A prediction model for wind speed ratios at pedestrian level with simplified urban canopies

Ikegaya, Naoki; Ikeda, Y.; Hagishima, Aya; Razak, Azli Abd; Tanimoto, Jun

doi:10.1007/s00704-015-1655-z

Cited by 34 publications

(7 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When the height of each building in the typical block was increased, the breeze zone on the leeward side of the buildings in the upwind area increased. This is consistent with the research findings of Ikegaya et al [43] , that is, regarding the correlation coefficient between the wind speeds averaged over the entire region, the values in the front or side region were greater than 0.9, while in the area behind a building, the wind speeds were weakly correlated. The proportion of the calm wind in the typical block increased, and the proportion of the light air significantly decreased.…”

Section: Impact Of Building Height Changes On Wind Environmentsupporting

confidence: 93%

Research on multi-scale urban natural ventilation climate guidance: A case study in the Shijiazhuang metropolitan area

Zhang,

Fang,

Cheng

et al. 2024

Preprint

View full text Add to dashboard Cite

Optimizing the urban spatial layout is an important guarantee for improving natural ventilation in cities. Based on meteorological observation statistical analysis, numerical model simulation, and remote sensing inversion calculation, a natural ventilation planning technology covering both the city and community scales is proposed and applied in the Shijiazhuang metropolitan area in Hebei Province, China. Meteorological data obtained from observation stations were utilized to analyze local wind speed, direction, and frequency. The results revealed diverse wind characteristics in different regions. Winds blowing from the western mountainous area, characterized by high vegetation coverage, are predominantly west and northwest. This wind is a significant source of clean air and serves as a natural ventilation inlet for Shijiazhuang. In the northern area, winds are primarily northwest and north, while in the southern area, winds are mainly southeast and south. Additionally, there is a notable heat island effect within the second ring road, which has an elliptical shape with the long axis oriented from east to west and the short axis oriented from south to north. This effect shows a clear trend of eastward expansion. Based on this research, six primary ventilation corridors and thirteen secondary ventilation corridors have been established. The direction of these corridors aligns with the local wind patterns, and the width of the corridor is calculated based on the city’s capacity and required ventilation efficiency. Subsequently, an urban climate analysis map (UCAnMap) was developed considering climate sensitivity. Planning recommendations were provided to enhance the urban climate environment and optimize spatial layout in different climate zones. It’s worth nothing that there exists a negative correlation between ventilation efficiency and building height within the blocks. Increasing the height of the buildings will decrease the proportion of comfortable wind zones, and the overall ventilation efficiency of the block will weaken. Based on the principle that the average wind speed ratio is greater than or equal to 0.5, it is concluded that the average building height of a typical block should be controlled within 45 m, which matches the ventilation performance requirements, and these results can also serve as a guide for building parameters that are conducive to ventilation. The ventilation efficiency of the block has a certain negative correlation with the building density. By reducing the building density, the mean wind velocity ratio and the comfortable wind zone ratio of the block can be appropriately increased. If the building density decreases by more than 10%, the proportion of calm wind areas will decrease by about 2–5% compared to the original situation.

show abstract

Section: Impact Of Building Height Changes On Wind Environmentsupporting

confidence: 93%

Research on multi-scale urban natural ventilation climate guidance: A case study in the Shijiazhuang metropolitan area

Zhang,

Fang,

Cheng

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Frontal area index (FAI) has been adopted in urban thermal [26] [27] and wind environment studies [28] [29]. The FAI is an indicator describing the blocking effect of buildings on wind [30], and it describes an averaged status of urban forms at the entire urban canopy level [31] [32].…”

Section: Introductionmentioning

confidence: 99%

Variabilities of Land Surface Temperature and Frontal Area Index Based on Local Climate Zone

Zhao

Wang

et al. 2022

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

View full text Add to dashboard Cite

Urban temperature increase brings a challenge to public health so that urban warming has been widely concerned. Within the central area of Shenyang, a 3×3 fishnet with nine grids was built, to analyze land surface temperature (LST) and frontal area index (FAI) variations based on the local climate zone (LCZ) classification and to explore relationships among them to generate implications for using wind for urban cooling. The results indicate that LST in the 4# grid (central grid) was the highest (35.11 °C) among the nine grids. In general, a higher LST occurred in the grid with a larger building area, and vice versa. LCZ-G underwent the largest temperature reduction among the 17 LCZ types. LCZ-2 had the highest LST, while the LCZ-1 had the lowest LST among the three high and intensive building types, except for the LST in the 2# and 4# grids. The FAI in Shenyang decreased from the center to the surroundings. The FAI value was greatest in the 4# grid, and the lowest was in the 2# and 8# grids under the prevailing wind of summer and winter. The FAI variations suggested that prevailing SW, SSW, and S winds in summer were difficult to penetrate central urban area, and wind cooling effect could not perform. The prevailing NEN and EEN winds in winter could enter the central urban area, enhancing wind cooling effect, while it was a disadvantage in winter. Overall, there was a significant positive relationship among LST, FAI and area of LCZ-building.

show abstract

“…The heat island intensity was categorized into seven levels [12]: a strong cold island (SCI), sub-strong cold island (SSCI), weak cold island (WCI), no heat island (NHI), weak heat island (WHI), sub-strong heat island (SSHI), and strong heat island (SHI) (Table 1). Studies have shown that in summer, urban surface temperatures follow the following pattern: bodies of water < forests < crops < lawns < bare lands < buildings [13]. Due to the temperature difference between the built-up area and water bodies or forest land, the flow of cold fresh air can be generated even under weak background wind conditions, which can effectively alleviate the urban heat island effect [14].…”

Section: Assessment Of Thermal Environmentmentioning

confidence: 99%

Multi-Scale Urban Natural Ventilation Climate Guidance: A Case Study in the Shijiazhuang Metropolitan Area

Zhang,

Fang,

Cheng

et al. 2024

Atmosphere

View full text Add to dashboard Cite

The rapid development of urbanization has caused obstructed urban natural ventilation and the contribution rate of urbanization is relatively high. Therefore, there is an urgent need for urban development planning that should respect natural ventilation and local climate to reduce negative impacts. By optimizing the urban construction layout to reduce obstruction and leave a passageway for wind to blow in, the natural ventilation environment could be improved. This paper presents a promising approach for natural ventilation planning at both the city and community scales. Based on the assessment of wind environment, heat island intensity, and ventilation potential, the results revealed that winds blowing from the western and northern mountainous area of Shijiazhuang play a natural ventilation inlet role which can provide clean air. The SSHI and SHI were mainly distributed within the Second Ring Road, which has a large proportion of the low ventilation potential level. Thus, six first-class ventilation corridors and thirteen secondary corridors were recommended, which were set to be adapted to the dominant wind direction. Subsequently, an urban climate analysis map (UCAnMap) was developed considering climate sensitivity, and planning recommendations were provided for different climate zones. The relationship between architectural spatial structure and ventilation efficiency was analyzed; the results revealed that increasing the height of the buildings will decrease the proportion of comfortable wind zones, and the overall ventilation efficiency will weaken, so the average building height of a typical block should be controlled within 45 m, which matches ventilation performance requirements. The ventilation efficiency of the block has a certain negative correlation with the building density, and as the building density decreased by more than 10%, the proportion of the comfortable wind zones could increase by 4–5%.

show abstract

A prediction model for wind speed ratios at pedestrian level with simplified urban canopies

Cited by 34 publications

References 19 publications

Research on multi-scale urban natural ventilation climate guidance: A case study in the Shijiazhuang metropolitan area

Research on multi-scale urban natural ventilation climate guidance: A case study in the Shijiazhuang metropolitan area

Variabilities of Land Surface Temperature and Frontal Area Index Based on Local Climate Zone

Multi-Scale Urban Natural Ventilation Climate Guidance: A Case Study in the Shijiazhuang Metropolitan Area

Contact Info

Product

Resources

About