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1.
  • Jönsson, Åsa, 1965, et al. (författare)
  • Life cycle assessment of flooring materials: Case study
  • 1997
  • Ingår i: Building and Environment. - 0360-1323. ; 32:3, s. 245-255
  • Tidskriftsartikel (refereegranskat)abstract
    • The environmental impact of the three flooring materials linoleum, vinyl flooring and solid wood flooring during their life cycles was assessed and compared through life cycle assessment (LCA). The scenarios used describe a Swedish situation. Only impacts on the natural environment were studied The quantitative results of the inventory analysis were evaluated by using three different assessment methods. According to the results, solid wood flooring proved to be clearly the most environmentally sound flooring. Linoleum was ranked as more environmentally sound than vinyl flooring, although this was less evident in comparison with ranking the solid wood flooring.
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2.
  • Karimipanah, Taghi, 1953- (författare)
  • Deflection of wall-jets in ventilated enclosures described by pressure distribution
  • 1998
  • Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 34:3, s. 329-333
  • Tidskriftsartikel (refereegranskat)abstract
    • The pressure field in fluid systems reflects the flow configuration. Measurements of the pressure along the perimeter of a slot ventilated room have been conducted for different room sizes. The momentum of the jet at the end of the room is decreased with increasing room length. The impingement region (region where the influence of the opposing wall is present) starts, independent of room size, when the distance from the supply device is about 70% of the room length. Corner flows could not be predicted by CFD using the linear eddy viscosity or standard stress models. However, these effects may be captured by using a second moment closure turbulence model with a new near wall approach now available in literature.
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3.
  • Karimipanah, Taghi, 1953-, et al. (författare)
  • Theoretical and experimental investigation of impinging jet ventilation and comparison with wall displacement ventilation
  • 2002
  • Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 37:12, s. 1329-1342
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper focuses on evaluating the performance of a new impinging jet ventilation system and compares its performance with a wall displacement ventilation system. Experimental data for an impinging jet in a room are presented and non-dimensional expressions for the decay of maximum velocity over the floor are derived. In addition, the ventilation efficiency, local mean age of air and other characteristic parameters were experimentally and numerically obtained for a mock-up classroom ventilated with the two systems. The internal heat loads from 25 person-simulators and lighting were used in the measurements and simulations to provide a severe test for the two types of ventilation systems. In addition to a large number of experimental data CFD simulations were used to study certain parameters in more detail. The results presented here are part of a larger research programme to develop alternative and efficient systems for room ventilation.
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4.
  • Larsson, Ulf, 1966-, et al. (författare)
  • Experimental investigation of downdraught from well-insulated windows
  • 2002
  • Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 37:11, s. 1073-1082
  • Tidskriftsartikel (refereegranskat)abstract
    • Since the climate in the Nordic countries is cold for several months a year, windows are crucial in building envelopes. The current trend to reduce heat losses by building components has resulted in many modifications to window design in order to improve thermal performance and the indoor climate. Improvements in window construction have resulted in a higher surface temperature on the inner pane and considerably lower downdraught, which in turn has created an opportunity for the unconventional design of the heating and ventilation systems. The impetus for this paper is to experimentally investigate the effect of thermal performance, window bay and displacement ventilation on the downdraught. The measurements show that the use of well-insulated windows, besides lowering energy consumption, gives rise to a higher quality of indoor climate. The results show a considerably reduced velocity and turbulent intensity by employing a well-insulated window instead of a conventional one. The influence of the window bay on the downdraught is also shown in the paper. © 2002 Elsevier Science Ltd. All rights reserved.
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5.
  • Mundt, Elisabeth, 1946- (författare)
  • Non-buoyant pollutant sources and particles in displacement ventilation
  • 2001
  • Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 36:7, s. 829-836
  • Tidskriftsartikel (refereegranskat)abstract
    • Particle transportation and ventilation efficiency, with non-buoyant pollutant sources, in a displacement-ventilated room were evaluated. A resuspension of floor deposited particles caused by the influence of the supply air or people moving around may increase the number of particles in the convection flows. Particle concentrations at different positions under steady state and transient conditions were measured. The results indicate that there seem to be little risk of resuspension of particles, in the measured size interval, by the influence of the supply air. With a forced resuspension the particle concentrations in the convection flows differ from the concentration outside the convection flow. The contaminant removal effectiveness was much dependent on the position of the pollutant sources.
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6.
  • Rolfsman, Björn (författare)
  • CO2 emission consequences of energy measures in buildings
  • 2002
  • Ingår i: Building and Environment. - 0360-1323 .- 1873-684X. ; 37:12, s. 1421-1430
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper studies the way in which CO2 emission levels are affected by different measures to reduce energy consumption in a building. A case study is presented which deals with a residential building in Navestad, a suburb of the Swedish city Norrköping. The building is supplied with district heating primarily delivered from a combined heat and power (CHP) plant. Three types of energy measures are studied: extra insulation, new types of window and the introduction of a heat pump. The first perspective is the city of Norrköping, with the system boundary encompassing the residential building and the CHP plants. A second worst case scenario is then presented: a Nordic perspective in which electricity produced in coal condensing power plants is assumed to cover the marginal electricity production. With the former perspective, the measures extra insulation and new windows reduce the CO2 emissions, and with the latter both measures increase the CO2 emissions. The measures extra insulation and new windows are ranked, with respect to cost for the first perspective, using a cost reduction curve for CO2 emissions. In the paper, costs from the ExternE research project are also used. © 2002 Elsevier Science Ltd. All rights reserved.
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7.
  • Aarts, Mariëlle P.J., et al. (författare)
  • Performance of personally worn dosimeters to study non-image forming effects of light : Assessment methods
  • 2017
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 117, s. 60-72
  • Tidskriftsartikel (refereegranskat)abstract
    • When determining the effects of light on human beings, it is essential to correctly measure the effects, and to correctly measure the adequate properties of light. Therefore, it is important to know what is being measured and know the quality of the measurement devices. This paper describes simple methods for identifying three quality indices; the directional response index, the linearity index and the temperature index. These indices are also checked for several commonly used portable light measurement devices. The results stresses what was already assumed, the quality and the outcome of these devices under different circumstances were very different. Also, the location were these devices are normally worn has an impact on the results. The deviation range between worn vertically at eye level and the wrist is between 11% (outdoor) to 27% (indoor). The smallest deviation, both in indoor and outdoor, was found when the device was placed on the sides of the eye (7%). 
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8.
  • Abdul Hamid, Akram, et al. (författare)
  • Hygrothermal assessment of internally added thermal insulation on external brick walls in Swedish multifamily buildings
  • 2017
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 123, s. 351-362
  • Tidskriftsartikel (refereegranskat)abstract
    • Proper and efficient renovation requires understanding the behavior of existing buildings and of different building materials. Analyzing hygrothermal measurements in two case studies, one with and the other without an internally added thermal insulation system, enabled us to identify factors of critical importance for further assessment through simulations, and to validate a hygrothermal simulation model of a solid brick masonry wall, a model used then to assess internally added thermal insulation systems of different types. A mold resistance design (MRD) model shows that, in connection with all internally added thermal insulation systems, the risk of mold growth is appreciable when brought on by solar driven vapor from the exterior. This, if biological material is present in either of two critical areas, those of the boundary between the thermal insulation and either 1) the existing masonry wall, or 2) the exterior surface of an internally added vapor barrier. Furthermore, assessments of corrosion risks are conducted for two critical placements of the bed-joint reinforcement. At a depth of 30 mm from the exterior surface, the corrosion risk was found to be less with use of capillary-active vapor-open systems than when no thermal insulation was employed, other systems increase the corrosion risk. At a depth of 90 mm, all thermal insulation systems increase the corrosion risk. Excluding precipitation uptake eliminates all risks, showing that this is the most crucial factor. Solutions that limit this uptake or increase the drying-out rate should thus be considered beneficial.
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9.
  • af Klintberg, Tord, 1951-, et al. (författare)
  • Air Gap Method : Dependence of water removal on RH in room and height of floor air gap
  • 2012
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 56, s. 1-7
  • Tidskriftsartikel (refereegranskat)abstract
    • This study is performed in combined floor and wall constructions with air gaps within and with a heating cable in the vertical air gap. All surfaces of the air gap are covered with polystyrene plastic to avoid leakage into the construction. Wet gypsum boards that are weighed at start and end of experiment are used to measure the dry out process.Three different heights of the floor air gap, 25 mm, 15 mm and 5 mm are investigated. The influences of the RH in the surrounding room and of the wetness of the gypsum boards are also investigated.It is shown that the height of the floor air gap has a great impact on the rate of drying. The optimal height is less than 25 mm and somewhere between 15 and 5 mm.
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10.
  • Albuquerque, Daniel P., et al. (författare)
  • Experimental and numerical investigation of pumping ventilation on the leeward side of a cubic building
  • 2020
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 179
  • Tidskriftsartikel (refereegranskat)abstract
    • Unstable interaction between shear layers that form in the wake of an isolated building exposed to wind can drive natural pumping ventilation in windward and leeward facing rooms with two or more horizontally separated openings. This paper presents an experimental and numerical study of pumping ventilation in a three-story cubic building with two leeward openings in its middle floor. Reduced-scaled measurements were performed in the University of Gävle atmospheric-boundary-layer wind tunnel. The ventilation mechanism was investigated using smoke visualization, hot wire anemometry and particle image velocimetry. Effective ventilation rates were obtained using a tracer gas decay method. Experimental results confirmed that pumping ventilation is a 3D oscillatory unstable phenomenon with periodic behavior over several oscillation cycles. Measured flowrates show a linear relation between the effective ventilation rate and window separation. The numerical simulations used two turbulence modeling approaches: unsteady Reynolds-averaged Navier-Stokes (URANS) and large eddy simulation (LES). Both URANS and LES could predict vortex shedding frequency with an error below 5%. LES showed a good agreement with the measured ventilation rates, with an error below 10%, while URANS underestimated ventilation rates by at least 40%. The ventilation efficiency, obtained by LES, ranged between 0.60 and 0.75 (for the case with larger window separation). The results show that LES may be a suitable simulation approach for pumping ventilation. In contrast, URANS cannot simulate pumping ventilation.
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11.
  • Ameen, Arman, 1976-, et al. (författare)
  • Numerical investigation of the flow behavior of an isothermal corner impinging jet for building ventilation
  • 2022
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 223
  • Tidskriftsartikel (refereegranskat)abstract
    • The corner impinging jet concept has been proposed as a new air distribution system for use in office environments. The present paper reports the mean flow field behavior of an isothermal corner-based turbulent impinging jet in a room. A detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed using three turbulence models. RNG k−ε model was chosen for this study. This study investigates the influence different configuration parameters such as jet discharge height, diffuser geometry (shape and size) and supply airflow rate have on the flow field. The results show that the diffuser geometries used in this study had in general a minor effect on the velocity developments along the centerline of the floor, maximum velocity decay and jet spreading rate except for some specific cases. When evaluating the triangle geometry cases, the results show that all the cases with volume flow <20 L/s are able to meet Boverket's building regulations velocity requirement both for summer and winter. The applicability evaluation show that the results can be considered for room sizes between ≈25 and 100 m2. In addition, the wall confinement effect (90° vs. 180°) is having a significant impact on the maximum velocity decay for corner impinging jet ventilation. In the regression analysis the results shows that the distance along the diagonal centerline of the room has the most impact on the evaluation of maximum velocity decay and jet spreading rate.
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12.
  • Aminipouri, M., et al. (författare)
  • Urban tree planting to maintain outdoor thermal comfort under climate change: The case of Vancouver's local climate zones
  • 2019
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 158, s. 226-236
  • Tidskriftsartikel (refereegranskat)abstract
    • Spatiotemporal variation of mean radiant temperature (Tmrt), a major driver of outdoor human thermal comfort, is driven by exposure to solar and longwave radiation, which in turn respond to local patterns of shading, wind speed, air humidity and air temperature. In this study, the SOlar and LongWave Environmental Irradiance Geometry (SOLWEIG) model was used to simulate how changes in minimum and maximum air temperature and solar radiation under Representative Concentration Pathways (RCP) 4.5 and 8.5 climate projections would change Tmrt in Vancouver over the 2070-2100 period. With micrometeorological variables representative of a changed climate, days with Tmrt above 65 degrees C were predicted to increase three-to five-fold under RCP 4.5 and 8.5, respectively. SOLWEIG was also used to quantify the potential of maximum feasible street tree cover to reduce Tmrt for the hottest day on record for Vancouver (July 29, 2009), and an end-of-century hot day under the two future climate scenarios. SOLWEIG simulations with maximum feasible street tree cover under RCP 4.5 demonstrated an average reduction of 1.3 degrees C in Tmrt, compared to the contemporary extreme heat day with current street trees. However, average Tmrt increased by 1.9 degrees C under the RCP 8.5 scenario even with maximum feasible street tree cover, relative to the contemporary extreme heat day. We conclude that adding street trees has the potential to offset Tmrt increases under the RCP 4.5 scenario, however this measure is insufficient to maintain contemporary Tmrt under the RCP 8.5 scenario.
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13.
  • Andersson, Harald, et al. (författare)
  • Experimental and numerical investigations of a new ventilation supply device based on confluent jets
  • 2018
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 137, s. 18-33
  • Tidskriftsartikel (refereegranskat)abstract
    • In developed countries, heating, ventilation, air conditioning (HVAC) systems account for more than 10% of national energy use. The primary function of a HVAC system is to create proper indoor environment. A number of ventilation strategies have been developed to minimize HVAC systems’ energy use whilst still maintaining a good indoor environment. Among these strategies are confluent jet ventilation and variable air volume. In this study, an air supply device with a novel nozzle design that uses both of the above-mentioned strategies was investigated both experimentally and numerically at three different airflow rates. The results from the numerical investigation using the SST k - ω turbulence model regarding velocities and flow patterns are validated by experimental data carried out by Laser Doppler Anemometry. The results from both studies show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for the airflow rates investigated.
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14.
  • Antoniou, Nestoras, et al. (författare)
  • CFD and wind-tunnel analysis of outdoor ventilation in a real compact heterogeneous urban area : evaluation using “air delay”
  • 2017
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 126, s. 355-372
  • Tidskriftsartikel (refereegranskat)abstract
    • Outdoor urban ventilation in a real complex urban area is investigated by introducing a new ventilation indicator – the "air delay". Computational Fluid Dynamics (CFD) simulations are performed using the 3D steady Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The up-to-date literature shows the lack of detailed evaluations of the two approaches for real compact urban areas. This study further presents a systematic evaluation of steady RANS and LES for the assessment of the ventilation conditions in a dense district in Nicosia, Cyprus. The ventilation conditions within the urban area are investigated by calculating the distribution of the age of air. To better assess the outdoor ventilation, a new indicator, the "air delay" is introduced as the difference between the local mean age of air at an urban area and that in an empty domain with the same computational settings, allowing the comparison of the results in different parts of the domain, without impact of the boundary conditions. CFD results are validated using wind-tunnel measurements of mean wind speed and turbulence intensity performed for the same urban area. The results show that LES can accurately predict the mean wind speed and turbulence intensity with the average deviations of about 6% and 14%, respectively, from the wind-tunnel measurements while for the steady RANS, these are 8% and 31%, respectively. The steady RANS simulations overestimate the local mean air delay. The deviation between the two approaches is 52% at pedestrian level (2 m).
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15.
  • Arghand, Taha, et al. (författare)
  • An experimental investigation of the flow and comfort parameters for under-floor, confluent jets and mixing ventilation systems in an open-plan office
  • 2015
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 92, s. 48-60
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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16.
  • Arghand, Taha, 1982, et al. (författare)
  • Individually controlled localized chilled beam with background radiant cooling system: Human subject testing
  • 2022
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 218
  • Tidskriftsartikel (refereegranskat)abstract
    • This study examines the responses of twenty-four subjects to an individually-controlled localized chilled beam (LCB) and compares it to a mixing ventilation (MV) as the reference system. Both LCB and MV also used ceiling cooling (CC) panels for background cooling (forming LCBCC and MVCC systems). The LCB directed the supply air towards the subjects to create a micro-environment around them. Four experimental conditions were established using a combination of two room temperatures (26 °C and 28 °C) and two primary ventilation rates (10 l/s and 13 l/s). During the 90 min-long experiments, the subjects were asked to assess their perceived air quality, thermal sensation, comfort, air movement acceptability and acceptability of the work environment. The results indicated that the LCBCC was superior to the MVCC with significantly higher acceptability of the work environment, perceived air quality and thermal sensation. Perceived air quality and thermal sensation were rated near the “clearly acceptable” level for both room temperatures when LCBCC was used. Moreover, thermal sensation votes were close to the “neutral” level for room temperatures as high as 26 °C and 28 °C. The micro-environment established by the LCB was found to be resilient to changes in room temperature. With the MVCC, the thermal environment was rated as “slightly warm”. No major potential risk of draught among the subjects was reported when using the LCBCC. The findings of this study contribute to the development of high-temperature cooling systems in general, and localized ventilation systems in particular.
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17.
  • Arsenault, Helene, et al. (författare)
  • Effects of glazing colour type on perception of daylight quality, arousal, and switch-on patterns of electric light in office rooms
  • 2012
  • Ingår i: Building and Environment. - : Elsevier BV. - 1873-684X .- 0360-1323. ; 56, s. 223-231
  • Tidskriftsartikel (refereegranskat)abstract
    • A study is presented about the effects of three glazing colour types (blue, neutral, bronze) on daylight quality, arousal and switch-on patterns for electric lights. This study was carried out using a scale model (1:4) of an office room, where subjective evaluations of the luminous conditions were performed by 36 participants (mean age 23.8 years) with their upper bodies immersed in the model. The evaluations were achieved using questionnaires designed to assess five light quality factors: 1) visual comfort; 2) naturality; 3) pleasantness; 4) precision (of details and textures) and 5) light level. Mixed model analyses of the questions revealed significant higher scores for pleasantness (p = 0.003) comfort (p = 0.015) and light level (p = 0.044) for the bronze glazing type compared to the blue and neutral glazing, confirming results of earlier studies. Results from a paired t-test on the Karolinska Sleepiness Scale (KSS) scores indicated that the level of self-reported arousal decreased in presence of the blue glazing. However, the analysis did not reveal significant results regarding switch-on patterns of electric lights. Overall, the study shows that there is a preference for daylight filtered through bronze window glazing and that the glazing colour type may have a significant effect on arousal level of office workers. (C) 2012 Elsevier Ltd. All rights reserved.
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18.
  • Asphaug, Silje Kathrin, et al. (författare)
  • Moisture Control Strategies of Habitable Basements in Cold Climates
  • 2020
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 169
  • Tidskriftsartikel (refereegranskat)abstract
    • In many countries with a cold climate, basements are used as dwellings. This presents a major challenge concerning moisture safety design. Climate change is expected to increase the risk of moisture-related damage in basements owing to increasing amounts of stormwater, annual precipitation, and annual temperatures. This study examines the primary moisture control strategies for habitable basements in western cold climate countries by identifying the main differences and similarities in national building recommendations for new buildings. Using Norwegian design guides as a baseline, we identified ten key challenges and compared them with four other cold climate countries’ recommendations given by experts in the field of building physics (building science). The results showed that other countries’ recommendations differ from those of Norway in various key challenges. However, similar but varying recommendations pertaining to ground surface slopes, drainage layers, drainage pipes, capillary breaking layers in floors, avoiding thermal bridges, airtightness, and ventilation were noted. The key differences pertained to the exterior damp proofing of walls, use and position of dimpled membranes and vapour barriers, and use of permeable thermal insulation. The outcome is that countries emphasise the ten key challenges differently. Although the recommendations have many similarities, the weighting (or prioritizing) distinguishes the five countries’ moisture control strategies.
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19.
  • Assefa, Getachew, et al. (författare)
  • Environmental assessment of building properties — Where natural and social sciences meet : the case of EcoEffect
  • 2007
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 42:3, s. 1458-1464
  • Tidskriftsartikel (refereegranskat)abstract
    • The EcoEffect method of assessing external and internal impacts of building properties is briefly described. The external impacts of manufacturing and transport of the building materials, the generation of power and heat consumed during the operation phase are assessed using life-cycle methodology. Emissions and waste; natural resource depletion and toxic substances in building materials are accounted for. Here methodologies from natural sciences are employed. The internal impacts involve the assessment of the risk for discomfort and ill-being due to features and properties of both the indoor environment and outdoor environment within the boundary of the building properties. This risk is calculated based on data and information from questionnaires; measurements and inspection where methodologies mainly from social sciences are used. Life-cycle costs covering investment and utilities costs as well as maintenance costs summed up over the lifetime of the building are also calculated.The result presentation offers extensive layers of diagrams and data tables ranging from an aggregated diagram of environmental efficiency to quantitative indicators of different aspects and factors. Environmental efficiency provides a relative measure of the internal quality of a building property in relation to its external impact vis-à-vis its performance relative to other building properties.
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20.
  • Assefa, Getachew, et al. (författare)
  • Quality versus impact : Comparing the environmental efficiency of building properties using the EcoEffect tool
  • 2010
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 45:5, s. 1095-1103
  • Tidskriftsartikel (refereegranskat)abstract
    • There are tools that are developed for the assessment of the environmental impact of buildings (e.g. ATHENA). Other tools dealing with the indoor and outdoor environmental quality of building properties (referred to as real estates in other literature) are also available (e.g. GBTool). A platform where both the aspects of quality and impact are presented in an integrated fashion are few. The aim of this contribution is to present how the performance of different building properties can be assessed and compared using the concept of environmental efficiency in a Swedish assessment tool called EcoEffect. It presents the quality dimension in the form of users' satisfaction covering indoor and outdoor performance features against the weighted environmental impact covering global and local impacts. The indoor and outdoor values are collected using questionnaires combined with inspection and some measurements. Life cycle methodology is behind the calculation of the weighted external environmental impact. A case study is presented to show the application of EcoEffect using a comparative assessment of Lindas and a Reference property. The results show that Lindas block is better in internal environment quality than the Reference property. It performs slightly worse than the Reference property in the external environmental impact due to emissions and waste from energy and material use. The approach of integrated presentation of quality and impact as in EcoEffect provides with the opportunity of uncovering issues problem shifting and sub-optimisation. This avoids undesirable situations where the indoor quality is improved through measures that result in higher external environmental impact.
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21.
  • Azizi, Shoaib, et al. (författare)
  • Application of Internet of Things in academic buildings for space use efficiency using occupancy and booking data
  • 2020
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 186
  • Tidskriftsartikel (refereegranskat)abstract
    • Environmental sustainability in academic buildings can be improved with management interventions such as improving space use efficiency supported by large data from the Internet of Things (IoT). Due to the potentials, the interest in the use of IoT tools for facility management is high among universities. However, empirical studies on this topic are scarce. To address the knowledge gap in this area, this study proposes and examines a process model with steps to measure space use and to improve space use efficiency by IoT tools in academic buildings. The applicability of the model is investigated in 8 lecture halls in a university building by using occupancy and booking data from IoT tools. Four space use indicators are developed to visualize the data and quantify space use, and based on them, the strategies and interventions for space use efficiency are proposed and discussed.
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22.
  • Barjot, Zoé, et al. (författare)
  • Limit values in LCA-based regulations for buildings – System boundaries and implications on practice
  • 2024
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 259
  • Tidskriftsartikel (refereegranskat)abstract
    • Rapidly reducing the climate impacts of the construction and use of buildings is acknowledged as a key lever to meet European and national climate goals. Life cycle-based regulations, in the form of mandatory declaration of the climate impact of new-build, are being introduced, often planned to be or already complemented with performance-based limit values. This development has increasingly raised questions on how different system boundaries for similar limit values applied in various countries might lead to diverging implications in practice. A sample of 50 real-life case buildings of different typologies, representative of contemporary Swedish construction, is used to compare implications of two different system boundaries for embodied GHGe assessment: SB1) life cycle modules A1-A5 i.e. initial, that is upfront GHGe and SB2) life cycle modules A1-A5 + B2–B4, i.e. adding recurring GHGe, according to the European EN 15978 standard. The results show that for the two system boundaries applied, no difference is seen concerning the sample buildings' ability to perform below a limit value as defined in current Swedish regulatory plans, nor would it lead to different design choices to ensure that a building performs below the limit value. The results of sensitivity analyses along with the relative nature of the results, suggest these conclusions are also relevant for other regulatory contexts. As a conclusion, this study shows that implementing LCA-based regulations focusing on initial embodied GHGe is an important step to rapidly and effectively address GHGe associated with new-build.
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23.
  • Bayat Pour, Mohsen, et al. (författare)
  • A Literature Review of Probabilistic Hygrothermal Assessment for Building Envelopes
  • 2024
  • Ingår i: Building and Environment. - 0360-1323. ; 261
  • Forskningsöversikt (refereegranskat)abstract
    • This study presents a state-of-the-art review of the evolution of probabilistic hygrothermal assessments of building envelopes. First, relevant literature was identified by employing a systematic methodology, including scoping and systematic searches, quality assessment, and study analysis. The analysis, based on 143 selected publications, provides statistical insights into uncertainty propagation and sensitivity analysis methods, geographical distributions, climatic conditions, sustainability perspectives, uncertain parameter groups, employed metamodels, hygrothermal analysis tools, model dimensions, building usage, and moisture-related damage models. The results illustrate that the majority of probabilistic hygrothermal assessment studies, exceeding 95%, are not explicitly incorporating sustainability perspectives, including environmental, economic, and societal. Also, to enhance the accuracy in this field, it is important to integrate hygrothermal functions as uncertain input variables, given their potential to significantly impact hygrothermal performance compared to single material properties. While 90% of studies are confined to 1D modelling, extending research to 2D and 3D is advised to capture more complicated details. Moreover, case studies in tropical climates, where moisture-related issues can be prevalent, are noticeably lacking. Sensitivity analysis faces limitations due to its transient nature and variable interactions, necessitating identification of methods capable of non-linear and interactive analyses with low computational costs. Furthermore, several studies neglect ambient conditions and building usage considerations as stochastic variables, highlighting the need for comprehensive analyses. Lastly, understanding the merits and limitations of metamodeling methods is crucial for achieving reliable and robust hygrothermal analyses. The paper concludes by outlining the identified gaps and offering recommendations for future research in this field.
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24.
  • Bayat Pour, Mohsen, et al. (författare)
  • Robust probabilistic modelling of mould growth in building envelopes using random forests machine learning algorithm
  • 2023
  • Ingår i: Building and Environment. - 0360-1323. ; 243
  • Tidskriftsartikel (refereegranskat)abstract
    • Probabilistic methods can be used to account for uncertainties in hygrothermal analysis of building envelopes. This paper presents methods for robust mould reliability analysis and identification of critical parameters. Mould indices are calculated by probabilistic hygrothermal analysis, followed by the application of the "Finnish mould growth model." To increase the robustness of the mould growth analysis, a random forests metamodel is first trained on the dataset and then used to expand the number of simulations. Finally, the reliability is calculated based on the probability of exceeding a given maximum mould index limit state. Critical parameters are identified through a sensitivity analysis based on linear and non-linear dependencies between inputs and maximum mould index. The methods are demonstrated by analysing three external wall assemblies. In conclusion, the mould reliability analysis method helps to assess the robustness of the hygrothermal analysis and mould assessment by investigating the influence of hygrothermal variables' uncertainties on the maximum mould index. By combining a metamodel with probabilistic analysis, it is possible to significantly reduce the amount of time required to evaluate a large number of scenarios.
  •  
25.
  • Belarbi, Rafik, et al. (författare)
  • Experimental and theoretical investigation of non-isothermal transfer in hygroscopic building materials
  • 2008
  • Ingår i: Building and Environment. - : Elsevier BV. - 1873-684X .- 0360-1323. ; 43:12, s. 2154-2162
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper a modified two-dimensional Luikov model for evaluating the non-isothermal moisture migration in porous building materials was proposed. The coupled heat and moisture transfer problem was modeled. Vapor content and temperature were chosen as the principal driving potentials. The coupled equations were solved by a numerical method, which consists of a finite difference technique with a fully implicit scheme in time. Two validation experiments were developed in this study. The evolution of transient moisture distributions in both one-dimensional and two-dimensional cases wits measured. A comparison between experimental results and those obtained by the numerical model proves that they are fully consistent with each other. The modified model can be integrated into a whole building heat, air and moisture transfer model. (C) 2007 Elsevier Ltd. All rights reserved.
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26.
  • Bluyssen, Philomena M., et al. (författare)
  • Comfort of workers in office buildings : The European HOPE project
  • 2011
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 46:1, s. 280-288
  • Tidskriftsartikel (refereegranskat)abstract
    • Previous studies have shown that building, social and personal factors can influence one's perceived health and comfort. The aim of the underlying study was to get a better understanding of the relationships between these factors and perceived comfort. Self-administered questionnaires from 5732 respondents in 59 office buildings and building-specific data from the European Health Optimisation Protocol for Energy-efficient buildings (HOPE) study were used. Principal Component Analysis (PCA), reliability analyses, and linear regression analysis were performed. The outcome showed that perceived comfort is strongly influenced by several personal, social and building factors and that their relationships are complex. Results showed that perceived comfort is much more than the average of perceived indoor air quality, noise, lighting and thermal comfort responses. Perceived comfort is a phenomenon that deserves more research.
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27.
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28.
  • Bok, Gunilla, 1961, et al. (författare)
  • Mass occurrence of Penicillium corylophilum in crawl spaces, south Sweden
  • 2009
  • Ingår i: Building and Environment. - 0360-1323. ; 44, s. 2413-2417
  • Tidskriftsartikel (refereegranskat)abstract
    • Buildings with crawl space foundations are looked upon as high-risk constructions with respect to mould growth, especially on the blind floor. This mould growth can be extensive and cover several square meters of the blind floor with potential health risks as a consequence. Mould occurrence and mould species diversity were investigated in a large small-house area in the south of Sweden, comprising 212 buildings. The crawl spaces were inspected and samples from the blind floor were taken. The relative humidity was measured and reached 80–100% for several consecutive months. Subsets of the samples were cultured and the fungi isolated were further analyzed by sequencing of the Internal Transcribed Spacer (ITS) region of nuclear ribosomal Deoxyribo Nucleic Acid (DNA). The results were compared with results from other, relevant studies and confirm that Penicillium corylophilum is the completely dominating mould species in crawl spaces. The occurrences could not be explained as accidental since the extensive occurrence in many dwellings had developed over several years.
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29.
  • Bournas, I. (författare)
  • Daylight compliance of residential spaces : Comparison of different performance criteria and association with room geometry and urban density
  • 2020
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 185
  • Tidskriftsartikel (refereegranskat)abstract
    • Currently, policy makers in Sweden are considering updating building regulations with respect to daylight provision. Given this context, the present paper aims to provide insight on the level of compliance of residential spaces when tested against five daylight performance criteria. These included the criterion currently in force in Sweden, the two performance criteria set by European Standard EN17037, a daylight factor-based criterion (BREEAM) and a climate-based criterion founded on the UDI metric. Compliance was tested by performing Radiance simulations on a representative sample of Swedish multi-dwelling buildings, including 10888 rooms. The criteria were compared according to the compliance they yield for different buildings and room types. Compliance per criterion was also associated with room geometry to evaluate which geometric measures affect it most substantially, and with urban density to evaluate which criterion best captures the effect of surrounding obstructions. Results indicate that the implementation of different criteria deem different building types to be better or worse performing. A consistent finding is that the vast majority of evaluated spaces are deemed to be incompliant when tested against the daylight-factor-based criterion of EN17037, which is significantly harder to comply with compared to its climate-based counterpart. The highest compliance is achieved when testing against the current Swedish criterion. The results also indicate that the Vertical Sky Component and glass-to-floor ratio affect compliance most substantially compared to other geometric measures. Finally, when daylight compliance was associated with urban density, the strongest association was acquired when rooms were tested using the UDI criterion.
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30.
  • Bournas, Iason, et al. (författare)
  • Daylight regulation compliance of existing multi-family apartment blocks in Sweden
  • 2019
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 150, s. 254-265
  • Tidskriftsartikel (refereegranskat)abstract
    • This research investigates the daylight regulation compliance of existing multi-family housing developments located primarily in Stockholm (Lat.: 59,33 °N), Sweden. A representative sample of 54 buildings consisting of 10.888 individual rooms was modelled according to archived documentation drawings and evaluated by use of Radiance simulations, to test their compliance with the current Swedish daylight regulation. The studied buildings were selected according to their relevance to major architectural typologies of Swedish urban planning history (1926–1991). The assessment was based on a point Daylight Factor scheme (DFP), which stipulates that a specific point in a room should achieve a Daylight Factor DFP ≥ 1%, for the room to be sufficiently daylit. Results indicate that specific architectural typologies consistently yield poor DFP levels compared to other ones. A moderate correlation was found between the density of surroundings and the percentage of compliant rooms per housing development. Finally, the results indicate the existence of distinct periods during Swedish urban planning history, when daylight performance of multi-family houses was affected by different planning practices. Future investigations are under development to evaluate the occupants’ perception of daylight in their apartments, to help define new daylight performance indicators and benchmarks for Swedish households, taking into consideration the limitations of the daylight indicator embedded in the current regulation.
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31.
  • Bournas, Iason, et al. (författare)
  • Perceived daylight conditions in multi-family apartment blocks – Instrument validation and correlation with room geometry
  • 2020
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 169
  • Tidskriftsartikel (refereegranskat)abstract
    • This article investigates the relation between subjective evaluations and objective measurements of daylighting in multi-family residential buildings. More specifically, the suitability of an observer-based environmental assessment (OBEA) instrument to assess indoor daylight conditions was tested in a field study conducted in six typical multi-family apartment buildings in the central and metropolitan area of Malmö (Latitude: 55.6 °N), Sweden. The OBEA used self-administered questionnaires based on bipolar semantic scales aiming to capture two perceived daylight qualities: brightness and distribution. Following a factorial approach, one component pertaining to perceived brightness was deducted (“Brightness”, Cronbach's alpha = 0.89) and validated by associating it with outdoor global horizontal irradiance (Spearman's rS = 0.566, p = 0.006), which was monitored during the survey. Subsequently, this component was correlated with key geometric attributes of the investigated apartments to highlight the most important associations between perceived brightness and room geometry. Results indicate that the OBEA displays high internal reliability for the derived component, and is fit for daylight perception evaluations in residential spaces. In addition, the analysis showed a tendency for variables pertaining to window size to associate with perceived brightness, but also contributing to this association was the level of global horizontal irradiance.
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32.
  • Bournas, Iason, et al. (författare)
  • Residential electric lighting use during daytime : A field study in Swedish multi-dwelling buildings
  • 2020
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 180
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper evaluates the effect of room function and orientation on daytime electric lighting use in dwellings, and the confounding role of room design aspects. A questionnaire survey was conducted in six multi-dwelling buildings including 75 apartments located in Malmö, Sweden (Latitude: 55.6 °N). Occupants were asked how often they use electric lighting during daylight hours, in three rooms of different functions, namely the kitchen, the living room and the bedroom. In a preliminary step, the behavior of occupants regarding electric lighting use was evaluated, to test whether design and orientation can affect switch-on behavior or whether it is random and unpredictable. In the next step, statistical analysis was performed to verify whether there is a relation between daytime electric lighting and room function, room orientation or both. Results indicate that electric lighting use did not vary significantly among occupants living in rooms of similar geometry, especially when living in West-oriented rooms. With respect to room function, overall it was shown that daytime electric lighting use was more frequent in kitchens. However, the study showed that electric lighting use in kitchens is associated with specific design features and not with room function per se. With respect to orientation, a consistent finding was that West-facing rooms use electric lighting less frequently compared to rooms of other orientations, and significantly less frequently compared to East-facing rooms, which can be explained by diurnal occupancy patterns characterizing residential spaces. The implications of the findings on daylight design criteria for residences are discussed.
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33.
  • Bournas, Iason (författare)
  • Swedish daylight regulation throughout the 20th century and considerations regarding current assessment methods for residential spaces
  • 2021
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 191
  • Tidskriftsartikel (refereegranskat)abstract
    • Daylight availability for buildings has been an integral part of architecture since ancient times, yet for the vast majority of countries, criteria for daylight provision were not normative until the 20th century. This article examines the case of Sweden, where the term “daylight” first appeared in regulations in 1960, and assesses the daylight compliance of multi-dwelling buildings before and after that, in the timespan between 1920 and 2000. Firstly, the study evaluates whether the introduction of daylight criteria improved building performance. Secondly, the two current assessment methods are compared, as a disagreement was expected given that one method is formulated based on the glass-to-floor ratio scheme (GFR-method) while the other on a daylight factor scheme (DFP). Thirdly, the applicability and limitations of each method are evaluated. Results indicate that dwellings built following the introduction of daylight criteria do not necessarily outperform their predecessors. With respect to assessment methods, it was shown that the GFR-method is of limited applicability due to geometric constraints stipulated in its formulation, primarily due to the violation of the fenestration width condition. When comparing methods, the GFR-method yielded higher compliance compared to DFP, but only marginally. Eventually, the study highlights methodological flaws in the formulation of each criterion. Overall, the work contributes to knowledge supporting the development of daylight requirements for residential spaces. It provides background information suitable for planners and policy makers in their endeavors to define daylight performance criteria.
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34.
  • Brown, Nils W. O., et al. (författare)
  • Embodied greenhouse gas emissions from refurbishment of residential building stock to achieve a 50% operational energy reduction
  • 2014
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 79, s. 46-56
  • Tidskriftsartikel (refereegranskat)abstract
    • Mitigating climate change through operational energy reduction in existing buildings is of highest priority for policy-makers in Europe and elsewhere. At the same time there is increasing understanding of the significance of impacts arising from material production for buildings. The aim of this work has therefore been to evaluate the importance of embodied GWP for refurbishment for operational energy reduction on a stockwide basis. It is further intended to judge the relative significance of embodied GWP for specific refurbishment measures implemented for operational energy reduction. We study the case of operational energy reduction in the Swedish residential building stock by 50% compared to 1995. The total embodied GWP to achieve the noted operational energy reduction is 0.35 Mt CO2-e/year. 83% of this total is due to ventilation and window measures alone. Compared with previous studies assessing GWP mitigation from operational energy reduction, the "GWP payback time" is just over 3 years. Many types of measure that contribute significantly to achieving the above operational energy goal had average embodied GWP between 10 and 20 g CO2-e/kW h operational energy reduction, notably window and ventilation measures. Indoor temperature reduction (to 20 degrees C), was also significant for stockwide operational energy reduction but had a very low GWP of 0.4 g CO2-e/kW h operational energy reduction. If this measure proves unfeasible to implement on a stockwide basis then more expensive measures with higher embodied GWP will be needed to achieve the stated energy reduction goal.
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35.
  • Brown, Nils W. O., et al. (författare)
  • Sustainability assessment of renovation packages for increased energy efficiency for multi-family buildings in Sweden
  • 2012
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 61, s. 140-148
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we propose a method for assessing renovation packages drawn up with the goal of increasing energy efficiency. The method includes calculation of bought energy demand, life-cycle cost (LCC) analysis and assessment of the building according to the Swedish environmental rating tool Miljöbyggnad (MB). In this way the methodology assesses economic, indoor environmental quality (IEQ) and specifically environmental aspects associated with energy demand of such packages from a sustainability point-of-view. Through MB, energy efficiency packages are placed in context with other necessary measures required to improve environmental performance in buildings, providing a consistent and systematic basis other than simply financial performance by which to compare capital improvements. The method is further explained and analyzed by applying it in three case studies. In each case study a multi-family building representing a typologically significant class in the Swedish building stock is considered, and for each building a base case and two renovation packages with higher initial investment requirement and higher energy efficiency are defined. It is shown that higher efficiency packages can impact IEQ indicators both positively and negatively and that packages reducing energy demand by approx. 50% have somewhat higher LCC. Identified positive IEQ impacts point to added value for packages that may not otherwise be communicated, while negative impacts identify areas where packages need to be improved, or where MB indicators may be referred to as specifications in procurement procedures.
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36.
  • Byström, Alexandra, et al. (författare)
  • Full-scale experimental and numerical studies on compartment fire under low ambient temperature
  • 2012
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 51, s. 255-262
  • Tidskriftsartikel (refereegranskat)abstract
    • A fire experiment with wood crib was conducted in a concrete building under low ambient temperature of −10 °C to explore fire development and temperature distribution. The concrete building consists of a two-storey compartment with the size of 9.0 m by 5.0 m by 4.8 m high and a four-storey stairwell with the size of 5.0 m by 2.4 m by 10.0 m high. The fuel mass loss rate and temperatures at different positions were measured. Two fire cases, with different assumed ambient temperatures of −10 °C and 20 °C respectively, were then simulated by using FDS software to investigate the effect of ambient temperature and compare with the experimental results. The numerical results show that the calculated heat release rate is in reasonably good agreement with the measured full-scale result before water suppression. The calculated temperatures in the hot combustion gas layer at different positions agree also very well with the measured values. However, the measured fresh air temperature at the floor level near the fire source is higher than the calculated value. This discrepancy may partly depend on measuring errors as analyzed in the paper.
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37.
  • Cabovska, Blanka, 1990, et al. (författare)
  • Ventilation strategies and indoor air quality in Swedish primary school classrooms
  • 2022
  • Ingår i: Building and Environment. - Göteborg : IVL Svenska Miljöinstitutet AB. - 0360-1323 .- 1873-684X. ; 226, s. 109744-109744
  • Tidskriftsartikel (refereegranskat)abstract
    • The present study aimed at investigating the effects of ventilation strategies on indoor air quality (IAQ) in schools. Measurements of thermal environment and IAQ were performed over 5 school days in 45 primary school classrooms in Gothenburg, Sweden, grouped into three categories according to their ventilation system: category A) natural or exhaust ventilation, or automated window opening; category B) balanced mechanical ventilationsystems with constant air volume (CAV) and category C) balanced mechanical ventilation systems with variable air volume (VAV). The classrooms performed equally well with respect to temperature and relative humidity regardless of the ventilation system. The concentrations of the air pollutants in all classrooms were generally below the respective guideline values. The concentrations of CO2, formaldehyde, PM10, and PM2.5 were lower in the B and C category classrooms with higher ventilation rates than in the A category classrooms. Indoor Air Pollution Index integrating concentrations of multiple pollutants was significantly higher the A category classrooms, reflecting poorer IAQ. Majority of the classrooms had lower ventilation rates than the Swedish ventilation requirements. The periodically reduced ventilation rates in the classrooms with VAV systems did not lead to substantial increase in the measured indoor pollutant concentrations.
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38.
  • Calzolari, Giovanni, et al. (författare)
  • Deep learning to replace, improve, or aid CFD analysis in built environment applications : A review
  • 2021
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 206
  • Forskningsöversikt (refereegranskat)abstract
    • Fast and accurate airflow simulations in the built environment are critical to provide acceptable thermal comfort and air quality to the occupants. Computational Fluid Dynamics (CFD) offers detailed analysis on airflow motion, heat transfer, and contaminant transport in indoor environment, as well as wind flow and pollution dispersion around buildings in urban environments. However, CFD still faces many challenges mainly in terms of computational expensiveness and accuracy. With the increasing availability of large amount of data, data driven models are starting to be investigated to either replace, improve, or aid CFD simulations. More specifically, the abilities of deep learning and Artificial Neural Networks (ANN) as universal non-linear approximator, handling of high dimensionality fields, and computational inexpensiveness are very appealing. In built environment research, deep learning applications to airflow simulations shows the ANN as surrogate, replacement for expensive CFD analysis. Surrogate modeling enables fast or even real-time predictions, but usually at a cost of a degraded accuracy. The objective of this work is to critically review deep learning interactions with fluid mechanics simulations in general, to propose and inform about different techniques other than surrogate modeling for built environment applications. The literature review shows that ANNs can enhance the turbulence model in various way for coupled CFD simulations of higher accuracy, improve the efficiency of Proper Orthogonal Decomposition (POD) methods, leverage crucial physical properties and information with physics informed deep learning modeling, and even unlock new advanced methods for flow analysis such as super-resolution techniques. These promising methods are largely yet to be explored in the built environment scene. Unavoidably, deep learning models also presents challenges such as the availability of consistent large flow databases, the extrapolation task problem, and over-fitting, etc.
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39.
  • Carlucci, S., et al. (författare)
  • Modeling occupant behavior in buildings
  • 2020
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 174
  • Tidskriftsartikel (refereegranskat)
  •  
40.
  • Carrilho da Graça, Guilherme, et al. (författare)
  • Pumping ventilation of corner and single sided rooms with two openings
  • 2021
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 205
  • Tidskriftsartikel (refereegranskat)abstract
    • Corner rooms with two or more open windows in perpendicular facades can be naturally ventilated in cross-ventilation or pumping ventilation. These two airflow regimes also occur in rooms with two openings in the same façade, in the form of single sided pumping or cross sided ventilation. This paper presents an experimental and numerical simulation study of the scale and occurrence of these two flow regimes for rooms in a rectangular building exposed to wind. Flow visualization and tracer gas measurement of effective airflow were performed in an atmospheric boundary layer wind tunnel using a rectangular model of a three-story building (1/20 scale) with a ventilated middle floor. Experimental results show that pumping ventilation occurs when the wind is perpendicular to the façade (single sided rooms) or aligned with the building corner (corner rooms). In addition to these two perfectly aligned wind directions, pumping also occurs for a range of incoming wind angles: ±19° for single sided; and ±9° for corner rooms. As a result, for isolated rectangular buildings that have, at least, one single sided and two corner rooms in each facade, pumping ventilation can potentially occur in two or more rooms for 62 % of incoming wind directions. To investigate the transition between steady cross-ventilation and unsteady pumping ventilation, three-dimensional computational fluid dynamics large eddy simulations were performed to obtain wind generated pressures in the ventilation openings. Results show that the transition from cross-ventilation to pumping occurs when the steady pressure becomes smaller than the unsteady component. These results are used to develop a pressure based simplified model for corner ventilation that can predict effective airflow from external wind generated pressures with an average error below 10.2 %. © 2021 Elsevier Ltd
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41.
  • Cehlin, Mathias, et al. (författare)
  • Numerical modeling of a complex diffuser in a room with displacement ventilation
  • 2010
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 45:10, s. 2240-2252
  • Tidskriftsartikel (refereegranskat)abstract
    • A micro/macro-level approach (MMLA) has been proposed which makes it possible for HVAC engineers to easily study the effect of diffuser characteristics and diffuser placement on thermal comfort and indoor air quality. In this article the MMLA has been used to predict the flow and thermal behavior of the air in the near-zone of a complex low-velocity diffuser. A series of experiment has been carried out to validate the numerical predictions in order to ensure that simulations can be used with confidence to predict indoor airflow. The predictions have been performed by means of steady Reynolds Stress Model (RSM) and the results have good agreement both qualitatively and quantitatively with measurements. However, measurements indicated that the diffusion of the velocity and temperature was to some extent under-predicted by the RSM, which might be related to high instability of the airflow close to the diffuser. This effect might be captured by employing unsteady RSM. The present study also shows the importance of detailed inlet supply modeling in the accuracy of indoor air prediction.
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42.
  • Chen, Ailu, et al. (författare)
  • Indoor and outdoor particles in an air-conditioned building during and after the 2013 haze in Singapore
  • 2016
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 99, s. 73-81
  • Tidskriftsartikel (refereegranskat)abstract
    • Particles released from biomass burning can contribute to severe air pollution. We monitored indoor and outdoor particles in a mechanically ventilated and air-conditioned building during and after the 2013 haze event in Singapore. Continuous monitoring of time-and size-resolved particles in the diameter range 0.01–10 μm was conducted for two weeks in each sampling campaign. During the haze event, the averaged size-resolved outdoor particle volume concentrations (dV/d(logDp)) for diameters larger than 0.3 μm were considerably higher than those during the post-haze days (9–185 μm3 cm−3versus 1–35 μm3 cm−3). However, the average number concentration of particles with diameters in the range 10–200 nm was substantially lower on the hazy days than on the post-haze days (11,400 to 14,300 particles cm−3 for hazy days, versus an average of 23,700 particles cm−3 on post-haze days). The building mechanical ventilation system, equipped with MERV 7 filters, attenuated the penetration and persistence of outdoor particles into the monitored building. Indoor particle concentrations, in the diameter ranges 0.3–1.0 μm and 1.0–2.5 μm, closely tracked the corresponding patterns of outdoor particle concentrations. For particles in the size range 0.01–1.0 μm, the size-resolved mean indoor/outdoor (I/O) ratios were in the range 0.12–0.65 with the highest mean I/O ratio at 0.3 μm (0.59 in AC on mode and 0.64 in AC off mode). The air conditioning and mechanical ventilation system with MERV 7 filters provided low single-pass removal efficiency (less than ∼ 30%) for particles with diameters of 0.01–1.0 μm. During the haze, for particles larger than ∼0.2 μm, lower I/O ratios and higher removal efficiencies occurred with the air conditioning operating as compared to with mechanical ventilation only. This observation suggests the possibility of particle loss to air conditioning system surfaces, possibly enhanced by thermophoretic or diffusiophoretic effects.
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43.
  • Chen, Huijuan, et al. (författare)
  • Computational investigation on the factors influencing thermal comfort for impinging jet ventilation
  • 2013
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 66, s. 29-41
  • Tidskriftsartikel (refereegranskat)abstract
    • Impinging jet ventilation (IJV) has been proposed to achieve an effective ventilation of an occupied zone in office and industrial buildings. For IJV systems, draught discomfort is the issue of most concern since it supplies cooled air directly to the occupied zone. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with IJV. The factors considered were: shape of air supply device, discharge height, supply airflow rate and supply air temperature. The Response Surface Methodology (RSM) was used to identify the level of the significance of the parameters studied, as well as to develop the predictive models for the local thermal discomfort. Computational fluid dynamics (CFD) was employed to perform a set of required studies, and each simulation condition was determined by the Box – Behnken design (BBD) method. The results indicated that at a low discharge height, the shape of air supply device had a major impact on the flow pattern in the vicinity of the supply device because of the footprint from impinging jet, which consequently affected the draught risk level in the occupied zone. A square-shaped air supply device was found to result in lower overall draught discomfort than rectangular and semi-elliptic shapes. The RSM analysis revealed that the supply airflow rate had a significant impact on the draught discomfort, while the shape of air supply device and discharge height had moderate effects. The temperature stratification in the occupied zone was mostly influenced by the supply air temperature within the range studied.
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44.
  • Chen, Huijuan, et al. (författare)
  • Investigation on the flow and thermal behavior of impinging jet ventilation systems in an office with different heat loads
  • 2013
  • Ingår i: Building and Environment. - Oxford : Elsevier. - 0360-1323 .- 1873-684X. ; 59, s. 127-144
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the flow and temperature field within an office using impinging jet ventilation (IJV) under different heat loads ranging from 17 to 65 W per square meter floor area. The measurement was carried out in a full-scale test room to verify the reliability of three turbulence models, i.e., the RNG k-epsilon, SST k-omega and (nu(2)) over bar - f models. It is found that all the tested models show good agreements with measurements, while the (nu(2)) over bar - f model shows the best performance, especially on the overall temperature prediction. less thanbrgreater than less thanbrgreater thanThe (nu(2)) over bar - f model is used further to investigate a number of important factors influencing the performance of the IJV. The considered parameters are: cooling effect of chilled ceiling, external heat load as well as its position, number of occupants and supplied air conditions. The interaction effect of chilled ceiling and heat sources results in a complex flow phenomenon but with a notable feature of air circulation. The appearance and strength of the air circulation mainly depends on the external heat load on window and number of occupants. It is found that with higher external heat load on window (384 W and 526 W), the air circulation has a strong tendency towards the side wall in the opposite direction to occupant, while with lower power on window (200 W) the air circulation has a strong tendency in the center of the room and extends to a larger area. When two occupants are present, two swirling zones are formed in the upper region. The effects of air circulation consequently alter the temperature field and the level of local thermal comfort.
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45.
  • Chen, Huijuan, et al. (författare)
  • Numerical investigation of the flow behavior of an isothermal impinging jet in a room
  • 2012
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 49, s. 154-166
  • Tidskriftsartikel (refereegranskat)abstract
    • The impinging jet concept has been proposed as a new ventilation strategy for use in office and industrial buildings. The present paper reports the mean flow field behavior of an isothermal turbulent impinging jet in a room. The detailed experimental study is carried out to validate the numerical simulations, and the predictions are performed by means of the RNG k-ε and SST k-ω model. The comparisons between the predictive results and the experimental data reveal that both of the tested turbulence models are capable of capturing the main qualitative flow features satisfactorily. It is found that the predictions from the RNG k-ε model predicts slightly better of the maximum velocity decay as jet approaching the floor, while the SST k-ω model accords slightly better in the region close to the impingement zone. Another important perspective of this study is to investigate the influence of different flow and configuration parameters such as jet discharge height, diffuser geometry, supply airflow rate and confinement from the surrounding environment on the impinging jet flow field with the validated model. The obtained data are presented in terms of the jet dimensionless velocity distribution, maximum velocity decay and spreading rate along the centerline of the floor. The comparative results demonstrate that all the investigated parameters have certain effects on the studied flow features, and the diffuser geometry is found to have the most appreciable impact, while the supply airflow rate is found to have marginal influence within the moderate flow range. 
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46.
  • Chen, Huijuan, et al. (författare)
  • Numerical investigation of ventilation performance of different air supply devices in an office environment
  • 2015
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 90, s. 37-50
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to compare ventilation performance of four different air supply devices in an office environment with respect to thermal comfort, ventilation efficiency and energy-saving potential, by performing numerical simulations. The devices have the acronyms: Mixing supply device (MSD), Wall confluent jets supply device (WCJSD), Impinging jet supply device (IJSD) and Displacement supply device (DSD). Comparisons were made under identical set-up conditions, as well as at the same occupied zone temperature of about 24.2°C achieved by adding different heat loads and using different air-flow rates. Energy-saving potential was addressed based on the air-flow rate and the related fan power required for obtaining a similar occupied zone temperature for each device. Results showed that the WCJSD and IJSD could provide an acceptable thermal environment while removing excess heat more efficiently than the MSD, as it combined the positive effects of both mixing and stratification principles. This benefit also meant that this devices required less fan power than the MSD for obtaining equivalent occupant zone temperature. The DSD showed a superior performance on heat removal, air exchange efficiency and energy saving to all other devices, but it had difficulties in providing acceptable vertical temperature gradient between the ankle and neck levels for a standing person. 
  •  
47.
  • Chen, L., et al. (författare)
  • Numerical investigations of wind and thermal environment in 2D scaled street canyons with various aspect ratios and solar wall heating
  • 2021
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 190
  • Tidskriftsartikel (refereegranskat)abstract
    • Optimizing urban ventilation is an effective way to improve urban air quality and thermal environment. For this purpose, under the validation of wind-tunnel experiments, flow regimes and micro thermal environment in typical reduced-canyon models with aspect ratios (AR) of 1.1, 2.4, 4 and 5.67 were investigated by CFD simulations using periodic boundary condition. ANSYS Fluent 15.0 with a solar ray tracing model and radiation model was performed to numerically study turbulence characteristics with wind-driven force and solar-heating conditions. Results revealed that, with wind-driven condition, a clockwise vortex existed in normal and deep street canyon (AR = 1.1 and 2.4) while two counter-rotating vortices appeared in extremely deep canyon (AR = 4 and 5.67). Moreover, different turbulence structures and air temperature distribution existed in canyons with different solar-heating conditions. When the leeward wall or ground was heated, the pedestrian-level velocity increased and street ventilation was strengthened compared to wind-driven condition for all AR values. Particularly, the single main vortex was strengthened (AR = 1.1 and 2.4), and the two-vortex structure in extremely deep canyons (AR = 4 and 5.67) changed to single-vortex structure. When the windward wall was heated, the clockwise main vortex at AR = 1.1 and 2.4 was deformed, and a new sub vortex gradually appeared near street bottom. Furthermore, at AR = 4 and 5.67, windward solar heating destroyed the two-vortex structure and slightly improved pollutant dilution capacity. This work implied that extremely deep street design with weak pedestrian-level ventilation should be avoided. It also provides a meaningful reference for urban planning.
  •  
48.
  • Chen, Lan, et al. (författare)
  • The impacts of building height variations and building packing densities on flow adjustment and city breathability in idealized urban models
  • 2017
  • Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 118, s. 344-361
  • Tidskriftsartikel (refereegranskat)abstract
    • Improving city breathability has been confirmed as one feasible measure to improve pollutant dilution in the urban canopy layer (UCL). Building height variability enhances vertical mixing, but its impacts remain not completely explored. Therefore, both wind tunnel experiments and computational fluid dynamic (CFD) simulations are used to investigate the effect of building height variations (six height standard deviations σH = 0%–77.8%) associated to building packing densities namely λp/λf = 0.25/0.375 (medium-density) and 0.44/0.67 (compact) on city breathability. Two bulk variables (i.e. the in-canopy velocity (UC) and exchange velocity (UE)) are adopted to quantify the horizontal and vertical city breathability respectively, which are normalized by the reference velocity (Uref) in the free flow, typically set at z = 2.5H0 where H0 is the mean building height. Both flow quantities and city breathability experience a flow adjustment process, then reach a balance. The adjustment distance is at least three times longer than four rows documented in previous literature. The medium-density arrays experience much larger UC and UE than the compact ones. UE is found mainly induced by vertical turbulent fluxes, instead of vertical mean flows. In height-variation cases, taller buildings experience larger drag force and city breathability than lower buildings and those in uniform-height cases. For medium-density and compact models with uniform height, the balanced UC/Uref are 0.124 and 0.105 respectively, moreover the balanced UE/Uref are 0.0078 and 0.0065. In contrast, the average UC/Uref in height-variation cases are larger (115.3%–139.5% and 125.7%–141.9% of uniform-height cases) but UE/Uref are smaller (74.4%–79.5% and 61.5%–86.2% of uniform-height cases) for medium-density and compact models. 
  •  
49.
  • Cheng, Hong, et al. (författare)
  • Home environment exposure and sick building syndrome (SBS) symptoms among adults in southern China : Health associations in 2010 and 2019
  • 2024
  • Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 248
  • Tidskriftsartikel (refereegranskat)abstract
    • We studied time trends in home environment and sick building syndrome (SBS) symptoms in a repeat study in five cities in southern China. Moreover, we studied associations between home environment exposure and SBS symptoms. Parents from randomly selected day care centers were invited. One parent per family answered a questionnaire on the home environment and their own SBS symptoms. Data collection was performed in two surveys in 2010 and 2019 (27,292 participants in 2010 and 32,073 in 2019). We used two-level logistic regression to analyze health associations. Asthma decreased from 1.7% to 1.5% (P < 0.05) but allergic rhinitis increased from 6.5% to 16.4% (P < 0.001). All SBS symptoms decreased from 2010 to 2019 (all P < 0.001). Most aspects of the home environment improved from 2010 to 2019 but there were less cleaning, more cats, dogs, and urbanization in 2019. Redecoration, new furniture, and pests were associated with most types of SBS symptoms, similarly in 2010 and 2019. Environmental tobacco smoke (ETS) was associated with SBS symptoms in 2019 only. In conclusion, prevalence of SBS symptoms among young parents in southern China decreased from 2010 to 2019 but allergic rhinitis increased. Cockroaches, rats, mice, mosquitoes or flies can be consistent biological risk factors for SBS symptoms. Redecoration, buying new furniture and traffic air pollution are other risk factors for SBS symptoms. Daily cleaning, frequently putting bedding to sunshine, and having a fan in the bathroom can be protective factors. ETS is an emerging risk factor for SBS symptoms.
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50.
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