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Edwards AJ, King MF, López-García M, Peckham D, Noakes CJ. Assessing the effects of transient weather conditions on airborne transmission risk in naturally ventilated hospitals. J Hosp Infect 2024; 148:1-10. [PMID: 38447806 DOI: 10.1016/j.jhin.2024.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 03/08/2024]
Abstract
BACKGROUND Many UK hospitals rely heavily on natural ventilation as their main source of airflow in patient wards. This method of ventilation can have cost and energy benefits, but it may lead to unpredictable flow patterns between indoor spaces, potentially leading to the unexpected transport of infectious material to other connecting zones. However, the effects of weather conditions on airborne transmission are often overlooked. METHODS A multi-zone CONTAM model of a naturally ventilated hospital respiratory ward, incorporating time-varying weather, was proposed. Coupling this with an airborne infection model, this study assessed the variable risk in interconnected spaces, focusing particularly on occupancy, disease and ventilation scenarios based on a UK respiratory ward. RESULTS The results suggest that natural ventilation with varying weather conditions can cause irregularities in the ventilation rates and interzonal flow rates of connected zones, leading to infrequent but high peaks in the concentration of airborne pathogens in particular rooms. This transient behaviour increases the risk of airborne infection, particularly through movement of pathogens between rooms, and highlights that large outbreaks may be more likely under certain conditions. This study demonstrated how ventilation rates achieved by natural ventilation are likely to fall below the recommended guidance, and that the implementation of supplemental mechanical ventilation can increase ventilation rates and reduce the variability in infection risks. CONCLUSION This model emphasises the need for consideration of transient external conditions when assessing the risk of transmission of airborne infection in indoor environments.
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Affiliation(s)
- A J Edwards
- EPSRC Centre for Doctoral Training in Fluid Dynamics, University of Leeds, Leeds, UK.
| | - M-F King
- School of Civil Engineering, University of Leeds, Leeds, UK
| | | | - D Peckham
- Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - C J Noakes
- School of Civil Engineering, University of Leeds, Leeds, UK
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A review on indoor airborne transmission of COVID-19– modelling and mitigation approaches. JOURNAL OF BUILDING ENGINEERING 2023; 64:105599. [PMCID: PMC9699823 DOI: 10.1016/j.jobe.2022.105599] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/11/2022] [Accepted: 11/21/2022] [Indexed: 06/09/2023]
Abstract
In the past few years, significant efforts have been made to investigate the transmission of COVID-19. This paper provides a review of the COVID-19 airborne transmission modeling and mitigation strategies. The simulation models here are classified into airborne transmission infectious risk models and numerical approaches for spatiotemporal airborne transmissions. Mathematical descriptions and assumptions on which these models have been based are discussed. Input data used in previous simulation studies to assess the dispersion of COVID-19 are extracted and reported. Moreover, measurements performed to study the COVID-19 airborne transmission within indoor environments are introduced to support validations for anticipated future modeling studies. Transmission mitigation strategies recommended in recent studies have been classified to include modifying occupancy and ventilation operations, using filters and air purifiers, installing ultraviolet (UV) air disinfection systems, and personal protection compliance, such as wearing masks and social distancing. The application of mitigation strategies to various building types, such as educational, office, public, residential, and hospital, is reviewed. Recommendations for future works are also discussed based on the current apparent knowledge gaps covering both modeling and mitigation approaches. Our findings show that different transmission mitigation measures were recommended for various indoor environments; however, there is no conclusive work reporting their combined effects on the level of mitigation that may be achieved. Moreover, further studies should be conducted to understand better the balance between approaches to mitigating the viral transmissions in buildings and building energy consumption.
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Thermal Draft Load Coefficient for Heating Load Differences Caused by Stack-Driven Infiltration by Floor in Multifamily High-Rise Buildings. ENERGIES 2022. [DOI: 10.3390/en15041386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The stack effect is dominant in multifamily high-rise buildings (MFHRBs) in winter because of the considerable height of MFHRBs, which causes a difference in the infiltration amount between floors. This difference causes a heating load difference between floors in a MFHRB. However, there are no indicators to quantify the heating load differences in previous studies. In this article, an indicator—the thermal draft load coefficient (TDLC)—is proposed that can be used to estimate and evaluate the differences between floors in a MFHRB. The TDLC is built on a theoretical model of the stack effect and leakage area of the airflow paths, considering the entire building airflow in a MFHRB. The theoretical model was validated by comparison with a simulation model. The winter average coefficient of variation of the root mean square error and the normalized mean bias error of the theoretical model were acceptable (17.1% and 9.3%, respectively). The TDLC resulted in a maximum of 2.5 and a minimum of approximately 0.1 in the target MFHRB. The TDLC can pre-evaluate the load difference in the building design stage and can be utilized to build design standards or guidelines.
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Zheng K, Ortner P, Lim YW, Zhi TJ. Ventilation in worker dormitories and its impact on the spread of respiratory droplets. SUSTAINABLE CITIES AND SOCIETY 2021; 75:103327. [PMID: 34545319 PMCID: PMC8443870 DOI: 10.1016/j.scs.2021.103327] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 05/29/2023]
Abstract
Most of the COVID-19 cases in Singapore have primarily come from foreign worker dormitories. This people group is especially vulnerable partly because of behavioural habits, but the built environment they live in also plays a significant role. These dormitories are typically densely populated, so the living conditions are cramped. The short lease given to most dormitories also means the design does not typically focus on environmental performance, like good natural ventilation. This paper seeks to understand how these dormitories' design affects natural ventilation and, subsequently, the spread of the COVID-19 particles by looking at two existing worker dorms in Singapore. Findings show that some rooms are poorly orientated against the prevailing wind directions, so there is dominant stagnant air in these rooms, leading to respiratory droplets' long residence times. These particles can hover in the air for 10 min and more. Interventions like increased bed distance and removing upper deck beds only showed limited ventilation improvements in some rooms. Comparatively, internal wind scoops' strategic placement was more effective at directing wind towards more stagnant zones. Large canyon aspect ratios were also effective at removing particles from higher elevations.
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Affiliation(s)
- Kai Zheng
- Architecture and Sustainable Design, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore
| | - Peter Ortner
- Architecture and Sustainable Design, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore
| | - Yu Wen Lim
- Architecture and Sustainable Design, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore
| | - Tay Jing Zhi
- Architecture and Sustainable Design, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore
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Zhang Y, Wang Y, Wang F, Xu X, Wu X. Numerical investigation on the transmission and dispersion of aerosols in a 7-stories building drainage system. BUILDING AND ENVIRONMENT 2021; 201:108009. [PMID: 34075270 PMCID: PMC8161830 DOI: 10.1016/j.buildenv.2021.108009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/14/2021] [Accepted: 05/24/2021] [Indexed: 05/08/2023]
Abstract
In previous reports, the positive SARS-CoV-2 nucleic acid was detected in the fecal samples from confirmed pneumonia patients, suggesting a high probability of the fecal-oral transmission. To date, however, the role played by the drainage system of a high-rise building in the virus transmission is not clear and especially studies on the dynamics mechanism behind is scarce. From this point of view, the present work carries out a computational fluid dynamics (CFD) modeling to investigate the effects of the water seal effectiveness of the floor drain, the negative/positive pressures (P 1 , P 2 ) in the bathroom, temperature differential (ΔT), outside wind velocity (v), the piping fittings and the negative pressure at the cowl (P 3 ) on the transmission of the virus-laden aerosol particles in a drainage system of a typical 7-storeys residential building. The CFD models are first validated by the previous experiments in literature. Numerical results imply that the drainage system might play an essential role to the virus transmission. Then, results indicate that, the leakage risk of the aerosol particles via the floor drain with inefficient water-seal (UFD) mainly exists at the upper floors above the neutral pressure level (NPL). Besides, the negative and positive pressures at the bathroom can enhance and reduce the exposure risk of aerosol particles from the corresponding UFD, respectively. The ΔT increasing does not modify the location of the NPL. Moreover, the exposure risk of aerosol particles can be effectively avoided by the well water-sealed floor drains and/or the presence of a proper negative pressure at the cowl on the top floor. Finally, based on the CFD results, several protection suggestions on the drainage system and human activities are provided.
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Affiliation(s)
- Yuan Zhang
- School of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yikang Wang
- School of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Feifei Wang
- School of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xinhua Xu
- School of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xiaohui Wu
- School of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
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Reichman R, Dubowski Y. Gaseous pollutant transport from an underground parking garage in a Mediterranean multi-story building-Effect of temporal resolution under varying weather conditions. BUILDING SIMULATION 2021; 14:1511-1523. [PMID: 33649710 PMCID: PMC7905197 DOI: 10.1007/s12273-020-0757-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 11/29/2020] [Accepted: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Indoor air dynamics and quality in high density residential buildings can be complex as it is affected by both building parameters, pollution sources, and outdoor meteorological conditions. The present study used CONTAM simulations to investigate the intra-building transport and concentration of an inert pollutant continuously emitted from an underground garage of a 15-floor building under moderate Mediterranean weather. The effects of outdoor meteorological conditions (air temperature, wind speed and direction) on indoor distribution of the emitted pollutant was tested under constant conditions. The importance of using actual transient meteorological data and the impact of their temporal resolution on calculated concentrations and exposure levels were also investigated. Vertical profiles of air exchange rate (AER) and CO concentration were shown to be sensitive to indoor-outdoor temperature difference, which controls the extent of the stack effect and its importance relative to wind effect. Even under constant conditions, transient mode simulations revealed that the time needed for pollutant distribution to reach steady state can be quite long (>24h in some cases). The temporal resolution (1h vs. 8h) of the meteorological data input was also found to impact calculated exposure levels, in an extent that varied with time, meteorological conditions and apartment position.
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Affiliation(s)
- Rivka Reichman
- Faculty of Civil and Environmental Engineering, Technion — Israel Institute of Technology, Haifa, 32000 Israel
| | - Yael Dubowski
- Faculty of Civil and Environmental Engineering, Technion — Israel Institute of Technology, Haifa, 32000 Israel
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7
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Effects of Neighboring Units on the Estimation of Particle Penetration Factor in a Modeled Indoor Environment. URBAN SCIENCE 2020. [DOI: 10.3390/urbansci5010002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ingress of air from neighboring apartments is an important source of fine particulate matter (PM2.5) in residential multi-story buildings. It affects the measurement and estimation of particle deposition rate and penetration factor. A blower-door method to measure the particle deposition rate and penetration factor has previously been found to be more precise than the traditional decay-rebound method as it reduces variability of PM2.5 ingress from outside. CONTAM is a multi-zone indoor air quality and ventilation analysis computer program to aid the prediction of indoor air quality. It was used in this study to model the indoor PM2.5 concentrations in an apartment under varying PM2.5 emission from neighboring apartments and window opening and closing regimes. The variation of indoor PM2.5 concentration was also modeled for different days to account for typical outdoor variations. The calibrated CONTAM model aimed to simulate environments found during measurement of particle penetration factor, thus identifying the source of error in the estimates. Results show that during simulated measurement of particle penetration factors using the blower-door method for three-hour periods under a constant 4 Pa pressure difference, the indoor PM2.5 concentration increases significantly due to PM2.5 generated from adjacent apartments, having the potential to cause an error of more than 20% in the estimated value of particle penetration factor. The error tends to be lower if the measuring time is extended. Simulated measurement of the decay-rebound method showed that more PM2.5 can penetrate inside if the PM2.5 was generated from apartments below under naturally variable weather conditions. A multiple blower-door fan can be used to reduce the effects of neighboring emission and increase the precision of the penetration estimates.
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Lozinsky CH, Touchie MF. Inter-zonal airflow in multi-unit residential buildings: A review of the magnitude and interaction of driving forces, measurement techniques and magnitudes, and its impact on building performance. INDOOR AIR 2020; 30:1083-1108. [PMID: 32643179 DOI: 10.1111/ina.12712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/15/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
Inter-zonal airflows within multi-unit residential buildings (MURBs) have profound impacts on an array of building performance metrics, including energy, indoor air quality (IAQ), fire and acoustical separations, and distribution of ventilation air. Although there are wide-ranging implications, most building codes/standards have yet to incorporate airtightness requirements for interior partitions in large, multi-zone structures, and instead focus primarily on exterior envelope airtightness. Despite the multi-disciplinary nature of the topic, previous reviews have been limited to one domain (eg, energy performance, IAQ, specific test methods). This paper presents a comprehensive summary of the literature on inter-zonal airflow in MURBs including the magnitude and interaction of driving forces; its relevance to/effect on building performance; current code requirements; testing methods; and previous measurements. While considerable efforts have been made in recent years to quantify and control inter-zonal airflows, most measurement techniques are still labor-intensive and disruptive, and there is no framework for how to implement performance-based requirements into building codes and standards. Further research efforts should be focused on refining testing methods and preparing the construction industry for code changes.
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Affiliation(s)
- Cara H Lozinsky
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, Canada
| | - Marianne F Touchie
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, Canada
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
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Wang J, Huo Q, Zhang T, Wang S, Battaglia F. Numerical investigation of gaseous pollutant cross-transmission for single-sided natural ventilation driven by buoyancy and wind. BUILDING AND ENVIRONMENT 2020; 172:106705. [PMID: 32287994 PMCID: PMC7116971 DOI: 10.1016/j.buildenv.2020.106705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/28/2020] [Accepted: 01/29/2020] [Indexed: 05/13/2023]
Abstract
Single-sided natural ventilation was numerically investigated to determine the impact of buoyancy and wind on the cross-transmission of pollution by considering six window types commonly found in multistory buildings. The goal of this study was to predict the gaseous pollutant transmission using computational fluid dynamics based on the Reynolds-averaged Navier-Stokes equations and baseline k-ω turbulence equations. The results indicated that ventilation rates generally increased with increasing wind speeds if the effects of buoyancy and wind were not suppressed; however, the re-entry ratio representing the proportion of expelled air re-entering other floors and the corresponding risk of infection decreased. If the source of the virus was on a central floor, the risk of infection was the highest on the floors closest to the source. Different window types were also considered for determining their effectiveness in controlling cross-transmission and infection risk, depending on the source location and driving force (e.g., buoyancy and wind).
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Affiliation(s)
- Jihong Wang
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Qiannan Huo
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Tengfei Zhang
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Shugang Wang
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Francine Battaglia
- Department of Mechanical & Aerospace Engineering, University at Buffalo, 339 Jarvis Hall, Buffalo, NY, 14260, USA
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Shao Z, Yin X, Bi J, Ma Z, Wang J. Spatiotemporal Variations of Indoor PM 2.5 Concentrations in Nanjing, China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E144. [PMID: 30621102 PMCID: PMC6339030 DOI: 10.3390/ijerph16010144] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 12/19/2018] [Accepted: 12/27/2018] [Indexed: 11/20/2022]
Abstract
Indoor fine particulate matter (PM2.5) is important since people spend most of their time indoors. However, knowledge of the spatiotemporal variations of indoor PM2.5 concentrations within a city is limited. In this study, the spatiotemporal distributions of indoor PM2.5 levels in Nanjing, China were modeled by the multizone airflow and contaminant transport program (CONTAM), based on the geographically distributed residences, human activities, and outdoor PM2.5 concentrations. The accuracy of the CONTAM model was verified, with a good agreement between the model simulations and measurements (r = 0.940, N = 110). Two different scenarios were considered to examine the building performance and influence of occupant behaviors. Higher PM2.5 concentrations were observed under the scenario when indoor activities were considered. Seasonal variability was observed in indoor PM2.5 levels, with the highest concentrations occurring in the winter and the lowest occurring in the summer. Building characteristics have a significant effect on the spatial distribution of indoor PM2.5 concentrations, with multistory residences being more vulnerable to outdoor PM2.5 infiltration than high-rise residences. The overall population exposure to PM2.5 in Nanjing was estimated. It would be overestimated by 16.67% if indoor exposure was not taken into account, which would lead to a bias in the health impacts assessment.
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Affiliation(s)
- Zhijuan Shao
- State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
| | - Xiangjun Yin
- Nanjing Urban Planning & Research Center, Nanjing 210029, China.
| | - Jun Bi
- State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
- Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China.
| | - Zongwei Ma
- State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
- Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China.
| | - Jinnan Wang
- State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
- State Environmental Protection Key Laboratory of Environmental Planning and Policy Simulation, Chinese Academy for Environmental Planning, Beijing 100012, China.
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Wang J, Zhang T, Wang S, Battaglia F. Gaseous pollutant transmission through windows between vertical floors in a multistory building with natural ventilation. ENERGY AND BUILDINGS 2017; 153:325-340. [PMID: 32288118 PMCID: PMC7127727 DOI: 10.1016/j.enbuild.2017.08.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/25/2017] [Accepted: 08/09/2017] [Indexed: 05/19/2023]
Abstract
Natural ventilation is an effective strategy to control thermal comfort in buildings, and can be enhanced depending on the window style. The combination of natural ventilation and window can also facilitate the removal or dilution of gaseous pollutants from indoor sources in newly decorated buildings. However, the windows on the same facade may cause gaseous pollutant cross-transmission during single-sided natural ventilation between households on different floors close to the source. Although some research has focused on the pollutant cross-transmission in buildings, the simplification of windows into rectangular openings often affects accurate knowledge of pollutant transmission characteristics. Therefore, this investigation explored gaseous pollutant cross-transmission through real windows during single-sided, buoyancy-driven ventilation in a multistory building. Six types of windows were modeled for the indoor pollutant of gaseous formaldehyde (HCHO). Computational fluid dynamics (CFD) was utilized to solve characteristics of pollutant transmission inside and outside the multistory building. The results indicated that the ventilation rates, thermal profiles and pollutant transmission inside and outside the building varied for each window type, although the open window areas were identical. The re-entry ratio of exhausted air entering upper floors and the infection risk of epidemic viruses caused by airborne cross-transmission was sensitive to ventilation rates and window configurations, while the sensitivities for window configurations varied case by case. The comparisons also revealed that the specification of ambient temperature and pollutant release rate ultimately did not affect the evaluation of pollutant cross-transmission using CFD.
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Affiliation(s)
- Jihong Wang
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China
- Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, 635 Prices Fork Road, Blacksburg, VA 24061, USA
| | - Tengfei Zhang
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China
| | - Shugang Wang
- School of Civil Engineering, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China
| | - Francine Battaglia
- Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, 635 Prices Fork Road, Blacksburg, VA 24061, USA
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Mu D, Shu C, Gao N, Zhu T. Wind tunnel tests of inter-flat pollutant transmission characteristics in a rectangular multi-storey residential building, part B: Effect of source location. BUILDING AND ENVIRONMENT 2017; 114:281-292. [PMID: 32287970 PMCID: PMC7117001 DOI: 10.1016/j.buildenv.2016.12.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/22/2016] [Accepted: 12/23/2016] [Indexed: 05/19/2023]
Abstract
The pollutant behavior in and around a naturally ventilated building requires to be investigated quantitatively as the growing concern on air quality within the built environment. The objective of the present study is to further investigate the wind induced inter-flat pollutant transmission and cross contamination routes in typical buildings in Shanghai. In this paper, a set of experiments was carried out in a boundary layer wind tunnel using a 1:30 reduced scale model that represented the typical configuration of rectangular multi-storey residential buildings. Sulfur hexafluoride (SF6) was employed as a tracer gas in the wind tunnel tests. Two natural ventilation modes, single-sided ventilation and cross ventilation were considered. The conditions under prevailing wind direction with different source locations on the windward side were compared. The pressure coefficients on all of the building façades and tracer gas concentration distributions were monitored and analysed. The experimental results elucidated that contaminant released from windward units could spread vertically and horizontally to other units on the source façade and downstream units. The source location was a significant influence factor on the pollutant concentration in various units. In the single-sided ventilated building, the infected risks of leeward units were even higher than those in some windward units. In the cross ventilated building, the vertical transmission could be suppressed and the horizontal transmission was reinforced. The study is helpful for further understanding of the inter-flat airborne transmission within an isolated building.
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Affiliation(s)
| | | | - Naiping Gao
- School of Mechanical Engineering, Tongji University, Shanghai, China
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