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  • 1.
    Arghand, Taha
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Awbi, Hazim
    School of Construction Management and Engineering, University of Reading, United Kingdom.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory.
    An experimental investigation of the flow and comfort parameters for under-floor, confluent jets and mixing ventilation systems in an open-plan office2015In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 92, p. 48-60Article in journal (Refereed)
    Abstract [en]

    There is a new trend to convert the workplaces from individual office rooms to open offices for motivating money saving and better communication. With such a shift the ability of existing ventilation systems in meeting the new requirements is a challenging question for researchers. The available options could have an impact on workers' health in terms of providing acceptable levels of thermalcomfort and indoor air quality. Thus, this experimental investigation focuses on the performances of three different air distribution systems in an open-plan office space. The investigated systems were: mixing ventilation with ceiling-mounted inlets, confluent jets ventilation and underfloor air distribution with straight and curved vanes. Although this represents a small part of our more extensiveexperimental investigation, the results show that all the purposed stratified ventilation systems (CJV and UFAD) were more or less behaving as mixing systems with some tendency for displacement effects. Nevertheless, it is known that the mixing systems have a stable flow pattern but has the disadvantage of mixing contaminated air with the fresh supplied air which may produce lower performance and in worst cases occupants' illness. For the open-plan office we studied here, it will be shown that the new systems are capable of performing better than the conventional mixing systems. As expected, the higher air exchange efficiency in combination with lower local mean age of air for corner-mounted CJV and floor-mounted UFAD grills systems indicates that these systems are suitable for open-plan offices and are to be favored over conventional mixing systems.

  • 2.
    Broström, Tor
    et al.
    Gotland University, Department of Building Conservation.
    Linden, Elisabet
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Lindström, Svante
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Mattsson, Magnus
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Convective heating in a medieval church: Effects of air-to-air heat pumps on air movements, particle deposition and temperature distribution2009Conference paper (Refereed)
    Abstract [en]

    In Europe many historic buildings use direct electric heating. Air-to-air heat pumps are an interesting alternative, in particular for conservation heating.  However, the convective heating may accelerate soiling of walls and artefacts by increasing the velocity and turbulence.

     

    The objective of the present paper is to discuss the general problem, the methodology for studying air motions and temperature distribution, and to present the results from a case study where air-to-air heat pumps and bench heaters were used for heating in a medieval church. The temperatures, velocities and humidity in the church have been measured for four different heating modes.

     

    The present study does not indicate any major disadvantages of using heat pumps for background heating in stone churches of the studied kind. More detailed long term studies are needed to ascertain the effects over time.

  • 3.
    Forsberg, Ann-Kristin
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Winkler Pettersson, Lars
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Linden, Elisabet
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    An augmented-reality approach to co-located visual exploration of indoor climate data in real rooms2005In: Indoor Air 2005: Proceedings of the 10th International Conference on Indoor Air Quality and Climate, 2005, p. 2860-2860Conference paper (Other academic)
    Abstract [en]

    We live in two spaces, the visible space and the non-visible but otherwise sensed space. Both spaces must satisfy our needs and there is a relation between them. If parts of the room are too cold this will lead to a restriction of the use of the room. We cannot endure draft for any longer time. Draft caused by a ventilation supply frequently leads to blockage of the supply device, which in turn gives rise to a reduction of the ventilation rate. The final result may be a deterioration of the air quality. Therefore, to be able to guarantee the air quality it is necessary to make the invisible thermal climate visible. In this paper a novel method based on Augmented Reality for presenting die thermal climate is presented and discussed. The data, e.g. temperatures and velocities, are shown on a lightweight display. Several people can walk around in a real room and see on a screen where the hot and/or cold spots may appear. Different ventilation solutions could in that way be compared in a dialogue between different actors in the building process.

  • 4.
    Hayati, Abolfazl
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Mattsson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Evaluation of two air infiltration models on a church2013In: Conference proceedings: Cultural heritage preservation – 3rd European Workshop on Cultural Heritage Preservation, 2013, p. 47-53Conference paper (Refereed)
    Abstract [en]

    Air infiltration in ancient churches and other historical and monumental buildings is of great importance considering moisture transfer, energy consumption, thermal comfort and indoor surface soiling. Two of the most established models for simulatingand predicting air infiltration in buildings are the Lawrence BerkeleyLaboratory (LBL) model and the Alberta air Infiltration Model (AIM-2). The applicability of these models in superimposing wind and buoyancy driven infiltration in large single zone buildings such as churches are evaluated in this study by comparing model predictions with field measurements in a 19thcentury stone church. Both tested air infiltration models yielded significant positive correlations between measured and predicted data, and it is concludedthat the AIM-2 model works better than the LBL model for the studied church. Both models tend however to over-predict the air infiltration rate significantly. The over‑predictions were larger in cases with high wind speed and it seems that the models are more fragile in wind dominating conditions. Inclusion of crawl space coefficients in the AIM-2 model improved however the predictions, especially at high wind speeds. It seems that models of the tested kind can be useful in predicting air infiltration in churches and similar buildings, but that some empirically attained model coefficients might need some adjustment to suit this kind of buildings better.

  • 5.
    Kabanshi, Alan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Sattari, Amir
    School of Technology and Business Studies, Dalarna University, Sweden.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Experimental study on contaminant entrainment in air distribution systems with free jets2017In: Healthy Buildings 2017 - Europe, ISIAQ , 2017, article id 0040Conference paper (Refereed)
    Abstract [en]

    This is a preliminary study to an ongoing experimental and theoretical study of ambient entrainment of room air into axisymmetric free jets. The study herein aims to understanding characteristic behaviour of free jets, especially in low mixing ventilation technologies in order to get the best of such applications. In this paper, we explore the interaction of a free jet and its ambient, the effect on jet development, characteristics and behaviour at different Reynold numbers. Measurements were done with Particle Image Velocimetry (PIV) under isothermal conditions. As shown, at lower Reynolds numbers the jet is mostly laminar but is unstable consequently shortening the penetration distance into the ambient. As the Reynolds numbers increase the instability reduces and the penetration distance increases, but entrainment increases as vortices are generated closer to the nozzle exit. The current study suggests that’s further investigation is needed to define limits within which low and high mixing can be achieved with free jets, as this will have practical implications on optimization and implementation of free jets.

  • 6.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Broberg, Björn
    Olsson, Sören
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Towards making the indoor climate visible in practice2004In: The 9th International Conference on Air Distribution in Rooms, 2004, p. 168-169Conference paper (Other academic)
  • 7.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Cehlin, Mathias
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Temperature and velocity measurements on a diffuser for displacement ventilation with whole field methods2000In: The 7th International Conference on Air Distribution in Rooms, 2000Conference paper (Other academic)
  • 8.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Elvsén, Per-Åke
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Whole field mapping of temperature pattern in the near zone of an elevated displacement diffuser2002In: The 8th International Conference on Air Distribution in Rooms, 2002, p. 765-768Conference paper (Other academic)
    Abstract [en]

    This paper deals with the effect of discharging the air from a diffuser elevated above the floor. The temperatures have been measured and the airflow patterns visualised close to a diffuser for displacement ventilation, results from the whole-field method (using infrared thermography) were images of different colours representing different temperatures of the air close to the diffuser.. The aim of the measurements was to see how the elevations of the diffuser above floor level and the thermal jet length of the supply could affect the near zone.

  • 9.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Hellström, Jennie
    Cehlin, Mathias
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för energi- och maskinteknik.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Virtual reality presentation of temperature measurements on a diffuser for displacement ventilation2001In: The 4th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, 2001Conference paper (Other academic)
  • 10.
    Linden, Elisabet
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Control of jets for ventilation by using different combinations of blowing and suction2011In: Proceedings Roomvent 2011 Trondheim Norway Juni 2011, Tapir Academic Press , 2011Conference paper (Refereed)
  • 11.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Westerberg, Ulla
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Wind field in an urban space explored by different methods2006In: The 6th International Conference on Urban Climate (ICUC6), 2006Conference paper (Other academic)
  • 12.
    Linden, Elisabet
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Todde, Valentino
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Indoor Low Speed Air Jet Flow: Three-Dimensional Particle Streak Velocimetry1998In: The 6th International Conference on Air Distribution in Rooms, 1998Conference paper (Refereed)
  • 13.
    Mattsson, Magnus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Broström, Tor
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Lindström, Svante
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Fan Convectors vs. Bench heaters in Churches – impact on air velocities2011In: EEHB 2011: Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström & Lisa Nilsen, Visby: Gotland University Press, 2011Conference paper (Refereed)
    Abstract [en]

    Air movements in churches affect the deposition rate of airborne particles on surfaces, and hence influence soiling of valuable artifacts of different kinds. Sooting from candles and the thermal comfort of people is also affected by indoor air velocities. In an experimental field study, two different heating systems were compared regarding their effect on room air velocities in a church: air-to-air heat pumps with indoor fan convectors vs. a combination of bench heaters and radiators. Hot-sphere and 3-D sonic anemometers were used to record air velocities in the church. Strong buoyant air flows were found both in the supply air flow path of the heat pumps and above the bench heaters, but the air velocities were rather low outside of these air currents. A ~25 cm thick downdraught air flow was found along walls and windows, with a magnitude that was similar at both heating systems and much larger than the outdoor air infiltration rate.

  • 14.
    Mattsson, Magnus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Broström, Tor
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Lindström, Svante
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Impact of heating system on air velocities in a medieval stone church2011In: Roomvent 2011: 12th International conference on air distribution in rooms, Trondheim, Norge: Tapir Akademisk Forlag , 2011Conference paper (Refereed)
    Abstract [en]

    The air flow pattern and magnitude of air velocities in churches and other historic buildings are of interest since they influence the deposition rate of airborne particles on surfaces, and hence affect soiling of valuable artifacts of different kinds. Increased air movements might also cause enhanced sooting from candles and it has an influence on the thermal comfort of people. The type of installed indoor heating units is likely to be important here since these usually induce substantial air movements through natural or forced convection. In an experimental field study, two different heating systems were compared regarding their effect on room air velocities in a medieval stone church: air-to-air heat pumps with indoor fan convectors vs. a combination of bench heaters and radiators. Hot-sphere anemometers were used to record air velocities in the near-zone of the heat pumps and their surroundings, and 3-D sonic anemometers were used to measure downdraught air velocities at the surfaces of a wall and a window. Smoke was used to visualize air flow patterns.

    It was found that the heat pumps caused strong buoyant air jets that rose to the ceiling, but that the air velocities were rather low outside of these jets. The bench heaters caused buoyant plumes, which also seemed to attain rather high air velocities and reach the ceiling. As regards downdraught along wall and window, no significant difference between the two heating systems could be seen, although there was a tendency towards slightly higher air velocities at these surfaces when the heat pumps were in use. Since the air flow pattern at the surfaces appeared similar, also the particle deposition mechanisms and soiling rate can be expected to be similar.

  • 15.
    Mattsson, Magnus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory.
    Test av luftrenare i Visby domkyrka2016Report (Other academic)
    Abstract [sv]

    Efter den senaste renoveringen av Visby domkyrka, som bl a innefattade rengöring av innerväggar (våren 2014), noterades en oväntat snabb försmutsning av rengjorda väggytor, orsakad av avsättning av partiklar i inneluften. Med syfte att minska försmutsningstakten installerades två fristående luftrenare av elektrostatisk modell i kyrkan i oktober 2015. Föreliggande studie har haft som främsta syfta att utvärdera dessa luftrenares effektivitet i att rena inneluften på luftburna partiklar, framför allt från levande ljus. Utvärderingen har gjorts genom att mäta hur partikelhalten i kyrksalen förändrades vid olika driftfall på luftrenarna. Två olika flödesinställningar på luftrenarna provades: maxflöde resp. lågflöde, där maxflödet provades med både horisontellt och vertikalt riktat utblås av den renade luften. Anledningen till att även ett lägre luftreningsflöde provades var att luftrenarna bullrade så mycket vid maxflöde att detta driftförhållande endast torde bli aktuellt utanför besökstid. Studien har även inkluderat luftomsättningsmätning med spårgasteknik, luft- och yttemperaturmätningar, samt kallrasmätning vid vägg. Även ett vädringstest via portöppning har ingått. 

    Resultaten tyder på att luftrenarna har en klart renande effekt avseende luftburna partiklar i kyrksalen. Den minskning i antalet partiklar som luftrenarna åstadkom (partikelrenings-effektiviteten) varierade emellertid med partikelstorleken. I lågflödesfallet erhölls en reduktion av de minsta partiklarna (ultrafina, 0,02-0,3 µm) med ca 31 %, medan den för större partiklar (0,3-10 µm) var av storleksordningen 65‑75 %. I maxflödesfallet blev motsvarande siffror ca 58 % för de minsta partiklarna och 80‑90 % för de större. I välbesökta kyrkor där levande ljus ofta tänds – som i Visby domkyrka – utgör emissionerna från ljusen förmodligen den största partikelkällan. För dessa tycks de minsta partiklarna dominera avseende partikelyta (som kan tänkas täcka/försmutsa invändiga ytor), varför den sammantagna partikelreningseffektiviteten avseende försmutsning hamnar närmare den för de minsta partiklarna. Det är dock troligt att partikelreningseffektivitet blir något högre sommartid, då de riktigt stora besökarskarorna kommer i fallet Visby domkyrka.

    Riktningen på utblåset på luftrenarna hade ingen nämnvärd inverkan på partikelrenings-effektiviteten. Dock indikerade mätningarna av kallras (nedfallande luft) längs yttervägg i kyrkan att detta blir något större vid uppåtriktat utblås på luftrenarna, vilket riskerar att öka partikelavsättningstakten vid ytan. Detta fenomen behöver dock studeras närmare. Testet med vädring genom portöppning indikerade att ett avsevärt luftutbyte erhölls med denna metod, och att tillfällig vädring därför kan vara en lämplig åtgärd (även som komplement till luftrenare) vid tillfällen med många besökare och/eller mycket ljusbränning. Både partikel- och spårgasmätningarna påvisade god luftomblandning i kyrksalen, vilket är positivt för spridningen av den renade luften, och detta bidrar till att placeringen av luftrenarna är mindre kritisk. Sommartid kan dock luftomblandningen bli sämre; detta kan behöva undersökas närmare. Förutom minskad försmutsning kan luftrenarna förväntas bidra till en hälsosammare innemiljö ett minskat städbehov i kyrkan.

  • 16.
    Mattsson, Magnus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Lindström, Svante
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Methods to Identify Air Leakages in the Building Envelope of Churches2011In: EEHB 2011: Conference on Energy Efficiency in Historic Buildings / [ed] Tor Broström & Lisa Nilsen, Visby, Sweden, 2011Conference paper (Refereed)
    Abstract [en]

    Frequently there is a wish to reduce the natural ventilation rate in churches in order to save energy and/or improve the thermal comfort. It is then often difficult to ascertain exactly which the dominating leaks in the building envelope are, and where tightening measures would be most effective. A number of different methods to identify these leakages are discussed here. It appears that valuable help can be attained by a combination of several measuring techniques, including IR-thermography, tracer gas and pressure measurements. These techniques can also be useful in verifying the effect of tightening measures.

  • 17.
    Mattsson, Magnus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Lindström, Svante
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Tracer gas techniques for quantifying the air change rate in churches – field investigation experiences2011In: Proc. Roomvent 2011: 12th International conference on air distribution in rooms / [ed] Hans Martin Mathisen, Trondheim, Norge: Tapir Akademisk Forlag , 2011Conference paper (Refereed)
    Abstract [en]

    Two different tracer gas techniques for quantifying the air change rate were tested in three naturally ventilated churches. The techniques were the decay method (or tracer gas dilution method) and a passive tracer gas method. It appeared that the room air in the studied churches tended to be fairly well mixed when the churches are heated, presumably due to strong natural convection air currents occurring at heat sources and cooler outer building surfaces. This seems to entail that both the decay and the passive method are fairly easy to apply during times of heating. It then doesn’t seem to matter much were the tracer gas is injected or where it is sampled. During non-heating periods, however, spatial differences in tracer gas concentrations were observed, making tracer gas measurements more difficult to perform.

  • 18.
    Sandberg, Mats
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Linden, Elisabet
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Westerberg, Ulla
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Claesson, Leif
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Elvsén, Per-Åke
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Air flow pattern and pressure distribution within a street network in an urban area with a high building area density2006In: The 6th International Conference on Urban Climate: Preprints, 2006, p. 188-191Conference paper (Other academic)
    Abstract [en]

    We report on the effect of the overall shape of a city on the flow within the street network. We start with a solid round block, aspect ratio, diameter/ height = 6. The block is subdivided into smaller blocks and step by step an increasing number of streets are introduced. In the wind tunnel visualization with helium filled soap bubbled was carried out for obtaining qualitative information about the flow pattern. The pressure distribution on the ground within the street network was recorded in 400 points. CFD predictions provided the overall flow balance; flow entering through the street portals, leaving through the exit street portals and the updraft.

  • 19.
    Sandberg, Mats
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Mattsson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Claesson, Leif
    University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory. University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory.
    Khan, Mubashar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Viewpoints on wind and air infiltration phenomena at buildings illustrated by field and model studies2015In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 92, p. 504-517Article in journal (Refereed)
    Abstract [en]

    Ventilation and infiltration caused by wind are difficult to predict because they are non-local phenomena: driving factors depend on the surrounding terrain and neighbouring buildings and on the building orientation with respect to the wind direction. Wind-driven flow through an opening is complex because wind can flow through the opening or around the building, in contrast to buoyancy driven flow. We explored wind and air infiltration phenomena in terms of pressure distributions on and around buildings, stagnation points, flow along façades, drag forces, and air flow through openings. Field trials were conducted at a 19th-century church, and wind tunnel tests were conducted using a 1:200 scale model of the church and other models with openings.

     

    The locations of stagnation points on the church model were determined using particle image velocimetry measurements. Multiple stagnation points occurred. The forces exerted on the church model by winds in various directions were measured using a load cell. The projected areas affected by winds in various directions were calculated using a CAD model of the church. The area-averaged pressure difference across the church was assessed. A fairly large region of influence on the ground, caused by blockage of the wind, was revealed by testing the scale model in the wind tunnel and recording the static pressure on the ground at many points. The findings of this study are summarized as a number of steps that we suggest to be taken to improve analysis and predictions of wind driven flow in buildings.

  • 20.
    Sandberg, Mats
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Neophytou, Marina
    University of Cyprus.
    Fokaides, Paris
    University of Cyprus.
    Panagiotou, I
    Ioannou, I
    University of Cyprus.
    Petrou, M
    Wigö, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Linden, Elisabet
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, BMG Laboratory.
    Batchvarova, Ekaterina
    Bulgarian Academy of Science.
    Videnov, P
    Dimitroff, B
    Bulgarian Academy of Science.
    Ivanov, A
    Towards optimization of urban planning and architectural parameters for energy use minimization in Mediterranean cities2011In: WREC 2011, 2011Conference paper (Refereed)
  • 21. Todde, Valentino
    et al.
    Linden, Elisabet
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Indoor Low Speed Air Jet Flow: Fibre Film Probe Measurements1998In: The 6th International Conference on Air Distribution in Rooms, 1998Conference paper (Other academic)
  • 22.
    Westerberg, Ulla
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Linden, Elisabet
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Nilsson, Håkan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Perceived windiness in urban spaces.2006In: The 6th International Conference on Urban Climate - Preprints, 2006, p. 209-212Conference paper (Other academic)
    Abstract [en]

    The paper discusses the perception of windiness in the urban environment and especially its visual aspects. Various urban spaces in two cities, both with a reputation of being windy, have been chosen for field studies. Perceived windiness of the spaces has been investigated through questionnaire surveys and on-site interviews simultaneous to climate measurements. Result: Windy has a negative connotation that interacts with other environmental aspects such as beauty and comfort. Also naturalness and mental images of what constitutes sheltered and windy places seem to influence the survey as well as the on-site assessments of windiness.

1 - 22 of 22
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