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  • 1. Al-Ayish, N.
    et al.
    During, O.
    Malaga, K.
    Silva, N.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    The influence of supplementary cementitious materials on climate impact of concrete bridges exposed to chlorides2018In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 188, p. 391-398Article in journal (Refereed)
    Abstract [en]

    In order to reach a specific service life of reinforced concrete structures a certain cover thickness is needed. At present, this is regulated by national standards that also limit the amount and type of supplementary cementitious materials in different exposure environments. The regulations do not, however, consider the actual durability performance of concrete with supplementary cementitious materials. As a consequence, the LCA results might be misleading. This paper shows the environmental impact of concrete with supplementary cementitious materials in chloride environment considering their specific performances. Prescriptive and performance based service life prediction models for chloride ingress are applied and compared. 

  • 2.
    Al-Ayish, Nadia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    During, Otto
    Malaga, Katarina
    Silva, Nelson
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    The influence of supplementary cementitious materials on climate impact of concrete bridges exposed to chloridesManuscript (preprint) (Other academic)
  • 3.
    Al-Ayish, Nadia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Mueller, Urs
    Malaga, Katarina
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Life cycle assessment of facade solutions made of durable reactive powder concrete2017Conference paper (Refereed)
  • 4.
    Björk, Folke
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    af Klintberg, Tord
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Simhallar – ett övergripande perspektiv på teknik, hälsa, beständighet och ekonomi2019Report (Other academic)
    Abstract [sv]

    Simhallar har olika problem, avseende både hälsoaspekter och beständighet. Dessutom förbrukar simhallar stora resurser ur ett ekonomiskt perspektiv. Neris-projektet har skaffat sig ett helikopterperspektiv på simhallars olika delar och risker och många av dessa risker orsakas av desinfektionen av badvattnet. I dagsläget så syftar hygien, rengöring och desinfektion främst till att hålla mikroorganismer på låga nivåer och det är viktigt att hygienen samt rengöringen optimeras. När det gäller desinfektionen av badvattnet så har klorering används under mycket lång tid, metoden är mycket effektiv för att döda de flesta mikroorganismerna, men orsakar även lungbesvär och korrosion som förkortar hallarnas livslängd.

    Denna rapport har inte hittat några vetenskapliga artiklar som belägger vilka kloreringsnivåer som bör tillämpas i en simhall. Dessa nivåer förefaller basera sig på tradition och på ett kunskapsläge då lungbesvär och korrosion inte beaktades. Det är tveksamt om exempelvis Folkhälsomyndighetens gränsvärden för klorhalter är grundade på ett spårbart sätt i vetenskapliga arbeten, som de bör vara.

    Det vore önskvärt att vetenskapligt undersöka vilka klornivåer som är tillräckliga och göra en sammansatt optimering med avseende på mikroorganismer, lungbesvär och korrosion.

    Blått ljus i simhall och fotokatalys i reningsverk  reducerar behovet av klorering, vilket har visats i Enskedehallens babysim. Vidare är det möjligt att få en bättre beskrivning av den mikrobiella situationen i badvatten med hjälp av partikelmätning, vilket kan minska de bakteriella riskerna i en simhall.  Dessa metoder bör bli föremål för vidare forskning.

    Hur stor är den sammanlagda korrosiviteten i en simhallsbyggnad? Det finns olika faktorer som samverkar i en simhall, som hög temperatur, högt fuktinnehåll i luften, klorider, underklorsyrlighet, och säkert fler faktorer, som inte är identifierade. Det är en forskningsuppgift att utföra olika metodtester för de olika delarnas korrosiva del och samverkande korrosivitet. Det finns inga rutiner för att avlägsna klorider som hamnat i simhallsrummet. Det vore bra att utarbeta sådana rutiner.  

    Det kan finnas ett motsatsförhållande mellan beständighet och energibesparing. Exempelvis så sparas energi om ett minimum av vatten blöder av, men detta ökar kloridkoncentrationen i badvattnet. På samma sätt ökas kloridkoncentrationen i simhallsbyggnaden om luften får gå i rundgång med ökad korrosionsrisk som följd.

    Avdunstningen är mycket energikrävande och det vore då intressant att minimera ventilationen över vattenytan. Den ventilationen är i dagsläget behövlig för att få bort skadliga gaser, exempelvis kloroform och trikloramin, som är en följd av kloreringen. Om klorering kan minska så kan även ventilationen över vattenytan minimeras, med energibesparing som följd

    Simhallsprojektet i Stad x riskerar att bli mellan 50 och 100 miljoner dyrare än vad som beräknades i förstudien. Förstudien har visat sig att vara optimistisk med avseende på fördelar, men svag med avseende på kostnader. Detta har försatt staden i en ekonomisk knipa, som riskerar att exempelvis materialval blir sämre med kortare beständighet som följd.. Förstudier inför ett simhallsbygge kan bli bättre. Det vore till exempel bra att göra en tredjepartskontroll med avseende på intäkter och kostnader.

    En kommun skulle kunna etablera en expertgrupp av kunniga tekniker och ekonomer som skulle kunna beakta och besluta över tekniska renoverings-, underhåll- och driftsfrågor. Detta vore en strategisk kunskap, som vore bra att ha in house.

  • 5.
    Gohardani, Navid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Sustainable building renovation and refurbishment with applications of Vacuum Insulation Panels2011In: SB11 World Sustainable Building Conference: Proceedings Vol. 2, 2011Conference paper (Refereed)
    Abstract [en]

    A large part of the available energy in the European Union is used for space heating of houses. This utilized energy presents an economical challenge as well as an environmental problem that ultimately must be dealt with by reducing the thermal losses through the climatic envelope. This reduction however, is intricate due to the spatial constraints in designated living areas and complexities arising from retrofitting of historical and cultural façades of the existing building stock. In light of the aforementioned problems, Vacuum Insulation Panels (VIP) may provide attractive solutions as they employ a thickness about one tenth of the required thickness, when using conventional insulation materials. This study contains a comparative analysis of VIP and traditional insulation materials and several other means of retrofitting in terms of life cycle energy and costs. Particular attention is given to the comparison of exterior and interior applications of VIP and the effects on the thermal bridges at the joints between the external wall and the adjacent floor slabs and balconies.

  • 6.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    A parametric study of a metal sandwich VIP2009Conference paper (Refereed)
  • 7.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    A Parametric study of the thermal performance of embedded Vacuum Insulation Panels2011Conference paper (Refereed)
  • 8.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Alternative approaches to moisture transfer in building materials: the use of natural stable isotopes and tracer gas2000Licentiate thesis, comprehensive summary (Other academic)
  • 9.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Alternative methods for analysing moisture transport in buildings: Utilisation of tracer gas and natural stable isotopes2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    New methods, based on tracer gas measurements and isotopicanalysis can be used to evaluate the moisture properties ofbuilding materials and provide the means for forensic analysisof the origins and history of excessive water in buildings, theimmediate practical consequences of which will be the abilityto improve the moisture performance of constructions.

    It is shown, in theory and through measurements how thewater vapour permeability of porous building materials can witha good degree of accuracy be estimated with tracer gasmeasurements that provide an efficient alternative to the cupmethod. Complementary measurements may be carried out in orderto evaluate the contribution of surface diffusion and theeventual enhancing effects of moisture content on the diffusioncoefficient. The Random Hopping Model is used to illustrate howthe surface diffusion coefficient depends on the amountadsorbed and the activation energy of migration that can beevaluated from the sorption isotherms.

    It is explained how the abundance ratios of two of the mostordinary isotopes of hydrogen and oxygen in water can be usedto determine its history. These isotopes are stable and givethe water a distinct signature that can be used to reveal itssource as shown in a case study. In a contrary manner themeasured isotopic separation can be used to determine therelevance of different transport processes and reactions. It isof central importance that not only does the magnitude ofisotopic separation for the reactions vary for deuterium andoxygen-18 but even the ratio thereof. One of the challenges hasbeen to construct an experimental method for retrieving samplesof water for comparison.

    Furthermore this thesis includes an evaluation of a new typeof a light weight construction with loose-fill cellulose fibre,in which the conventional polyethylene vapour barrier has beenreplaced with polypropylene fabric. With a verified model ithas been investigated how the construction would perform fordifferent internal moisture loads and reference climate fromthe literature. The results suggest that this type ofconstruction is not to be recommended.

    KEYWORDS:tracer gas, water vapour permeability,diffusion, surface diffusion, isotopic analysis, deuterium,oxygen-18, fractionation, vapour barrier, transient numericalmodelling of diffusion.

  • 10.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Building Sciences and Engineering.
    An approach to determining the water vapour transport properties of buildingmaterials2003In: Nordic Journal of Building Physics: Acta Physica Aedificiorum, ISSN 1402-5728, Vol. 3Article in journal (Refereed)
    Abstract [en]

    An analytical model, based on the literature, is used to show how the material parameters that rule the transport of water vapour in porous building materials can be evaluated by tracer gas measurements. A distinction is made between viscous flow, Knudsen diffusion and continuum diffusion. Each transportmechanism is formulated by explicit functions of the textural properties of the material and the thermodynamic properties of the gas. Tracer gas measurements can therefore be used to reveal the textural properties of amaterial, from which the potential water vapour transport, in gas phase, can be derived from the thermodynamic properties of water vapour.The well known concentration dependency of the diffusion coefficient is explained with the random hoppingmodel. The random hopping describes how the surface diffusion of adsorbed molecules relates to the amount adsorbed and the energies involved in adsorption. It is also described how the activation energies of surfacemigration can be obtained from sorption measurements and how the constant parameters of the surface diffusioncoefficient can be determined by stationary or transient wet-cup measurements.

  • 11.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Finding the source of excessive water with isotopic measurements2005In: The 7th symposium on Building Physics in the Nordic Countries - Reykjavík, 2005Conference paper (Refereed)
  • 12.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Building Sciences and Engineering.
    Forensic analysis of moisture transport in building materials with natural stable isotopesIn: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684XArticle in journal (Other academic)
  • 13.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Heat and moisture conditions in walls with vacuum insulation panels2011Conference paper (Refereed)
  • 14.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Building Sciences and Engineering.
    Isotopic tracing of moisture in buildings2001In: Nordic Journal of Building Physics: Acta Physica Aedificiorum, ISSN 1402-5728, Vol. 2, p. 1-10Article in journal (Refereed)
    Abstract [en]

    The means of tracing the flows of moisture in a building by using the stable isotopes of oxygen-18 and deuteriumare described. It is shown that knowledge of the effects of the transport mechanisms and reactions on the isotopiccomposition can be used to identify the sources of moisture. This is illustrated by an example from a building inthe southern part of Sweden.

  • 15.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Isotopsammansättning vid analys av byggfukt2000In: Bygg & Teknik, no 5, p. 29-30Article in journal (Other (popular science, discussion, etc.))
  • 16.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Civil and Architectural Engineering.
    PKM metoden: Funktionsupphandling av entreprenader mot givna pris-, kvalitets- och miljömål2004Report (Other academic)
  • 17.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    PQE: A METHOD FOR TENDER EVALUATION2005In: SB05 Tokyo: Action for Sustainability - The 2005 World Sustainable Building Conference in Tokyo, Japan, 27 - 29 September 2005, 2005, p. 4063-4068Conference paper (Refereed)
    Abstract [en]

    In a misguided ambition to benefit the environment some severe restrictions are often put on the design process which can lead to a limited competition among the contractors that will result in higher prices and will obstruct the use of innovative solutions. Moreover the environmental objectives can be vague and lack the association to the quality of the object. The PQE method is intended to overcome these obstructions by providing an instrument for dynamic decision making in the tender evaluation process of buildings in which the production, quality and environment are balanced in a way that reflects the goals and prerequisites of the client. This can be done by applying cost functions that describe the performance of the building with respect to its durability, materials and environmental impact, health and comfort, moisture protection, sound insulation, energy usage and the depletion of resources. The dynamic cost parameters are then given a monetary value in accordance to the goals and values of the client, on the basis of which the client can choose the most economically feasible alternative that meets the functional requirements of the program as well as the demands of the national legislator and the local building authorities. The method is based on functional requirements, as opposed to prescribed solutions, since the aim has been to develop a tool that does not favour any particular actors or methods and thereby supports the use of inventive technical solutions. Paramount to the method is that the building be approached on a system level and from a life-cycle perspective. The choice of function categories aims to capture the factors with the greatest potential to contribute to sustainable development as well the most common areas of problems in the Swedish building industry.

  • 18.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Takläcka kan spåras via vatten2005In: Husbyggaren : organ för Svenska byggnadsingenjörers riksförbund, SBR, ISSN 0018-7968, no 3, p. 16-19Article in journal (Other (popular science, discussion, etc.))
  • 19.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Tracer gas measurements of water vapor2002Conference paper (Refereed)
  • 20.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Building Sciences and Engineering.
    Tracer gas measurements of water vapour permeability of porous building materialsIn: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684XArticle in journal (Other academic)
  • 21.
    Gudmundsson, Kjartan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    af Klintberg, Tord
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Söderström, Ove
    The drying out capacity of a ventilated internal cavity with a heating cable, analytical model and empirical verification2012In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 52, p. 171-176Article in journal (Refereed)
    Abstract [en]

    This study is concerned with the use of interior air channels in walls for the drying out of surplus water in floor constructions. The floor is to be dried out by the means of an air gap, while a heating cable at the bottom of an adjacent wall channel provides a driving force for the flow. The model of this study can be used to quantify the drying out capacity of such a construction, given the geometrical configuration and the effect of the cable. By posing heat and mass balance equations for a star network equivalent to the delta network of the actual physical problem the temperature and moisture profiles for the floor channel are obtained. The wetted surface of the floor is assumed to be saturated, while the saturated moisture content varies with temperature along the surface. The temperature and moisture distributions along the air gap and the drying out capacity are obtained as a function of the flow rate. The physical problem of the wall channel is posed in terms of the governing equations of conservation. The Boussinesq approximation is used to restrict the variation in density to that of the gravitational force. The buoyancy generated by the cable is related to the frictional forces of the channel walls, providing a relationship between the flow rate and the effect of the cable. The analytical results are compared with laboratory measurements and show good agreement for a number of different heights of the air gap in the floor.

  • 22.
    Gudmundsson, Kjartan
    et al.
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Björk, Folke
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Plywood i kombination med stål1996Report (Other academic)
  • 23.
    Gudmundsson, Kjartan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Jóhannesson, Gudni
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Koniorczyk, Marcin
    Sampling and Analysis of Natural Isotopes in Moisture Transport from Porous Materials: Applications to Capillary Suction2008In: NSB 2008: Nordic Symposium on Building Physics, 2008, p. 967-Conference paper (Refereed)
  • 24.
    Gudmundsson, Kjartan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Karami, Peyman
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Simulations of Heat and Moisture Conditions in a Retrofit Wall Construction with Vacuum Insulation Panels2013In: Journal of Civil Engineering and Architecture, ISSN 1934-7359, Vol. 7, no 7, p. 781-788Article in journal (Refereed)
    Abstract [en]

    Vacuum insulation panels provide unprecedented possibilities for renovating the existing building stock in a manner that reduces the thermal losses through the building envelope. This study is focused on the implementation of VIPs (vacuum insulation panels) in energy retrofit projects with rendered outer walls. Particular emphasis is put on reducing the thermal bridges due to mechanical fasteners and at the joints of the panels. These are evaluated through a parametric study of the impact of the thermal conductivity of the joints of the panels and the adjacent insulation layer as well as the material of the fasteners. The study is carried out with 3D FEM (finite element method) simulations software. Furthermore, the moisture conditions in the construction are studied. The dynamic moisture behavior of a wall construction is modeled with a two dimensional FEM model. The long term effects of vapor diffusion are investigated in terms of accumulated moisture and the risk of condensation. The results illustrate that vacuum insulation on the outside of the wall construction does not pose a moisture problem to the construction. The simulations are based on a draft of a new technical solution for the refurbishment of a building that is typical for the great Swedish building program of the 1970s.

  • 25.
    Gudmundsson, Kjartan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Karami, Peyman
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Björk, Folke
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Vakuumisoleringspaneler2013In: Bygg & teknik, ISSN 0281-658X, Vol. 105, no 8, p. 25-28Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Vakuumisoleringspaneler erbjuder ett spännande alternativ till traditionella isoleringsmaterial eftersom de kräver endast en bråkdel av isoleringstjockleken. Det finns dock några områden som kräver ytterligare forskning om vakuumisolering ska till fullo kunna användas i byggnader.

  • 26.
    Gudmundsson, Kjartan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Sjöström, Christer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Norberg, Peter
    Wolfram, Trinius
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Twumasi, Ebenezer
    Durable and robust vacuum insulation technology for buildings2011Conference paper (Refereed)
  • 27.
    Hoseini, Hanif
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Jóhannesson, Gudni
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Symphony: industrial production of MULTI-STOREY buildings: report from the research tower project2006In: Proceedings of the Joint International Conference on Computing and Decision Making in Civil and Building Engineering, 2006Conference paper (Refereed)
  • 28.
    Hoseini, Hanif
    et al.
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Jóhannesson, Gudni
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Gudmundsson, Kjartan
    KTH, Superseded Departments, Civil and Architectural Engineering.
    Symphony: a flexible system for sustainable building2003In: Dense Living Urban Structures: Proceedings of The International conference on Open Building in Hong Kong, 2003Conference paper (Refereed)
    Abstract [en]

    Buildings are not meant to be static objects in time; they should be allowed to evolve together with the city. While three-dimensional flexibility is of uttermost importance it is equally important that movement is allowed along the time axis. Future changes should be incorporated in the buildings erected today. This article is to present Symphony, a concept that makes way for:

    • optimisation of the construction technology to minimize production time, material waste and global environmental impact as well as significantly improving the total economy.
    • buildings with components and material combinations that can literally be dismounted and reused or recycled.
    • an internal space that is possible to reconstruct for future requirements since the construction system makes the plan highly flexible and variable.

    The use of multi-floor vertical light weight building elements offers fast assembly and dismounting. Furthermore the façade elements are completely finished on the outside and finished till gypsum board on the inside including windows and all the vertical installations. With time, they can easily be replaced by a glass façade, for example to hold offices. The concept is highly focused on cost effectiveness since the right price will facilitate the sustainable way of building.

  • 29.
    Karami, Peyman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Al-Ayish, Nadia
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology. CBI, Swedish Cement.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    A comparative study of the environmental impact of Swedish residential buildings with vacuum insulation panels2015In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 109, p. 183-194Article in journal (Refereed)
    Abstract [en]

    A large part of the energy consumption in the European Union member states is related to space heating, a significant share of which is due to transmission losses through the building envelope. Vacuum insulation panels (VIPs), with unique thermal insulation properties, do therefore provide an interesting alternative for the building industry. This paper presents the results of a life cycle analysis (LCA) study that compares the environmental impact of three hypothetical buildings, a standard residential building, a regular well-insulated building and a building insulated with VIPs. The environmental impact includes the global warming potential (GWP) and the primary energy (PE) use, from the material production stage to the building operational phase (50 years). The cradle-to-gate environmental impact categories of ozone depletion potential (ODP), acidification potential (AP) and eutrophication potential (EP) of all building components are also assessed. The study shows a comparatively lower operational energy for the VIP insulated building and a relatively lower total greenhouse gas emission as well as the possibility to save significant living space. The results also show that the VIPs have measurable environmental impact during the product stage while the core material of the VIPs has considerable impact on the results.

  • 30.
    Karami, Peyman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology. University of Gävle, Sweden.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Björk, Folke
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Heymans, Luc
    ETICS with VIPs for improving buildings from the Swedish million unit program “Miljonprogrammet”Manuscript (preprint) (Other academic)
  • 31.
    Karami, Peyman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology. University of Gävle, Sweden.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Norberg, Peter
    University of Gävle, Sweden.
    Sjöström, Christer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Evaluation of the thermal conductivity of a new nanoporous silica material for VIPs: trends of thermal conductivity versus densityManuscript (preprint) (Other academic)
  • 32.
    Karami, Peyman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Twumasi Afriyie, Ebenezer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Norberg, Peter
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. University of Gävle, Sweden.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    A study of the thermal conductivity of granular silica materials for VIPs at different levels of gaseous pressure and external loads2014In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 85, p. 199-211Article in journal (Refereed)
    Abstract [en]

    Fast and reliable methods for the determination of thermal properties of core materials for vacuum insu-lation panels (VIPs) are needed. It is of great importance to know the thermal performance of a VIP core atdifferent levels of vacuum and external loads. In this study a new self-designed device, consisting of twocylindrical cavities connected to a Transient Plane Source instrument, is used to determine the thermalconductivity of low-density nanoporous silica powders, from atmospheric pressure down to 0.1 mbarwhile applying different levels of external pressure up to 4 bars. The study includes a brief theoreticaldiscussion of methods. The TPS is validated through comparison with available data for commercial silicaas well as through independent stationary measurements with a hot plate apparatus and with a TransientHot Bridge method. The different materials illustrate clear but different trends for the thermal conductiv-ity as a function of the level of vacuum and external pressure. The analysis of experimental results showsthat the transient methods are less suitable for measuring the thermal conductivity of low-density sil-ica powders, especially for the cases when the density is less than a limit at which the heat transfer byradiation becomes dominant compared to pure conduction.

  • 33.
    Karami, Peyman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Twumasi, Ebenezer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    A comparative study of methods for evaluating the thermal conductivity of nanoporous silica materials for vacuum insulation panelsArticle in journal (Other academic)
  • 34. Koniorczyk, Marcin
    et al.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Johannesson, Gudni
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Sampling and Analysis of Natural Isotopes in Moisture Transport from Porous Materials: Applications to Capillary Suction2009In: Journal of Building Physics, ISSN 1744-2591, E-ISSN 1744-2583, ISSN 1744-2591, Vol. 33, no 1, p. 83-96Article in journal (Refereed)
    Abstract [en]

    Apart from the most common H-1 and O-16 we have the sister isotopes: deuterium D and O-18 in water. Isotope fractionation (the change in its concentration) occurs in any thermodynamic reaction. The isotopic composition serves as a distinct mark for each water sample. To carry out the isotope analysis of pore water, which may be used to reveal the source of excessive water in building elements, firstly one has to extrude water from voids. For this we tested three different methods of retrieving water from the porous material: squeezing and evaporation - the direct methods, dilution - the indirect method. The influence of capillary suction on the hydrogen and oxygen isotopes abundance ratio was also analysed. Materials whose substantial part of voids are gel pores (cementitious materials) act as a membrane during isotope transport separating lighter from heavier isotopes and therefore cause the fractionation of isotopes. The results of performed experiments indicate that moisture transport (capillary suction) has an influence on the isotopic composition of water. Therefore the isotope analysis can be useful in the investigation of moisture behaviour of porous building materials.

  • 35.
    Levin, Per
    et al.
    KTH, Superseded Departments (pre-2005), Building Sciences and Engineering.
    Gudmundsson, Kjartan
    KTH, Superseded Departments (pre-2005), Building Sciences and Engineering.
    Moisture in Constructions with Loose-Fill Insulation and no Vapour Barrier1999In: Nordic Journal of Building Physics, Vol. 2Article in journal (Refereed)
    Abstract [en]

    Out of concern for the environment, the traditional polyethylene vapour barrier in lightweight constructions has sometimes been replaced with more diffusion open materials, such as polypropylene fabric. In order to evaluate how this may affect the risk of condensation in the constructions, in-situ measurements of the moisture content and temperature in the walls, roofs and floors of three houses have been conducted. Furthermore, the measurements have been used to establish a model that can be used to predict the moisture performance for design moisture supply loads. Measurements of moisture content and temperature in the outermost part of the insulation of the constructions have been carried out every three weeks over a two-year period, during which the indoor temperature and relative humidity were continuously registered. Based on indoor climatic data as well as information from a nearby weather station, the moisture conditions have been calculated using a one-dimensional transient diffusion model that takes into account the sorption properties of the materials.

    The results of the measurements indicate that for the low moisture supply loads in the three houses there is no immediate risk of moisture damage. The results of the simulations show good correlation with measurements for the walls and a floor. The calculation model was therefore used to simulate the conditions for a design moisture supply of 2 and 4 g/m^{3} using a reference climate for Stockholm from the literature. The results show that even for the lower design value, moisture would accumulate and condense in the wall construction. Since high relative humidity would for long periods of time coincide with temperatures feasible for mould growth, the wall construction is not to be recommended. A similar simulation of the piled floor construction shows that even for moderate moisture supply loads the risk for condensation is high. A correlation for the roof construction could not be achieved without adjusting parameters and therefore the model was not considered valid for the roof. There are strong indications that this is due to ongoing settling of the loose fill insulation in the roof construction, since no evidence of convection could be found from the measurement results.

  • 36.
    Molinari, Marco
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    An Application of the Screening Analysis to Rank the Potential for the Reduction of the Energy Demand in RenovationArticle in journal (Other academic)
  • 37.
    Pourghazian, Hanif
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    The impact of industrialized construction on the production cost of dwellings2008In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891Article in journal (Other academic)
  • 38.
    Twumasi Afriyie, Ebenezer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Karami, Peyman
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Norberg, Peter
    Högskolan i Gävle.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Textural and thermal conductivity properties of a low density mesoporous silica material2014In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 75, p. 210-215Article in journal (Refereed)
    Abstract [en]

    In this study, the pore structure, tapped density and thermal conductivity properties of a new type of nanoporous silica material have been studied. We have applied nitrogen physisorption, high resolution scanning microscopy and Transient Plane Source thermal conductivity measurements to investigate these properties. The new mesoporous silica SNP have large BET surface area, 400-439 m2 g-1 and possess high porosity in the range of 95-97%. The results further show pore diameter centred at 43 nm or 47 nm for the two materials studied. Tapped densities as low as 0.077 g/cm3 have so far been obtained and the thermal conductivity of these materials has been measured to 0.0284 and 0.0294 W (m K)-1 at room temperature and atmospheric pressure. The effects of tapped density, pore size diameter and particle morphology on thermal conductivity are discussed.

  • 39.
    Vrána, Tomáš
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Comparison of fibrous insulations: cellulose and stone wool in terms of moisture properties resulting from condensation and ice formation2010In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 24, no 7, p. 1151-1157Article in journal (Refereed)
    Abstract [en]

    Cellulose fibres are often used as thermal insulation in buildings. The organic nature of cellulose fibres, however, makes the insulation sensitive to high moisture content. This study investigates the moisture performance of cellulose insulation when exposed to a subzero environment. The paper is focused on the condensation and freezing in the material and includes comparison with the authors previous studies on stone-wool insulation. While the used stone-wool samples were water repellent due to resin binders,cellulose is a typical representative for hydrophilic thermal insulation to which anycontact with water condensate can be crucial.

    Test specimens of loose-fill cellulose were placed in a special laboratory device providing high moisture load. During a period of 100 hours the specimens were subjected to a continuous load of moisture at atmospheric conditions on one side while the other side of the specimen faced a surrounding temperature of 0, -10 and -20°C and the laboratory tests were repeated three times for each set of the specific thermal conditions(Ti=+20°C, Te=0, -10 and -20°C). The results indicate that there are minor changes inthe water vapour permeability of the specimens. The experimental data from the investigation is compared with a mathematical model that simulates moisture diffusivityof cellulose together with accumulation due to sorption and freezing, using the actual climatic data.

  • 40.
    Vrána, Tomáš
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Gudmundsson, Kjartan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Stone-wool insulation under offence of massive condensation and ice formationand their impact on moisture propertiesManuscript (preprint) (Other academic)
    Abstract [en]

    Building constructions are often under the offense of condensation. In extreme cases, watercondensation can also be accompanied by formation of frost in layers adjacent to outdoorsurfaces. In general, these problems happen due to sudden climate changes during buildingworks, misuse of building materials or delayed work on sites. Troubles with moisture proceedin the layer of thermal insulation thanks to its high moisture capacity and material thickness.Mineral wool is one of the most used thermal insulation materials in the building industry.Previous research and measurements have proved that fibrous insulations (e.g. stone wool)have varying material properties, when wet. Both thermal and moisture properties arechanged.

    This paper refers to laboratory tests concentrating on existence of frost formation in stonewoolspecimens exposed to extreme moisture load and temperature gradients (Vrána, Björk,2008). The executed research of that study did show that moisture resistance factor (μ-valueor μ-factor) is affected by condensation and freezing in the material. This paper illustrates acalculation model based on the monitored indoor and outdoor data (surface T and RH) of thetested materials. These climate data were used to create a functional mathematical model thatcan simulate moisture balance of stone wool. Finally, the model was compared to outputobtained from laboratory measurements.

1 - 40 of 40
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