigeria.
    Althoey, Fadi
    Najran University, Najran, Saudi Arabia.
    Bahrami, Alireza
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Apuye, Pius U.
    Covenant University, Ota, Nigeria.
    Bendezu R, L.M.
    Ricardo Palma University, Lima, Peru.
    Alotaibi, Badr S.
    College of Engineering, Najran, Saudi Arabia.
    Meza, Jesus M.P.
    Ricardo Palma University, Lima, Peru.
    Abuhussain, Mohammed A.
    College of Engineering, Najran, Saudi Arabia.
    Structural retrofitting of RC slabs using bamboo fibre laminate: Flexural performance and crack patterns2024Inngår i: Heliyon, E-ISSN 2405-8440, Vol. 10, nr 2, artikkel-id e23999Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Enhancing the durability of structural elements is a viable approach to promote sustainability in civil engineering. Research has shown that well-maintained slabs outperform degraded ones, which deteriorate rapidly due to insufficient upkeep. The occurrence of cracking and deformation in slabs subjected to sustained loads significantly impacts their functionality. However, the implementation of appropriate retrofitting techniques utilizing locally available materials can effectively minimize deflection and crack propagation while also improving flexural capacity. This particular study aimed to evaluate the flexural performance of slabs that were retrofitted using bamboo fibre laminate (BFL). Also, the study investigated two alternative replacement methods alongside the conventional mix; one involved replacing all fine aggregates with ceramic fine aggregate and the other involved a complete replacement of coarse aggregates with ceramic coarse aggregate. These mixes were represented in both the retrofitted and non-retrofitted samples. The retrofitting process included using the combined external bonding and near surface-mounted method. Twelve slab samples were made, with six being non-retrofitted and the other six retrofitted with BFL. Each of the samples had dimensions of 300 mm × 300 mm × 50 mm for reinforced concrete (RC) slabs. The slabs were tested employing the three point-bending system, and the retrofitted slabs with the conventional mix exhibited the highest ultimate failure load and flexural strength (62.1 kN), which compared to the non-retrofitted slabs of the same mix was a 60.76% increase. Additionally, the study did a thorough analysis of the presence of flexural and diagonal shear cracks, as well as the occurrence of debonding between BFL and the slabs. Non-destructive tests were also conducted on the slab samples to further confirm accurate results. These findings offer helpful insights into the development and application of a sustainable retrofitting material that can remarkably improve RC slabs.

    Fulltekst (pdf)
    fulltext
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