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Jiang, Z., Kobayashi, T., Yamanaka, T. & Sandberg, M. (2023). A literature review of cross ventilation in buildings. Energy and Buildings, 291, Article ID 113143.
Open this publication in new window or tab >>A literature review of cross ventilation in buildings
2023 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 291, article id 113143Article in journal (Refereed) Published
Abstract [en]

There is a growing body of literature that recognizes that natural ventilation plays avital role in indoor air quality, thermal comfort and building energy consumption. This papersystematically reviews the previously published research of the most efficient and typical naturalventilation type - cross ventilation, aiming to present the main research topics in contemporaryresearch and provide an agenda for future studies. The methodologies, airflow pattern, ventilationmodels and influencing parameters of cross ventilation were comprehensively summarized anddiscussed. The chained analysis and data-driven methods are the potential approaches to study crossventilation more efficiently. The comparisons of different ventilation models of cross ventilationhelp to better understand the basic mechanisms that drive the cross ventilation airflow.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Cross ventilation, Natural ventilation, Power balance model, Local dynamic similarity, Discharge coefficient
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41743 (URN)10.1016/j.enbuild.2023.113143 (DOI)001009105400001 ()2-s2.0-85159367213 (Scopus ID)
Available from: 2023-05-09 Created: 2023-05-09 Last updated: 2023-07-20Bibliographically approved
Jiang, Z., Kobayashi, T., Sandberg, M., Yamanaka, T., Kobayashi, N., Choi, N., . . . Toyosawa, K. (2023). Analysis of single-sided ventilation flows of a generic isolated building using particle tracking method in LES simulation. Building and Environment, 235, Article ID 110230.
Open this publication in new window or tab >>Analysis of single-sided ventilation flows of a generic isolated building using particle tracking method in LES simulation
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2023 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 235, article id 110230Article in journal (Refereed) Published
Abstract [en]

The main objective of this study is to investigate the airflow patterns in single-sided ventilation of isolated buildings in which the ventilation rate can not be easily predicted by the conventional Orifice equation. The research focuses on buildings with two openings located either at the front or back external wall, with building aspect ratios of 1:1 and 1:2.The study utilizes Large Eddy Simulation (LES) with the particle tracking technique validated by velocity data obtained from a wind tunnel experiment. Ventilation performance is evaluated by Airflow Rate (AFR) and Purging Flow Rate (PFR). AFR was obtained based on the instantaneous velocity over the openings, and PFR was determined by the tracer gas method. The results show that the influence of pulsation flow and eddy penetration both exist in single-sided ventilation. The comparison of AFR and PFR indicates part of the airflow through the opening does not contribute to effectively removing the indoor contaminants, which is quantitively evaluated by ventilation efficiency (ev) defined as the ratio of PFR and AFR. In order to explicitly observe and depict the airflow, the massless particles were emitted at the opening, and the trajectories were analysed. The Probability Density Function (PDF) of indoor residence and indoor travel distance was calculated. The high probability of short indoor travel distance and the residence time, which is mainly caused by the eddy at the openings and time-variant pulsation flow, can explain the difference between AFR and PFR.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Natural ventilation; Single-sided ventilation; CFD; LES; Ventilation efficiency; Particle tracking
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-41242 (URN)10.1016/j.buildenv.2023.110230 (DOI)2-s2.0-85151061834 (Scopus ID)
Available from: 2023-03-28 Created: 2023-03-28 Last updated: 2023-04-13Bibliographically 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
Jiang, Z., Kobayashi, T., Sandberg, M., Yamanaka, T., Choi, N. & Sano, K. (2023). Statistical Analysis Approach of Single-sided Ventilation Based on Particle Track Technique Using Large Eddy Simulation. In: Ooka R. (Ed.), 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. EDP Sciences, 396, Article ID 02012.
Open this publication in new window or tab >>Statistical Analysis Approach of Single-sided Ventilation Based on Particle Track Technique Using Large Eddy Simulation
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2023 (English)In: E3S Web of Conferences / [ed] Ooka R., EDP Sciences , 2023, Vol. 396, article id 02012Conference paper, Published paper (Refereed)
Abstract [en]

The main objective of this study is to investigate the airflow characteristics in single-sided ventilation. A CFD method of large eddy simulation (LES) using particle track technique was conducted in this study, and the simulation results are validated by experiment results. The mostly used ventilation efficiency indicators of natural ventilation are Air Flow Rate (AFR) and Purging Flow Rate (PFR). AFR is the volumetric airflow exchange rate through the openings and PFR is the effective airflow rate that removes indoor air pollutants. The ventilation efficiency (ϵν) of natural ventilation, which is defined as the ratio of PFR and AFR, is not well investigated in previous research, therefore, this study discusses the case of the ϵν of single-sided ventilation and tries to explain the distinction between AFR and PFR by statistical analysis approach based on particle movements. Particles are emitted from the opening and the particles' movements are tracked by tracing their locations at different time steps. The residence time measures the time between the time that particles enter the room and the time that particles leave the room, and indoor travel distance indicates the sum of the displacement when the particle travels in the room. The Probability Density Function (PDF) of the residence time and indoor travel distance is used to depict airflow characteristics of the ventilation path of single-sided ventilation. The analysis method of study might be another useful approach to studying natural ventilation in detail.

Place, publisher, year, edition, pages
EDP Sciences, 2023
Series
E3S Web of Conferences, ISSN 2555-0403
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-42780 (URN)10.1051/e3sconf/202339602012 (DOI)2-s2.0-85164463888 (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: 2023-07-24 Created: 2023-07-24 Last updated: 2023-07-24Bibliographically approved
Cehlin, M., Lin, Y., Sandberg, M., Claesson, L. & Wallhagen, M. (2023). Towards benchmarking of urban air quality based on homogenous surface emission. Results in Engineering (RINENG), 20, Article ID 101617.
Open this publication in new window or tab >>Towards benchmarking of urban air quality based on homogenous surface emission
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2023 (English)In: Results in Engineering (RINENG), ISSN 2590-1230, Vol. 20, article id 101617Article in journal (Refereed) Published
Abstract [en]

Here, it is presented a possible methodology and experimental model for benchmarking of air quality in cities. The concept behind the methodology is that a city’s inherent structure affects the potential for contaminant removal due to the resistance it poses to inflow. The approach is based on homogenous emission across the street surface network, representing a worst-case situation. Different levels of complexity can be used for benchmarking, making it valuable for evaluating different layouts. Additionally, an urban ventilation index suitable for these kinds of experimental studies has been suggested. 

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Urban ventilation, City ventilation, Air quality, Wind tunnel, Tracer gas, Experimental model
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-43313 (URN)10.1016/j.rineng.2023.101617 (DOI)001127737100001 ()2-s2.0-85178337839 (Scopus ID)
Funder
Swedish Research Council Formas, 2018-00238
Available from: 2023-11-22 Created: 2023-11-22 Last updated: 2024-01-04Bibliographically approved
Jiang, Z., Kobayashi, T., Yamanaka, T., Sandberg, M., Choi, N., Kobayashi, N., . . . Toyosawa, K. (2023). Wind tunnel experiment of wind-induced single-sided ventilation under generic sheltered urban area. Building and Environment, 242, Article ID 110615.
Open this publication in new window or tab >>Wind tunnel experiment of wind-induced single-sided ventilation under generic sheltered urban area
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2023 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 242, article id 110615Article in journal (Refereed) Published
Abstract [en]

Natural ventilation is an important ventilation method due to its potential to improve indoor air quality and provide an acceptable thermal environment without energy consumption. In the urban area, the ventilation performance of the natural ventilation is very sensitive to surrounding building density. This paper presents a wind tunnel experiment to assess the influence of urban density on the ventilation rate of single-sided ventilation. Spacing density, wind direction, and the number of openings were factors that were investigated in this experiment. The ventilation rate is evaluated by a continuous dose method of the tracer gas technique. The wind pressure coefficient at openings of the sealed model without openings was measured by pressure transducers. The streamwise velocity at the street canyon was measured by a split-film probe with a constant temperature anemometer unit. The ventilation rate, wind pressure coefficient fluctuations and velocity of an isolated building are compared to those of a building with two layers of surrounding buildings with the spacing of 0.5H (H is building height), 1H and 1.5H. A higher building density decreases the ventilation performance of windward opening cases and increases the ventilation performance of the leeward opening cases. The simplified ventilation rate prediction methods for wind-induced ventilation are presented.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Natural ventilation, Wind pressure coefficients, Wind tunnel experiment, Urban canopy flow
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-42769 (URN)10.1016/j.buildenv.2023.110615 (DOI)001042673200001 ()
Available from: 2023-07-15 Created: 2023-07-15 Last updated: 2023-08-24Bibliographically approved
Lin, Y., Sandberg, M., Cehlin, M., Claesson, L. & Wigö, H. (2022). Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements. In: 5th International Conference on Building Energy and Environment (COBEE 2022): . Paper presented at COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022. Springer, Article ID 1419.
Open this publication in new window or tab >>Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements
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2022 (English)In: 5th International Conference on Building Energy and Environment (COBEE 2022), Springer , 2022, article id 1419Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Springer, 2022
Keywords
City ventilation, Compact urban morphology, Wind tunnel experiment, Tracer gas measurement, Single-side ventilation
National Category
Fluid Mechanics and Acoustics
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-39649 (URN)10.1007/978-981-19-9822-5_311 (DOI)2-s2.0-85172730229 (Scopus ID)9789811998218 (ISBN)
Conference
COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022
Funder
Swedish Research Council Formas, 2018-00238
Available from: 2022-08-03 Created: 2022-08-03 Last updated: 2023-11-23Bibliographically approved
Kobayashi, T., Sandberg, M., Fujita, T., Lim, E. & Umemiya, N. (2022). Numerical analysis of wind-induced natural ventilation for an isolated cubic room with two openings under small mean wind pressure difference. Building and Environment, 226, Article ID 109694.
Open this publication in new window or tab >>Numerical analysis of wind-induced natural ventilation for an isolated cubic room with two openings under small mean wind pressure difference
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2022 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 226, article id 109694Article in journal (Refereed) Published
Abstract [en]

Wind-induced natural ventilation through openings with small wind pressure differences was examined using large eddy simulation (LES) modelling. This study focused on cases in which the ventilation rate is predicted using a standard Orifice equation. The purpose of this study was to clarify how the ventilation rate is underestimated in such cases for both single-sided and double-sided openings, and to clarify the difference between the effective ventilation rate (purging flow rate, PFR) and bulk airflow rate (AFR), which have not been sufficiently and systematically understood. A simple cubic-room model with two openings was analysed using LES by varying the opening position after validation, and the ventilation rate, velocity field, and wind pressure coefficient were compared with experimental results. The PFR was determined by tracing particles, and the AFR was obtained based on the instantaneous velocity over the openings. The AFR predicted by the Orifice equation was underestimated when the difference in the mean wind pressure coefficient (Delta(C-p) over bar) was less than 0.1. The main feature of this study was to show the ventilation effectiveness defined by the PFR divided by AFR, which was approximately 70-80%, 60%, and 90% for the double-sided openings, single-sided openings on the lateral side, and windward and leeward sides, respectively. Another feature was to propose a method for estimating the AFR reflecting two key phenomena, namely pulsating flow and eddy penetration. In addition, a simple equation considering the standard deviation of wind pressure coefficient difference (sigma(Delta Cp)), and external local velocity around an opening (V-vic) was obtained.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Natural ventilation, Single-sided ventilation, Cross-ventilation, Wind tunnel test, CFD
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-40506 (URN)10.1016/j.buildenv.2022.109694 (DOI)000878643200004 ()2-s2.0-85140302173 (Scopus ID)
Available from: 2022-11-24 Created: 2022-11-24 Last updated: 2022-12-05Bibliographically approved
Ikegaya, N., Ito, K. & Sandberg, M. (2022). Rigorous mathematical formulation of net escape velocity and net escape probability determining a macroscopic concentration. Indoor Air, 32(7), Article ID e13072.
Open this publication in new window or tab >>Rigorous mathematical formulation of net escape velocity and net escape probability determining a macroscopic concentration
2022 (English)In: Indoor Air, ISSN 0905-6947, E-ISSN 1600-0668, Vol. 32, no 7, article id e13072Article in journal (Refereed) Published
Abstract [en]

Net escape velocity (NEV) and net escape probability (NEP) are concepts that describe that scalar quantity discharged from a source in an indoor air environment is expressed by the unique velocity scales of the returning and escaping populations. Despite the conceptual description and applications of several numerical simulations, the definitions were not precisely explained using a mathematical formula. Here, we derive rigorous mathematical formulations of the NEV and NEP. These formulations provide us with the physical interpretation of NEV, clarify the sufficient condition of perfect escape, and lead to a further formulation of the transfer probability of the scalar. To justify and apply the derived relationships, two simple problems were numerically solved: One was a diffusion equation, and the other was an advection–diffusion equation. The results of the diffusion problem clearly demonstrate that only the outgoing scalar flux exists on the surface of the control volume, covering the source at any location. In contrast, the advection–diffusion problem reveals that there is a returning population of the scalar in most locations, despite both diffusion and turbulent parts working to remove the scalar. This rigorous formulation contributes to apply NEV as an appropriate air quality index with the clear physical interpretation to determine the local scalar concentration.

Place, publisher, year, edition, pages
Wiley, 2022
Keywords
indoor ventilation; net escape probability; net escape velocity; purging flow rate; scalar concentration; transfer probability
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-39681 (URN)10.1111/ina.13072 (DOI)2-s2.0-85135180900 (Scopus ID)
Available from: 2022-08-13 Created: 2022-08-13 Last updated: 2022-09-19Bibliographically approved
Sandberg, M. (2022). The dual role of an air distribution system, both reducing the concentration of infectious agents and spreading infectious agents. Frontiers in Built Environment, 7, Article ID 728968.
Open this publication in new window or tab >>The dual role of an air distribution system, both reducing the concentration of infectious agents and spreading infectious agents
2022 (English)In: Frontiers in Built Environment, E-ISSN 2297-3362, Vol. 7, article id 728968Article in journal (Refereed) Published
Abstract [en]

Ventilation removing and spreading contaminants. A large number of people becoming sick due to the COVID -19 pandemic are infected in their homes. Therefore, the spread of infectious agents, when infectious and susceptible individuals are together in their homes, is an important issue. Usually, ventilation is regarded as a process of only diluting and removing contaminants, but it is also a mechanism for spreading contaminants. The latter issue is of major importance when there is a pandemic. An air distribution system must, therefore, be viewed from a wider perspective than is generally the case. There is a need for a shift of paradigm. The scope of this study is to introduce new concepts that will make it possible to analyze air distribution systems from such a wider perspective.

Place, publisher, year, edition, pages
Frontiers, 2022
Keywords
purging flow rate, visiting frequency, entrainment, delivery capacity of clean air, two populations of air, flooding of contaminants
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-37960 (URN)10.3389/fbuil.2021.728968 (DOI)000751993600001 ()2-s2.0-85124194445 (Scopus ID)
Funder
Swedish Research Council Formas, 2021-01606
Available from: 2022-02-17 Created: 2022-02-17 Last updated: 2022-02-21Bibliographically approved
Projects
A new ventilation technique based on velocity variation as a method to improve thermal comfort and ventilation efficiency [2008-64_Formas]; University of GävleTowards an optimisation of urban-planning and architectural parameters for energy use minimisation in miditerranean cities (Urban Net) [2008-327_Formas]; University of Gävle; Publications
Sandberg, M., Neophytou, M., Fokaides, P., Panagiotou, I., Ioannou, I., Petrou, M., . . . Ivanov, A. (2011). Towards optimization of urban planning and architectural parameters for energy use minimization in Mediterranean cities. In: WREC 2011: . Paper presented at The Word Renewable Energy Congress 2011, Linköping 8-13 May 2011.
Energy saving in churches: Measuring air leakage, soiling and micro climate [P34964-1_Energi]; University of GävleStadsventilation [2018-00238_Formas]; University of Gävle; Publications
Cehlin, M., Lin, Y., Sandberg, M., Claesson, L. & Wallhagen, M. (2023). Towards benchmarking of urban air quality based on homogenous surface emission. Results in Engineering (RINENG), 20, Article ID 101617. Lin, Y., Sandberg, M., Cehlin, M., Claesson, L. & Wigö, H. (2022). Evaluation of the Equivalent Purging Flow Rate for Single-side Ventilated Model with Tracer Gas Measurements. In: 5th International Conference on Building Energy and Environment (COBEE 2022): . Paper presented at COBEE 2022, Concordia University, Montreal, Canada, 25-29 July 2022. Springer, Article ID 1419. Buccolieri, R., Lin, Y., Wigö, H. & Sandberg, M. (2021). Drag force rose representing the interaction between urban geometries and wind. In: 15th ROOMVENT (Roomvent 2020) virtual conference: Energy efficient ventilation for healthy future buildings. Paper presented at 15th Roomvent virtual conference, 15-17 February 2021, Turin, Italy (pp. 85-88). Cehlin, M., Ameen, A., Sandberg, M., Claesson, L., Wigö, H. & Lin, Y. (2020). Urban Morphology and City Ventilation. In: : . Paper presented at 10th International Conference on Future Environment and Energy (ICFEE 2020).
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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1121-2394

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