Ventilation Corridors Research Articles

Circuit VRC: A circuit theory-based ventilation corridor model for mitigating the urban heat islands

This paper reports on Circuit VRC, a ventilation corridor model that integrates circuit theory and ventilation resistance coefficient (VRC) to address urban heat island mitigation. Taking Wuhan's main urban area as an example, the Circuit VRC model was employed to identify the paths and barriers of the urban ventilation corridors and simulate the airflow at a macro scale. Combined with land surface temperature (LST) maps, the accuracy of the Circuit VRC model was evaluated. This paper further proposes an optimization strategy for ventilation corridors based on this model. The results indicated that (1) The proposed Circuit VRC model exhibited high reliability. Under the prevailing wind direction, the mitigation effect of Circuit VRC-based ventilation corridor areas on urban heat islands is on average 46.3% higher than that of non-corridor areas. (2) The airflow values in Circuit VRC-based ventilation corridors showed a non-linear correlation with LST. As the airflow value increases from 0 to 0.5, the LST reduces significantly. (3) The constructed ventilation corridors can be greatly optimized by using the floor area ratio (FAR)-controlled method in the Circuit VRC model. The maximum increase in airflow value in the ventilation corridor caused by a 0.1 FAR decrease within the barriers is 17.8%. The model proposed in this study provides crucial technical support for mitigating urban heat islands.

Comparison of the influences of different ventilation corridor forms on the thermal environment in Wuhan City in summer

The ventilation corridor is an essential element in urban planning and design to improve the climate and environment. In this paper, four forms of two ventilation corridors were set up in the southeast of Wuhan City based on its urban planning outline to quantitatively study the influences of different ventilation corridor forms on the urban thermal environment in summer. The urban micro-meteorological environment was simulated using the next-generation mesoscale Weather Research and Forecast (WRF) model coupled with an urban canopy model (UCM). Critical time-dependent meteorological values were extracted and plotted, including temperature and wind difference fields, average temperature at 2-m height, average wind speed at 10-m height, and surface energy flux. By conducting a comparative analysis of the quantitative results, the ventilation corridors in construction land are arranged at intervals in the upwind position of the city in summer, which can slightly adjust the thermal environment of the central area of the city, and have an effective regulation on the temperature of the corridors and surrounding areas during the daytime. Especially at 15:00 pm when the temperature is at its highest during the day, the temperature can be reduced by 0.8 °C. Compared to other corridors, the wind speed in and around the corridor is the strongest 11 h a day. Due to the internal arrangement of construction land, this corridor form is more advantageous in the urban land utilization. After considering comprehensively, the ventilation corridor form with construction land arranged at intervals is the preferred corridor form in the southeast of Wuhan. The experimental results can provide quantitative reference for the layout of ventilation corridors in hot inland cities located in central China.

Evaluating planting strategies for outdoor thermal comfort in high-rise residential complexes: a computational fluid dynamics simulation study.

This study aims to examine the impact of planting strategies on improving thermal comfort in relation to the existing buildings within real high-rise residential complexes. Using numerical simulation via ENVI-met, we compare six planting scenarios characterized by two locational schemes-open-space planting and building-vicinity planting-and three tree quantities. The results highlight the importance of planting greater numbers of trees, and also of their locations, to moderate the thermal environment. The findings of the study demonstrated that increasing the number of trees in the open space by threefold of the advisory guidelines led to a significant reduction in the average air temperature by 0.87°C, mean radiant temperature (MRT) by 11.00°C, physiological equivalent temperature (PET) by 4.50°C, and wind speed by 0.30m/s. Planting the minimum number of trees under building-vicinity reduced air temperature by 0.07°C, MRT by 2.48°C, and PET by 0.92°C, while showing a slight increase in wind speed of approximately 0.01m/s. To achieve improvements in both thermal condition and air flow, we suggest planting rows of trees parallel to the prevailing wind direction in the ventilation corridors at some distance from buildings, to minimize overlap of shade from trees and from buildings. The findings of this study will provide useful guidelines for effective planting design in dense residential areas.

Identification of a wetland ecological network for urban heat island effect mitigation in Changchun, China

The rapid development of cities has led to severe fragmentation of wetland landscapes, destroying their ecological function in climate regulation. However, most studies on the climate regulation services of wetlands focused on isolated wetland units, ignoring the overall function of wetland networks. The climate regulation function of wetlands can be improved by integrating fragmented wetland resources and building a stable wetland network. A case study was carried out in Changchun City, China, to improve the method of identifying ecological networks by considering the network energy flows. First, morphological spatial pattern analysis and landscape connectivity index combined with the wetland cooling index were used to identify ecological sources with high cooling capacity, and an ecological resistance surface was constructed with surface temperature as the main factor. The minimum cumulative resistance model was then used to identify the ecological network, which was then optimized by integrating patches as stepping stones to form the optimized ecological network. Finally, the importance of ecological corridors was evaluated by identifying ventilation corridors and integrated with the complex network theory to determine the ecological network robustness. We found that the degree of fragmentation in the studied wetlands was relatively high, and that construction of an ecological network with patches as stepping stones can improve its robustness. Each component in the ecological network had a high potential to mitigate the urban heat island effect, which can be further promoted by ecological corridors with high ventilation potential. Mutations in ecological nodes that cause network robustness played a key role in maintaining ecological network stability. This improved methodology effectively improves the scientific and practical application of wetland networks to mitigate the urban heat island effect and provides regions facing the contradiction of rapid development and wetland protection with strategies to reduce the threat of this effect.

Identification of ventilation corridors through a simulation scenario of forest canopy density in the metropolitan area

Ventilation corridors are widely utilized around the world, which will direct cold air into the city and mitigate the urban heat island effect. However, the extension of high-density cities has resulted in the degradation of green infrastructure (GI) and the deterioration of wind and thermal environments. In Taiyuan metropolitan area, this study explores the spatial distribution of ventilation corridors after the forest canopy density (FCD) growth and proposes protection strategies. The results show that (1) The regression model of FCD, topographic factors, and land surface temperature (LST) is constructed by random forest having high accuracy. (2) Various level of ventilation corridors shows significant differences in spatial distribution characteristics. (3) If the average value of FCD grows from 0.31 to 0.40, the average LST of the study area will decrease by 2.32 °C and that of the peripheral areas of the built-up area is 1.86 °C. Unlike traditional methods that are limited to the prevailing situation, this study is the first to identify ventilation corridors predictably through simulated scenarios and finds that FCD has a significant effect on the regional wind-thermal environment. Hence, an anticipatory analysis of the ventilation corridor should be applied by assessing the GI quality, which is conducive to the sustainable development of cities.

City-scale ventilation analysis using 3D buildings with Guangzhou case

Ventilation environments are critical for urban climate. The traditional city-scale ventilation analysis method considers only a single building form, and the analysis results cannot cover the entire study area. In this study, an analysis method combining the comprehensive ventilation cost index (CVCI) and least accumulative cost analysis based on a geographic information system was proposed. The CVCI was designed to comprehensively characterise the ventilation resistance in different wind directions. By creating the maps of CVCI and least accumulative cost, ventilation performance was visualised for the urban area, and different urban ventilation corridors were compared and analysed. Starting from the micro 3D building forms and combined with the urban environment, this method realised macro-scale ventilation analysis. Three major advantages of the method were demonstrated by the case study: it (1) dynamically observed the urban ventilation characteristics under different wind directions; (2) comprehensively considered the resistance of the 3D forms of the building to ventilation from three levels, height, volume, and façade; and (3) simply and effectively analysed the ventilation environment of the entire area. This study may provide technical guidance for exploring the impact of existing buildings on urban wind environments and promoting urban sustainable development in urban planning.

Urban ventilation corridors exacerbate air pollution in central urban areas: Evidence from a Chinese city

Urban ventilation corridors are effective in improving urban air quality and alleviating heat island problems, and are widely used in cities around the world. This paper studies typical smog-polluted cities in China to examine whether urban ventilation corridors will worsen air pollution in cities and then proposes countermeasures. First, this paper identifies compensation spaces outside the central urban area of Xi'an and then analyses the prevailing wind direction in these compensation spaces. Based on these findings, this paper identifies potential cold air passages and assesses the air cleanliness in these compensation spaces according to the spatial distributions of PM2.5 and PM10. The study finds that four compensation spaces are found outside the central urban area of Xi'an and seven potential cold air passages, including six expressways and one railway, and the PM10 and PM2.5 concentrations in three of the four compensation spaces are higher than those in the central urban area. From the beginning (located in the compensation space) to the end (located in the action space) of the cold air passages P1 and P2, PM2.5 decreased by 11.88% and 11.82%, and PM10 decreased by 9.40% and 9.76%. This study discovers that if the urban compensation spaces are located in areas with high concentrations of pollutants, the polluted cold air will be introduced to the central urban area along the cold air passages due to the prevailing wind. Unlike previous studies which concluded that urban ventilation corridors improve air quality in central urban areas, this study demonstrates that urban ventilation corridors are at risk of exacerbating air pollution in central urban areas. Therefore, when planning urban ventilation corridors, a city should make an assessment of the air cleanliness of the compensation spaces mandatory to avoid worsening air pollution in the central urban area and creating an unsustainable climate environment due to the planning of urban ventilation corridors, which may further lead to economic losses and threats to public health.

Identification and Construction of Ecological Nodes in the Fuzhou Ecological Corridors

Ecological corridor construction is an important support of the current pursuit of high-quality urbanization. Fuzhou is a mountain–water city characterized by a unique spatial structure. However, rapid urbanization has exacerbated the rate of ecosystem fragmentation, negatively impacting the livable living environment. The construction of ecological corridors is of great significance for efforts to restore the broken landscape and form the urban ecosystem as an organic whole in Fuzhou. In the present study, Fuzhou was considered as the study area, and the water, green, and ventilation corridors, as well as surface temperature data, were analyzed using the kernel density analysis method to generate surface-temperature-based ecological nodes. The impacts of various corridors and surface temperatures on the construction of the Fuzhou ecological corridors were assessed using ecological theory, and the ecological resistance surfaces of the influencing factors were obtained. We constructed ecological corridors for the mitigation of the urban heat island in Fuzhou using the MCR model with four levels and then evaluated the network connectivity of the corridors. The results revealed the following findings: (1) The study area comprises 32 ecological nodes, including nine in Minhou County and Changle District, four in Mawei and Cangshan Districts, and two in Gulou, Taijiang, and Jin’an Districts. (2) Fuzhou contains 63 ecological corridors with a total length of approximately 494.65 km. These include 31 first-level (201.16 km), 11 second-level (98.56 km), 14 third-level (129.12 km), and 7 fourth-level (65.81 km) corridors. (3) The degree of closure (α), the point rate of lines (β), the degree of connectivity (γ), and the degree of connectivity (Cr) indexes of the network structure for the ecological corridors were 0.27, 2.03, 0.72, and 0.87, respectively. They indicate that the overall ecological effectiveness of the network is high and can provide a theoretical basis for the construction of ecological corridors in the future.

The Effect of Village Morphological Variation Caused by Economic Development on Residents’ Health and Rural Ventilation in Tianjin

Many multi-story residential buildings have been built in villages to improve the living quality of rural residents in China. Therefore, village morphology has dramatically changed compared to the past. Since northern China continues to suffer from environmental problems, improving village ventilation by optimizing village morphology is essential for creating a good rural environment. In this study, 17 morphology models were categorized based on 383 actual villages in Tianjin. In addition, the ventilation capacity of courtyards and streets and residents’ health risks of different morphology cases were analyzed. For the northwest wind direction, the ventilation capacity of the courtyards in the northern part of the village can be improved when there are multi-story residences in the north or west of the village. Accordingly, in the southeast wind direction, multi-story buildings in the south or east of the village can improve the courtyard ventilation in the southern part of the village. In addition, multi-story buildings in the west or east of the village can form ventilation corridors in the northwest or southeast wind direction. The morphologies without multi-story buildings in the west or east of the village were recommended to be applied in the village planning in Tianjin due to good ventilation capacity and low exposure risks.

Planning scenarios and microclimatic effects: The case of high-density riverside residential districts in Seoul, South Korea

Water bodies, such as rivers, ponds, and lakes, act as natural landscape resources to improve the urban microclimate. However, the cooling effects of water bodies may be lessened as a result of poorly planned buildings along the waterfront due to the “wall effect.” This research aimed to investigate the microclimate impacts of the following three strategies typically used in waterfront development: 1) building height restriction, 2) ventilation corridors, and 3) stepped building height variation. To compare the microclimate change after applying each strategy, we calculated the air temperature, wind speed, mean radiant temperature, and thermal comfort using the numerical simulation with microclimate simulation software, ENVI-met. The results showed that each strategy led to different microclimate patterns. The restriction on building height had a negative impact on the microclimate, increasing the physiological equivalent temperature by up to 1.34 °C. In contrast, the ventilation corridor provided a moderate cooling effect during the afternoon. Lastly, the stepped building height variation strategy did not have an effect on thermal comfort. The results suggest that the microclimate-related strategies for waterfront development did not always contribute to the improvement of thermal comfort; thus, additional heat-mitigation solutions are needed.

Urban ventilation planning and its associated benefits based on numerical experiments: A case study in beijing, China

Urban ventilation planning (UVP) are critically important to sustainable and green urban development. However, the climatic-environmental effects and benefits of urban ventilation corridors have yet to be fully understood. In this study, high-resolution simulation tests were carried out for winter of 2018 and summer of 2019 using the weather research and forecasting model (WRF) coupled with the urban canopy model (UCM) and the refined surface type and UVP of Beijing City. After the construction of the ventilation corridors, the average temperature in the Beijing urban area can be reduced by 0.18 °C, and the wind speed and relative humidity can be increased by 0.33 m s−1 and 2.83%, respectively. The major contributions of the ventilation corridors to local meteorological elements are the wind speed enhancement-induced advection effect and the improvement of the turbulent flux over urban surface. Further, the cost-benefit analysis of UVP show that the urban heat island intensity (UHII), the average PM2.5 concentration, and the number of days with light or above levels of air pollution will be decreased by 13.7%, 11.7%, and 20.2%, respectively. This implies that, disregarding the reduction of the UHII and its effect, urban ventilation corridor is conducive to improving the winter urban living environment. However, the problems of haze pollution cannot be completely resolved by ventilation corridors alone, and the weakening of the winter UHII in the northern city is a disadvantage to energy-saving and habitat comfort. Our findings provide a reference base for policy decisions and technical guidelines for UVP of high-density cities.

Urban ventilation corridors and spatiotemporal divergence patterns of urban heat island intensity: a local climate zone perspective.

Urban ventilation corridors introduce fresh air into urban interiors and improve urban livability, while mitigating the urban heat island (UHI) effect. However, few studies have assessed the impact of urban ventilation corridors on UHI intensity (UHII) from the perspective of the local climates of different cities. Therefore, this study integrated multisource data to construct ventilation corridors from the perspective of local climate zone (LCZ) and analyzed its impact on UHII. The results showed the following: (1) the average UHII of constructed LCZs was higher than that of natural LCZs, among which the building type LCZ10 (heavy industry) had the highest intensity (5.77°C); (2) in extracted ventilation corridors, the pixel number of natural LCZs was substantially larger than that of constructed LCZs, among which LCZE (bare soil/paved) was the largest; and (3) for natural LCZs, the average UHII of each LCZ was lower within the ventilated corridors than within the non-ventilated corridors (except for LCZG [water]), with the UHII of LCZB (scattered trees) exhibiting the greatest mitigation effect. Quantitative research on the composition and function of ventilation corridors can not only assess the ability of ventilation corridors to mitigate UHIs, but also provide a reference for urban ventilation corridor planning.

Intelligent Mining of Urban Ventilated Corridor Based on Digital Surface Model under the Guidance of K-Means

With the acceleration of urbanization, climate problems affecting human health and safe operation of cities have intensified, such as heat island effect, haze, and acid rain. Using high-resolution remote sensing mapping image data to design scientific and efficient algorithms to excavate and plan urban ventilation corridors and improve urban ventilation environment is an effective way to solve these problems. In this paper, we use unmanned aerial vehicle (UAV) tilt photography technology to obtain high-precision remote sensing image digital elevation model (DEM) and digital surface model (DSM) data, count the city’s dominant wind direction in each season using long-term meteorological data, and use building height to calculate the dominant wind direction. The projection algorithm calculates the windward area density of this dominant direction. Under the guidance of K-means, the binarized windward area density map is used to determine each area and boundary of potential ventilation corridors within the threshold range, and the length and angle of each area’s fitted elliptical long axis are calculated to extract the ventilation corridors that meet the criteria. On the basis of high-precision stereo remote sensing data from UAV, the paper uses image classification, segmentation, fitting, and fusion algorithms to intelligently mine potential urban ventilation corridors, and the effectiveness of the proposed method is demonstrated through a case study in Zhuji City, Zhejiang Province.

Identifying urban ventilation corridors through quantitative analysis of ventilation potential and wind characteristics

Urban heat islands (UHIs) are mainly caused by mismanaged urban development. Urban ventilation corridors (UVCs) can effectively reduce UHIs. Hangzhou, a large, dense city in eastern China, is one of the nation's hottest cities and must urgently improve its ventilation. In this study, a newly developed method combining land surface temperature retrieval, GIS spatial analysis, and weather data was employed to design city-level UVCs. The functional space and compensation space of UVCs are identified based on the LandsatETM8 image data inversion of surface temperature. The contribution of affect factors, such as building density, building height, green land area, waterbody, roads, and urban terrain, to the urban ventilation potential is calculated using AHP and GIS. Areas with tremendous ventilation potential were identified as possible ventilation corridors by using an evaluation model and considering wind characteristics. Fifty-four high-temperature zones and 48 low-temperature zones were identified as functional and compensative spaces in Hangzhou, respectively. On the urban scale, green space (area >500ha), water bodies (area >300ha or width >100 m), and roads (width >50 m) were considered to be the factors that have the greatest impact on urban ventilation potential. The LCP method was used to verify the accuracy and rationality of the method proposed in this study to determine the city-scale UVC. UVC planning schemes and construction measures were proposed to provide rich information and a reference basis for the new general land and space planning of Hangzhou. However, to improve the accuracy of the potential ventilation results, the urban underlying surface criteria should be re-evaluated more comprehensively.

Research on the Planning of an Urban Ventilation Corridor Based on the Urban Underlying Surface Taking Kaifeng City as an Example

With the rapid development of urbanization, various urban problems such as air pollution, urban heat islands, poor ventilation, and so on have followed. Ventilation corridors can improve the internal ventilation conditions of a city and can effectively alleviate these urban problems. Taking Kaifeng as an example of a medium-sized city, this study used meteorological analysis and remote sensing (RS) technology and a geographical information system (GIS) to plan ventilation corridors. Through analysis of the thermal environment, the influential factors of the underlying surface (building density, road length, water length, vegetation coverage) and wind environment in Kaifeng, the compensation space and action space, and the comprehensive values of the ventilation potential in each region were determined. The results show that with the use of the single-window algorithm and Landsat8 data, high-resolution ground temperature can be retrieved. Moreover, although the ventilation potential value of Kaifeng in the northern part is better than that in the southern part, the temperature in the north is higher than that in the south. Through comparison and analysis of the location of the low-temperature zone, the air duct opening of the ventilation corridor can be determined and the source areas of three ecological ventilation corridors identified. According to the ventilation corridor air duct opening, the urban underlying surface and the dominant wind direction of Kaifeng city, two ventilation corridors located on the eastern and western sides of Kaifeng city were planned. This urban ventilation corridor planning method, which is based on temperature difference analysis and determination of the source area of the ventilation corridor, can provide a reference for the construction of an ecologically livable city.

Wind environment assessment and planning of urban natural ventilation corridors using GIS: Shenzhen as a case study

The development of high-density cities has aggravated the harshness of the urban microclimate in face of global warming. However, an adequate urban ventilation system can introduce clean and cool air into high-temperature areas of a city, which can alleviate the urban heat island (UHI) effect and increase residents' thermal comfort. In this study, we devise an integrated air ventilation assessment (IAVA) method to assess the urban wind environment using multi-source data, with Shenzhen as an example. The IAVA map illustrates that developed areas in the south and west of Shenzhen form a “wind wall” that reduces wind speeds and prevents wind flow into inland areas. In light of the results of the IAVA, potential ventilation corridors across Shenzhen are then created using the least cost path method. Subsequently, the optimized ventilation corridors are generated via super-imposition over a satellite image and the identification of functioning and compensating areas. Notably, the IAVA introduces the effects of terrain, vegetation, and open space, thus providing a more pragmatic evaluation of the wind environment than frontal area density results. Furthermore, it provides planning guidance for local governments that considers the quality of the urban wind environment in the low-cost and efficient construction of ecological and livable cities.

Assessing the environmental benefits of urban ventilation corridors: A case study in Hefei, China

Precise and timely assessments of the environmental benefits of urban ventilation corridors are important for understanding urban sustainability. Previous studies have mainly focused on the construction of urban ventilation corridors, while less attention has been given to the subsequent environmental benefits that are generated. Taking the main urban area of Hefei as an example, this study proposed a corridor construction model that was based on the ventilation resistance coefficient (VRC) and quantified and compared the environmental indicators for different corridor levels to understand the environmental benefits that were created. Datasets that combined architecture morphology and wind frequency were utilized to construct four-season urban ventilation corridors at a macro level. Three environmental indicators were adopted combined with the VRC model: i) reduction of air pollutant concentrations (PM2.5), ii) reduction of land surface temperatures (LST), and iii) utilization efficiency of vegetation space (NDVI). The results indicated that (1) the VRC that was based on the architecture morphology datasets had a significant correlation with urban environmental benefits, including the PM2.5, LST and NDVI levels. (2) Compared with current project-based ventilation corridors, those constructed by considering the VRC can provide greater environmental benefits. (3) The intersection nodes had higher ventilation benefits than other areas of the ventilation corridors and showed significant spatial aggregation characteristics in alleviating the PM2.5 concentrations and surface temperatures. The method proposed in this study provides important theoretical support for the improved construction of future urban ventilation corridors.

Intelligent Mining of Urban Ventilation Corridors Based on High-Precision Oblique Photographic Images.

With the advancement of urbanization and the impact of industrial pollution, the issue of urban ventilation has attracted increasing attention. Research on urban ventilation corridors is a hotspot in the field of urban planning. Traditional studies on ventilation corridors mostly focus on qualitative or simulated research on urban climate issues such as the intensified urban heat island effect, serious environmental pollution, and insufficient climate adaptability. Based on the high-precision urban remote sensing image data obtained by aeromagnetic oblique photography, this paper calculates the frontal area density of the city with reference to the urban wind statistics. Based on the existing urban patterns, template matching technology was used to automatically excavate urban ventilation corridors, which provides scientific and reasonable algorithmic support for the rapid construction of potential urban ventilation corridor paths. It also provides technical methods and decision basis for low-carbon urban planning, ecological planning and microclimate optimization design. This method was proved to be effective through experiments in Deqing city, Zhejiang Province, China.

미세먼지 저감을 위한 그린인프라 계획요소 도출† - 텍스트 마이닝을 활용하여 -

Green infrastructure planning represents landscape planning measures to reduce particulate matter. This study aimed to derive factors that may be used in planning green infrastructure for particulate matter reduction using text mining techniques. A range of analyses were carried out by focusing on keywords such as ‘particulate matter reduction plan’ and ‘green infrastructure planning elements’. The analyses included Term Frequency-Inverse Document Frequency (TF-IDF) analysis, centrality analysis, related word analysis, and topic modeling analysis. These analyses were carried out via text mining by collecting information on previous related research, policy reports, and laws. Initially, TF-IDF analysis results were used to classify major keywords relating to particulate matter and green infrastructure into three groups: (1) environmental issues (e.g., particulate matter, environment, carbon, and atmosphere), target spaces (e.g., urban, park, and local green space), and application methods (e.g., analysis, planning, evaluation, development, ecological aspect, policy management, technology, and resilience). Second, the centrality analysis results were found to be similar to those of TF-IDF; it was confirmed that the central connectors to the major keywords were ‘Green New Deal’ and ‘Vacant land’. The results from the analysis of related words verified that planning green infrastructure for particulate matter reduction required planning forests and ventilation corridors. Additionally, moisture must be considered for microclimate control. It was also confirmed that utilizing vacant space, establishing mixed forests, introducing particulate matter reduction technology, and understanding the system may be important for the effective planning of green infrastructure. Topic analysis was used to classify the planning elements of green infrastructure based on ecological, technological, and social functions. The planning elements of ecological function were classified into morphological (e.g., urban forest, green space, wall greening) and functional aspects (e.g., climate control, carbon storage and absorption, provision of habitats, and biodiversity for wildlife). The planning elements of technical function were classified into various themes, including the disaster prevention functions of green infrastructure, buffer effects, stormwater management, water purification, and energy reduction. The planning elements of the social function were classified into themes such as community function, improving the health of users, and scenery improvement. These results suggest that green infrastructure planning for particulate matter reduction requires approaches related to key concepts, such as resilience and sustainability. In particular, there is a need to apply green infrastructure planning elements in order to reduce exposure to particulate matter.

Modeling the Impacts of City-Scale “Ventilation Corridor” Plans on Human Exposure to Intra-Urban PM2.5 Concentrations

Increasingly, Chinese cities are proposing city-scale ventilation corridors (VCs) to strengthen wind velocities and decrease pollution concentrations, although their influences are ambiguous. To assess VC impacts, an effort has been made to predict the impact of VC solutions in the high density and diverse land use of the coastal city of Shanghai, China, in this paper. One base scenario and three VC scenarios, with various VC widths, locations, and densities, were first created. Then, the combination of the Weather Research and Forecasting/Single-Layer Urban Canopy Model (WRFv.3.4/UCM) and Community Multiscale Air Quality (CMAQv.5.0.1) numerical simulation models were employed to comprehensively evaluate the impacts of urban spatial form and VC plans on PM2.5 concentrations. The modeling results indicated that concentrations increased within the VCs in both summer and winter, and the upwind concentration decreased in winter. These counter-intuitive results could be explained by decreased planetary boundary layer (PBL), roughness height, deposition rate, and wind speeds induced by land use and urban height modifications. PM2.5 deposition flux decreased by 15–20% in the VCs, which was attributed to the roughness height decrease for it weakens aerodynamic resistance (Ra). PBL heights within the VCs decreased 15–100 m, and the entire Shanghai’s PBL heights also decreased in general. The modeling results suggest that VCs may not be as functional as certain urban planners have presumed.