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Kabanshi, A., Andersson, H., Sundberg, M., Senkic, D. & Sandberg, M. (2024). Assessing airborne infection risk through a model of airflow evacuation and recirculation dynamics.. In: : . Paper presented at RoomVent Conference, April 22-25, Stockholm, Sweden.
Open this publication in new window or tab >>Assessing airborne infection risk through a model of airflow evacuation and recirculation dynamics.
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2024 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In a ventilated room, the indoor airflows are complicated but can generally be defined by an internal recirculating airflow generated by flooding of ventilation air. This concept categorizes the internal room flow (air and contaminants) as consist of two populations: One leaving the room and the other recirculating. The one recirculating is spreading the contaminants while the one leaving is evacuating the contaminants, which are quantified by the transfer probability between the source and other locations in the room and by purging flow rate, respectively. This concept accounts for spatial and temporal aspects in risk of airborne infection transmission. The current paper proposes and discusses a revised risk infection model based on this concept and has demonstrated applicability of the model with a test measurement setup with both mixing and displacement ventilation systems. The results emphasize the importance of considering both spatial and temporal factors in assessing airborne infection risks. It underscores the need for dynamic models like the proposed revised Wells-Riley model to provide a more accurate representation of infection risks in various indoor environments. Additionally, it discusses the necessity for longer measurement periods to fully understand the evolving nature of these risks. 

Keywords
Infectious respiratory disease, Airborne infection risk, Air recirculation, purging flowrate, Contaminant flooding
National Category
Building Technologies Mechanical Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-44122 (URN)
Conference
RoomVent Conference, April 22-25, Stockholm, Sweden
Available from: 2024-04-26 Created: 2024-04-26 Last updated: 2024-04-29Bibliographically approved
Andersson, H., Sundberg, M., Senkic, D., Sandberg, M. & Kabanshi, A. (2024). FAST-AIR: Fast analytic systems for tracer-gas assessment in indoor research: Development and testing of CO2 tracer-gas system.. In: : . Paper presented at RoomVent Conference, 22nd - 25th April, Stockholm Sweden.
Open this publication in new window or tab >>FAST-AIR: Fast analytic systems for tracer-gas assessment in indoor research: Development and testing of CO2 tracer-gas system.
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2024 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The time constant of ventilation of rooms in buildings is between 15 minutes (in office spaces) to 2 hours (in residential buildings). Currently, most of the tracer gas system analyzers on the market have a minute-based time constant and depending on the channels a cycle of sampling and analysis may take up to 6 minutes, E.g., 6 channel system. Essentially, only mean values are recorded with most present tracer gas analyzers. This is a hindrance for detailed temporal analysis of conditions in the room and consequently is does not capture the resolution of the influence of the internal flow on air and contaminant distribution. The current paper presents work on the development and testing of a fast response CO2 tracer-gas system with a time constant of 1 second. In contrast to the present analyzers, not only the mean values but also the whole statistical distribution of variables can be recorded, and pulse responses can be analyzed. This makes the system viable for measurement and analysis of not only spatial but also temporal distribution of contaminants. For example, recirculating airflow in the room generated by flooding of ventilation air is possible to be measured and thus making it easy to extend the analyses of the process of ventilation far beyond the possibilities with current systems.

Keywords
Tracer-gas Analyzer, fast response, temporal distribution, contaminant transport, indoor measurements
National Category
Mechanical Engineering Building Technologies
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-44121 (URN)
Conference
RoomVent Conference, 22nd - 25th April, Stockholm Sweden
Funder
Swedish Research Council Formas, Dnr: 2021-01606
Available from: 2024-04-26 Created: 2024-04-26 Last updated: 2024-05-02Bibliographically approved
Kabanshi, A., Chocarro de Erauso, B. & Sandberg, M. (2023). Experimental study on augmentation of mixing within a stratified indoor environment by erosion of density interface. In: E3S Web of Conferences: . Paper presented at IAQVEC 2023. 11th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, Tokyo, 20-23 May 2023. , 396, Article ID 02037.
Open this publication in new window or tab >>Experimental study on augmentation of mixing within a stratified indoor environment by erosion of density interface
2023 (English)In: E3S Web of Conferences, 2023, Vol. 396, article id 02037Conference paper, Published paper (Refereed)
Abstract [en]

The current study aims to address the problem associated with warm air heating in passive houses. Warm air eating is cheaper and easy to operate in passive houses, however, this creates problems of shortcut ventilation and thermal discomfort due to stratification as warm air is confined to the ceiling. In the current study, we explore a new method of creating resonance between stratification frequency and the periodic variation of the ventilation supply frequency to increase mixing of the supplied warm air and the room air consequently destratifying the room conditions. A basic water model study is used to understand the interaction between the frequency variations and the resulting standing waves with stratification characteristics in a room. Measurements at three different input frequencies and at three input paddle locations have been performed, gathering vertical temperature gradients and visualization data from them. The results show the shift in the inversion point because of an increase augmentation across the inversion between the fluids with different densities close to resonance. There is also a dependency on paddle location showing that the type of ventilation system will have different mixing rates due to different fluid energetic behaviours.  

Series
E3S Web of Conferences, ISSN 2555-0403
Keywords
Stratification, Mixing, Density interface, Water model, Pasive houses
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41918 (URN)10.1051/e3sconf/202339602037 (DOI)2-s2.0-85164475352 (Scopus ID)
Conference
IAQVEC 2023. 11th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, Tokyo, 20-23 May 2023
Available from: 2023-05-31 Created: 2023-05-31 Last updated: 2023-07-24Bibliographically approved
Ogbuagu, C.-C. T., Linden, E., MacCutcheon, D., Nilsson, E., Persson, T. & Kabanshi, A. (2023). On the Performance of Diffuse Ceiling Ventilation in Classrooms: A Pre-Occupancy Study at a School in Southern Sweden. Sustainability, 15(3), Article ID 2546.
Open this publication in new window or tab >>On the Performance of Diffuse Ceiling Ventilation in Classrooms: A Pre-Occupancy Study at a School in Southern Sweden
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2023 (English)In: Sustainability, E-ISSN 2071-1050, Vol. 15, no 3, article id 2546Article in journal (Refereed) Published
Abstract [en]

The implementation and application of diffused ceiling ventilation (DCV) is gradually gaining momentum, especially in Denmark, Finland, and the Netherlands. In countries such as Sweden, the application is limited despite the favorable conditions for implementation. The current study investigates the performance of DCV and mixing ventilation in a pre-occupancy field study for newly renovated classrooms in Southern Sweden. Two classrooms at the school were installed with diffuse ceiling ventilation while the rest had mixing ventilation. The objective of the study was to compare and evaluate the ventilation performance in terms of indoor environmental quality parameters such as thermal comfort, air quality indexes, airflow, and temperature distribution. Pre-occupancy measurements were performed in two classrooms with similar room characteristics, with one room running under mixing ventilation and the other under DCV. Constant temperature anemometers, thermocouples, and INNOVA thermal comfort were used to measure the indoor air speeds, temperature, and thermal comfort, respectively. Tracer gas measurements, with SF6, were performed to assess air quality. Additionally acoustic measurements were conducted to assess the acoustic benefits of DCV on reducing ventilation noise. The results demonstrate that DCV offers similar indoor environmental conditions to mixing ventilation but has better acoustic performance especially on reducing the ventilation noise. Indoor environmental conditions were very homogeneous under DCV with mixing ventilation showing tendencies for short circuit ventilation. This study demonstrates that DCV has a potential for implementation in Swedish schools with minimal system modification on existing ventilation and air distribution systems.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
diffused ceiling ventilation; ventilation performance; indoor air quality; air distribution; classrooms
National Category
Civil Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-40984 (URN)10.3390/su15032546 (DOI)000930378100001 ()2-s2.0-85147884667 (Scopus ID)
Available from: 2023-02-01 Created: 2023-02-01 Last updated: 2023-03-09Bibliographically approved
Mulenga, E., Kabanshi, A., Mupeta, H., Ndiaye, M., Nyirenda, E. & Mulenga, K. (2023). Techno-economic analysis of off-grid PV-Diesel power generation system for rural electrification: A case study of Chilubi district in Zambia. Renewable energy, 203, 601-611
Open this publication in new window or tab >>Techno-economic analysis of off-grid PV-Diesel power generation system for rural electrification: A case study of Chilubi district in Zambia
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2023 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 203, p. 601-611Article in journal (Refereed) Published
Abstract [en]

The study explores the techno-economic feasibility and viability of a Photovoltaic-Diesel Hybrid system for rural electrification in sub-Sahara Africa with a case study of Chilubi island, a remote district without access to electricity in the Northern Province of Zambia. Using HOMER (Hybrid Optimization of Multiple Electric Renewables) Pro software, the best and most feasible technical solutions through different hybrid system configurations, combinations and the district's rate of access to electricity were considered based on the least Levelized Cost of Energy (LCoE) and life cycle costs of the project. The results show that operating diesel generators as stand-alone is not economically sustainable and has a high LCoE. Influencing factors include variability in diesel pump prices, high fuel transportation costs, high cost of operation and maintenance, among other factors of concern. 100% photovoltaic (PV) with a battery system gave the lowest LCoE. However, the initial capital cost of solar energy projects in Zambia is relatively high compared to the equivalent diesel-based plants, as shown herein. It explains why diesel power plants are favoured for off-grid settlements. On the hand, the low operational cost and LCoE of PV power plants favour rural districts as they offset the high initial capital costs. Additionally, the continued downward trend in the cost of PV installations per kWp has opened discussions among policymakers and energy planners in Zambia to favour rural electrification with renewable energy-based power generation. This study contributes to this discussion.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
PV/Diesel hybrid, Microgrid, Rural electrification, Techno-economic comparison, Sub-Sahara Africa, HOMER
National Category
Energy Engineering Energy Systems Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Sustainable Urban Development; Intelligent Industry
Identifiers
urn:nbn:se:hig:diva-40643 (URN)10.1016/j.renene.2022.12.112 (DOI)000991804300001 ()2-s2.0-85145279926 (Scopus ID)
Available from: 2022-12-31 Created: 2022-12-31 Last updated: 2023-06-08Bibliographically approved
Kabanshi, A., Choonya, G., Ameen, A., Liu, W. & Mulenga, E. (2023). Windows of Opportunities: Orientation, Sizing and PV-Shading of the Glazed Area to Reduce Cooling Energy Demand in Sub-Sahara Africa. Energies, 16(9), Article ID 3834.
Open this publication in new window or tab >>Windows of Opportunities: Orientation, Sizing and PV-Shading of the Glazed Area to Reduce Cooling Energy Demand in Sub-Sahara Africa
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2023 (English)In: Energies, E-ISSN 1996-1073, Vol. 16, no 9, article id 3834Article in journal (Refereed) Published
Abstract [en]

In hot climates, such as sub-Sahara Africa, window sizing and orientation pose challenges as they add, through solar insolation, to the building cooling energy demand and thus the cause of indoor overheating risk. This risk can be reduced through passive building-design-integrated measures, e.g., optimizing the window size, orientation and solar shading strategies. Through an IDA-ICE building performance simulation tool, the current study explores the impact of window size, optimization and building-integrated PV panels as shading strategies on cooling energy demands in three cities (Niamey, Nairobi and Harare) in sub-Sahara Africa. Results show that thermal comfort and cooling energy demand are sensitive to a window-to-wall ratio (WWR) > 70%, while the need for artificial lighting is negligible for a WWR > 50%, particularly in the north for cities in the Southern hemisphere and the south in the Northern hemisphere. A WWR > 70% in the east and west should be avoided unless shading devices are incorporated. Internal blinds perform better in improving occupant thermal comfort but increase artificial lighting while integrating PV panels, as external shading overhangs reduce cooling energy but also produce energy that can be utilized for building services, such as air conditioning. In this study, the results and implications of the optimization of window size, orientation and building-integrated shading and operation are discussed.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
glazing area, window shading, cooling energy demand, thermal comfort, building-integrated photovoltaics
National Category
Energy Systems
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41705 (URN)10.3390/en16093834 (DOI)000987072000001 ()2-s2.0-85159341251 (Scopus ID)
Available from: 2023-04-29 Created: 2023-04-29 Last updated: 2023-08-28Bibliographically approved
Liu, W., Sun, H., Lai, D., Xue, Y., Kabanshi, A. & Hu, S. (2022). Performance of fast fluid dynamics with a semi-Lagrangian scheme and an implicit upwind scheme in simulating indoor/outdoor airflow. Building and Environment, 207(B), Article ID 108477.
Open this publication in new window or tab >>Performance of fast fluid dynamics with a semi-Lagrangian scheme and an implicit upwind scheme in simulating indoor/outdoor airflow
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2022 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 207, no B, article id 108477Article in journal (Refereed) Published
Abstract [en]

Computational fluid dynamics can be time consuming for predicting indoor airflows and pollutant transport in large-scale problems or emergency management. Fast fluid dynamics (FFD) is able to accomplish efficient and accurate simulation of indoor/outdoor airflow. FFD solves the advection term of the Navier–Stokes equations either by a semi-Lagrangian (SL) scheme or an implicit upwind (IU) scheme. The SL scheme can be highly efficient, but its first-order version is not conservative and introduces significant numerical diffusion. To improve its accuracy, a high-order temporal and interpolation scheme that not only reduces dissipation and dispersion errors but also guarantees the convergence speed should be applied. Otherwise, an IU scheme instead could be used to solve the advection term. The IU scheme is conservative and introduces minor numerical diffusion, but it may increase the computation time. Therefore, this study investigated the performance of FFD with SL scheme using high-order temporal and interpolation schemes and that with IU scheme. The comparisons used experimental data of two indoor airflows and one outdoor airflow. The results showed that FFD with IU scheme was overall more accurate than FFD with SL scheme. In simulating indoor airflow, both methods were robust and the predictions were independent of time step sizes if the Courant number was less than or equal to one. In simulating the outdoor airflow, the FFD with SL scheme performed better than the FFD with IU scheme for large time step sizes. The FFD with IU scheme consumed 44%–61% computing time of the FFD with SL scheme.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Pressure-correction scheme, Numerical diffusion, Time step size, OpenFOAM, building simulations
National Category
Building Technologies Fluid Mechanics and Acoustics Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-37332 (URN)10.1016/j.buildenv.2021.108477 (DOI)000779437000004 ()2-s2.0-85119196058 (Scopus ID)
Available from: 2021-11-08 Created: 2021-11-08 Last updated: 2022-12-05Bibliographically approved
Kabanshi, A., Linden, E., Ogbuagu, T.-C., MacCutcheon, D. & Persson, T. (2022). Plenum airflow distribution and its influence on the performance of a diffuse ceiling ventilation. In: Li A., Olofsson T., Kosonen R. (Ed.), E3S Web Conf. Volume 356, 2022 The 16th ROOMVENT Conference (ROOMVENT 2022): . Paper presented at 16th ROOMVENT Conference, ROOMVENT 2022, Xi'an, China, 16-19 September 2022. Xian, 356, Article ID 01026.
Open this publication in new window or tab >>Plenum airflow distribution and its influence on the performance of a diffuse ceiling ventilation
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2022 (English)In: E3S Web Conf. Volume 356, 2022 The 16th ROOMVENT Conference (ROOMVENT 2022) / [ed] Li A., Olofsson T., Kosonen R., Xian, 2022, Vol. 356, article id 01026Conference paper, Published paper (Refereed)
Abstract [en]

Implementation of diffuse ceiling ventilation (DCV) is slowly gaining momentum and applications in building ventilation have taken off with countries like Denmark, Finland and Netherlands taking the lead in Europe. However, DCV is yet to gain a foothold in Sweden and so not many installations are known, and their performance in relation to Swedish building practice is not yet established. A school in southern Sweden was subsequently renovated and two classrooms were equipped with a sound-absorbent suspended ceiling compatible with DCV. DCV has possible benefits for educational environments including improved thermal comfort as well as lower costs and noise levels. However, it is currently still unknown how supply conditions in the plenum affect the diffusion of air and resulting conditions within the room. To assess airflow characteristics and whether these influence flow conditions in the classroom, we investigated and compared the performance of DCV with two different supply conditions in the plenum. Air speeds and temperature distribution measurements in the plenum and classroom were performed with constant temperature anemometers and thermocouples respectively. The general observation from this study and the system setup herein is that airflow and temperature characteristics in the classroom were independent of the airflow conditions in the plenum. Further investigations in a controlled climate chamber are recommended to investigate and optimise system performance in accordance with Swedish building practice.

Place, publisher, year, edition, pages
Xian: , 2022
Keywords
Air Distribution, Indoor Environment, Diffuse Ceiling Ventilation
National Category
Building Technologies
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-39952 (URN)10.1051/e3sconf/202235601026 (DOI)2-s2.0-85146846926 (Scopus ID)
Conference
16th ROOMVENT Conference, ROOMVENT 2022, Xi'an, China, 16-19 September 2022
Available from: 2022-09-19 Created: 2022-09-19 Last updated: 2023-02-06Bibliographically approved
Mupeta, H., Nyirenda, E., Mulenga, E. & Kabanshi, A. (2021). Techno-economic analysis of PV-Diesel hybrid system as an option for rural electrification in Zambia. In: Christoph Pfeifer, Rafat Al Afif & Abdul Ghani Olabi (Ed.), 13th International Conference on Sustainable Energy & Environmental Protection: Solar Energy, Vienna, Austria. September 13-16, 2021: . Paper presented at SEEP 2021.
Open this publication in new window or tab >>Techno-economic analysis of PV-Diesel hybrid system as an option for rural electrification in Zambia
2021 (English)In: 13th International Conference on Sustainable Energy & Environmental Protection: Solar Energy, Vienna, Austria. September 13-16, 2021 / [ed] Christoph Pfeifer, Rafat Al Afif & Abdul Ghani Olabi, 2021Conference paper, Published paper (Refereed)
Abstract [en]

The study explores the viability of the PV-Diesel Hybrid system for rural electrification in Sub-Sahara Africa with a study case of a remote district without access to electricity in the Northern Province of Zambia. Using HOMER (Hybrid Optimization of Multiple Electric Renewables) software, the study investigates the best and most feasible technical solution through different hybrid system configurations and combinations, taking into account the least Levelized Cost of Electricity of the project. The results show that operating diesel generators as stand-alone is not economically sustainable and gives a high LCoE due to variability in diesel pump prices, and a high cost of operation and maintenance. Furthermore, the study shows that the initial capital cost of solar energy projects in Zambia is relatively high compared to the equivalent diesel-based plants. However, the authors project that this will likely change because of the continued downward trend in capital costs of PV per kWp. Additionally, the high initial capital costs are offset by the low operational costs and the clean/environmentally friendly energy from PV systems.

Keywords
PV-Diesel Hybrid, Microgrid, Rural Electrification, Techno-economic comparison, HOMER.
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-37023 (URN)978-3-900932-87-9 (ISBN)
Conference
SEEP 2021
Available from: 2021-09-14 Created: 2021-09-14 Last updated: 2021-09-21Bibliographically approved
Kabanshi, A., Choonya, G. & Ameen, A. (2021). Window size optimization and shading with photovoltaic panels: Simulation of cooling energy demand in the tropics in the southern hemisphere. In: Christoph Pfeifer, Rafat Al Afif & Abdul Ghani Olabi (Ed.), 13th International Conference on Sustainable Energy and Environmental Protection: Solar Energy. September 13-16, 2021, Vienna, Austria.: . Paper presented at SEEP 2021.
Open this publication in new window or tab >>Window size optimization and shading with photovoltaic panels: Simulation of cooling energy demand in the tropics in the southern hemisphere
2021 (English)In: 13th International Conference on Sustainable Energy and Environmental Protection: Solar Energy. September 13-16, 2021, Vienna, Austria. / [ed] Christoph Pfeifer, Rafat Al Afif & Abdul Ghani Olabi, 2021Conference paper, Published paper (Refereed)
Abstract [en]

 Window size and orientation of holding façade influences the quantity of solar insolation into buildings and consequently the heating/cooling demand and occupant thermal comfort. In cold climates, window optimization (size and the orientation) can reduce the heating requirements if well integrated into the building envelope. However, in hot climates window sizing and orientation poses challenges as it only adds to the cooling energy demand. In addition to design strategies like window size and orientation, passive strategies like blinds or shades are recommended to reduce and control the solar insolation. The current study, through IDA-ICE building simulations, explores optimization of window size, orientation and shading configurations (internal blinds and PV as external shades) and its influence on the cooling energy demand in Harare, Zimbabwe, located in the tropic of Capricorn in the Southern Hemisphere. The results shows that cooling demand and occupant thermal comfort was sensitive to the North facing facades, and slightly on the west, but not on the South and west oriented windows. Shading reduced the cooling demand and use of PV panels proved equally effective although only a slight improvement in thermal comfort level was obtained compared to using internal blinds. However, PV panels produced electricity that could help offset the cooling demand by powering a heat pump or reduce the imported power for other building services. Implications of the results on building design and operation are discussed.

Keywords
Glazing area, Solar insolation, Shading, Cooling energy demand, thermal comfort. IDA-ICE simulation
National Category
Building Technologies
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-37022 (URN)978-3-900932-87-9 (ISBN)
Conference
SEEP 2021
Available from: 2021-09-14 Created: 2021-09-14 Last updated: 2023-05-11Bibliographically approved
Projects
Ventilation as a strategy to reduce indoor transmission of airborne diseases: development of new strategies and a risk assessment model [2021-01606_Formas]; University of Gävle; Publications
Kabanshi, A., Andersson, H., Sundberg, M., Senkic, D. & Sandberg, M. (2024). Assessing airborne infection risk through a model of airflow evacuation and recirculation dynamics.. In: : . Paper presented at RoomVent Conference, April 22-25, Stockholm, Sweden.
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2171-3013

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