Research on Urban Heat Island and Heavily Polluted Cities

A special issue of Buildings (ISSN 2075-5309). This special issue belongs to the section "Building Energy, Physics, Environment, and Systems".

Deadline for manuscript submissions: closed (20 July 2023) | Viewed by 28496

Special Issue Editors


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Guest Editor
School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 712000, China
Interests: environmental fluid dynamics; urban wind environment analysis; urban heat island

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Guest Editor
School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Interests: green building design; building simulation; building energy; urban heat island; sustainable urban development
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Guest Editor
Nikken Sekkei Research Institute, Mitsuwa Ogawamachi Bldg. 3F-7-1 Kanda Ogawamachi, Chiyoda-ku, Tokyo, Japan
Interests: smart community planning; smart building management
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

According to the high speed of urban development in cities, the accompanying urban typology changes and urban anthropogenic heat emission have caused urban environmental problems such as urban heat islands and urban air pollution, which are attracting increasing attention from academic societies. Urban wind environment is providing the main effects on urban heat distribution and urban air pollution diffusion. Therefore, the mechanisms of the environmental effects from urban planning factors, including development intensity, urban building density, urban street typology, urban open space, and urban vegetation, have been well studied over the last few decades, and innovative simulation theory has been developed for microscaled urban wind environmental evaluation. Meanwhile, because of the high population density and the increased urban energy consumption, anthropogenic heat and air pollution emission from building and transportation sections have been evaluated for solution development. Low-carbon building design technology development and transportation-oriented urban planning could be considered for heat and air pollution emission reduction. Related measurements, evaluation, and solutions should be further studied for urban development and redevelopment in the future.

Prof. Dr. Zhaolin Gu
Dr. Yupeng Wang
Dr. Liyang Fan
Guest Editors

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Keywords

  • urban heat island
  • urban air pollution
  • urban environmental simulation
  • sustainable urban planning
  • urban typology
  • anthropogenic heat emission
  • urban wind environment
  • urban vegetation
  • urban transportation

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Published Papers (10 papers)

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Research

Jump to: Review

17 pages, 16981 KiB  
Article
Association between Wind Environment and Spatial Characteristics of High-Rise Residential Buildings in Cold Regions through Field Measurements in Xi’an
by Qian Zhang, Dian Zhou, Duo Xu and Alessandro Rogora
Buildings 2023, 13(8), 2007; https://doi.org/10.3390/buildings13082007 - 7 Aug 2023
Cited by 1 | Viewed by 1226
Abstract
Research on the correlation between wind and block spatial form focuses mainly on hot and humid cities. However, cold regions are also experiencing high summer temperatures due to global climate change. Enhancing wind speed in blocks through urban spatial control improves comfort. Existing [...] Read more.
Research on the correlation between wind and block spatial form focuses mainly on hot and humid cities. However, cold regions are also experiencing high summer temperatures due to global climate change. Enhancing wind speed in blocks through urban spatial control improves comfort. Existing research cannot be directly applied to cold regions due to natural differences. Using Xi’an as an example, this study explores the impact of high-rise residential block spatial form on internal and external wind environments through field measurements and simulations. Optimal strategies for block planning and architectural design are identified to improve the wind environment. Results show that blocks with high buildings on the south and north sides and low buildings in the middle achieve a more comfortable internal wind environment. Gradually increasing building height from south to north has minimal impact on downwind blocks. Reducing the angle between the main facade and dominant wind direction enhances the residential area’s wind environment. Specific spatial planning and design strategies are summarized for early-stage decision-making. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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17 pages, 5541 KiB  
Article
The Influence of Block Morphology on Urban Thermal Environment Analysis Based on a Feed-Forward Neural Network Model
by Yansu Qi, Xuefei Li, Yingjie Liu, Xiujuan He, Weijun Gao and Sheng Miao
Buildings 2023, 13(2), 528; https://doi.org/10.3390/buildings13020528 - 15 Feb 2023
Cited by 3 | Viewed by 1720
Abstract
Morphological indicators, which are important for urban planning, can be adjusted to effectively mitigate the heat island effect and promote a more comfortable urban environment. Most studies obtain the relationship between morphological indicators and land surface temperature (LST) from the urban scale, and [...] Read more.
Morphological indicators, which are important for urban planning, can be adjusted to effectively mitigate the heat island effect and promote a more comfortable urban environment. Most studies obtain the relationship between morphological indicators and land surface temperature (LST) from the urban scale, and it is difficult to apply the results to urban management and construction projects. Traditional research methods have ignored the complex and interactive relationship between morphological indicators and LST. In this work, the feed-forward neural network (FNN) model is utilized to model the nonlinear relationship between morphological indicators and LST at the block scale. After validation and comparison, the FNN model achieved MAE of 0.885 and RMSE of 1.184, indicating that the influence of morphological indicators on LST could be precisely mapped. In addition, using cooling LST as the optimization target, the specific indicator scheme is suggested based on the FNN model, where the percentage of green space is 17.1%, the percentage of impervious surface is 82.9%, the percentage of water is 0, the bare soil percentage is 0, the floor area ratio is 0.814, the building cover percentage is 32.2%, and the average building height is 7.2 m. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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23 pages, 5762 KiB  
Article
The Relation between Green Visual Index and Visual Comfort in Qingdao Coastal Streets
by Dong Sun, Xiang Ji, Weijun Gao, Fujian Zhou, Yiqing Yu, Yumeng Meng, Meiqi Yang, Junjie Lin and Mei Lyu
Buildings 2023, 13(2), 457; https://doi.org/10.3390/buildings13020457 - 7 Feb 2023
Cited by 13 | Viewed by 2703
Abstract
The public’s mental health is obviously impacted by the perception of green quantity in urban streets. As one of the important urban spatial indicators, the Green View Index (GVI) reflects the green quantity of streets, which is helpful in revealing the level of [...] Read more.
The public’s mental health is obviously impacted by the perception of green quantity in urban streets. As one of the important urban spatial indicators, the Green View Index (GVI) reflects the green quantity of streets, which is helpful in revealing the level of street vegetation from the perspective of pedestrians. The GVI can improve the attraction and the visual experience in urban streets. Taking Qingdao Coastal Streets as an example, the study used OpenStreetMap, Baidu Street View (BSV) image, DeepLabV3+ semantic segmentation, and the SD method to obtain the GVI and Visual Comfort (VICO), and the correlation and influence mechanisms were discussed. The result showed that the greening landscape of the overall Qingdao Coastal Streets was of high quality, and the historic district was the most outstanding. The greening quality was a little low in the transitional district and the western modern district, which should be improved. In addition, the relationship between GVI and VICO showed a strong positive correlation. The spatial distribution of the VICO was more consistent with the GVI. The street VICO was affected by the GVI, plant richness, the street scale, and landscape diversity. Moreover, with the increase of the GVI, the increase trend of the VICO instead gradually decreased. The contribution of this study was not only accurately diagnosing the problems of street greening quality, shedding light on the relationship between GVI and VICO, but also providing theoretical support for urban greening planning and management, especially for healthy street design. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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26 pages, 20176 KiB  
Article
Energy-Use and Indoor Thermal Performance in Junior High School Building after Air-Conditioning Installation with the Private Finance Initiative
by Dian Sekartaji, Yuji Ryu, Didit Novianto, Kazuma Eto and Weijun Gao
Buildings 2023, 13(2), 455; https://doi.org/10.3390/buildings13020455 - 7 Feb 2023
Cited by 3 | Viewed by 2671
Abstract
Japan’s government has adopted the “Private Finance Initiative (PFI)” as a project method for monitoring “air-conditioning (AC)” performance after AC installation projects to overcome heatstroke increase in schools during the summer. However, this project was conducted long after schools were built, which raises [...] Read more.
Japan’s government has adopted the “Private Finance Initiative (PFI)” as a project method for monitoring “air-conditioning (AC)” performance after AC installation projects to overcome heatstroke increase in schools during the summer. However, this project was conducted long after schools were built, which raises the question: what is the AC “energy-use (EU)” and how comfortable will the classroom be when it is installed without going through the planning stage? Minimizing AC EU while keeping indoor thermal comfort is the main concern for low-carbon building design technology development. This research aims to evaluate the AC EU and summer indoor thermal comfort in classrooms by position and zone. This research method analyzes PFI monitoring data, field measurement data, and questionnaires with sensitivity analysis. It found that AC EU in the summer was higher than in the winter. In addition, the AC setting temperatures in the summer (cooling) were below the government-recommended value of 28 °C. Although the indoor thermal comfort percentage in the summer had reached 75.3%, there was a seating position with a smaller comfort percentage than others. The result further shows that most students felt “neutral”. However, the number of students who felt “slightly cool” and “cool” were more than those who felt “slightly warm” and “warm”. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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18 pages, 1714 KiB  
Article
Does Digital City Construction Contribute to Air Pollution Control? Evidence from China
by Zhen Yang, Weijun Gao, Chune Wang and Jiawei Li
Buildings 2023, 13(2), 444; https://doi.org/10.3390/buildings13020444 - 6 Feb 2023
Cited by 4 | Viewed by 2391
Abstract
With the quick advancement of new generation information technologies like the Internet, big data, cloud computing, artificial intelligence, and blockchain, digitalization is emerging as a crucial tool for restructuring factor resources, reshaping the economic landscape, and altering competitiveness. However, there is no literature [...] Read more.
With the quick advancement of new generation information technologies like the Internet, big data, cloud computing, artificial intelligence, and blockchain, digitalization is emerging as a crucial tool for restructuring factor resources, reshaping the economic landscape, and altering competitiveness. However, there is no literature on the impact and mechanism of digitalization on environmental pollution management. Thus, this study measured the level of digital development in each province using principal component analysis based on panel data of 30 Chinese provinces during 2006–2019. On this basis, the impact of digitalization on haze and its mechanisms were explored using regression models and mediating effect models, respectively. The findings demonstrate that (1) haze pollution may be reduced through digital progresses, and there is an inverse U-shaped non-linear link between them, that is, as digital technology is refined, its impact on haze pollution shifts from facilitation to suppression; (2) digital development can reduce haze pollution by promoting technological innovation and improving the efficiency of environmental management; and (3) there is regional heterogeneity in the influence of digitalization on air pollution. In heavily polluted areas, the suppression effect of digital technology on air pollution is more than three times that of other areas. The goal of this study is to investigate how digitalization affects haze pollution and its mechanisms, as well as to offer some scientific guidance for China’s efforts to build a “Digital China” under the banner of digitalization. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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14 pages, 19609 KiB  
Article
Comparison of Summer Outdoor Thermal Environment Optimization Strategies in Different Residential Districts in Xi’an, China
by Xuefeng Zhang, Yupeng Wang, Dian Zhou, Chao Yang, Huibin An and Teng Teng
Buildings 2022, 12(9), 1332; https://doi.org/10.3390/buildings12091332 - 30 Aug 2022
Cited by 10 | Viewed by 2131
Abstract
Residential districts account for the most common type of urban land coverage. Massive developments with high density have a huge impact on the urban climate. In this study, we explored the thermal environment optimization strategies of residential districts with different development intensities (plot [...] Read more.
Residential districts account for the most common type of urban land coverage. Massive developments with high density have a huge impact on the urban climate. In this study, we explored the thermal environment optimization strategies of residential districts with different development intensities (plot ratios) from the perspective of urban renewal and residential district design in Xi’an, China. We selected residential districts with low, medium, and high plot ratios in Xi’an City for field measurements and environmental simulation according to five proposed optimization strategies. By comparing the air temperature, mean radiant temperature, and physiological equivalent temperature at the pedestrian height, 1.5 m from the ground, we explored the thermal environment optimization texture of each strategy. The results showed that the same strategy introduced different effects in different residential districts. Increasing the road reflectivity had the best effect on residential districts that had a low plot ratio, whereas planting trees was the best effect in districts with medium and high plot ratios. Planting lawns had a better effect in districts with high plot ratios. The findings of this study provide suggestions for the optimization and reconstruction of residential districts and contribute to future residential district development and design. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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28 pages, 13068 KiB  
Article
Exposure Assessment of Traffic-Related Air Pollution Based on CFD and BP Neural Network and Artificial Intelligence Prediction of Optimal Route in an Urban Area
by Lulu Ren, Farun An, Meng Su and Jiying Liu
Buildings 2022, 12(8), 1227; https://doi.org/10.3390/buildings12081227 - 12 Aug 2022
Cited by 13 | Viewed by 2629
Abstract
Due to rapid global economic development, the number of motor vehicles has increased sharply, causing significant traffic pollution and posing a threat to people’s health. People’s exposure to traffic-related particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) primarily [...] Read more.
Due to rapid global economic development, the number of motor vehicles has increased sharply, causing significant traffic pollution and posing a threat to people’s health. People’s exposure to traffic-related particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) primarily occurs during commuting. Many studies have used exposure risk assessment models to assess the possible adverse effects of PM2.5, but few have used them to plan low-risk pathways for commuters. This study simulated the pollutant concentration distribution in an idealized urban area in different scenarios. We then used a back propagation (BP) neural network to predict the pollutant concentration. The commuter respiratory deposition dose was calculated based on the BP prediction results, and the respiratory deposition dose was converted into obstacles on the commuting map. Finally, the rapidly exploring random tree star (RRT*) algorithm was used to plan low-risk paths for commuters. The results indicate that pollutants discharged by cars and tree planting can significantly affect the pollutant concentration. A 30.25 μg/m3 increase in the pollutant concentration discharged by cars resulted in a 7~13 μg/m3 increase in the traffic-related air pollution concentration on sidewalks. Combining a computational fluid dynamics simulation, a BP neural network model, and the RRT* algorithm provides a system to plan low-risk paths for commuters. This work proposes artificial-intelligence-based models for calculating the exposure risk to traffic-related pollutants (PM2.5) and choosing a low-risk commuting path to ensure healthy travel. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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Review

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18 pages, 3931 KiB  
Review
Review of the Numerical Simulation of the Wind and Pollutant Diffusion in Urban Street Canyon under the Influence of Trees
by Le Wang, Wenxin Tian and Peilin Zheng
Buildings 2023, 13(4), 1088; https://doi.org/10.3390/buildings13041088 - 20 Apr 2023
Cited by 3 | Viewed by 2378
Abstract
Tree is an essential factor affecting airflow and pollutant diffusion in the urban street canyon. The wind environment in the urban street canyon will be effectively improved by expounding the mechanism and implementing greening measures. Moreover, it will help decrease the pollutant concentration [...] Read more.
Tree is an essential factor affecting airflow and pollutant diffusion in the urban street canyon. The wind environment in the urban street canyon will be effectively improved by expounding the mechanism and implementing greening measures. Moreover, it will help decrease the pollutant concentration around the street canyon. This paper reviews the airflow and pollutant diffusion numerical simulation in the street canyon under the tree influence. Firstly, the numerical mathematical model used for pollutant diffusion and airflow in urban street canyons under the influence of trees is summarized. The representation of trees’ numerical mathematical model in the simulation domain is mainly proposed. Secondly, the wind environment and pollutant distribution factors influencing urban street canyons are elaborated and analyzed, including tree characteristics, layout, street canyon shape, and thermal. Furthermore, current research progress and deficiencies are discussed. Finally, the future research direction of wind environment and pollutant distribution simulation in urban streets under the influence of trees is pointed out. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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17 pages, 1587 KiB  
Review
Materials to Mitigate the Urban Heat Island Effect for Cool Pavement: A Brief Review
by Zheng Wang, Yugang Xie, Minghao Mu, Lichao Feng, Ning Xie and Na Cui
Buildings 2022, 12(8), 1221; https://doi.org/10.3390/buildings12081221 - 12 Aug 2022
Cited by 14 | Viewed by 4077
Abstract
The urban heat island (UHI) effect has a significantly negative impact on the living environment in urban areas. Asphalt pavement is one of the most widely used infrastructures that absorbs solar energy, which leads to the UHI effect and premature failure. As a [...] Read more.
The urban heat island (UHI) effect has a significantly negative impact on the living environment in urban areas. Asphalt pavement is one of the most widely used infrastructures that absorbs solar energy, which leads to the UHI effect and premature failure. As a result, cool pavement technology has been rapidly developed in recent years to mitigate the UHI effect originating from asphalt pavement. Although several outstanding review articles have analyzed previous studies on cool pavement technologies, very few review articles have focused on how to design and expand cool pavement technology from a materials perspective. In this mini-review article, the theoretical and practical factors of the solar reflective coatings and phase-change materials, which are significantly dependent on the design of new materials, have been summarized. The main challenges and potential problem-solving ideas have been presented. In a cool pavement, the solar reflective coatings are composed of epoxy resin or acrylic polymer matrix filled with solar reflective nanoparticles, such as TiO2, SiO2, ZnO, Al2O3, or Fe2O3. The main challenges of the solar reflective coatings are the spalling of the coating polymers from the asphalt pavement surface and the dispersion of the solar reflective nanoparticle in the polymer matrix. Most importantly, it is critical to harmonize the balance between the bonding strength, aging rate, solar reflectance, curing requirements, mechanical properties, and durability of the solar reflective coating. For the nanofillers, the cost of the filler materials, the balance between UV, visible light, and near-infrared reflectance and the dispersion status of the nanofillers in the polymer matrix are the primary factors that must be concerned. For the phase-change materials (PCMs), the interaction between the asphalt and the PCMs, the decomposition of the PCMs, the toxicity of the PCMs, the distribution status of the PCMs in the asphalt matrix, and the cost are the main factors that have to be considered in constructions. This review article can not only provide basic knowledge for the development of new solar reflective pavement materials but also serve as a guide for practical applications of cool pavement in the field. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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23 pages, 6296 KiB  
Review
Knowledge Map of Urban Morphology and Thermal Comfort: A Bibliometric Analysis Based on CiteSpace
by Yuan Chen, Yupeng Wang and Dian Zhou
Buildings 2021, 11(10), 427; https://doi.org/10.3390/buildings11100427 - 23 Sep 2021
Cited by 21 | Viewed by 4804
Abstract
In the context of global climate change, urban morphology is closely related to thermal comfort and contributes to sustainable urban development. Academics started to pay attention to related topics and carried out many studies during the last decades. This paper aims to summarize [...] Read more.
In the context of global climate change, urban morphology is closely related to thermal comfort and contributes to sustainable urban development. Academics started to pay attention to related topics and carried out many studies during the last decades. This paper aims to summarize the research achievements and the development track for future studies. The Web of Science database and CiteSpace were used in this paper to conduct a bibliometric analysis of 556 studies in related fields from 1993 to 2020. Using a three-level co-occurrence analysis of 446 keywords, 1187 cocited literature clusters, and 15 landmark studies, the research topics and mainstream research frameworks were identified. The results show that with the increasing participation of disciplines such as computer science, ecology, and chemistry, the purpose of future research will shift to a focus on anthropogenic heat emissions, energy consumption, air pollution, and other aspects, and new research tools will be needed. In addition to building-scale and block-scale morphology, urban-scale morphology and green infrastructure will become the focus in the future. This study provides a systematic review of research about urban morphology and thermal comfort, which can inspire other researchers and policy makers. Full article
(This article belongs to the Special Issue Research on Urban Heat Island and Heavily Polluted Cities)
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