The Effect of Sky View Factor on Air temperature in High-rise Urban Residential Environments

Baghaeipoor, Golnar; Nasrollahi, Nazanin

doi:10.15627/jd.2019.6

Cited by 13 publications

(7 citation statements)

References 45 publications

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“…Contrarily, in high-rise urban residential environments in Tehran, Iran [14], it was found that during the hottest and the coldest days in the year, there was a direct relation between SVF and air temperature during the day and an inverse relation at night. In the temperate oceanic climatic region, such as southern Brazil, which has dry winter seasons [10], it was found that the variation in T mrt was closely related to the variation in SVF.…”

Section: Introductionmentioning

confidence: 99%

Correlating the Sky View Factor with the Pedestrian Thermal Environment in a Hot Arid University Campus Plaza

2021

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In hot, arid regions on university campuses, students are more vulnerable to heat stresses than in street canyons in terms of function; however, the knowledge of the impact of built environments on thermal performance is still lacking. In two summer and winter days, the shading effect of the existing urban trees pattern in a university campus in Egypt was examined to correlate their Sky View Factor (SVF) with the thermal environment, meteorology, Physiological Equivalent Temperature (PET), and Universal Thermal Comfort Index (UTCI). The ENVI-met model was used in order to assess meteorological parameters, followed by SVF calculation in the Rayman program. Meteorological field measurements validated the simulation model and measured the Leaf Area Index (LAI) of two native urban trees to model the in-situ canopies foliage. In summer, the results showed a significant direct impact of the SVF on mean radiant temperature (Tmrt), PET, and UTCI; however, the excessive shading by trees on materials with a low albedo and low wind speed could lead to a slight increase in air temperature. Meanwhile, in the winter, SVF did not affect the microclimatic variables, PET, or UTCI. The resulting insight into the correlation between SVF and Tmrt emphasizes the importance of urban trees in modifying the microclimates of already-existing university plazas.

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Section: Introductionmentioning

confidence: 99%

Correlating the Sky View Factor with the Pedestrian Thermal Environment in a Hot Arid University Campus Plaza

2021

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“…The microclimate at the street level is inf luenced by urban geometry, which includes factors such as aspect ratio, sky view factor, and street orientation (Ahmadi Venhari et al, 2019;Jamei & Rajagopalan, 2015;Krüger, 2011). The street orientation and aspect ratio of buildings determine solar exposure and shadow patterns, affecting surface and air temperature variations throughout the day (Baghaeipoor & Nasrollahi, 2019;Cliff Moughtin, 2003;Svensson, 2004). In additional, the density of buildings can inf luence wind speed, leading to changes in thermal conditions.…”

Section: Literature Reviewmentioning

confidence: 99%

Assessing pedestrian thermal comfort to improve walkability in the urban tropical environment of Nagpur city

Mohite,

Surawar

2024

Geographica Pannonica

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Walking can be an efficient and sustainable mode of transportation for "last mile" connectivity. However, the willingness to walk largely depends on the availability of infrastructure, safety, and comfort. Improving thermal comfort on streets connected to transit stations is crucial for encouraging walking and public transit use. This study assesses seasonal and spatiotemporal variations in pedestrian thermal comfort (PTC) on an N-S-oriented street in Nagpur (India). Thermal walk surveys simultaneously monitored environmental conditions and human thermal perception (thermal sensation vote-TSV). The findings revealed that urban geometry significantly influences PTC and TSV, and the level of influence varied spatiotemporally in both seasons. This study shows the relationship between urban street geometry, microclimate, and PTC, emphasizing the necessity of a multidimensional assessment approach.

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“…This factor is influenced by the components of the urban fabric, street furniture and trees: values close to 1 correspond to a large visible portion, while values close to 0 indicate a limited view of the sky. SVF can be classified into four categories [73,74]: SVF < 0.25, dense space; 0.25 < SVF < 0.50, semi-dense space; 0.50 < SVF < 0.75, semiopen space; and SVF > 0.75, open space. Moreover, SVF plays an important role in the description of urban radiation properties: the higher its value, the greater the incidence of direct solar radiation (Jiao et al, 2019).…”

Section: Sky View Factor (Svf)mentioning

confidence: 99%

“…Concerning urban morphology, mean SVF equal to 0.80 suggested the predominance of open spaces [73,74], resulting in a high sky exposure and a greater amount of solar radiation (RJ = 5236.5 Wh/m 2 , on average) with respect to the cool-spots (SVF = 0.69 and RJ = 4505.19 Wh/m 2 , on average).…”

Section: Hot-spot Sitesmentioning

confidence: 99%

Thermal Summer Diurnal Hot-Spot Analysis: The Role of Local Urban Features Layers

et al. 2021

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This study was focused on the metropolitan area of Florence in Tuscany (Italy) with the aim of mapping and evaluating thermal summer diurnal hot- and cool-spots in relation to the features of greening, urban surfaces, and city morphology. The work was driven by Landsat 8 land surface temperature (LST) data related to 2015–2019 summer daytime periods. Hot-spot analysis was performed adopting Getis-Ord Gi* spatial statistics applied on mean summer LST datasets to obtain location and boundaries of hot- and cool-spot areas. Each hot- and cool-spot was classified by using three significance threshold levels: 90% (LEVEL-1), 95% (LEVEL-2), and 99% (LEVEL-3). A set of open data urban elements directly or indirectly related to LST at local scale were calculated for each hot- and cool-spot area: (1) Normalized Difference Vegetation Index (NDVI), (2) tree cover (TC), (3) water bodies (WB), (4) impervious areas (IA), (5) mean spatial albedo (ALB), (6) surface areas (SA), (7) Shape index (SI), (8) Sky View Factor (SVF), (9) theoretical solar radiation (RJ), and (10) mean population density (PD). A General Dominance Analysis (GDA) framework was adopted to investigate the relative importance of urban factors affecting thermal hot- and cool-spot areas. The results showed that 11.5% of the studied area is affected by cool-spots and 6.5% by hot-spots. The average LST variation between hot- and cold-spot areas was about 10 °C and it was 15 °C among the extreme hot- and cool-spot levels (LEVEL-3). Hot-spot detection was magnified by the role of vegetation (NDVI and TC) combined with the significant contribution of other urban elements. In particular, TC, NDVI and ALB were identified as the most significant predictors (p-values < 0.001) of the most extreme cool-spot level (LEVEL-3). NDVI, PD, ALB, and SVF were selected as the most significant predictors (p-values < 0.05 for PD and SVF; p-values < 0.001 for NDVI and ALB) of the hot-spot LEVEL-3. In this study, a reproducible methodology was developed applicable to any urban context by using available open data sources.

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The Effect of Sky View Factor on Air temperature in High-rise Urban Residential Environments

Cited by 13 publications

References 45 publications

Correlating the Sky View Factor with the Pedestrian Thermal Environment in a Hot Arid University Campus Plaza

Correlating the Sky View Factor with the Pedestrian Thermal Environment in a Hot Arid University Campus Plaza

Assessing pedestrian thermal comfort to improve walkability in the urban tropical environment of Nagpur city

Thermal Summer Diurnal Hot-Spot Analysis: The Role of Local Urban Features Layers

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