publications

2023

1. A CFD approach to reduce the risk of Covid-19 airborne transmission in a typical office

   Yibing Hu, Jialei Shen, Jianshun Jensen Zhang, and 1 more author

   2023

   Abs PDF

   The Covid-19 virus can spread rapidly in the air and cause the epidemic to rage around the world. This study takes a typical office as the research object and proposes four different partition settings to suppress the spread of the virus in the air based on displacement ventilation. And these strategies are verified by DPM model simulations of two daily situations of indexed person for coughing and talking. This study then employed a modified Wells-Riley model to evaluate the effectiveness of these strategies in mitigating the risk of viral infection. As expected, in the absence of a partition, a susceptible person at the other end of the seat greatly increased the risk of infection. Partitions can significantly reduce the risk of infection (100% → 20%), while partitions with a full-wrapped structure can reduce the risk of infection to less than 1%. For the instantaneous release scenario of coughing, the barrier can capture a large particle diameter (>50 μm) particles, and the smaller particle diameter can be discharged out of the room with the thermal plume. The strategies provided in this study can provide recommendations for indoor epidemic prevention and control in the context of the Covid-19 pandemic.

2. J. Build. Eng.

   A field measurement study of the effects of outdoor pollutants and room volumes on indoor fine particle and ozone concentrations

   Fusuo Xu, Jialei Shen, and Zhi Gao

   2023

2022

1. Build. Simul.

   On the effects of urban-like intersections on ventilation and pollutant dispersion

   Xin Guo, Riccardo Buccolieri, Zhi Gao, and 4 more authors

   2022

   Abs

   Focusing on the effect of street morphology on the ventilation efficiency, this paper presents 3D computational fluid dynamics (CFD) simulations of airflow and pollutant dispersion within urban-like three-way intersections, four-way intersections and roundabouts. The steady-state Reynolds-averaged Navier-Stokes (RANS) k-ε turbulence model is adopted and eight directions of the approaching wind are considered. The ventilation efficiency is evaluated using the ventilation indices purging flow rate (PFR) and the net escape velocity (NEV). Results show the sensitivity of the ventilation efficiency to the type of intersection, to the wind direction and to the number of branches. Specifically, the ventilation efficiency of the investigated three-way intersections is found to be better than that of the other intersections, especially when the angle between the streets is large, while that of roundabouts is also considerable, even with a similar average wind velocity, among the cases evaluated in this paper. Further, the influence of the wind direction for the three-way and four-way intersections is greater than that on roundabouts. Studies on the ventilation efficiency at urban intersections are not common in the literature and this work may help urban planners to better design such hub nodes of urban traffic, where traffic-related pollutants are not easily dispersed, thus avoiding harm to the health of pedestrians and surrounding residents.

2. Estimation of infection risk through airborne transmission in large open spaces with different air distributions

   Jialei Shen, Kaloki Nabutola, Michael J. Birnkrant, and 3 more authors

   2022

   Best Paper Award

   This paper received the Best Paper Award at the ROOMVENT 2022 conference.

3. Managing IAQ at Multiple Scales: From Urban to Personal Microenvironments

   Jianshun Jensen Zhang, Jialei Shen, and Zhi Gao

   2022

2021

1. Build. Environ.

   Effect of greening on pollutant dispersion and ventilation at urban street intersections

   Xin Guo, Zhi Gao, Riccardo Buccolieri, and 2 more authors

   2021

   Abs

   To improve ventilation efficiency and reduce pollution concentration in urban spaces, eco-strategies, including greening, have been suggested. However, there is still very little evidence to assert the benefits of such greening options, particularly at urban street intersections. Therefore, in this work, air flow and pollutant dispersion within urban-like three-way, four-way, and roundabouts intersections are investigated with three simple and five combined greening layouts. Three-dimensional computational fluid dynamics (CFD) analysis using the Reynolds-averaged Navier–Stokes model was conducted considering multiple wind directions. The ventilation efficiency was evaluated using the ventilation indices purging flow rate (PFR) and net escape velocity (NEV). The investigation of simple greening layouts shows that shrubs alone may enhance increase ventilation (i.e., increase PFR and NEV), and trees could increase the pollutant concentration at the pedestrian level. A comparison of greening layouts combining trees and shrubs shows that the presence of greening reduces ventilation and worsens the pollution condition at street intersections, except for shrubs located in the central zone within roundabouts. Specifically, NEV decreases by 16%–43% at four-way and three-way intersections owing to the presence of greening. Greening layouts with two rows of trees located 2.2 m away from buildings show overall significant negative effects on ventilation, particularly for wind directions ϕ = 0°, 45°, and 90°. The impact of shrubs and trees on ventilation at the roundabout is less significant, with NEV varying by 4%–11%.

2. SCS

   Urban ventilation of typical residential streets and impact of building form variation

   Yunlong Peng, Zhi Gao, Riccardo Buccolieri, and 2 more authors

   2021

   Abs

   This paper numerically investigates the ventilation of residential streets bounded by buildings of different forms. The aim is to provide suggestions for the design of environmentally sustainable urban streets in residential areas. Four representative building form variations along residential streets in Nanjing, located in the Yangtze River Delta region in China, i.e. ‘rotation’, ‘stagger’, ‘bend’ and ‘annex building’, are considered and several idealized models are finally built for the ventilation analysis. The focus is on the most common East-West (EW) and North-South (NS) oriented streets subjected to parallel, perpendicular and inclined wind directions. Results show that, for the investigated wind directions, NS oriented streets experience a better ventilation than EW oriented streets for all wind directions. For EW oriented streets, it is suggested to avoid buildings parallel to the street to prevent poor street ventilation conditions, while bended buildings are found to improve the ventilation. For NS oriented streets, keeping the buildings perpendicular to the street as much as possible is the most effective way to improve the street ventilation. Moreover, the presence of annex buildings, employed for commercial purposes, although reduces the airpath between buildings, for a given wind direction has little effect on street ventilation.

3. STBE

   Airborne transmission of SARS-CoV-2 in indoor environments: A comprehensive review

   Jialei Shen, Meng Kong, Bing Dong, and 2 more authors

   2021

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4. Build. Environ.

   A systematic approach to estimating the effectiveness of multi-scale IAQ strategies for reducing the risk of airborne infection of SARS-CoV-2

   Jialei Shen, Meng Kong, Bing Dong, and 2 more authors

   2021

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5. Build. Simul.

   Green Design Studio: A modular-based approach for high-performance building design

   Jialei Shen, Bess Krietemeyer, Amber Bartosh, and 2 more authors

   2021
6. Ventilation and Pollutant Concentration for the Pedestrian Zone, the Near-Wall Zone, and the Canopy Layer at Urban Intersections

   Mingjie Zhang, Zhi Gao, Xin Guo, and 1 more author

   2021

2019

1. Build. Environ.

   Emission rates of indoor ozone emission devices: A literature review

   Chao Guo, Zhi Gao, and Jialei Shen

   2019

   Abs

   As a strong oxidizing gas, ozone can damage the human respiratory tract and cardiovascular system. Aside from ambient outdoor ozone that enters buildings, indoor ozone emission devices (IOEDs) such as disinfectors, air purifiers, and printing devices are the primary source of indoor ozone. This review briefly presents the types and ozone emission mechanisms of IOEDs, the setups and procedures for measuring the ozone emission rate (OER) of IOEDs, and various equations for analyzing test results. This review also summarizes and compares the OERs of different IOEDs and analyzes the factors affecting the OER. The average OERs of in-duct air cleaners, ozone generators, room air purifiers, photocopiers, laser printers, and other small household devices are 62.8, 76.3, 4.6, 3.3, 0.8, and 0.4 mg/h, respectively. The OERs of in-duct air cleaners and ozone generators are generally larger than those of printing devices. The highest and lowest OERs of room air purifiers in the surveyed literature are 30.5 mg/h and 56 μg/h, respectively, with a difference of approximately 550 times. The ozone emission per unit paper for printing devices and per kilowatt hour for other IOEDs are also calculated and compared. In addition, the effects of the design and working mechanism of IOEDs on the OER are also discussed in detail. Users’ operation and daily maintenance of an IOED and the OER test conditions can also affect the OER. Finally, analytical equations are used to compare the influence of the test result processing method on the OER for the same IOED.

2. Build. Environ.

   Commuter exposure to particulate matters in four common transportation modes in Nanjing

   Jialei Shen, and Zhi Gao

   2019
3. An approach to develop a green building technology database for residential buildings

   Jialei Shen, and Jianshun Zhang

   2019

2018

1. Forests

   The Impact of Green Space Layouts on Microclimate and Air Quality in Residential Districts of Nanjing, China

   Liyan Rui, Riccardo Buccolieri, Zhi Gao, and 2 more authors

   2018

   Abs PDF

   This study numerically investigates the influence of different vegetation types and layouts on microclimate and air quality in residential districts based on the morphology and green layout of Nanjing, China. Simulations were performed using Computational Fluid Dynamics and the microclimate model ENVI-met. Four green indices, i.e., the green cover ratio, the grass and shrub cover ratio, the ecological landscaping plot ratio and the landscaping isolation index, were combined to evaluate thermal and wind fields, as well as air quality in district models. Results show that under the same green cover ratio (i.e., the same quantity of all types of vegetation), the reduction of grass and shrub cover ratio (i.e., the quantity of grass and shrubs), replaced by trees, has an impact, even though small, on thermal comfort, wind speed and air pollution, and increases the leisure space for occupants. When trees are present, a low ecological landscaping plot ratio (which expresses the weight of carbon dioxide absorption and is larger in the presence of trees) is preferable due to a lower blocking effect on wind and pollutant dispersion. In conjunction with a low landscaping plot ratio, a high landscaping isolation index (which means a distributed structure of vegetation) enhances the capability of local cooling and the general thermal comfort, decreasing the average temperature up to about 0.5 °C and the average predicted mean vote (PMV) up to about 20% compared with the non-green scenario. This paper shows that the relationship vegetation-microclimate-air quality should be analyzed taking into account not only the total area covered by vegetation but also its layout and degree of aggregation.

2. Build. Environ.

   Ozone removal on building material surface: A literature review

   Jialei Shen, and Zhi Gao

   2018
3. Ventilation and Air Quality in Student Dormitories in China: A Case Study during Summer in Nanjing

   Zhe Yang, Jialei Shen, and Zhi Gao

   2018

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4. Improving residential building arrangement design by assessing outdoor ventilation efficiency in different regional spaces

   Wei You, Jialei Shen, and Wowo Ding

   2018

2017

1. Outdoor and Indoor Ozone Concentration Estimation Based on Artificial Neural Network and Single Zone Mass Balance Model

   Jialei Shen, Jie Chen, Xinyi Zhang, and 2 more authors

   2017

   Abs

   Both outdoor and indoor ozone concentrations have negative health effects on human. This paper proposes an artificial neural network to estimate the outdoor ozone concentrations and a mass balance model tool to estimate indoor ozone concentrations. The prediction of outdoor and indoor ozone concentration levels is of great significance for people’s health. The estimation models are validated by the measured data selected from the monitoring stations and field measurements in a room in Nanjing, respectively. The accuracy of the estimation models is evaluated. The neural network built in this paper can generally estimate the outdoor ozone concentrations to some extent, while the single zone mass balance model is useful for predicting indoor ozone concentration levels.

2. Atmos. Environ.

   An investigation on the effect of street morphology to ambient air quality using six real-world cases

   Jialei Shen, Zhi Gao, Wowo Ding, and 1 more author

   2017
3. Improving wind environment design based on assessing spatial distribution of ventilation efficiency in regional space

   Wei You, Jialei Shen, and Wowo Ding

   2017
4. Improving Wind Environment of Residential Neighborhoods by Understanding the Relationship between Building Layouts and Ventilation Efficiency

   Wei You, Jialei Shen, and Wowo Ding

   2017