| 1. |
- Joudi, Ali, 1980-
(författare)
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Radiation properties of coil-coated steel in building envelope surfaces and the influence on building thermal performance
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent studies have shown that the optical properties of building exterior surfaces are important in terms of energy use and thermal comfort. While the majority of the studies are related to exterior surfaces, the radiation properties of interior surfaces are less thoroughly investigated. Development in the coil-coating industries has now made it possible to allocate different optical properties for both exterior and interior surfaces of steel-clad buildings. The aim of this thesis is to investigate the influence of surface radiation properties with the focus on the thermal emittance of the interior surfaces, the modeling approaches and their consequences in the context of the building energy performance and indoor thermal environment.The study consists of both numerical and experimental investigations. The experimental investigations include parallel field measurements on three similar test cabins with different interior and exterior surface radiation properties in Borlänge, Sweden, and two ice rink arenas with normal and low emissive ceiling in Luleå, Sweden. The numerical methods include comparative simulations by the use of dynamic heat flux models, Building Energy Simulation (BES), Computational Fluid Dynamics (CFD) and a coupled model for BES and CFD. Several parametric studies and thermal performance analyses were carried out in combination with the different numerical methods.The parallel field measurements on the test cabins include the air, surface and radiation temperatures and energy use during passive and active (heating and cooling) measurements. Both measurement and comparative simulation results indicate an improvement in the indoor thermal environment when the interior surfaces have low emittance. In the ice rink arenas, surface and radiation temperature measurements indicate a considerable reduction in the ceiling-to-ice radiation by the use of low emittance surfaces, in agreement with a ceiling-toice radiation model using schematic dynamic heat flux calculations.The measurements in the test cabins indicate that the use of low emittance surfaces can increase the vertical indoor air temperature gradients depending on the time of day and outdoor conditions. This is in agreement with the transient CFD simulations having the boundary condition assigned on the exterior surfaces. The sensitivity analyses have been performed under different outdoor conditions and surface thermal radiation properties. The spatially resolved simulations indicate an increase in the air and surface temperature gradients by the use of low emittance coatings. This can allow for lower air temperature at the occupied zone during the summer.The combined effect of interior and exterior reflective coatings in terms of energy use has been investigated by the use of building energy simulation for different climates and internal heat loads. The results indicate possible energy savings by the smart choice of optical properties on interior and exterior surfaces of the building.Overall, it is concluded that the interior reflective coatings can contribute to building energy savings and improvement of the indoor thermal environment. This can be numerically investigated by the choice of appropriate models with respect to the level of detail and computational load. This thesis includes comparative simulations at different levels of detail.
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| 2. |
- Sadrizadeh, Sasan, et al.
(författare)
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A systematic review of operating room ventilation
- 2021
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 40, s. 102693-
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Forskningsöversikt (refereegranskat)abstract
- Ventilation systems are the primary way of eliminating airborne pathogenic particles in an operating room (OR). However, such systems can be complex due to factors such as different surgical instruments, diverse room sizes, various staff counts, types of clothing used, different surgical types and duration, medications, and patient conditions. OR ventilation should provide a thermally comfortable environment for the surgical staff team members while preventing the patient from suffering from any extreme hypothermia. Many technical, logistical, and ethical implications need to be considered in the early stage of designing a ventilation system for an OR. Years of research and a significant number of publications have highlighted the controversy and disagreement among infection specialists, design engineers, and ventilation experts in this context. This review article aims to provide a good understanding of OR ventilation systems in the context of air quality and infection control from existing research and provide multidimensional insights for appropriate design and operation of the OR. To this end, we have conducted a systematic review of the literature, covering 253 articles in this context. Systematic review and meta-analyses were used to map the evidence and identify research gaps in the existing clinical, practical, and engineering knowledge. The present study is categorized into six research focuses: ventilation system, thermal comfort, staff work practice and obstacles, door operation and passage, air cleaning technology, emission rate, and clothing systems. In the conclusion, we summarize the key limitations of the existing studies and insights for future research direction.
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| 3. |
- Yuan, Feng, et al.
(författare)
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Dynamic characteristics of particulate matter resuspension due to human activities in indoor environments. : A comprehensive review
- 2023
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 79
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Tidskriftsartikel (refereegranskat)abstract
- Particulate matter (PM) resuspension from indoor surfaces is one of the leading causes of occupant exposure to PM. It has been recognized as a main source of indoor air pollution by many field studies. This review article explores the mechanisms and effects of single and multiple influential factors on PM resuspension, distribution characteristics, spatial and temporal PM distribution characteristics and interactions of human activities and mitigation measures. A roadmap is proposed to provide a strong basis for subsequent research into the dynamic characteristics of PM resuspension. The synthesis of existing literature suggests that the mechanism behind the opposite effect caused by multiple influential factors deserves further exploration. Microscopic simulations of motion over short periods and richer activity features based on various scenarios are needed to get more accurate results. More advanced strategies should be considered to change the control process and enhance the efficiency of the purification devices. Collaboration between multiple disciplines is required to get the complete picture of PM resuspension.
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| 4. |
- Yuan, Feng, et al.
(författare)
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The influence of activity patterns and relative humidity on particle resuspension in classrooms
- 2024
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 946
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the impact of children's recess activity patterns on particulate matter (PM) resuspension in indoor environments, highlighting the complex, multi-dimensional nature of these activities and their interaction with environmental parameters. Despite the recognized role of indoor human activity in PM resuspension, research specifically addressing the effects of children's movements has been sparse. Through experimental scenarios that account for the characteristics of student activities, such as movement speed, trajectory, the number of participants, aisle widths, and varying humidity levels, this study uncovers significant differences in PM resuspension rates. It reveals that not only do movement speed and trajectory have a profound impact, but also the interaction between humidity and these factors plays a critical role, especially under lower humidity conditions. Additionally, the study demonstrates how the combination of people density and spatial configurations can significantly influence resuspension rates. The findings offer valuable insights for designing strategies to mitigate particle pollution in classrooms and similar indoor environments.
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| 5. |
- Yuan, Feng, et al.
(författare)
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Thermal comfort in hospital buildings - A literature review
- 2022
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 45
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Forskningsöversikt (refereegranskat)abstract
- Hospital buildings are required to secure a variety of indoor environments according to the diverse requirements of patients and staff. Among these requirements, thermal comfort is an important design criterion for indoor environmental quality that affects patients' healing processes and the wellbeing of medical staff. The patients' thermal comfort is given priority due to their medical conditions and impaired immune systems. Thermal comfort and related contexts have been well-covered in many research articles; however, the number of review articles is limited. This article aims to conduct a holistic and critical review of existing studies offering insights on future research trends (180 articles were analyzed). The key research themes are identified using scientometric analysis. Focus is on influencing factors, field-surveys, improving measures and energy saving related to thermal comfort. The primary outcome concludes that ventilation systems play a key role in maintaining acceptable, thermally-comfortable conditions for patients and medical staff. It is also found that acceptable thermal comfort is highly case-dependent and varies substantially based on the health condition of the patient as well as the type and level of staff activities. The measures currently mentioned to minimize energy consumption are also discussed. Some interesting issues, including the inaccuracy arising from the use of predicted mean vote (PMV) and the impact of gender, age, and related factors on thermal comfort, have been noted. This review provides insights into the design and assessment of hospital thermal environments.
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