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  • 1. Arlinger, Stig
    et al.
    Hagerman, Björn
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Kähäri, Kim
    Landström, Ulf
    Poulsen, Torben
    Musik och höga ljudnivåer: praktiska riktlinjer för musik- och underhållningsbranschen2009Report (Other academic)
  • 2. Arlinger, Stig
    et al.
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Landström, Ulf
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Kähäri, Kim
    Hagerman, Björn
    Poulsen, Torben
    Bengtsson, Johanna
    Musik, musiker och hörsel: en kunskapssammanställning om höga ljudnivåer och hörselskaderisker i musik- och underhållningssektorn2007Report (Other academic)
  • 3. Bengtsson, Johanna
    et al.
    Persson Waye, Kerstin
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Evaluations of effects due to low frequency noise in a low demanding work situation2004In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 278, no 1-2, 83-99 p.Article in journal (Refereed)
    Abstract [en]

    Noise sources with a dominating content of low frequencies (20-200 Hz) are found in many occupational environments. This study aimed to evaluate effects of moderate levels of low-frequency noise on attention, tiredness and motivation in a low demanding work situation. Two ventilation noises at the same A-weighted sound pressure level of 45 dB were used: one of a low-frequency character and one of a flat frequency character (reference noise). Thirty-eight female subjects worked with six performance tasks for 4 h in the noises in a between-subject design. Most of the tasks were monotonous and routine in character. Subjective reports were collected using questionnaires and cortisol levels were measured in saliva. The major finding in this study was that low-frequency noise negatively influenced performance on two tasks sensitive to reduced attention and on a proof-reading task. Performances of tasks aimed at evaluating motivation were not significantly affected. The difference in work performance was not reflected by the subjective reports. No effect of noise was found on subjective stress or cortisol levels. (C) 2004 Elsevier Ltd. All rights reserved.

  • 4. Bengtsson, Johanna
    et al.
    Persson Waye, Kerstin
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Sound characteristics in low frequency noise and their relevance for the perception of pleasantness2004In: Acta Acoustica united with Acustica, ISSN 1610-1928, Vol. 90, no 1, 171-180 p.Article in journal (Refereed)
    Abstract [en]

    Noise sources with a dominant content of low frequencies (20-200 Hz) are found in many occupational environments. Work efficiency has been found in two earlier studies to be impaired to a larger degree when working in a low frequency ventilation noise than when working in a flat frequency ventilation noise at the same A-weighted sound pressure level. Other previous studies indicate that different sound characteristics found in low frequency noise are important for the way in which low frequency noise affects humans, and better knowledge of these characteristics could lead to better methods for assessing low frequency noise in occupational environments. The aim of this study was to evaluate the influence of frequency balance between low and high frequencies, which affects the slope of the frequency spectra, and the modulation frequency on subjects' perception of a pleasant low frequency noise. The results showed that the subjects preferred either a higher or a lower modulation frequency as compared to that of the original low frequency noise, both choices leading to less perceivable modulations. Furthermore, the subjects preferred a lower relative content of frequencies below 500 Hz, but only as long as the original low frequency noise contained modulations and the variations were made within a constant A-weighted sound pressure level. The results are discussed in relation to improved guidelines and to the previously suggested theory of slope of the frequency spectra and problems involved with the implementation of that theory.

  • 5.
    Björling, Mikael
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för naturvetenskap.
    Stymne, Hans
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Boman, Carl-Axel
    Pentiaq AB.
     The Indoor Climate of a Naturally Ventilated Church2009In: Healthy Buildings 2009, Sept 13-18, Syracuse, NY USA, IAQ , 2009, 1-4 p.Conference paper (Refereed)
    Abstract [en]

     

    The indoor air climate of a church, with a total building volume of 9500 m3, was investigated from January to October, 2008. During this time, infiltration and ventilation measurements were performed at four periods ranging from 17 to 45 days. The local mean age of air was determined in several locations at different heights using passive samplers and homogeneous emission of PFTs. In addition, the temperature and relative humidity was measured at selected locations. The total infiltration of fresh air into the church was found to be mainly driven by the difference between indoor and outdoor temperature. The rate of infiltration ranges from 780 m3/h (deltat=14.8 degrees C) in January to 240 m3/h (deltat=3.5 degrees C) in August. The local mean age of air in the upper and lower air volumes were found to be roughly equal, both during the heating season and in the summer. This indicates that the air volume in the church is well-mixed throughout the year. Transient measurements to assess the effects of doors opening in the summer were also performed using pumped sampling.

  • 6.
    Björling, Mikael
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för naturvetenskap.
    Stymne, Hans
    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.
    Blomqvist, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Ventilation measurements combined with pollutant concentration measurements discriminate between high emission rates and insufficient ventilation2007In: IAQVEC 2007 Indoor Air Quality Ventilation and Energy Conservation: sustainable Buildings. P. 2, 2007, 402-409 p.Conference paper (Refereed)
    Abstract [en]

    High local concentrations of a pollutant can be the result of high local emission rates of the pollutant or insufficient ventilation. Using tracer gases to map the ventilation in multi-zone buildings combined with measurements of the local pollutant concentration provide the means to discriminate between these causes. In a similar manner, the propagation rate of pollutants from a source to a target zone and the emission rate of the pollutants at the source may be determined quantitatively.

    The paper presents both the theoretical framework for the techniques and experimental examples of the proposed methods.

  • 7.
    Blomqvist, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Conversion of Electric Heating in Buildings: an Unconventional Alternative2008In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 40, no 12, 2188-2195 p.Article in journal (Refereed)
    Abstract [en]

    To decrease the electric energy used for heating buildings it has become desirable to convert direct electrical heating to other heat sources. This paper reports on a study of the possibility of using an unconventional method for conversion to avoid installing an expensive hydronic system. The conversion method combines the ventilation and heating systems and uses air instead of water for distribution of heat within the building, taking advantage of thermal forces and the special properties of gravity currents. Full-scale tests have been carried out in a test apartment inside a laboratory hall where the conditions could be controlled. Temperatures and efficiency of ventilation have been measured to ensure that the demands with respect to thermal climate and air exchange were fulfilled. The results show that it is possible to use the method for heating and ventilation when converting the heating system, but further work has to be done to develop a detailed solution that works in practice.

  • 8.
    Blomqvist, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Distribution of Ventilation Air and Heat by Buoyancy Forces inside Buildings: an Experimental Study2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main task of the ventilation system in a building is to maintain the air quality and (together with the heating or cooling system) the thermal climate at an acceptable level within the building. This means that a sufficient amount of ventilation air at the appropriate temperature and quality must be supplied to satisfy thermal comfort and air quality demands and that this air is distributed to the parts of the building where people reside. Air movements caused by buoyancy forces can determine the distribution of ventilation air within buildings. The purpose of this thesis is to advance the state of knowledge of buoyancy-driven air movements within buildings and to determine their importance both for ventilation air distribution and the maintenance of thermal comfort and air quality in buildings. The work is focused on studying thermally-driven air movements through large openings, both horizontal and vertical (i.e. doorways). The properties of a special type of thermally-driven currents, so called gravity currents, have also been explored. Large vertical openings like doorways are important for air exchange between rooms within a building. Air movements through doorways separating rooms with different air temperatures are often bidirectional and the buoyancy-driven flow rates are often greater than those caused by the mechanical ventilation system alone. Bidirectional flows through doorways can effectively spread contaminants, for example, from a kitchen or a hospital rooms, yet the results of this study indicate that the conversion of a thermally-driven bidirectional flow to a unidirectional flow via an increase of the mechanically forced flow rate requires forced flows that are more than three times greater than the thermally-driven flows. Experiments conducted in this project indicate that the resistance to buoyancy-driven flows in horizontal openings is significantly greater than that in vertical openings. Model tests have shown, however, that this problem may be mitigated if a simple model of a staircase located in the centre of the room (being ventilated) is linked to the horizontal ventilation opening. Gravity currents in rooms occur in connection with so called displacement ventilation as cool gravity currents propagate along the floor that are driven by the density difference of the ventilation air and the ambient, warmer air within the room. As these gravity currents easily pass obstacles and to a certain extent are self-controlling, they can effectively distribute the cool air within rooms in a building. Likewise, warm gravity currents occur when warmer air introduced in a room rises and spreads along the ceiling plane. One application where warm gravity currents may be used to advantage is when converting buildings from electric heating to district hot water heating thus, avoiding the introduction of an expensive hydronic heating system. This report includes a full-scale laboratory study of the basic properties of thermally-driven warm air gravity currents in a residential building and examines the possibilities of using the resulting air movements for the distribution of ventilation air as well as heat. Results from laboratory tests show that this conversion method may prove effective if certain conditions on the layout of the building are fulfilled.

  • 9.
    Blomqvist, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Kan man styra luftfördelningen i en byggnad med hjälp av ventilationssystemet?2009In: Forskning, ISSN 1654-8876, no 4, 46-46 p.Article, review/survey (Other (popular science, discussion, etc.))
  • 10.
    Blomqvist, Claes
    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.
    A Note on Air Movements through Horizontal Openings in Buildings2002In: The 8th International Conference on Air Distribution in Rooms: Inividual Controlled Environment, 2002Conference paper (Refereed)
  • 11.
    Blomqvist, Claes
    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.
    Air Movements through Horizontal Openings in Buildings: A Model Study2004In: The International Journal of Ventilation, ISSN 1473-3315, Vol. 3, no 1, 1-10 p.Article in journal (Refereed)
    Abstract [en]

    A building contains a number of large openings like doors and staircases. When the temperature of the spaces connected by these openings differs, the difference in density will cause air movements through them. Horizontal air movements through vertical openings in buildings like doors and windows are well investigated while studies of air movements through horizontal openings like stairwells are less frequent and therefore this work is focusing on this case.

    The paper reports on an experimental study of the possibility of using buoyancy forces to distribute air and heat through horizontal openings. The experiments have been carried out in a scale model with water as the operating fluid.

    The result of the study shows that the flow rate through a horizontal opening is roughly half of the flow rate through a vertical opening for the same conditions, probably caused by the more complex flow pattern in the horizontal opening. A staircase below the horizontal opening will guide the flow somewhat and will cause a small increase of the fluid exchange through the opening.

  • 12.
    Blomqvist, Claes
    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.
    Measurements and Control of Air Movements within a Building1997In: AIVC 18th Conference, proceedings of "Ventilation and Cooling", 1997, 427-436 p.Conference paper (Other academic)
    Abstract [en]

    There are a number of methods available concerning with distribution of air in buildings. Within control research, one can find new control algorithms which have not yet been used in practice. These new algorithms open the possibility of developing and implementing of new demand controlled ventilation systems.

    In a building the internal air motions are due both to differences in temperature and pressure differences caused by the ventilation system. Therefore, one fundamental question is to what extent it s possible to control the air motions within a building using fan powered ventilation in combination with temperature control.

    The aims of this paper is to report on measurements done to examine the influence of temperature differences between rooms on the air exchange through open doors in a building and to explore the use of modern control technique to minimise the temperature difference.

    The result of the measurements shows that even very small (0.1-0.2°C) temperature differences between rooms cause bi-directional air flows in the doorways of a magnitude that exceed the flow rates caused by the mechanical ventilation system. Therefore it is necessary to control the temperatures in the rooms to make it possible for the ventilation system to distribute the air to those parts of the building where it is needed.

  • 13.
    Blomqvist, Claes
    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.
    Spread of Gravity Currents in Multi Room Buildings2000In: The 7th International Conference on Air Distribution in Rooms: Ventilation for Health and Sustainable Environment, 2000Conference paper (Refereed)
  • 14. Boman, CarlAxel
    et al.
    Holmberg, Jan
    Stymne, Hans
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Monitoring of Air Infiltration in Museums, Case study: The National Museum of Fine Arts, Stockholm, Sweden2004In: The 6th Indoor Air Quality Meeting: Padova, Italy, 2004Conference paper (Other academic)
    Abstract [en]

    This paper describes tracer gas measurements at the National Museum of Fine Arts in Stockholm. The building was erected 1850-1860 and the architect was Friedrich August Stüler. He created several museums of Fine Arts, among them Neues Museum in Berlin. The museum building in Stockholm has a volume of almost 90 000 m3 and the number of registered objects of art is well over 600 000. The collection includes one of the world’s most prestigious collections of drawings and graphical prints. In this case study the aim was to determine the infiltration through the main entrance and stairwell, through windows and outside walls. The measurement technique used was the Homogeneous Emission Technique added with a 2-zone set up, by using two different tracer gases. Several interesting results were obtained. One result was that more airtight entrance doors would decrease the infiltration into the main stairwell with 40 %. Another result of interest was that the very dry outdoor air was mixed with the indoor air quickly, and that the

    mechanical ventilation system with filters and humidifying units has to be upgraded to compensate for the outdoor air infiltration.

  • 15.
    Boman, Eva
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Noise in the school environment: Memory and Annoyance2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Objectives.The general objectives of this dissertationwere to examine the effects of acute exposure to meaningfulirrelevant speech and road traffic noise on memory performance,and to explore annoyance responses to noise exposure in theschool environment for pupils and teachers in different agegroups.

    Methods. The thesis comprises seven papers, representingdifferent methodological approaches: experiments, surveystudies and interviews. In the experiments, reported in PapersI-V, 288 pupils and teachers participated in the age groups,13-14 years (n=96), 18-20 years (n=96), 35-45 years (n=48) and55-65 years (n=48). The subjects were randomly assigned to oneof three conditions: (a) meaningful irrelevant speech, (b) roadtraffic noise, and (c) silence. The equivalent sound level inthe noise conditions was set to 66 dB(A). A test batteryreflecting episodic and semantic memory were used. The surveystudies, reported in Paper VI and VII, included 207 pupils(M=13.5) and 166 teachers (M=45.9). Two separate questionnairesmainly comprising items about annoyance, noise sensitivity andstress symptoms were administered. Paper VI presents results offocus group interviews (n=16) treating the main topics:disturbing sounds, emotions, ongoing activity, and suggestionsconcerning future changes. Results. The overall findings showedthat both noise sources affected episodic and semantic memoryto the same degree for all age groups. The results indicatedthat the similarity of semantic content between noise and thetask at hand was not the only suitable explanation model, sincea non-speech noise impaired memory as much as speech.

    Resultsalso indicated that attention effects did notmediate the obtained noise effects and that the noise effectsdid not differ between age groups. Therefore, it seemedunlikely that different memory and attentional capacities stoodout as explanatory factors of the memory effects. Sinceperformances of both episodic and semantic memory tasks wereimpaired, the explanation based on level of access to long-termmemory was also ruled out. However, the episodic memory task,reading comprehension, stood out to be most impaired by noise,suggesting that complexity of the task to perform was ofimportance. For reading comprehension there was also adifferent noise pattern obtained. Participants performance wasin this task, more impaired by meaningful irrelevant speechthan by road traffic noise. This effect indicated thatmeaningful irrelevant speech might reduce the availablecognitive resources necessary for learning the text. Theannoyance models derived from the survey studies indicated thatsensitivity acted as a mediator between hearing status andannoyance, with stress symptoms as an outcome. Whetherannoyance arises or not was also determined by control andpredictability of the noise. In the interviews a differentannoyance pattern was found, in that stress symptoms appearedto be a determinant of annoyance. To be involved, respected,take own responsibility and respect others were suggestions onhow to change the environment to become more silent.

    Conclusions.For both pupils and teachers acute exposureto meaningful irrelevant speech and road traffic noiseinfluenced both the achieving and providing of knowledge. Acommon annoyance pattern was also found for pupils andteachers, where individual and situational factors were ofimportance. To achieve a more silent school environment in thefuture, the pupils pointed out that the interaction betweenthemselves and their teachers was of importance.

    Key words:Noise, meaningful irrelevant speech, roadtraffic noise, memory, age groups, school environment, pupils,teachers

  • 16.
    Boman, Eva
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    The effects of noise and gender on children’s episodic and semantic memory.2004In: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 45, no 5, 407-416 p.Article in journal (Refereed)
    Abstract [en]

    The main objectives in the present study were to examine meaningful irrelevant speech and road traffic noise effects on episodic and semantic memory, and to evaluate whether gender differences in memory performance interact with noise. A total of 96 subjects, aged 13–14 years (n= 16 boys and 16 girls in each of three groups), were randomly assigned to a silent or two noise conditions. Noise effects found were restricted to impairments from meaningful irrelevant speech on recognition and cued recall of a text in episodic memory and of word comprehension in semantic memory. The obtained noise effect suggests that the meaning of the speech were processed semantically by the pupils, which reduced their ability to comprehend a text that also involved processing of meaning. Meaningful irrelevant speech was also assumed to cause a poorer access to the knowledge base in semantic memory. Girls outperformed boys in episodic and semantic memory materials, but these differences did not interact with noise.

  • 17.
    Boman, Eva
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Enmarker, Ingela
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Factors affecting pupils’ noise annoyance in schools: The building and testing of models2004In: Environment and Behavior, ISSN 0013-9165, E-ISSN 1552-390X, Vol. 36, no 2, 207-228 p.Article in journal (Refereed)
    Abstract [en]

    This article reports two studies intended to develop and assess conceptual models of how different factors mediate and moderate the annoyance reaction in school environments. In the first, a survey of 207 pupils was conducted where assumptions about mediators and moderators were formulated and tested. In the best model, general sensitivity and adaptation led to a higher degree of annoyance causing stress symptoms. In the second study, focus group interviews with 16 pupils were performed to set up a model of mediating and moderating factors from pupils' statements in the formation of annoyance. The objective was also to get their opinions about ways to improve the sound environment in school. The interviews indicated a serial arrangement in which stress symptoms and distraction mediated between chatter and disturbance. Thus, the two studies suggested different models for the prediction of the annoyance reaction. The pupils' views about how to improve the school sound environment are discussed in the framework of an empowerment model.

  • 18.
    Boman, Eva
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Enmarker, Ingela
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Noise and age effects on reading comprehension (Poster)2004In: XXVII International Congress of Psychology, 2004Conference paper (Other academic)
  • 19.
    Boman, Eva
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Enmarker, Ingela
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Strength of noise effects on memory as a function of noise source and age.2005In: Noise & Health, ISSN 1463-1741, Vol. 7, no 27, 11-26 p.Article in journal (Refereed)
    Abstract [en]

    The objectives in this paper were to analyse noise effects on episodic and semantic memory performance in different age groups, and to see whether age interacted with noise in their effects on memory. Data were taken from three separate previous experiments, that were performed with the same design, procedure and dependent measures with participants from four age groups (13-14, 18-20, 35-45 and 55-65 years). Participants were randomly assigned to one of three conditions: (a) meaningful irrelevant speech, (b) road traffic noise, and (c) quiet. The results showed effects of both noise sources on a majority of the dependent measures, both when taken alone and aggregated according to the nature of the material to be memorised. However, the noise effects for episodic memory tasks were stronger than for semantic memory tasks. Further, in the reading comprehension task, cued recall and recognition were more impaired by meaningful irrelevant speech than by road traffic noise. Contrary to predictions, there was no interaction between noise and age group, indicating that the obtained noise effects were not related to the capacity to perform the task. The results from the three experiments taken together throw more light on the relative effects of road traffic noise and meaningful irrelevant speech on memory performance in different age groups.

  • 20. Brinkworth, BJ
    et al.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    A validated procedure for determining the buoyancy-induced flow in ducts2005In: Building Services Engineering Research & Technology, ISSN 0143-6244, E-ISSN 1477-0849, Vol. 26, no 1, 35-48 p.Article in journal (Refereed)
    Abstract [en]

    A procedure is set out for calculating the buoyant flow induced in a duct with heat input at the wall, as in the cooling ducts used behind photovoltaic arrays. In these, buoyancy is opposed by various pressure losses, due to obstructions at the inlet and outlet, fluid friction at the walls and structural support members passing transversely through the duct. New methods are developed for calculating these losses, and each is validated separately by tests in a purpose-built isothermal rig. Measurements are also reported for some further losses, not yet amenable to calculation, due to nets and hoods at the duct ends, as might be used to exclude rain and wildlife. Finally, the whole procedure is validated by measurement of a duct with one heated wall.

    Practical application: Verified by measurements at every stage of its development, the method reported gives greater confidence in the routine calculation of the flow induced in ductwork where there is heat gain, as in systems for PV cooling and natural ventilation. The new treatments given for the hydrodynamic losses at basic components apply wherever these are used in the field of HEVAC.

  • 21. Brinkworth, BJ
    et al.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Design procedure for cooling ducts to minimise efficiency loss due to temperature rise in PV arrays2006In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 80, no 1, 89-103 p.Article in journal (Refereed)
    Abstract [en]

    The principal variable to be fixed in the design of a PV cooling duct is its depth, and hence the hydraulic diameter of its cross-section D. Analysis of the flow and heat transfer in the duct under still-air (buoyant flow) conditions, when the temperature rise is greatest, is validated by measurements on a full-scale test rig. It is shown that there is an optimum value of this design variable, such that for an array of length L the minimum temperature occurs when the ratio L/D is about 20. The optimum value is not affected much by other quantities, including the slope of the array.

    In practical situations, the flow is obstructed by devices across the duct inlet and outlet to exclude insects, birds and rain, and by structural support members crossing the duct interior. It is shown that the latter are no cause for concern, since the effect of the reduction in the flow-rate due to their presence is more than offset by an increase in heat transfer through additional turbulent mixing.

    It is also shown that array temperatures are strongly reduced by wind effects, which increase both the heat lost from the front surface of the array and by enhancement of the flow in the duct. Though the trends are clear, limitations are encountered in the present state of knowledge in both areas. (c) 2005 Elsevier Ltd. All rights reserved.

  • 22.
    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.

  • 23.
    Buccoliere, Riccardo
    et al.
    Universita di Lecce.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Study of the effect of building density and overall shape of a city on pollutant dispersion by combination of wind tunnel experiments and CFD simulations2008In: Proc. 12th Int. Conf. on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, 2008Conference paper (Refereed)
  • 24. Bullinger, M
    et al.
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Evans, G W
    Meis, M
    von Mackensen, S
    The psychological cost of aircraft noise for children1999In: International Journal of Hygiene and Environmental Medicine, ISSN 0934-8859, Vol. 202, no 2-4, 127-138 p.Article in journal (Refereed)
    Abstract [en]

    Psychological effects of aircraft noise exposure on children have only recently been addressed in the References. The current study took advantage of a natural experiment caused by the opening of a major new airport, exposing children in a formerly quiet area to aircraft noise. In this prospective longitudinal investigation, which employed nan-exposed control groups, effects of aircraft noise prior to and subsequent to inauguration of the new airport as well as effects of chronic noise and its reduction at the old airport (6 and 18 month post relocation), were studied in 326 children aged 9 to 13 years. The psychological health of children was investigated with a standardized quality of life scale as well as with a motivational measure derived from the Glass and Singer stress aftereffects paradigm. In addition a self report noise annoyance scale was used. In the children studied at the two airports over three time points, results showed a significant decrease of total quality of life 18 month after aircraft noise exposure as well as a motivational deficits operationalized by fewer attempts to solve insoluble puzzles in the new airport area. Parallel shifts in children's attributions for failure were also noted. At the old airport parallel impairments were present before the airport relocation but subsided there after. These findings are in accord with reports of impaired psychological health after noise exposure and indicate the relevance of monitoring psychological parameters as a function of environmental stressors among children.

  • 25. Byström, Pernilla
    et al.
    Johansson Hanse, Jan
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Appraised psychological workload, musculoskeletal symptoms, and the mediating effect of fatigue: a structural equation modelling approach2004In: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 45, no 4, 331-341 p.Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to test two structural models of the relationship between appraised psychological workload and musculoskeletal symptoms from the neck, shoulder, and upper and lower back with different aspects of perceived fatigue as mediating variables. In this cross-sectional study a questionnaire survey was conducted among employees at three Swedish assembly plants (n= 305). The proposed models were tested for one general fatigue dimension - lack of energy - and four specific fatigue dimensions - physical discomfort, physical exertion, lack of motivation, and sleepiness - using structural equation modeling. The results indicate that the role of perceived fatigue in the relationship between appraised workload and musculoskeletal symptoms is different for different aspects of fatigue. The general fatigue dimension, lack of energy, does not mediate the relationship. As regards the specific fatigue dimensions, the relationship is partially mediated by physical discomfort and lack of motivation but not by physical exertion or sleepiness. Appraised psychological workload has a unique effect on musculoskeletal symptoms not mediated by fatigue.

  • 26.
    Cehlin, Mathias
    et al.
    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.
    Computed tomography for indoor application2006In: The International Journal of Ventilation, ISSN 1473-3315, Vol. 4, no 4, 349-364 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with tomographic techniques for two-dimensional spatially resolved concentration measurements indoors. This represents a significant advance over the traditional point measuring method for mapping tracer gas and pollutants. Methods for recording of data are stressed as well as different types of tomographic reconstruction algorithms such as the Smooth Basis Function Minimization (SBFM) and the modified Low Third Derivative (LTDm) methods. Among the reconstruction algorithms available today, SBFM and LTDm are among the most promising. These algorithms show potential for reconstruction of gas concentration in rooms, since they are regularized to converge towards smooth concentration distributions. Using the LTD method and ‘snapshot’ configuration enables the examination and real-time monitoring of transient flows.

  • 27.
    Cehlin, Mathias
    et al.
    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.
    Computed Tomography for Indoor Applications2006In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 4, no 4, 349-364 p.Article in journal (Other academic)
    Abstract [en]

    This paper deals with tomographic techniques for two-dimensional spatially resolved concentration measurements indoors. This represents a significant advance over the traditional point measuring method for mapping tracer gas and pollutants. Methods for recording of data are stressed as well as different types of tomographic reconstruction algorithms such as the Smooth Basis Function Minimization (SBFM) and the modified Low Third Derivative (LTDm) methods. Among the reconstruction algorithms available today, SBFM and LTDm are among the most promising. These algorithms show potential for reconstruction of gas concentration in rooms, since they are regularized to converge towards smooth concentration distributions. Using the LTD method and ‘snapshot’ configuration enables the examination and real-time monitoring of transient flows.

  • 28.
    Cehlin, Mathias
    et al.
    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.
    Time evolution of gravity currents discharged from low velocity diffusers2007In: Roomvent 2007, 2007, 61-70 p.Conference paper (Refereed)
  • 29.
    Cehlin, Mathias
    et al.
    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.
    Time evolution of gravity currents discharged from low velocity diffusers2007In: Roomvent 2007: 10th International Conference on Air Distribution in Rooms, 13-15 June 2007, Helsinki, Finland, 2007, Vol. 3 61-70 p.Conference paper (Refereed)
  • 30.
    Chevalier, Jean-Luc
    et al.
    CSTB, France.
    Davies, Hywel
    Hywel Davies Consultance, UK.
    Sjöström, Christer
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Trinius, Wolfram
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Virk, Gurvinder Singh
    Massey Univ., NZ.
    Smart-ECO - Developing a Construction Sector Vision and Related Requirements for Sustainable Eco-buildings2008In: Durability of Building Materials & Components 11: Globality and Locality in Durability (vol. 4), Istanbul: Istanbul Technical University , 2008, 1671-1677 p.Conference paper (Refereed)
    Abstract [en]

    The EU project Smart-ECO brings together experienced organizations spanning the full range of stakeholders covering the area of sustainable building. These include universities, R&D organizations, companies developing, supplying and using innovative technologies, consultants, users, government and policy makers. Smart-ECO uses this core partnership together with a wider stakeholder group community to focus on global issues of sustainable building to identify and evaluate priorities for current and future RTD activities. Activities and policies are due to be mapped to identify gaps and to focus future efforts. Innovative technologies, as well as improvements of the construction process, and their introduction into the building sector will be considered in relation to sustainable development, life performance, ambient intelligence, and other relevant stakeholder concerns.

    The project focuses on routes and means to enable the uptake of efficient technological and non-technological innovation that in turn enable the building and construction sector to meet the requirement for sustainable building. The current situation and the vision of a more sustainable built environment sets the frame for the appreciation of the long term effectiveness of Eco-buildings and innovative technologies, especially renewable energy systems. Together, the vision and relevant EC policies will serve as a reference framework for the analysis of life performance aspects of innovative technologies applied to realise more energy efficient and more sustainable buildings.

    This paper presents and discusses the process of establishing a reliable vision for sustainable buildings and related performance requirements.

  • 31.
    Claesson, L
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Etheridge, D
    Unsteady Flow Reversal in Natural Ventilation Stack: Model Scale Tests2005In: The International Journal of Ventilation, ISSN 1473-3315, Vol. 4, no 1, 25-36 p.Article in journal (Refereed)
    Abstract [en]

    Measurements of the unsteady flow in a ventilation stack of a school have been made at model scale in an environmental wind tunnel. The results confirm the expectation that the stack is well-sited, in that it was difficult to induce flow reversal except over a narrow range of wind directions and the amount of reversal was small (reversal percentage < 5 %). The results also show that the technique is capable of reliably detecting such small reversal percentages.

  • 32. Elvsén, Per-Åke
    et al.
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Buoyant jet in ventilated rooms: velocity field, temperature field and airflow pattern analysed with three different whole field methods2009In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 44, no 1, 137-145 p.Article in journal (Refereed)
  • 33.
    Elvsén, Per-Åke
    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.
    Particle Streak Velocimetry for Room Air Flows-Some Improvements2004In: Roomvent, 2004Conference paper (Refereed)
  • 34.
    Enmarker, Ingela
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Effects of meaningful irrelevant speech and road traffic noise on teachers' attention, episodic and semantic memory.2004In: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 45, no 5, 393-405 p.Article in journal (Refereed)
    Abstract [en]

    The aim of the present experiment was to examine the effects of meaningful irrelevant speech and road traffic noise on attention, episodic and semantic memory, and also to examine whether the noise effects were age-dependent. A total of 96 male and female teachers in the age range of 35-45 and 55-65 years were randomly assigned to a silent or the two noise conditions. Noise effects found in episodic memory were limited to a meaningful text, where cued recall contrary to expectations was equally impaired by the two types of noise. However, meaningful irrelevant speech also deteriorated recognition of the text, whereas road traffic noise caused no decrement. Retrieval from two word fluency tests in semantic memory showed strong effects of noise exposure, one affected by meaningful irrelevant speech and the other by road traffic noise. The results implied that both acoustic variation and the semantic interference could be of importance for noise impairments. The expected age-dependent noise effects did not show up.

  • 35.
    Enmarker, Ingela
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Boman, Eva
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Noise annoyance responses of middle school pupils and teachers2004In: Journal of Environmental Psychology, ISSN 0272-4944, E-ISSN 1522-9610, Vol. 24, no 4, 527-536 p.Article in journal (Refereed)
    Abstract [en]

    The present survey study had three aims: (1) to compare pupils' and teachers' annoyance responses to classroom noise, (2) to compare females and males responses and (3) to test annoyance models that fitted both pupils and teachers. The study included 207 pupils, aged 13-14 years, and 166 teachers, aged 21-65 years. Both pupils and teachers rated chatter as the most disturbing noise source in the classroom. In line with predictions, the teachers experienced themselves as more sensitive to noise, had poorer hearing status, and reported more intense stress symptoms than the pupils. Contrary to expectations, the teachers were more annoyed and they perceived the noise to be more unpredictable than the pupils did. The control items showed a mixed pattern. There were no overall differences between females and males annoyance responses, but females reported having more stress symptoms than males. A conceptual model was tested with structural equation models, where noise sensitivity mediated the relationship between hearing status and annoyance, which in turn affected stress symptoms. Control and predictability were tested as moderators of the relations between stress symptoms and annoyance. The data fit the conceptual model reasonable well when both samples were included in the same test. (c) 2004 Elsevier Ltd. All rights reserved.

  • 36.
    Enmarker, Ingela
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Boman, Eva
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Pupils and teachers response structures of noise annoyanceManuscript (preprint) (Other academic)
  • 37.
    Enmarker, Ingela
    et al.
    University of Gävle, Department of Education and Psychology, Ämnesavdelningen för psykologi. Royal Institute of Technology, Stockholm, Sweden.
    Boman, Eva
    University of Gävle, Department of Education and Psychology, Ämnesavdelningen för psykologi. Royal Institute of Technology, Stockholm, Sweden.
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Structural equation models of memory performance across noise and age2006In: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 47, no 6, 449-460 p.Article in journal (Refereed)
    Abstract [en]

    Competing models of declarative memory were tested with structural equation models to analyze whether a second-order latent variable structure for episodic and semantic memory was invariant across age groups and across noise exposure conditions. Data were taken from three previous experimental noise studies that were performed with the same design, procedure, and dependent measures, and with participants from four age groups (13-14, 18-20, 35-45, and 55-65 years). Two noise conditions, road traffic noise and meaningful irrelevant speech, were compared to a quiet control group. The structural models put to the test were taken from Nyberg et al. (2003), which employed several memory tests that were the same as ours and studied age-groups that partly overlapped with our groups. In addition we also varied noise exposure conditions. Our analyses replicated and supported the second-order semantic-episodic memory models in Nyberg et al. (2003). The latent variable structures were invariant across age groups, with the exception of our youngest group, which by itself showed a less clear latent structure. The obtained structures were also invariant across noise exposure conditions. We also noted that our text memory items, which did not have a counterpart in the study by Nyberg et al. (2003), tend to form a separate latent variable loading on episodic memory.

  • 38. Erell, E
    et al.
    Etizon, Y
    Carlstrom, N
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Molina, J
    Maestre, I
    Maldonado, E
    Leal, V
    Gutschker, O
    "SOLVENT": development of a reversible solar-screen glazing system2004In: Energy and Buildings, ISSN 0378-7788, Vol. 36, no 5, 467-480 p.Article in journal (Refereed)
    Abstract [en]

    Preliminary experiments with a novel glazing system developed at the Desert Architecture and Urban Planning Unit of Ben-Gurion University of the Negev in Israel indicated that it may provide improved visual and thermal performance in buildings with large glazed areas located in sunny regions, regardless of orientation. In winter, it reduces glare, local over-heating and damage to furnishings caused by exposure to direct solar radiation, with only a small reduction in solar space heating. In summer, it reduces the penetration of unwanted radiation without obstructing the view through the window, to an extent that may render external shading devices unnecessary. The SOLVENT project was contracted to complete the development of the glazing system, which is based on the concept of converting short-wave solar radiation to convective heat and long wave radiation. The glazing system was modeled and evaluated experimentally; a suitable frame was developed for it; and a design tool required for its application was developed. The current paper reports on physical modeling and experimental evaluation of the glazing system.

  • 39. Evans, Gary
    et al.
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Noise and cognitive performance in children and adults2007In: Noise and its effects, Chichester: Wiley , 2007Chapter in book (Other (popular science, discussion, etc.))
  • 40. Evans, GW
    et al.
    Bullinger, M
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Chronic noise exposure and physiological response: A prospective study of children living under environmental stress1998In: Psychological Science, ISSN 0956-7976, E-ISSN 1467-9280, Vol. 9, no 1, 75-77 p.Article in journal (Refereed)
    Abstract [en]

    Chronic exposure to aircraft noise elevated psychophysiological stress (resting blood pressure and overnight epinephrine and norepinephrine) and depressed quality-of-life indicators over a 2-year period among 9- to 11-year-old children. Data collected before and after the inauguration of a major new international airport in noise-impacted and comparison communities show that noise significantly elevates stress among children at ambient levels far below those necessary to produce hearing damage.

  • 41. Evans, GW
    et al.
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Bullinger, M
    Chronic noise and psychological stress.1995In: Psychological Science, ISSN 0956-7976, E-ISSN 1467-9280, Vol. 6, no 6, 333-338 p.Article in journal (Refereed)
    Abstract [en]

    This article illustrates the value of incorporating psychological principles into the environmental sciences. Psycho-physiological, cognitive, motivational, and affective indices of stress were monitored among elementary school children chronically exposed to aircraft noise. We demonstrate for the first time that chronic noise exposure is associated with elevated neuroendocrine and cardiovascular measures, muted cardiovascular reactivity to a task presented under acute noise, deficits in a standardized reading test administered under quiet conditions, poorer long-term memory, and diminished quality of life on a standardized index. Children in high-noise areas also showed evidence of poor persistence on challenging tasks and habituation to auditory distraction on a signal-to-noise task. They reported considerable annoyance with community noise levels, as measured utilizing a calibration procedure that adjusts for individual differences in rating criteria for annoyance judgments.

  • 42.
    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, 2860-2860 p.Conference 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.

  • 43.
    Fredriksson, J
    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.
    The effect of false ceilings on the performance of passive chilled beams2007In: The 6th International Conference on Indoor Air Quality, Ventilation & Energy Conservation in Buildings, 2007, 13- p.Conference paper (Refereed)
  • 44.
    Fredriksson, Jan
    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.
    The effect of false ceiling on the cooling capacity of passive chilled beams2009In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 44, no 7, 1426-1430 p.Article in journal (Refereed)
    Abstract [en]

    Passive chilled beams are often used to provide cooling or additional cooling when the ventilation system cannot cope with the whole cooling load. The advantage of passive cooling is that it is a silent cooling. Often the chilled beams are installed above a false ceiling and thereby the room is subdivided into two compartments. From the chilled beam a plume is generated. Make-up air (return air) needs to flow into the upper compartment to substitute the airflow generated by the chilled beam. Therefore openings for this purpose are installed in the false ceiling. Small openings constitute a resistance to the flow and the locations of the openings affect the flow pattern. The overall performance was studied in a mock-up of a real office by changing both the size and position of the openings for the make-up air. A uniform heating source was arranged by covering the floor with a heating foil. The best location and size of the openings were explored by both recording the heat absorbed by the beam and the temperature in the room. Minimum temperature attained in the room is the signature of the most efficient cooling. To achieve efficient cooling with a uniform floor-based heating source, two conditions must be fulfilled: a) the return opening area must be at least equal to the horizontal area of the chilled beam; b) the return air openings must be located at the perimeter of the room. In general we can expect conditions a) and b) to be applicable irrespective of type of heat, but for point sources we could achieve the best cooling by placing the return air opening above the heat source.

  • 45. Hagström, Tom
    et al.
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Arbetsvärderingars stabilitet och föränderlighet i ett genusperspektiv: sjuksköterskor och högskoleingenjörer i övergången från yrkesutbildningen in i arbetslivet2005Book (Other academic)
  • 46. Hagström, Tom
    et al.
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Changeability and gender related challenges of work values2004In: 28th International Congress of Psychology, Beijing, 2004, 2004Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Changeability of work values was studied by longitudinal analyses of nurses and engineers from the Stockholm area in Sweden. Questionnaires were completed by 173 male and 48 female engineers and 353 female and 31 male nurses at three measurement occasions covering about four and half years from the end of their vocational education. Women's ratings of Social relations and Altruism remained higher than men's while women & acute; ratings of Benefit/career and Influence increased which eliminated the initial gender difference. The changeability of work values is discussed in terms of challenges and norms in working life.

  • 47.
    Hagström, Tom
    et al.
    Department of Education, Stockholm University, Sweden.
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Stability and change in work values among male and female nurses and engineers2007In: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 48, no 2, 143-151 p.Article in journal (Refereed)
    Abstract [en]

    Gender related changes of work values were analyzed in a longitudinal questionnaire study of 173 male and 48 female engineers and 353 female and 31 male nurses at three measurement occasions covering about four and half years from the end of their vocational education. At all occasions, Social relations were rated as more important by women than by men and Altruism was given higher ratings by the nurses than by the engineers. Within both occupations women’s mean Altruism ratings were higher than men’s mean ratings, and in all groups except male engineers the mean ratings dropped between the three occasions. Women’s ratings of Benefits and career and Influence were strengthened in both occupations, thereby eliminating an initial gender difference. The stability of work values is discussed in terms of challenges and norms in working life.

  • 48. Haines, M M
    et al.
    Stansfeld, S A
    Brentnall, S
    Head, J
    Berry, B
    Jiggins, M
    Hygge, Staffan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    The West London Schools Study: the effects of chronic aircraft noise exposure on child health2001In: Psychological Medicine, ISSN 0033-2917, E-ISSN 1469-8978, Vol. 31, no 8, 1385-1386 p.Article in journal (Refereed)
    Abstract [en]

    Background. Previous field studies have indicated that children's cognitive performance is impaired by chronic aircraft noise exposure. However, these studies have not been of sufficient size to account adequately for the role of confounding factors. The objective of this study was to test whether cognitive impairments and stress responses (catecholamines, cortisol and perceived stress) are attributable to aircraft noise exposure after adjustment for school and individual level confounding factors and to examine whether children exposed to high levels of social disadvantage are at greater risk of noise effects. Methods. The cognitive performance and health of 451 children aged 8-11 years, attending 10 schools in high aircraft noise areas (16 h outdoor Leq > 63 dBA) was compared with children attending 10 matched control schools exposed to lower levels of aircraft noise (16 h outdoor Leq < 57 dBA). Results. Noise exposure was associated with impaired reading on difficult items and raised annoyance, after adjustment for age, main language spoken and household deprivation. There was no variation in the size of the noise effects in vulnerable subgroups of children. High levels of noise exposure were not associated with impairments in mean reading score, memory and attention or stress responses. Aircraft noise was weakly associated with hyperactivity and psychological morbidity. Conclusions. Chronic noise exposure is associated with raised noise annoyance in children. The cognitive results indicate that chronic aircraft noise exposure does not always lead to generalized cognitive effects but, rather, more selective cognitive impairments on difficult cognitive tests in children.

  • 49.
    Hallberg, Daniel
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Stojanovic, Bojan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Kedbäck, Mikael
    Life Cycle Management System: a planning tool supporting Long-term based design and maintenance planning2008In: Durability of Building Materials & Components 11: Globality and Locality in Durability / [ed] A. Nil Türkeri, Özkan Sengül, Istanbul: Istanbul Technical University , 2008, 1871-1878 p.Conference paper (Refereed)
    Abstract [en]

    Construction projects include large amounts of information that has to be communicated to a number of actors, such as authorities, companies, clients and end users. Information exchange is complex, involving various players on different levels and phases of the construction process. For private clients, who generally have little experience and knowledge of this process, the on-going “Bygga Villa”-project has developed a web-portal, which offers them relevant information about the process and a number of services to facilitate realisation of their projects. One of the services provides a tool for supporting long-term strategy planning. The tool is based on the Life cycle Management System (LMS) that is a predictive and generic life cycle-based management system, aimed to support decision-making and planning of optimal design and maintenance of any construction works. The LMS-Bygga Villa tool estimates service life and maintenance intervals of different building parts and systems based on environmental-dependent degradation models. Simulated scenarios can give optimised solutions by applying life cycle cost analysis. This paper presents two case studies within LMS-Bygga Villa. The first case focuses on service life performance analysis of exterior parts of buildings. The second focuses on service life performance analysis of energy systems; here specifically a borehole assisted heat pump system used for heating a Swedish single-family residence.

  • 50. Hang, Jian
    et al.
    Li, Yuguo
    Sandberg, Mats
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Understanding Air Exchange and Pollutant Dispersion in a Very Long Street with a RBG k-e Model2006In: International Conference Megacities 2006, conference proceedings, 2006, 442-451 p.Conference paper (Other academic)
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