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  • 151.
    Chen, Huijuan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Linköpings universitet, Energisystem.
    Experimental and numerical investigations of a ventilation strategy – impinging jet ventilation for an office environment2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A well-functioning, energy-efficient ventilation system is of vital importance to offices, not only to provide the kind of comfortable, healthy indoor environment necessary for the well-being and productive work performance of occupants, but also to reduce energy use in buildings and the associated impact of CO2 emissions on the environment. To achieve these goals impinging jet ventilation has been developed as an innovative ventilation concept.

    In an impinging jet ventilation system, a high momentum of air jet is discharged downwards, strikes the floor and spreads over it, thus distributing the fresh air along the floor in the form of a very thin shear layer. This system retains advantages of mixing and stratification from conventional air distribution methods, while capable of overcoming their shortcomings.

    The aim of this thesis is to reach a thorough understanding of impinging jet ventilation for providing a good thermal environment for an office, by using Computational Fluid Dynamics (CFD) supported by detailed measurements. The full-field measurements were carried out in two test rooms located in a large enclosure giving relatively stable climate conditions. This study has been divided into three parts where the first focuses on validation of numerical investigations against measurements, the second addresses impacts of a number of design parameters on the impinging jet flow field and thermal comfort level, and the third compares ventilation performance of the impinging jet supply device with other air supply devices intended for mixing, wall confluent jets and displacement ventilation, under specific room conditions.

    In the first part, velocity and temperature distributions of the impinging jet flow field predicted by different turbulence models are compared with detailed measurements. Results from the non-isothermal validation studies show that the accuracy of the simulation results is to a great extent dependent on the complexity of the turbulence models, due to complicated flow phenomena related to jet impingement, such as recirculation, curvature and instability. The v2-f turbulence model shows the best performance with measurements, which is slightly better than the SST k-ω model but much better than the RNG k-ε model. The difference is assumed to be essentially related to the magnitude of turbulent kinetic energy predicted in the vicinity of the stagnation region. Results from the isothermal study show that both the SST k-ω and RNG k-ε models predict similar wall jet behaviours of the impinging jet flow.

    In the second part, three sets of parametric studies were carried out by using validated CFD models. The first parametric study shows that the geometry of the air supply system has the most significant impact on the flow field. The rectangular air supply device, especially the one with larger aspect ratio, provides a longer penetration distance to the room, which is suitable for industrial ventilation. The second study reveals that the interaction effect of cooling ceiling, heat sources and impinging jet ventilation results in complex flow phenomena but with a notable feature of air circulation, which consequently decreases thermal stratification in the room and increases draught discomfort at the foot level. The third study demonstrates the advantage of using response surface methodology to study simultaneous effects on changes in four parameters, i.e. shape of air supply device, jet discharge height, supply airflow rate and supply air temperature. Analysis of the flow field reveals that at a low discharge height, the shape of air supply device has a major impact on the flow pattern in the vicinity of the supply device. Correlations between the studied parameters and local thermal discomfort indices were derived. Supply airflow rates and temperatures are shown to be the most important parameter for draught and stratification discomfort, respectively.

    In the third part, the impinging jet supply device was shown to provide a better overall performance than other air supply devices used for mixing, wall confluent jets and displacement ventilation, with respect to thermal comfort, heat removal effectiveness, air exchange efficiency and energy-saving potential related to fan power.

  • 152.
    Chen, Huijuan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Linköpings universitet.
    Janbakhsh, Setareh
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Linköpings universitet.
    Larsson, Ulf
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Linköpings universitet.
    Numerical investigation of ventilation performance of different air supply devices in an office environment2015Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 90, s. 37-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to compare ventilation performance of four different air supply devices in an office environment with respect to thermal comfort, ventilation efficiency and energy-saving potential, by performing numerical simulations. The devices have the acronyms: Mixing supply device (MSD), Wall confluent jets supply device (WCJSD), Impinging jet supply device (IJSD) and Displacement supply device (DSD). Comparisons were made under identical set-up conditions, as well as at the same occupied zone temperature of about 24.2°C achieved by adding different heat loads and using different air-flow rates. Energy-saving potential was addressed based on the air-flow rate and the related fan power required for obtaining a similar occupied zone temperature for each device. Results showed that the WCJSD and IJSD could provide an acceptable thermal environment while removing excess heat more efficiently than the MSD, as it combined the positive effects of both mixing and stratification principles. This benefit also meant that this devices required less fan power than the MSD for obtaining equivalent occupant zone temperature. The DSD showed a superior performance on heat removal, air exchange efficiency and energy saving to all other devices, but it had difficulties in providing acceptable vertical temperature gradient between the ankle and neck levels for a standing person. 

  • 153.
    Chen, Huijuan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Comparing k-ε models on predictions of an impinging jet for ventilation of an office room2011Inngår i: Roomvent 2011 / [ed] Vojislav Novakovic, Sten Olaf Hanssen, Hans Martin Mathisen, tapir academic press , 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The objective of this study is to compare the performance of different k-ε models, i.e. the Standard k-ε, the Renormalization Group (RNG) k-ε, and the Realizable k-ε, with a two-layer model for the prediction of the mean velocity field and the temperature pattern from a newly designed impinging jet supply device for ventilation of an office room. The numerical predictions are validated against the detailed experimental measurements.

    The experimental investigation was performed in a test room with the dimensions 4.2×3.6×2.5 m, as a mock-up of a single-person office. Detailed velocity and temperature field measurements including the comfort zone and the jet developing region along the floor were carried out. The in-house made single-sensor hot-wire probe and the thermocouple are measuring instruments used to investigate the mean velocity, turbulence intensity and temperature. The boundary conditions for Computational Fluid Dynamics (CFD) study are obtained from the same set-up measurement.

    The results mainly consist of the flow field presentation, i.e., the velocity and temperature profiles in the comfort zone and the jet developing region along the floor. The comparisons between the results from the three versions of the k-ε models and measurements show generally satisfactory agreement, and better consistency is observed at the free jet region and the wall jet region that farther from the impingement zone. Among the three tested turbulence models, RNG shows the best overall performance.

  • 154.
    Chen, Huijuan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Computational investigation on the factors influencing thermal comfort for impinging jet ventilation2013Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 66, s. 29-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Impinging jet ventilation (IN) has been proposed to achieve an effective ventilation of an occupied zone in office and industrial buildings. For IJV systems, draught discomfort is the issue of most concern since it supplies cooled air directly to the occupied zone. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with IJV. The factors considered were: shape of air supply device, discharge height, supply airflow rate and supply air temperature. The Response Surface Methodology (RSM) was used to identify the level of the significance of the parameters studied, as well as to develop the predictive models for the local thermal discomfort. Computational fluid dynamics (CFD) was employed to perform a set of required studies, and each simulation condition was determined by the Box-Behnken design (BBD) method. The results indicated that at a low discharge height, the shape of air supply device had a major impact on the flow pattern in the vicinity of the supply device because of the footprint from impinging jet, which consequently affected the draught risk level in the occupied zone. A square-shaped air supply device was found to result in lower overall draught discomfort than rectangular and semi-elliptic shapes. The RSM analysis revealed that the supply airflow rate had a significant impact on the draught discomfort, while the shape of air supply device and discharge height had moderate effects. The temperature stratification in the occupied zone was mostly influenced by the supply air temperature within the range studied.

  • 155.
    Chen, Huijuan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Division of Energy Systems, Department of Management and Engineering, Linköping University.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Investigation on the flow and thermal behavior of impinging jet ventilation systems in an office with different heat loads2013Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 59, s. 127-144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the flow and temperature field within an office using impinging jet ventilation (IJV) under different heat loads ranging from 17 to 65 W per square meter floor area. The measurement was carried out in a full-scale test room to verify the reliability of three turbulence models, i.e., the RNG k-epsilon, SST k-omega and (nu(2)) over bar - f models. It is found that all the tested models show good agreements with measurements, while the (nu(2)) over bar - f model shows the best performance, especially on the overall temperature prediction. The (nu(2)) over bar - f model is used further to investigate a number of important factors influencing the performance of the IJV. The considered parameters are: cooling effect of chilled ceiling, external heat load as well as its position, number of occupants and supplied air conditions. The interaction effect of chilled ceiling and heat sources results in a complex flow phenomenon but with a notable feature of air circulation. The appearance and strength of the air circulation mainly depends on the external heat load on window and number of occupants. It is found that with higher external heat load on window (384 W and 526 W), the air circulation has a strong tendency towards the side wall in the opposite direction to occupant, while with lower power on window (200 W) the air circulation has a strong tendency in the center of the room and extends to a larger area. When two occupants are present, two swirling zones are formed in the upper region. The effects of air circulation consequently alter the temperature field and the level of local thermal comfort.

  • 156.
    Chen, Huijuan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Moshfegh, Bahram
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Cehlin, Mathias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik.
    Numerical investigation of the flow behavior of an isothermal impinging jet in a room2012Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 49, s. 154-166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impinging jet concept has been proposed as a new ventilation strategy for use in office and industrial buildings. The present paper reports the mean flow field behavior of an isothermal turbulent impinging jet in a room. The detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed by means of the RNG k-ε and SST k-ω model. The comparisons between the predictive results and the experimental data reveal that both of the tested turbulence models are capable of capturing the main qualitative flow features satisfactorily. It is found that the predictions from the RNG k-ε model predicts slightly better of the maximum velocity decay as jet approaching the floor, while the SST k-ω model accords slightly better in the region close to the impingement zone.

    Another important perspective of this study is to investigate the influence of different flow and configuration parameters such as jet discharge height, diffuser geometry, supply airflow rate and confinement from the surrounding environment on the impinging jet flow field with the validated model. The obtained data are presented in terms of the jet dimensionless velocity distribution, maximum velocity decay and spreading rate along the centerline of the floor. The comparative results demonstrate that all the investigated parameters have certain effects on the studied flow features, and the diffuser geometry is found to have the most appreciable impact, while the supply airflow rate is found to have marginal influence within the moderate flow range. 

  • 157.
    Chen, Lan
    et al.
    School of Amopheric Sciences, Sun Yat-sen University, HaiZhu, Guangzhou, China.
    Hang, Jian
    School of Amopheric Sciences, Sun Yat-sen University, HaiZhu, Guangzhou, China.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Claesson, Leif
    Högskolan i Gävle, Akademin för teknik och miljö, BMG-labbet.
    Di Sabatino, Silvana
    Department of Physics and Astronomy - DIFA, ALMA MATER STUDIORUM - University of Bologna, Bologna, Italy.
    The Influence of Building Packing Densities on Flow Adjustment and City Breathability in Urban-like Geometries2017Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 198, s. 758-769Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    City breathability refers to the air exchange process between the flows above and within urban canopy layers (UCL) and that of in-canopy flow, measuring the potential of wind to remove and dilute pollutants, heat and other scalars in a city. Bulk flow parameters such as in-canopy velocity (Uc) and exchange velocity (UE) have been applied to evaluate the city breathability. Both wind tunnel experiments and computational fluid dynamics (CFD) simulations were used to study the flow adjustment and the variation of city breathability through urban-like models with different building packing densities. We experimentally studied some 25-row and 15-column aligned cubic building arrays (the building width B=72 mm and building heights H=B) in a closed-circuit boundary layer wind tunnel. Effect of building packing densities (λp=λf=0.11, 0.25, 0.44) on flow adjustment and drag force of each buildings were measured. Wind tunnel data show that wind speed decreases quickly through building arrays due to strong building drag. The first upstream building induces the strongest flow resistance. The flow adjustment length varies slightly with building packing densities. Larger building packing density produces lower drag force by individual buildings and attains smaller velocity in urban canopy layers, which causes weaker city breathability capacity. In CFD simulations, we performed seven test cases with various building packing densities of λp=λf=0.0625, 0.11, 0.25, 0.36, 0.44 and 0.56. In the cases of λp=λf=0.11, 0.25, 0.44, the simulated profiles of velocity and drag force agree with experiment data well. We computed Uc and UE, which represent horizontal and vertical ventilation capacity respectively. The inlet velocity at 2.5 times building height in the upstream free flow is defined as the reference velocity Uref. Results show that UE/Uref changes slightly (1.1% to 0.7%) but Uc/Uref significantly decreases from 0.4 to 0.1 as building packing densities rise from 0.0625 to 0.56. Although UE is induced by both mean flows and turbulent momentum flux across the top surface of urban canopy, vertical turbulent diffusion is found to contribute mostly to UE.

  • 158.
    Chen, Lan
    et al.
    School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, PR China.
    Hang, Jian
    School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, PR China; Institute of Earth Climate and Environment System, Sun Yat-sen University, Guangzhou, PR China.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Claesson, Leif
    Högskolan i Gävle, Akademin för teknik och miljö, BMG-labbet.
    Di Sabatino, Silvana
    University of Bologna, Bologna, Italy.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    The impacts of building height variations and building packing densities on flow adjustment and city breathability in idealized urban models2017Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 118, s. 344-361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Improving city breathability has been confirmed as one feasible measure to improve pollutant dilution in the urban canopy layer (UCL). Building height variability enhances vertical mixing, but its impacts remain not completely explored. Therefore, both wind tunnel experiments and computational fluid dynamic (CFD) simulations are used to investigate the effect of building height variations (six height standard deviations σH = 0%–77.8%) associated to building packing densities namely λp/λf = 0.25/0.375 (medium-density) and 0.44/0.67 (compact) on city breathability. Two bulk variables (i.e. the in-canopy velocity (UC) and exchange velocity (UE)) are adopted to quantify the horizontal and vertical city breathability respectively, which are normalized by the reference velocity (Uref) in the free flow, typically set at z = 2.5H0 where H0 is the mean building height. Both flow quantities and city breathability experience a flow adjustment process, then reach a balance. The adjustment distance is at least three times longer than four rows documented in previous literature. The medium-density arrays experience much larger UC and UE than the compact ones. UE is found mainly induced by vertical turbulent fluxes, instead of vertical mean flows. In height-variation cases, taller buildings experience larger drag force and city breathability than lower buildings and those in uniform-height cases. For medium-density and compact models with uniform height, the balanced UC/Uref are 0.124 and 0.105 respectively, moreover the balanced UE/Uref are 0.0078 and 0.0065. In contrast, the average UC/Uref in height-variation cases are larger (115.3%–139.5% and 125.7%–141.9% of uniform-height cases) but UE/Uref are smaller (74.4%–79.5% and 61.5%–86.2% of uniform-height cases) for medium-density and compact models. 

  • 159.
    Chenyuan, Diao
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Xiaoyang, Li
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Solar Heating Industry in China and Sweden2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 160.
    Chilo, Johannes
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Heinola, Niina
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Luftomsättningsmätning med avklingningsmetoden: fältmätningar med CO2 som spårgas.: Studie i en 3-plansvilla med självdragsventilation.2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna uppsats redovisar ett resultat från en studie gjord på uppdrag av villaägare till ett hus från 1972 med självdragsventilation. Utifrån dialog med villaägarna har det framkommit att de misstänker att ventilationen inte är tillräcklig. Om ventilationen inte fungerar som avsett kan det uppstå hälsoproblem för människor, genom ökade halter av fukt och luftföroreningar. Boverket ställer krav på en lägsta luftomsättning på 0,5 oms/h uteluftsflöde, 0,35 l/s per m2 vid ny- och ombyggnation. Syftet med studien är att ta fram luftomsättning och CO2-halt med hjälp av avklingningsmetoden och CO2 som spårgas. Syftet är också att sammanställa vilka lagkrav, riktlinjer och rekommendationer som gäller för luftomsättning och luftflöde inomhus. Studien är begränsad till avklingningsmätningar i villans boarea. Avklingningsmetoden utfördes i fyra sovrum, två WC och ett badrum; samtliga försedda med en frånluftsventil. WC, badrummen och ett av sovrummen uppnådde det rekommenderade kravet på luftomsättning. Sovrummet med lägst omsättning uppnådde inte rekommendationen troligen på grund av horisontell och längre luftkanal. Sovrum, med frånluftskanal intill den varma kanalen från kaminen fick snabbare luftomsättning när det eldades i kaminen. Det andra sovrummet, med frånluftkanalen i skorstenen, men isolerad från den varma kanalen från kaminen, fick ingen märkbar ökning av luftomsättning. Datainsamling av temperatur, relativ fukthalt och CO2-halt mättes i fyra sovrum under två nätter, en natt med stängd dörr och en natt med helt öppen dörr. Luftkvalitén blev bättre med öppen än med stängd dörr nattetid. CO2-halten uppnådde inte några skadliga halter på tack vare sovrummens stora volymer. Avklingningsmetoden på totala boarean fick avbrytas på grund av att homogen omblandning av CO2 i luften inte kunde uppnås. Studien visar att självdragssystem är känsliga för väderförhållanden. Husets luftomsättning uppnådde inte rekommendationerna. I studieobjektet är frånluftsventiler är placerade i sovrum och därmed felaktigt placerade enligt Boverket och Folkhälsomyndigheten. De rekommenderar att tilluftsventiler tillför frisk luft i rum där människor vistas mest, exempelvis sovrum och vardagsrum. Rekommendationer till villaägarna är att inte förhindra ventilationssystemets flöde vid ombyggnationer. Exempelvis vid fönsterbyte bör fönsterventiler med tilluft installeras för att öka tilluftsflödet. Ventilationssystem bör ses över av en fackman om en konvertering till ett mekaniskt ventilationssystem är möjlig för att säkerställa en god och hälsosam inomhusmiljö. För att öka utomhusluftstillförseln bör vädring utföras regelbundet. Vi rekommenderar framtida studier att utföra mätningar under längre perioder och under olika årstider.

  • 161.
    Chith, Hussein
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik. Chalmers tekniska högskola.
    Den tillgängliga stationen: Gestaltning av en stationsmiljö på basis av tillgänglighet2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This report is about accessibility in a station environment. Studies have been made about how an accessible building should be designed. Accessibility is an important issue when striving for a society with equality as the foundation. Sweden is one of the most accessible countries when speaking about the built environment. A result of prosperity and a well-managed democracy. In spite of this there’s still a lot to do and in some areas the politics for disabled persons has major deficiencies. By continuing to strive against improvements Sweden could actually develop into one of the countries that sets the standard for the rest. Clearer directives from the European Union and the Swedish government during the last years has lead into several new laws and regulations about the design of the built environment. In this report studies have been done about how to attain an accessible surrounding with the focus on the environment in station-buildings. The station that has been studied is Nils Ericsson terminal in Gothenburg, Sweden. The aim has been to highlight good solutions for accessibility and to detect areas where it could be done in a different or perhaps better way. This type of studies is hard to do for a person without any disabilities since there, most often, is an obvious lack of personal relations to the issues. Therefore studies about different types of disabilities and a deeper understanding for the exposed people has been very important for the progression of the work. It has also laid the foundation for understanding the laws and the regulations around accessibility. The results showed that the studied terminal obviously had been designed with a wide thought about making it accessible. There were several solutions for helping the ones in need, for example distinctly marked patterns on the floor. Also, the actions for accessing the terminal had been done with great notice to the surrounding architecture since very few things stood out in contrast. The discussion is mostly about how the different solutions actually worked and fulfilled their purpose.

  • 162.
    Chung, Juyeon
    et al.
    Faculty of Engineering Sciences, Kyushu University, Fukuoka, Japan.
    Lim, Eunsu
    Faculty of Science and Engineering, Toyo University, Tokyo, Japan.
    Sandberg, Mats
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Ito, Kazuhide
    Faculty of Engineering Sciences, Kyushu University, Fukuoka, Japan.
    Returning and net escape probabilities of contaminant at a local point in indoor environment2017Inngår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 125, s. 67-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The quantified recirculation of a contaminant in a local domain is an essential property of the ventilation efficiency in a room. The returning probability of a contaminant (α) generated in a local domain and its net escape probability (NEP) are essential information for understanding the structure of the contaminant concentration distribution in a room and for controlling the indoor air quality. Here, we propose the fundamental definitions of α and NEP and discuss their potential relation with the net escape velocity (NEV) concept. NEP is defined at a local point and/or local domain as the probability that a contaminant is exhausted directly through an exhaust outlet and does not re-circulate to the target local point/domain again. In a computational fluid dynamics (CFD) simulation, the minimum local domain in a room corresponds to the control volume (C.V.) of discretization; hence, NEP in a C.V. is assumed as the probability in a point without volume. In this study, the calculation results of α, NEP, and NEV distributions in a simple two-dimensional model room and a three-dimensional room with push-pull type ventilation system are demonstrated and discussed.

  • 163.
    Chérif, Lobna
    et al.
    Royal Military College of Canada, Kingston, Canada.
    Wood, Valerie
    Royal Military College of Canada, Kingston, Canada.
    Marois, Alexandre
    École de psychologie, Université Laval, Québec, Canada.
    Labonté, Katherine
    École de psychologie, Université Laval, Québec, Canada.
    Vachon, François
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöpsykologi. École de psychologie, Université Laval, Québec, Canada.
    Multitasking in the military: Cognitive consequences and potential solutions2018Inngår i: Applied Cognitive Psychology, ISSN 0888-4080, E-ISSN 1099-0720, Vol. 32, nr 4, s. 429-439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multitasking-the performance of several tasks at the same time-is becoming increasingly prevalent in workplaces. Multitasking is known to disrupt performance, particularly in complex and dynamic situations, which is exactly what most military occupations entail. Because military errors can be consequential, the detrimental impact of multitasking on cognitive functioning in such contexts should be taken seriously. This review pertains to high-consequence military occupations that require strong multitasking skills. More specifically, it highlights cognitive challenges arising from different forms of multitasking and discusses their underlying cognitive processes. Because such challenges are not expected to diminish, this review proposes context-relevant solutions to decrease occupational workload, either by reducing the cognitive load ensuing from the to-be-performed tasks or by improving soldiers' multitasking abilities. To ensure effective implementation of these solutions, we stress the need to design context-adapted tools and procedures, and to guide human resource managers in developing particular strategies.

  • 164.
    Clark, Charlotte
    et al.
    University of London.
    Sörqvist, Patrik
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - tillämpad psykologi.
    A 3 year update on the influence of noise on performance and behavior2012Inngår i: Noise & Health, ISSN 1463-1741, E-ISSN 1998-4030, Vol. 14, nr 61, s. 292-296Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The effect of noise exposure on human performance and behavior continues to be a focus for research activities. This paper reviews developments in the field over the past 3 years, highlighting current areas of research, recent findings, and ongoing research in two main research areas: Field studies of noise effects on children's cognition and experimental studies of auditory distraction. Overall, the evidence for the effects of external environmental noise on children's cognition has strengthened in recent years, with the use of larger community samples and better noise characterization. Studies have begun to establish exposure-effect thresholds for noise effects on cognition. However, the evidence remains predominantly cross-sectional and future research needs to examine whether sound insulation might lessen the effects of external noise on children's learning. Research has also begun to explore the link between internal classroom acoustics and children's learning, aiming to further inform the design of the internal acoustic environment. Experimental studies of the effects of noise on cognitive performance are also reviewed, including functional differences in varieties of auditory distraction, semantic auditory distraction, individual differences in susceptibility to auditory distraction, and the role of cognitive control on the effects of noise on understanding and memory of target speech materials. In general, the results indicate that there are at least two functionally different types of auditory distraction: One due to the interruption of processes (as a result of attention being captured by the sound), another due to interference between processes. The magnitude of the former type is related to individual differences in cognitive control capacities (e.g., working memory capacity); the magnitude of the latter is not. Few studies address noise effects on behavioral outcomes, emphasizing the need for researchers to explore noise effects on behavior in more detail.

  • 165.
    Clark, Charlotte
    et al.
    Centre for Psychiatry, Barts, London School of Medicine, Queen Mary, University of London, London, United Kingdom.
    Sörqvist, Patrik
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - tillämpad psykologi.
    The influence of noise on performance and behavior - 3 year update2011Inngår i: Proceedings of the Institute of Acoustics, 2011, Vol. 33, s. 458-467Konferansepaper (Fagfellevurdert)
  • 166.
    Colding, Johan
    et al.
    Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; The Beijer Institute of Ecological Economics, Royal Academy of Sciences, Stockholm, Sweden.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden.
    An urban ecology critique on the "Smart City" model2017Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 164, s. 95-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this letter is to raise some critical concerns and gaps in the booming literature on Smart Cities; concerns that we think deserve greater attention from scientists, policy makers and urban planners. Using an urban ecology lens, we provide some reflections that need to forgo any wider-scale implementation of the Smart City-model with the goal to enhance urban sustainability. We discuss that the Smart City literature must better include analysis around social sustainability issues for city dwellers. Focus here should start on health issues and more critical analysis about whom the Smart City is for. Also, the literature must address issues of resilience and cyber security, including how Smart City solutions may affect the autonomy of urban governance, personal integrity and how it may affect the resilience of infrastructures that provide inhabitants with basic needs, such as food, energy and water security. A third major gap in this literature is how smart city developments may change human-nature relations. Focus here should start on how Smart City technologies may hinder or support children’s learning towards a stronger psychological connection with nature. Discussions are also needed on how the Smart City model may affect pro-environmental behavior more broadly.

  • 167.
    Colding, Johan
    et al.
    The Beijer Institute of Ecological Economics, The Royal Swedish Academy of Science; Stockholm Resilience Centre.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre.
    Resilience and Sustainable Development2017Inngår i: Dreams and Seeds: The role of campuses in sustainable urban development / [ed] Schewenius, M., Keränen, P., al Rawaf, R., Stockholm: Stockholm Resilience Centre and Metropolia University of Applied Sciences , 2017, 1, s. 28-29Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 168.
    Colding, Johan
    et al.
    The Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, Stockholm, Sweden; Stockholm Resilience Center, Stockholm University, Stockholm, Sweden.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Center, Stockholm University, Stockholm, Sweden.
    The Role of University Campuses in Reconnecting Humans to the Biosphere2017Inngår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 9, nr 12, artikkel-id 2349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we explore the potential for integrating university campuses in a global sustainability agenda for a closer reconnection of urban residents to the biosphere. This calls for a socio-cultural transition that allows universities and colleges to reconnect to the biosphere and become active stewards of the Earth System. Recognizing their pivotal role of fostering coming generations of humans, university campuses represent a unique socio-cultural setting to promote sustainable development in practice. Among others, this involves the nurturing of biodiversity and ecosystem services in the Antropocene era, which is characterized by ongoing climate change and massive loss of biodiversity and ecosystem services. We explore the traditional campus setting, its role as a community for rejuvenating town planning and its role as a governance authority that may promote or retard sustainable development with an ecological focus. We explore the “sustainable” university and describe the campus as an ecosystem and how a resilient campus can be designed to meet the novel and critical challenges of the Anthropocene. We conclude by providing some policy recommendations for higher educational institutes to speed up their ambitions in the area of sustainable biosphere management.

  • 169.
    Colding, Johan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Beijer Institute of Ecological Economics, Royal Academy of Sciences, Sweden.
    Colding, Magnus
    Colding Digital Teknik AB, Sweden.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre, Stockholm University, Sweden.
    The smart city model: A new panacea for urban sustainability or unmanageable complexity?2018Inngår i: Environment and Planning B: Urban Analytics and City Science, ISSN 2399-8083Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite several calls in this journal of debating the rapid growth of the literature on “smart cities”, such a debate has in large been absent. Smart cities are often un-critically launched as a sustainable way of developing cities. When cities become increasingly complex as its features are wired into the Internet, theories for their understanding is lagging behind. As it is prospected that a greater number of people and things will become connected by Information and Computer Technology, the complexity of urban systems will over time increase. Historical insights reveal that as complexity in societies increase, growth in energy consumption tends to follow. In this paper, we discuss whether complexity carried too far could lead to diminishing returns of energy saving and create unmanageable urban systems. As part of initiating such a debate, this commentary asks whether the smart cities development has a bearing on the issue whether a society can erode its capacity of sustaining itself? We pose this question against the backdrop that no one actually knows what type of society the smart cities model in the end will generate.

  • 170.
    Colding, Johan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Beijer Institute of Ecological Economics, Royal Academy of Sciences, Sweden.
    Colding, Magnus
    Colding Digital Teknik AB, Sweden.
    Barthel, Stephan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Stockholm Resilience Centre, Stockholm University, Sweden.
    The smart city model: A new panacea for urban sustainability or unmanageable complexity?2018Inngår i: Environment and Planning B: Urban Analytics and City Science, ISSN 2399-8083Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite several calls in this journal of debating the rapid growth of the literature on ‘‘smart cities’’, such a debate has in large been absent. Smart cities are often un-critically launched as a sustainable way of developing cities. When cities become increasingly complex as its features are wired into the Internet, theories for their understanding is lagging behind. As it is prospected that a greater number of people and things will become connected by Information and Computer Technology, the complexity of urban systems will over time increase. Historical insights reveal that as complexity in societies increase, growth in energy consumption tends to follow. In this paper, we discuss whether complexity carried too far could lead to diminishing returns of energy saving and create unmanageable urban systems. As part of initiating such a debate, this commentary asks whether the smart cities development has a bearing on the issue whether a society can erode its capacity of sustaining itself? We pose this question against the backdrop that no one actually knows what type of society the smart cities model in the end will generate.

  • 171.
    Compadre Senar, David
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Performance evaluation of a rooftop solar photovoltaic power plant in the Gävle Arenaby (Gävle, Sweden): Installation testing2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The current energy situation is taking a turn towards renewable energies, due to the new pacts to curb global warming. These agreements, together with governmental aid, are facilitating an escalation in the production and improvement of new energy systems and the price decrease due to a larger-scale production.

    Within these energy alternatives, solar energy is found, specifically the subject to be treated in this project is photovoltaic energy, due to its exponential growth in the last 10 years, new tools are being developed for its monitoring and modelling.

    Therefore, the main objective of this thesis is to develop a method  for installation testing of a PV-system. The method should give the installed nominal power of the system and show if the maximum power point trackers work as expected.

    A large PV-system was installed on the roof of Gävle Arenaby during 2017. A measurement system for monitoring of the power of the system and of the solar irradiance was installed.

    Different parameters have been taken into account for the adjustment of the model that vary the performance of the system. These factors are: the irradiance received, the module temperature and the angle of incidence.

    It has been concluded that the results obtained indicate a correct adjustment of the theoretical power against the real power, which means, a correct operation of the generated model. Besides, the expected power follows a linear trend, reaching the power set by the manufacturer for Standard Test Conditions. The results show that the monitored modules-strings fulffill the promised performance and the method for installation testing work as expected. The linear correlation between corrected power and irradiance means that the maximum power point tracker in the inverter works independent of the power.

  • 172.
    Contero, Francisco
    et al.
    University of Zaragoza.
    Gomes, João
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Gustafsson, Mattias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Karlsson, Björn O.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    The impact of shading in the performance of threee different solar PV systems2016Konferansepaper (Fagfellevurdert)
  • 173.
    Contero Salvadores, Jose Francisco
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Shadowing effect on the performance in solar PV-cells2015Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 174. Cooper, Ed
    et al.
    Etheridge, David
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Pressure Pulse Technique – A New Method for Measuring the Leakage of the Building Envelope of Churchesmms2011Konferansepaper (Fagfellevurdert)
  • 175.
    Cooper, Ed W
    et al.
    University of Nottingham, UK.
    Etheridge, David W
    University of Nottingham, UK.
    Mattsson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Wigö, Hans
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - installationsteknik.
    Measurement of the adventitious leakage of churches with a novel pulse technique2011Inngår i: Proc. Roomvent 2011: 12th International conference on air distribution in rooms / [ed] Hans Martin Mathisen, Trondheim, Norge: Tapir Akademisk Forlag , 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The University of Gavle is currently involved in a project on saving energy in historic buildings (churches). An important factor in the determination of the natural ventilation rate is the adventitious leakage of the envelope. Measurement of leakage is therefore a key feature of the investigations. It was decided to adopt a new technique developed at the University of Nottingham (UNott). It is a pulse technique compared to the conventional steady technique.

    The conventional technique consists of generating a steady and high pressure difference (50 Pa) across the envelope by means of a fan. Such pressures are rarely encountered in ventilation and this leads to errors in the low-pressure leakage. Furthermore the use of the conventional blower door technique in churches is difficult due to their large volume and the need to replace the doors.

    The underlying principle of the UNott technique is described and examples of results are given. The most important advantage of the Unott technique is that the leakage is determined at the low pressure differences that are encountered with ventilation e.g. 4 Pa. This is made possible primarily by the fact that the effects of wind and buoyancy at the time of the test are eliminated by taking account of the pressure variation before and after the pulse.

    For measurements in large buildings, a number of identical piston/cylinder units have to be operated simultaneously. The University of Gävle has developed a system whereby up to seven units can be used. Such a number is required for a leaky church and this is the first time this has been done.

  • 176.
    Cordeiro, Roberto
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Energy Storage System for Wind-Diesel Power System in Remote Locations2016Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The aim of this thesis is to show how much fuel can be saved in a power system based in diesel generators with integrated wind turbine (WDPS – Wind Diesel Power System) when a storage system is integrated. Diesel generator is still the most used power system for remote locations where the conventional grid doesn’t reach and its integration with wind turbine is seen as a natural combination to reduce diesel consumption. However, the wind intermittency brings some challenges that might prevent the necessary diesel savings to the level that justifies the integration with wind turbine. The introduction of a storage system can leverage the wind energy that would otherwise be wasted and use it during periods of high demand.The thesis starts by describing the characteristics of energy storage systems (ESS) and introducing the major ESS technologies: Flywheel, Pumped Hydro, Compressed Air and the four main battery technologies, Lead Acid, Nickel-Based, Lithium-ion and Sodium-Sulphur. The aim of this step it to obtain and compile major ESS parameters to frame then into a chart that will be used as a comparison tool.In the next step, wind-diesel power systems are described and the concept of Wind Penetration is introduced. The ratio between the wind capacity and diesel capacity determines if the wind penetration is low, medium and high and this level has a direct relation to the WDPS complexity. This step also introduces important concepts pertaining to grid load and how they are affected by the wind penetration.Next step shows the development of models for low, medium and high penetration WDPS with and without integrated ESS. Simulations are executed based on these models in order to determine the diesel consumption for each of them. The simulations are done by using reMIND tool.The final step is a comparative study where the most appropriated ESS technology is chosen based on adequacy to the system, system size and location. Once the technology is chosen, the ESS economic viability is determine based on the diesel savings obtained in the previous step.Since this is a general demonstration, no specific data about wind variation and consumer demand was used. The wind variation, which is used as the input for the wind turbine (WT), was obtained from a typical Weibull Distribution which is the kind of distribution that most approximate a wind pattern for long term data collection. The wind variation over time was then randomly generated from this distribution. The consumer load variation is based on a typical residential load curves. Although the load curve was generated randomly, its shape was maintained in conformity with the typical curves.This thesis has demonstrated that ESS integrated to WDPS can actually bring a reasonable reduction in diesel utilization. Even with a wind pattern with a low mean speed (5.31 m/s), the savings obtained was around of 17%.Among all ESS technologies studied, only Battery Energy Storage System (BESS) showed to be a viable technology for a small capacity WDPS. Among the four BESS technologies studied, Lead-Acid presents the highest diesel savings with the lower initial investment and shorter payback time.

  • 177.
    Crowley, Kieran
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energy mapping of public buildings: A study at Älvkarlebyhus2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The aim of this report is to identify all energy systems in the Skutskärs Vårdcentral and Folktandvården building, Centralgatan 12 building and the Library building to be studied in this report and carry out an investigation on whether the energy systems efficiency may be increased by improving on the elements or factors that affect the energy systems.

    A model of the buildings energy systems were created in Microsoft excels using the steady state method and modifying it to calculate an average heating session. Average monthly temperatures calculated over a thirty year period were used to calculate heat loss due to transmittance, infiltration and ventilation. Internal heat gains and losses were included in this model. Where calculation for heat gains or losses was to complex or the required data was not available rule of thumb was used.

    Once results were gained it was seen that the greatest area of loss of heat was from the building structure by transmittance of heat through the materials. An investigation was carried out to reduce the heat loss due to transmittance. Both solution involved adding insulation to the wall and top ceiling in both solution the insulation level was varied to show how much energy could be saved by varying the thickness of insulation. It was found in both solution that the energy saving ranged from 9% to 13%. Go to section 4.6 for details in improvements. Unfortunately quotes for material and labour for each method could not be obtained and without quotes a recommendation to which to invest in cannot be given. The Älvkarlebyhus management should use the areas of the external wall and ceiling area provided in appendix A to obtain quotes from respected companies in Sweden. The areas in appendix A should be double checked before looking for quotes to ensure accuracy in obtaining quotes. This was tried by the author but failed for the following reasons:

    • Companies would not respond to e-mails
    • Also when searching for Swedish companies online there web site was in Swedish and no English option to read the material on the site was available. Meaning the author could not gain the required information needed to calculate cost.

    The third solution involved lowering the internal temperature of the building. When the internal temperature was lowered to 17°C and 15°C reduction in energy usage by 10.95% and 16.82% was seen respectively.

    No other area where improvements could be carried out for the following reasons:

    • The heat pump combined with the district heating and the use of heat recovery devices makes the energy system providing heat for hot water and the heating system highly efficient. There are no improvement worth the financial cost and the interruption to the occupants of the buildings.
    • On Visual inspection the equipment was maintained to a high standard avoiding the need to create a maintenance schedule.
    • Insulation on pipes and ducts coming and going from plant rooms to the building were to a high standard. No repairs or improves are needed.
    • The lighting system is an area where energy can be reduced to justify the cost of installing more energy efficient lights and better controls. An experienced person should investigate this as it requires specify knowledge and experience to select the suitable lighting system to reduce cost. Implementing lights with the wrong controls system can cause poor lighting levels in the building and health problems such as headaches for the occupants. It may also increase the energy consumption of the building if the wrong lighting fixtures and controls were selected.

    A cheap and easily technique to implement would to advice the occupants of the building to turn off equipment and lights when are not needed. Hanging signs by exits of room as a reminder. This seems obvious but as the author carried out a visual inspection of the buildings concerned in this report it was noted that lights were left on in areas no one was to be seen. The same was seen for equipment such as computers.

    The insulation levels for the walls and ceiling should be increased to improve heat loss due to transmittance. Improving insulation would also decrease the heat loss due to infiltration. There is no reliable way of calculating the percentage of reduction as using the results from a pressure test is the only reliable way of calculating heat loss from infiltration once the improvements have been carried out. Also to compare before and after the improvements a pressure test would have to be done before any improvements are carried out to make an accurate comparison.

    The buildings in this report relies heavily on electricity for providing lighting, heating and ventilation. For this reasons it is recommended that a feasibility study be carried whether PV solar panels or wind turbines could produce electricity for the buildings studied in this report. The advantages and disadvantages of PV panels and wind turbines are covered in the conclusion section of this report.

    Älvkarlebyhus can be proud that the building in this thesis releases no CO2 or other harmful greenhouse gases as the greenhouses gases released from the production of the district heating system and electricity suppliers are taken into account by the suppliers of these energy sources. Making them an environmentally friendly building.

  • 178.
    Dahir, Mohamed
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Invändig eller Utvändig tilläggsisolering av ett flerbostadshus- LCC analys av optimal isoleringstjocklekar: Fallstudie på Sicksackvägen 39 i Gävle2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Stadsdelen Sätra som ligger 3 km norr om Gävle centrum uppfördes undermiljonprogrammet mellan 1960-1974. Det är enkelt och ta sig till och från Sätramed både fordon, cykel och till fots. AB Gavlegårdarna har tagit initiativ till attrenovera deras byggnadsbestånd som uppfördes under miljonprogrammet istadsdelen Sätra, däribland Sicksackvägen 39. Byggnaden har byggts 1969 ifunktionalistisk stil i närheten av Sätra Centrum.Syftet med denna studie var att undersöka den kostnadsoptimala isoleringstjocklenvid invändig eller utvändig tilläggsisolering av husets ytterväggar. Med hänsyn tillandra åtgärder som AB Gavlegårdarna vill genomföra vid renovering av denbefintliga byggnaden.För att genomföra denna studie har en okulärbesiktning, litteraturstudie,beräkningar, uppmätningar, undersökningar, samt energisimulering utförts. Därpåjämfördes lönsamheten vid tilläggsisolering med optimala isoleringstjocklekeninvändigt respektive utvändigt.Resultatet av denna studie visar att de komponenter i husets klimatskärm somläcker mest värme är ytterväggar och fönster. Med hänsyn taget till derenoveringsåtgärder som AB Gavlegårdarna ska genomföra blir den optimalaisoleringstjockleken invändigt är 45 mm och utvändigt 170 mm. Den åtgärd som germest lönsamhet är tilläggsisolering utvändigt med 170 mm mineralull i kombinationmed AB Gavlegårdarnas renoveringsåtgärder: fönsterbyte och uppgradering avventilationssystemet till FTX.

  • 179.
    Dahlberg, Håkan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    LCC på ventilationssystemet på en skola: en undersökning huruvida VAV eller CAV är mest ekonomiskt i längden2013Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Vid projektering idag ställs konstruktören ofta inför valet att projektera för antingen ventilation med konstanta flöden, eller med variabla flöden. Vidare kan även flödena varieras manuellt eller automatiskt. Det konstruktören måste ta hänsyn till är investeringskostnaden, men även potentiella energi- samt kostnadsbesparingar över tid. Många gånger är det svårt att veta hur energianvändningen påverkas av de olika systemvalen varför det är svårt att välja det mest optimala systemet.Detta arbete undersöker livscykelkostnaden, LCC, med nuvärdeskostnaden på en skola i Uppsala med tre olika system, antingen konstant ventilationsflöde, CAV med timer, manuellt styrd variabel ventilation, VAV, eller automatisk VAV med styrning på temperatur och CO2. Huvudanledningen till det är att skolor består av en mängd olika klassrum och lokaler som inte alltid används under skoltiden, risken finns alltså att skolan överventileras med ett traditionellt CAV. Johansson (2005) visade att VAV mycket väl vara ekonomiskt försvarbart just i skolor varför syftet med detta arbete är att se hur det föreligger i detta aktuella fall, och vilken av lösningarna som är mest ekonomisk.Skolan simuleras med programvaran VIP Energy 2.0.8, ett simuleringsprogram för energibalansberäkning, där de tre olika driftsfallen undersöks och hur energibehovet förändras men varierad ventilationsgrad. Även temperaturerna i klassrummen simuleras och beaktas. Kostnaderna för de olika installationerna presenteras där det visar sig mer avancerade system är betydligt dyrare. Den billigaste lösningen kostar 450 000 kr medan den dyraste kostar 680 000 kr. Vidare diskuteras kalkylräntan, energipris och energiprisförändringarna, och där används två olika kalkylräntor, 5 % och 10 %. Ett Sverigepris på energi presenteras, men även ett Europa-anpassat alternativ där elpriset antas dyrare. Realenergipriset antas öka med 3 % per år.Resultatet visar att de energivinster man gör med de mer avancerade variabla systemen som försvinner de på grund av de dyrare investeringskostnaderna. I vissa fall visar det som däremot att en manuell VAV styrning på ventilationen kan vara ekonomisk försvarbar.Ett problem som dock uppstår med sänkt ventilation under sommarhalvåret är innetemperaturer som överstiger de högstanivåer som Socialstyrelsen satt.

  • 180.
    Dahlberg, Merike
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Solvärmelastens, dagsljusfaktorns och det termiska klimatets inverkan med olika fönster för Miljöbyggnad: En studie på Kv. Svalan i Uppsala2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta examensarbete på 15 hp. har haft målet att kunna hitta en guide för planering av fönster för byggnader som ska certifieras med Miljöbyggnad. I certifieringsprocessen ingår beräkning av solvärmelasten, vilket ger en siffra på hur mycket solvärme som strålar in i byggnaden, som sedan kan behövas ventileras eller kylas bort under sommarhalvåret. I processen beräknas även dagsljusfaktorn, vilket ger en siffra på hur mycket dagsljus kommer in i byggnaden. Då dessa två aspekter påverkar negativt på varandra har olika tester gjorts med hjälp av olika datasimuleringar för att finna vilken fönsterarea skulle kunna vara lämplig för att få ett bra betyg i Miljöbyggnad. Här har även tester gjorts för det termiska klimatet, som är ytterligare en aspekt Miljöbyggnad ser på, och som fönstret kan påverka.

    För arbetet har en blivande kontorsbyggnad, Svalan i Uppsala, varit som mall för dessa tester. Då det finns väldigt många olika parametrar som behövs för att kunna göra alla simuleringar och uträkningar är det svårt att göra en guide som fungerar för alla projekt. I detta arbete finns två lika stora kontor som har fönster åt olika väderstreck och med olika g-värden, för att se skillnader på dessa har simuleringar gjorts för olika fönsterareor, och olika fönsterplaceringar. För simuleringarna har IDA 4 och Velux Daylight Visualizer använts.

    Arbetet resulterade i att fönstrets placering i rummet ger stor skillnad på dagljusfaktorn, och även för fönstrets utformning, dock ingen för solvärmelasten. För att påverka solvärmelasten kan glasarean i fönstret ändras, g-värdet, eller golvarean för rummet. När dessa parametrar verkar positivt för solvärmelasten, påverkar de negativt för dagsljusfaktorn, därför måste projektören hitta en bra nivå som fungerar för både solvärmelasten och dagsljusfaktorn.

    För projektet med två kontor i Svalan gav resultatet att få GULD i både solvärmelast och dagsljusfaktorn fungerar inte utan solavskärmning. Som bäst når den ena GULD och den andra SILVER, vilket kan i slutbetyget ändå räcka för att nå bästa betyget GULD med Miljöbyggnad, så länge de andra indikatorerna som Miljöbyggnad ser på är tillräckligt bra i projektet.

  • 181.
    Dahlbom, Jenny
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Massiva trägolv utan lim och skruv: En undersökning för företaget Setra i Valbo2006Independent thesis Basic level (university diploma), 10 hpOppgave
    Abstract [sv]

    Efter samtal med företaget Setra framkommer att de vill öka försäljningen av sina massiva trägolv. De tror att en förenkling av läggningsmomentet skulle öka försäljningen. I detta arbete har jag undersökt genom intervjuer med försäljare runt om i Sverige om de tror att det finns en marknad för sådana golv. Jag undersöker marknaden hur den ser ut idag och presenterar även ett nytt läggningsmoment för massiva trägolv.

  • 182.
    Dahlin, Linus
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Hedman, Marcus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Undersökning av värmeförluster genom kantbalk vid användning av golvvärme: En simuleringsundersökning i COMSOL Multiphysics2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I Sverige ställs allt högre krav på nya byggnader genom bestämmelser och lagar som påverkar energianvändningen. Byggnader kan värmas upp med hjälp av olika typer av distributionssystem såsom radiatorer och golvvärme. Värmebehovet hos byggnaden baseras på hur mycket värmeenergi som behövs för att uppnå termisk komfort. För att begränsa energianvändningen används isolering i syfte att minimera värmeförlusterna genom byggnadens klimatskärm.

    Denna undersökning syftar till att undersöka förluster som sker genom kantbalken vid användning av vattenburet golvvärmesystem och hur dessa förluster påverkas då grundkonstruktionen tilläggsisoleras på olika sätt. Kantbalken är den förstärkta del som finns under markplattan/platta på mark, tar upp krafter från bärande väggar och finns efter sidorna på byggnaden. Golvvärme är en uppvärmningsteknik där slingor placeras i grundkonstruktionen och förser byggnader med dess värmebehov. Golvvärmesystem installeras på olika sätt beroende på byggnaders förutsättningar och är ett energieffektivt uppvärmningssätt i kombination med värmepump.

    Undersökningen påbörjades genom att skapa en förenklad modell som behandlar en 2-dimensionell kantbalksutformning i COMSOL Multiphysics, som är ett program för modellering där statiska och dynamiska simuleringar genomförs i modeller med hjälp av finita-elementmetoden.

    Fyra modeller skapades med två olika CC-mått (centrumavstånd) och två olika golvmaterial. Därefter skapades tre fall med förbättrande åtgärder för att öka kantbalkens isolerförmåga. Dynamiska simuleringar genomfördes och hade tidsintervallet 365 dagar med varierande utetemperatur. När utetemperaturen varierade var effektbehovet hos golvvärmen olika vilket ledde till att golvvärmetemperaturen justerades efter utetemperaturen för att upprätthålla samma temperatur på golvytan.

    Resultaten visar att kantbalken står för cirka 50 % av markkonstruktionsförlusterna med installerat L-element. Vid komplettering av konstruktionen med två fall av tillläggsisolering framkom inga större förändringar i resultaten. Genom att byta ut L-elementet till ett U-element minskar dock värmeförlusterna genom kantbalken till ca 30 %. Markkonstruktionsförluster är de förluster som överförs från byggnaden till närliggande mark.

  • 183.
    Dahlström, Örjan
    et al.
    Linköpings universitet, Handikappvetenskap.
    Skagerstrand, Åsa
    Örebro University Hospital, Audiological Research Center.
    Lyxell, Björn
    Linköpings universitet, Handikappvetenskap.
    Thunberg, Per
    Örebro University, Department of Medical Physics.
    Sörqvist, Patrik
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöpsykologi.
    Lundin, Margareta
    Örebro University Hospital, Audiological Research Center.
    Johnsrude, Ingrid
    University of Western Ontario, School of Communication Sciences and Disorders.
    Rudner, Mary
    Linköpings universitet, Handikappvetenskap.
    Rönnberg, Jerker
    Linköpings universitet, Handikappvetenskap.
    Möller, Claes
    Örebro University Hospital, Audiological Research Center.
    Cognitive training and effects on speech-in noise performance in normal hearing and hearing impaired individuals2015Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Cognitive training might have potential to improve speech understanding under adverse listening conditions. Here, we have examined the effects of a 5-week computer-based cognitive training program on speech-in-noise-performance, in normal hearing (NH) participants and in participants with mild-to-moderate sensorineural hearing loss (HI).

    Two groups, matched on gender and age (45-65 years), of 20 participants each (HI and NH respectively) are recruited. Participants perform four test-sessions; inclusion (t0), five weeks (t1), ten weeks (t2) and six months (t3). Training is performed either between t0 and t1, or between t1 and t2 (using a cross-over design), using the computer-based Cogmed training program, approximately 30-40 minutes per day, five days per week, during five weeks. At each session participants are tested in three different ways: (a) cognitive testing (KIPS, SICSPAN, TRT); (b) auditory performance (pure tone-audiometry (air- and bone-conduction) and speech audiometry (HINT, Swedish SPIN-test (SNR +4dB))); (c) cortical activation (MR sessions where participants performed a speech-in-noise task using Hagerman-sentences with steady-state speech-spectrum noise (SSN) and with two competing talkers). MR imaging is performed on a Philips Achieva 1.5 Tesla scanner using a sparse imaging technique in which stimuli are presented during the silent period between successive scans. Participants listen to auditory stimuli under eight different conditions: clear speech, SSN or two competing talkers (each at 90%, 50% and 0% intelligibility), and silent rest. Pre- and post-training, hearing disability is assessed by the Speech-Spatial-Qualities-Questionnaire.

    The study is on-going and behavioral results as well as results from fMRI will be presented.

  • 184.
    Diez, Pablo
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik. EFFAB - Effektiv Energiåtervinning AB.
    Improvement of the energy efficiency of a drain water heat exchanger2015Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
  • 185.
    Dilan, Khazan
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Elewi, Susanna
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Kalkylarbete för byggnadsprojekt med Vico Office: För- och nackdelar med 5D BIM2015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Abstract

    Building Information Model/Modeling/Management (BIM) is a tool that allows for efficient working methods. BIM saves time and money while providing the potential for visualization. This method of working is based on a 3D-model, and then a fourth and fifth dimension are connected. 5D modeling means that a spreadsheet creates cost estimates based on the 3D model. This provides opportunities to carry out calculations in the early stages of the projects.

     

    Calculations are currently performed manually and do not contribute to the development that the construction industry requires. To examine the efficiency of 5D BIM, a comparison should be made with the traditional calculation method. The purpose of this study is to propose a more reliable quantity takeoff and to study the advantages and disadvantages of each method.

     

    The research questions to be studied in this thesis read as follows:

    •  How reliable is quantity takeoff with the help of Vico Office in contrast to traditional quantity takeoff?
    • What is required of a BIM model to perform a quantity takeoff in Vico Office?

     

    To create calculations manually, bills of quantities are performed with recipes for each building component and then price lists from recipe databases are used. With the 5D BIM, a spreadsheet is connected to the BIM model that generates price lists and calculations for each building component. Spreadsheet entries are created for the component that contain the right amount of information, that is then connected to the correct building component. Vico Office is a program that provides opportunities to import 3D models from CAD tools to then carry out timetables and calculations.

     

    Vico Office offers many advantages in contrast to the manual spreadsheet work in, among other things, time and cost. It is easy to handle and contributes to the development of BIM. It also contributes to increased communication between participants that makes it easier to handle delays. At the same time, the program needs new knowledge. The manual spreadsheet work gives uncertain calculations and the risk of measurement errors exist.

     

    To perform a complete quantity takeoff in Vico Office an architectural model and a construction model is required. It is also important to name the components in the model before it is imported to Vico Office. Vico Office gives more BIM, and it is easier to perform a quantity takeoff because all the tools are in one place. It is not possible to determine that it is actually more efficient with Vico Office because the building model was lacking in this study. 

     

    This thesis demonstrates the advantages of 5D BIM, but at the same time it requires an initiative of the companies to implement the system. This transition from manual spreadsheet work to 5D BIM can be complicated because it requires time and knowledge.

     

    Keywords: 5D BIM, Vico Office, Cost, Quantity Takeoff

  • 186.
    Djuric Ilic, Danica
    et al.
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Eriksson, Ola
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Ödlund, Louise
    Division of Energy Systems, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Åberg, Magnus
    Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    No zero burden assumption in a circular economy2018Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 182, s. 352-362Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A majority of previous studies on environmental problems caused by waste generation have focused on waste disposal issues without fully highlighting the primary reasons behind the problems. As a consequence, efforts to reduce these problems are usually directed towards the stakeholders that provide waste treatment and disposal instead of the stakeholders that contribute to waste generation. In order to detect connections between different problems of sustainability and to suggest measures which may contribute to their solutions, this study provides a simplified overview of the mechanisms behind waste generation and management. The results from the study show that the only way to eliminate problems of sustainability is to apply an upstream approach by dealing with the primary problems which occur in the early stages of the system (e.g. overconsumption of products, as well as use of finite resources, toxic materials, and non-recyclable materials). By dealing with these problems, the emergence of secondary problems would be prevented. Thereby, stakeholders who have the highest possibility to contribute to the sustainable development of the waste generation and management are the stakeholders from the origin of the product's life cycles, such as product developers, manufacturing companies, product users and policy makers. Different trade-off situations such as contradictions between economics, recyclability, energy efficiency, make it even harder to deal with issues of sustainability related to the system and to detect the stakeholders who may contribute to the development. One of the main conclusions from this study is that when transforming society towards a circular economy, the traditional view of separate systems for production and waste management must be changed. In order to refer to all problems of sustainability and also cover the top steps of the waste hierarchy, life cycle assessment of waste management should include manufacture and use of products ending up as waste. Waste entering the waste management system with “zero burden” by releasing the previous actors of the waste life cycle from any responsibility related to the environment (i.e. by shifting the total environmental burden into the waste management system), does not capture the problems with waste generation.

  • 187.
    Domkin, Dmitry
    et al.
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för arbets- och folkhälsovetenskap, Arbetshälsovetenskap. Högskolan i Gävle, Centrum för belastningsskadeforskning.
    Sörqvist, Patrik
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - tillämpad psykologi.
    Richter, Hans
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för arbets- och folkhälsovetenskap, Arbetshälsovetenskap. Högskolan i Gävle, Centrum för belastningsskadeforskning.
    Distraction of Eye-Hand Coordination varies with Working Memory Capacity2013Inngår i: Journal of motor behavior, ISSN 0022-2895, E-ISSN 1940-1027, Vol. 45, nr 1, s. 79-83Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The authors present a study of the relationship between individual variation in working memory capacity (WMC) and visually guided hand control in the face of visual distraction. WMC was assessed with the automated operation span task. Hand control was measured by requesting participants to track a visual target with a hand-held touch screen pen. Tracking error increased when nontarget visual objects (distractors) appeared, especially in individuals with low WMC. High-WMC individuals are less impaired by distractors than their low-WMC counterpart, because they resume target tracking more quickly after distractor onset. The results suggest that visual distractors cause a momentary interruption to tracking movements and that high WMC attenuates this interruption by facilitating visual search.

  • 188.
    Domkin, Dmitry
    et al.
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för arbets- och folkhälsovetenskap, CBF.
    Sörqvist, Patrik
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Byggvetenskap - tillämpad psykologi.
    Richter, Hans
    Högskolan i Gävle, Akademin för hälsa och arbetsliv, Avdelningen för arbets- och folkhälsovetenskap, CBF.
    Performance and fatigue perception during strenuous near work in persons with different levels of working memory capacity2012Konferansepaper (Fagfellevurdert)
  • 189.
    Dou, Chang
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Cooking fuels in China: contaminant emission and energy aspects2012Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hpOppgave
    Abstract [en]

    At present, the main cooking fuels inChinaare natural gas, coal gas, liquefied petroleum gas (LPG), coal, biogas, wood and straw. This paper reviews the characteristics, advantages, disadvantages and the current application status of these different cooking fuels. Moreover, a questionnaire survey is presented, dealing with different cooking fuels in Chinese households and the occupants’ perceived health, ventilation behaviors and general knowledge in potential health hazards. About 56% of the respondents of the questionnaire survey stated that symptoms like itching eyes, dry or irritated throat, irritated nose, running or blocked nose and headache were worse when they were cooking in their kitchens. This suggests that cooking fuel combustion has a significant influence on human health. The most evident health effect was that wood and straw as cooking fuel caused eye irritation. The present common house planning in Chinese countryside, where the kitchens are separated from the rest of the house via a courtyard, is very likely to reduce the stove contaminant exposure of all occupants.

     

    In general, the main cooking fuels of the cities tend to be better than the cooking fuels of the countryside. Natural gas appears to be the cleanest cooking fuel among all urban cooking fuels except electricity. For the rural residents, biogas or LPG is a better choice than wood, straw and coal as cooking fuel.

  • 190.
    Dresel, Eva
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Development and Characterization of a Light Diffuser for a Concentrating PV Collector2011Independent thesis Advanced level (degree of Master (One Year)), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    Hybrid solar systems as well as concentrating solar collectors are promising solar technologies. To run them efficiently in northern countries is a task Solarus AB is working on.The objective of this MSc project is to investigate and experimentally evaluate the option of implementing a light diffusing sheet in acompound parabolic concentrator (CPC) solar collector, called the “Scania Model”. This component should improve the non-uniform illumination of the photovoltaic cells in concentrating solar collectors.Therefore, scientific publications on this kind of solar collectors were read up on, e.g.Adsten, M. Brogren, M., Roos, A., Karlsson, B. Nilsson, J. and Leutz, R.After researching and procuring possible diffuser materials, experimental tests were carried out and the different materials were reviewed. Implemented in a solar simulator the IV curves of the collector with the different diffusers were generated. Furthermore, the influence of the materials on light was reviewed using daylight, laser light and an artificial light source. In the following, the light intensity distribution on the absorber of the Scania Model was defined and evaluated.The results of this project show that the main problem regarding diffuser material is to provide sufficient diffusion without much transmission losses.

  • 191.
    Duarte, Marta
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Heat recovery units in ventilation: Investigation of the heat recovery system for LB20 and LB21 in Building 99, University of Gävle2016Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Heating, ventilation and air-conditioning (HVAC) systems are widely distributed over the world due to their capacity to adjust some local climate parameters, like temperature, relative humidity, cleanliness and distribution of the air until the desired levels verified in a hypothetical ideal climate. A review of buildings’ energy usage in developed countries shows that in the present this energy service is responsible for a portion of about 20% of the final energy usage on them, increasing up to 50% in hot-humid countries. In order to decrease this value, more and more different heat recovery systems have been developed and implemented over the last decades. Nowadays it is mandatory to install one of these units when the design conditions are above the limit values to avoid such components, what is possible to verify mostly in non-residential buildings. Each one of those units has its own performance and working characteristics that turns it more indicated to make part of a certain ventilation system in particular. Air-to-air energy recovery ventilation is based on the heat recovery transfer (latent and/or sensible) from the flow at high temperature to the flow at lower temperature, pre-warming the outdoor supply air (in the case of the winter). Therefore, it is important to understand in which concept those units have to be used and more important than that, how they work, helping to visualize their final effect on the HVAC system. The major aims of this study were to investigate the actual performance of the heat recovery units for LB20 and LB21 in building 99 at the University of Gävle and make some suggestions that could enhance their actual efficiency. Furthermore, the energy transfer rates associated to the heat recovery units were calculated in order to understand the impact of such components in the overall HVAC system as also the possible financial opportunity by making small improvements in the same units. To assess the system, values of temperature and flow (among others) were collected in the air stream and in the ethylene-glycol solution that works as heat transfer medium between air streams and is  enclosed in pipes that make part of the actual run-around heat recovery units. After some calculations, it was obtained that for the coldest day of measurements, the sensible effectiveness was 42% in LB20 and 47% in LB21, changing to 44% and 43% in the warmer day, respectively. The actual heat transfer representing the savings in the supply air stream is higher on the coldest day, with values of 46 kW in LB20 and 84 kW in LB21, justifying the existence of the heat recovery units even if those ones imply the use of hydraulic pumps to ensure the loop. The low values of efficiency have shown that both heat recovery units are working below the desired performance similarly to the pumps that make part of the same units.  This fact, together with the degradation of the units that is possible to observe in the local, indicates that a complete cleaning (followed by a change of the heat transfer medium) of the heat recovery units and a new adjustment of pumps and valves for the further changes, are necessary. By doing this, it is expected to see the year average sensible effectiveness increase to close to 45% in both units which will lead to a potential economic saving of around 41 000 SEK per year.

  • 192.
    Edirisinghe, Sagara
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Study to evaluate the effectiveness of lighting system by using LED technoogy in Commerial buildings2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 193.
    Edkvist, Kristin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Powell, Linnéa
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Lerstensskiva med armering av fårull: Undersökning av böjhållfasthet, ånggenomsläpplighet, brandtålighet,värmekonduktivitet och praktisk användning.2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The focus of this study is aimed at the traditional building material; clay, together withsheep’s wool to act as reinforcement. The combination of the two materials created thebasis for an alternative board material. Soil-based building materials were used to alarge extent in the past. The oldest clay houses found were built as early as 8000 yearsBC. During the Middle Ages in Central Europe, soil and clay were used as fillers in timberframe structures. As new building materials evolved, clay based building methodshave suffered a more secluded position in the western world. New building materialshave caused the characteristics of traditional building materials to be forgotten. Sheep’swool, unlike clay, has previously not been classified as a building material, but ismostly used for textiles. Sheep are bred generally for two purposes; meat productionand wool production. The wool that comes from sheep that are in the meat productionbecomes a by-product that is usually reckoned as waste.The study presented below involves a product development of a board material containingclay and sheep’s wool. Nine different compositions were made in different series.Focus on the three different series was places on variety of sheep’s wool, amountof sheep’s wool and the viscosity of the clay. The manufacturing of the product wasmade by hand with own thought out and manufactured aids.The lack of aggregated material properties complicates the use of clay and sheep’swool. A performance based declaration and the CE marking of a product are requiredfor a building material to become an accepted product in the construction market.Building engineering research was carried out in the laboratory environment, and basedon standardized methods calculations were made on the Clay-wool board such as flexuralstrength, vapour permeability, thermal conductivity, fire resistance and practicaluse.The result shows that the Clay-wool board is comparable to other board materials. Thetechnical characteristics of the Clay-wool board regarding flexural strength reportedvalues between 118 N and 550 N, depending on the composition of clay and wool. Allthe boards showed that the point of breaking was viscous, since the wool held the clayslabs together. When calculation vapour permeability, the result showed values between2,289 x 106 m2/s and 3,571 x 106 m2/s.The thermal conductivity was measured on one single board, the one containing thelargest amount of wool, where the value was established to 0,218 W/m*K. It was noticedthat the thermal conductivity increased when wool was clay–dipped.

  • 194.
    Edström, Erik
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Gunnarsson, Christoffer
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Energikartläggning och energieffektiviseringav Sörbyskolans förskola: Simuleringar genomförda med IDA ICE 4.612014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Samhället idag är beroende av energi för att fungera och att eftersträva utveckling av förnybar energi bör ha högsta prioritet. År 2013 produceras 81,6% av världens totala energi av fossila bränslen. Bostads- och servicesektorn står idag för 38 % av Sveriges totala energianvändning. På grund av att bostäder och lokaler står för så stor del av energianvändningen är det väldigt viktigt att ha noggrann koll på energiprestandan av byggnader och lokaler samt vilka energieffektiviseringar som kan utföras.

    Sörbyskolan är belägen i södra delen av Gävle och fastigheten ägs och förvaltas av Gavlefastigheter. År 2015 planerar Gavlefastigheter en renovering av Sörbyskolan och vill ta fram energieffektiviseringsförslag. Skolan är uppdelad på sex byggnader som inkluderar en matsal, en gymnastiksal, en förskola och tre andra skolbyggnader. I denna rapport har förskolan med tillhörande passage undersökts. Förskolan och passagen är ett envåningshus med en area på 883 m2. Speciellt för passagen är att den är uppvärmd med direktverkande elenergi. Undersökningen har skett i simuleringsprogrammet IDA Indoor Climate and Energy.

    Boverket har satt upp riktlinjer och krav för hur mycket energi nybyggda lokaler och bostäder får använda beroende på vilken klimatzon byggnaden befinner sig i. Gävleborg befinner sig i klimatzon II och lokaler i denna klimatzon får max använda 100 kWh/m2, år.

    En basmodell av hur bygganden ser ut idag skapades för att identifiera vart de största energiförlusterna sker. Sedan jämfördes olika energieffektiviseringar med basmodellen för att se hur mycket energi som potentiellt skulle kunna sparas. Basmodellen skapades genom att få fram information om byggnaden och mata in i IDA ICE. Informationen skaffades bl.a. genom en fysisk undersökning, intervjuer, jämförelse med andra byggnader på Sörbyskolan m.m.

    Arbetet visar fördelningen av till- och bortförd energi i byggnaden och vilka energieffektiviseringsåtgärder som är mest lämpliga för att minska energianvändningen. Resultatet pekar på att byta till nya energieffektiva fönster ger den största energibesparingen och totalt sparas 19,8 kWh/m2,år. Om alla energieffektiviseringsåtgärder utförs ger det en energibesparing på 37,8 kWh/m2,år.

    Det har gjorts mycket antaganden och uppskattningar för att skapa basmodellen vilket gör att den skiljer sig en del ifrån verkligheten. För att få en mer korrekt modell skulle fler fysiska undersökningar och mätningar behöva utföras på byggnaden.

  • 195.
    Ekenståhl, Robert
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Medén, Oskar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Vilken hållfasthet har ett trädymlingsförband?2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Ett sätt att öka mängden trä i byggnader är att ersätta stålförband i takstolar med ett trädymlingsförband. Det bör dock undersökas om trädymlingsförbandet har tillräckligt högt hållfasthetsvärde.

    Denna studie undersöker hållfastheten på träförband förankrade med trädymlingar. Dymlingarna har tre olika dimensioner (8, 10 och 12 mm) och förankras i förbanden genom svällning. Teoretiska beräkningar utförs med formler från Eurokod 5 (2004) för stålskruvar. Formlerna modifieras för att kunna tillämpas på trä istället för stål. Trycktester utförs på tio tvåplansskjuvnings-modeller per dymlingsdimension. Studien anses vara statistisk och sammanställs i normalfördelningskurvor. Av data från testerna räknas karakteristiska värden för trädymlingarna med säkerhetsmarginalen 95 %. Karakteristiskt hållfasthetsvärdet för trädymlingsförbanden blev 2100 N för 8 mm, 2300 Nför 10 mm och 4400 N för 12 mm.

  • 196.
    Ekholm, Anton
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Furunäs, Mattias
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Påverkan till och från fiskodlingar med avseende på vattenkvalitén i svenska vattendrag: Fallstudie ”Slotts Lax AB”2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Ett flertal vattendrag i Sverige är idag förorenade (till viss grad), däribland Dalälven. Östersjön är ett utsatt hav vad gäller näringstillförsel, där Dalälven är en bidragande del till detta. I takt med att kunskapsnivån stiger kring hur vattenkvalitén påverkar organismer och människor så kan specifika åtgärder tas fram för enskilda vattendrag, för att förbättra kvalitén.

    Rapporten handlar om fiskodlingar och hur dem påverkas av utsläpp från mänskliga aktiviteter, samt hur odlingen påverkar dess omgivande vattendrag. Fiskodlingar används främst för att odla fisk som livsmedel, men även fisk som är avsedd för utplantering till sjöar och hav. Utplantering av fisk görs främst för att minska trycket på den vilda fisken. Att bedriva en fiskodling innebär stort ansvar för verksamhetsutövaren, där lagar och krav som är fastställda av riksdagen måste uppfyllas. För att kontrollera lagar och krav har man regelbundna kontroller vid fiskodlingar från olika myndigheter.

    Större delen av dagens fiskodlingar ligger i kontakt med sjöar och hav, och kan därmed påverkas av yttre faktorer i form av mänkliga aktiviteter, men även från själva odlingen i sig. Påverkan som bygger på utsläpp från dessa kan både vara positivt och negativt för vattendraget beroende på hur förutsättningarna hos denna ser ut. Fiskodlingar kan även placeras på land, men är dock betydligt mer kostsamt i jämförelse med en odling placerad i vattendrag.

    Det finns vissa risker med att bedriva en fiskodling i vattendrag, med avseende på sjukdomar och rymning. Sjukdomar inom en fiskodling kan resultera i slakt, och denna kan även spridas till utomstående vattendrag. En rymning kan bidra till hybridisering och därav påverka det vilda beståndet av fisk, den kan även rubba näringsväven hos vattendraget i form av konkurrens med det vilda beståndet, men även via bioackumulation och biomagnifikation.

    Det finns vissa faktorer som avgör placeringen av en fiskodling, detta allt efter hur förutsättningarna ser ut och vilken fisk som odlas. Slotts Lax AB, som är en fiskodlingsverksamhet i Dalarna, har valt att odla sin fisk i vattendrag, detta främst för att minimera kostnaderna och nyttja den miljö som erbjuds, vid Dalälven och Siljan. Fisk kan även odlas på land, detta görs främst för  att minimera riskerna med rymning av fisk och spridning av sjukdomar.

  • 197.
    Ekvall, Tomas
    et al.
    IVL.
    Åkeson, Lynn
    Lunds Universitet.
    Eriksson, Ola
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik.
    Finnveden, Göran
    KTH, Miljöstrategisk analys .
    Ljunggren Söderman, M
    IVL.
    Söderholm, Patrik
    Luleå Tekniska Universitet.
    Sundqvist, Jan-Olov
    IVL.
    von Borgstede, Chris
    Göteborgs Universitet.
    Bridging the gap between the sustainability pillars2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A thorough assessment of the sustainability performance of a product, a system, or a decision requires expertise on environmental, economic, and social aspects. In an assessment that involves researchers from different disciplines, communication is challenging because of different background knowledge, terminology, research traditions, etc.In the research program Towards Sustainable Waste Management, a new approach to interdisciplinary interaction was tested. The program included a group of researchers on life cycle assessment (LCA) and systems analysis of waste management. To this group, specialists in national economy, environmental psychology, and ethnology were linked in various projects. In each specific research project at least 20% of the budget was allocated to a waste LCA expert, who, through participating actively in the project, would be an interpreter, a two-way bridge between the disciplines. The first purpose of this LCA expert was to interpret the sustainability questions and to help make the research relevant for the overall purpose of the research program. The second purpose was to interpret the results of the specialists’ research and to help making the results useful for the overall program.Our experience demonstrates that this set-up forces the specialists and their interpreters/bridges to face the challenge of understanding each other. Establishing such an interdisciplinary interaction requires that the researchers share a mutual interest in trying to reach understanding. However, despite this interest and despite the significant resources made available for the participation, our collaboration was restricted by the fact that it can be difficult for the specialists to find suitable tasks in their projects for the LCA expert. The chance of the interaction being successful increases if the background knowledge of the researchers in the project overlaps, if they have similar research cultures, if they share a common interest in the research questions, and/or if the disciplinary scientists are accustomed to interdisciplinary collaboration.

  • 198.
    Eliassen, Hanna
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Ta bort tidstjuvarna!: Om tidsbesparande effektiviseringsåtgärder inom det kommunala bostadsföretaget Gavlegårdarnas byggprojekt2012Independent thesis Advanced level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Abstract

    The development of the construction industry is slower compared to other industries. This implies that there must be improvements in this field. One step to increased effectiveness in construction projects is making the construction process more efficient, therefore resulting in a positive result for both the actual construction project and for the overall branch. The purpose of this study is to identify areas for improvement within the municipal housing company Gavlegårdarna completed construction project, who will then contribute to increased efficiency in their upcoming projects. The work has been performed with the help of two case studies examine construction projects "Fullriggaren" and "The three nursing homes." Opinions about what could have improved the efficiency of these construction projects further have been collected with the help of an interview study among some of the project participants involved in both projects.

    There have been many studies addressing the topic of how the construction process can be streamlined and similar studies that have been previously conducted. From some of these studies the efficiency factors have taken a theoretical basis in this study. These factors are considered important in efforts to achieve an efficient construction process. Among these factors are: carrying it out right from the beginning, clear objectives, good communication and effective meetings, providing interaction and teamwork and good management of repetitions and experience interchange. The results of this study show that Gavlegårdarnas construction process is fragmented in all of these factors. The shortcomings that emerged are: not to getting tenants in time, unclear responsibilities, unclear objectives, time-consuming discussions at meetings, etc. The outcome of this study also supports previous studies conducted in the area. The study concludes with all of the resulting criticized fragmentations and a proposal of measures that show how Gavlegårdarna can counteract these deficiencies occurring in their future projects.

     

    Keywords: project participants, construction process, efficiency, communication, partnering

  • 199.
    Eliassi, Kamal
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik.
    Hur påverkas miljön av limträ- eller stålstomme för en lantbruksbyggnad?2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Global climate change is one of the most important tasks that scientists are trying to solve today. With the help of a Lifecycle Analysis (LCA) method, the impact that many materials and services have on the environment and humans, have been determined. 

    As a task given by Gävleborg County Administrative Board, this work examines which of the material, glulam or steel, is most suitable as load-bearing material for agricultural buildings (barns). The goal of this study is to perform a LCA (Life Cycle Assessment) of the two materials during production, use, transportation and reuse. The steel's advantage is to be reused again without losing its properties and the wood's benefits to be used as an energy source during combustion, is only one of the steps involved in a life cycle analysis. 

    The information that an LCA study requires can be infinite and complex and therefore needs limitations in resources and time. A system boundary makes a basis on which phases and influences are the vital parts of a study. The system boundary also includes geographical areas. The study examines only local agricultural buildings in Gävleborg, Sweden, with floor areas of approximately 1300 m2 and their global environmental impact. 

    Environmental impact of a product is usually allocated in several different environmental impact categories, in which the study examines only three of these: global warming, acidification and eutrophication. 

    The results show a great difference in emissions depending on how the materials are produced and how they are handled after use. It proves that glulam has significant fewer emissions than steel when it used as an energy source instead of being deposited. With help of the weighting method the result show that iron ore produced steel have 1.2 times greater emission then glulam with landfill and 5.2 times greater when it is used in energy recovery. The weight also shows that scrap produced steel have 0.5 less emission than glulam with landfill and 2.4 greater than glulam with energy recovery.

  • 200.
    Eliasson, Dennis
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Kyla med värme: En jämförelsestudie med huvudfokus på fjärrvärmedriven kyla2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Syftet med detta examensarbete är att värdera och jämföra ett antal utvalda kyltekniker, med huvudfokus på värmedriven kyla. Dels för en specifik befintlig byggnad men även en generell jämförelse som kan ligga till grund för andra projekt. Arbetet är utförti samarbete med ÅF i Borlänge. Den specifika byggnaden som har undersökts är belägen i Borlänge och kyls idag av stadsvatten, och har en kyleffektpå 655kW. Borlänge Energis fjärrvärmenät ligger till grund för samtliga beräkningar och antaganden. Huvudsyftet har varit att jämföra de olika kylteknikerna ur ett ekonomiskt perspektiv, men även snudda vid ett miljöperspektiv. Utöver detta så var syftet att undersöka hur en fjärrvärmeleverantör ska kunna leverera kyla till sin kund, utan att behöva gräva ner nya fjärrkylledningar.

    De kyltekniker som jämförts i detta arbete är absorptionskyla, adsorptionskyla, sorptiv kyla & eldriven kompressorkyla. För att kunna jämföra de olika teknikerna har den totala livscykelkostnaden beräknas. Investeringskostnader och data har erhållits ifrån leverantörer genom kontakt med kunniga säljare. Driftkostnader har beräknats fram med hjälp av driftdata samt energipriser hos Borlänge Energi. Kostnader för installation, frakt och lyft är inte medräknade i detta arbete.

    För den befintliga byggnaden visade det sig att den mest kostnadseffektiva lösningen är absorptionskyla, tätt följt av att komplettera befintligt system med frikyla i form utav en kylmedelkylare. Absorptionskylan har väldigt låga driftkostnader under sommarhalvåret, då fjärrvärmepriset är som lägst. Dyrast av teknikerna är adsorptionskyla, tack vare den dyra investeringskostnadenoch dess låga verkningsgrad.

    Även för den generella jämförelsen visade det sig att den mest kostnadseffektiva lösningen är absorptionskyla, tätt följt av eldriven kompressorkyla. Absorptionskylan har mycket låga driftkostnader, men kompressorkylan har istället en lägre investeringskostnad och mycket bättre verkningsgrad.

    Om Borlänge Energi skulle sälja fjärrvärmeproducerad kyla under sommaren, så skulle de vid 655kW kyleffekt ha en återbetalningstid avett absorptionskylaggregat på endast 2 år. Skulle de istället ha en kyleffekt på 100kW skulle återbetalningstiden vara ca 5 år.

    Slutsatser kan dras ifrån detta arbete att byggnader med högre kyleffekt är mer fördelaktiga för värmedriven kyla.

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