Sky View Factor Values Research Articles

Predictive model of solar potential on building façades with the sky view factor as shading indicator

Building façades represent a considerable part of the urban surface and the solar energy they receive can significantly contribute to the whole urban solar potential. Extending the use of building facades to produce more renewable energy can help address the challenges of climate change, promote energy independence, and create economic benefits.A major challenge in harnessing solar energy from vertical surfaces is the variation of solar availability on urban facades, which can be affected by orientation, neighboring buildings or vegetation. An easy, reliable and robust method for evaluating the solar potential of facades since the strategical stage of the building development can assist experts in designing façades where building integrated photovoltaics (BIPV) can be efficiently implemented.This study aims to identify a relationship between the variation of the sky view factor (SVF), a measure of the amount of sky that is visible from a given position, and the corresponding reduction of solar irradiation due to shading. This can then be used to predict the solar potential at each point on the façade on a monthly basis only depending on orientation, SVF value and geographical coordinates, drastically reducing the complexity of analysis and without requiring time-consuming tools.

Analyzing the effect of view factors on surface heat flux, surface temperature, and vegetation cover.

With the increase in population in cities, economic, social, and environmental problems continue to increase, and it is thought that the microclimatic conditions created by these problems will cause more environmental problems. One of the factors affecting the urban climate in urban areas is urban geometry. The climate of a region changes due to the shape of the land surface, human activities, atmospheric movements, and latent and sensible heat fluxes. Sky view factor (SVF), building view factor (BVF), and tree view factor (TVF) are actively used in the determination of urban geometry. However, studies on how these factors affect the thermal state of the urban environment are insufficient. Determining the land surface changes and thermal condition characteristics (LST, NDVI, SHF, and LHF) depending on urban growth and examining how these properties affect thermal conditions are very important in the construction of sustainable urban planning. In the study, SVF, BVF, TVF, LST, NDVI, SHF, and LHF values of 55 points determined for three different areas with different urban geometries were calculated. How these values affect each other and their situation on urban outdoor thermal comfort is evaluated. In the study, statistical analysis was performed to evaluate the relationship between surface temperature, surface heat fluxes, different view factors, and vegetation. As a result of ANOVA analysis, it was determined as very significant (p > 0.01) in all regions. Both SHF and LHF values differ with SVF. The SHF value has a direct relationship with the SVF value. LHF is inversely proportional to the SVF value. The situation is reversed for SHF variation concerning vegetation. LHF and NDVI are directly related. SHF and NDVI are inversely proportional. SVF and NDVI values also vary according to the LST value. It has been observed that LST has a direct relationship with SVF and an inverse relationship with NDVI.

HORAYZON v1.2: an efficient and flexible ray-tracing algorithm to compute horizon and sky view factor

Abstract. Terrain parameters like topographic horizon and sky view factor (SVF) are used in numerous fields and applications. In atmospheric and climate modelling, such parameters are utilised to parameterise the effect of terrain geometry on radiation exchanges between the surface and the atmosphere. Ideally, these parameters are derived from a high-resolution digital elevation model (DEM) because inferring them from coarser elevation data induces a smoothing effect. Computing topographic horizon with conventional algorithms, however, is slow because large amounts of non-local terrain data have to be processed. We propose a new and more efficient method, which is based on a high-performance ray-tracing library. The new algorithm can speed up horizon calculation by 2 orders of magnitude relative to a conventional approach. By applying terrain simplification to remote topography, the ray-tracing-based algorithm can also be applied with very high-resolution (<5 m) DEM data, which would otherwise induce an excessive memory footprint. The topographic horizon algorithm is accompanied by an SVF algorithm, which was verified to work accurately for all terrain – even very steep and complex terrain. We compare the computational performance and accuracy of the new horizon algorithm with two reference methods from the literature and illustrate its benefits. Finally, we illustrate how sub-grid SVF values can be efficiently computed with the newly derived horizon algorithm for a wide range of target grid resolutions (1–25 km).

Sky view factor estimation from street view images based on semantic segmentation

The sky view factor (SVF) has been recognized as an indicator to evaluate the openness of streets in the field of urban planning. It represents the ratio of the visible sky area to the total sky area at one point in space. However, due to the time-consuming and laborious acquisition of data and manual detection in traditional measurement methods, the SVF measurement in large-scale space has been greatly restricted. With the development of street view images (SVIs), some SVI services provide panorama data of the urban street level that can be used to estimate the SVF. In this research, we developed a method to measure street-level SVF based on semantic segmentation processing to extract sky area data from SVIs and estimated the fisheye photographic-based sky view factor (SVFf). Comparison with the previous research proves the reliability and efficiency of the SVF value estimated by this method. We further generated street-level SVFf maps, which served as a design base for creating more comfortable pedestrian street spaces. In the future, using our method, we can evaluate the urban thermal environment more comprehensively and accurately, and propose more targeted urban planning measures to alleviate the urban heat island effect.

Characteristics of daytime land surface temperature in wind corridor: A case study of a hot summer and warm winter city

With increasing urbanisation, the fraction of built-up areas and human activities increase, deteriorating the urban thermal environment and air quality. To improve the urban environment, wind corridors have attracted much research attention in recent years. In this study, a sky-view factor (SVF)-based method is proposed and verified for the potential wind corridor detection in a built-up urban area. The proposed method accurately identified wind corridors at a spatial resolution as high as 10 m. Characteristics of daytime land surface temperature (LST) were analysed based on Landsat-8 data. Results show that daytime LST in the wind corridor is higher than that in its adjacent non-corridor areas. To quantify the effect of SVF on LST over urban ground-level surfaces, the quantitative relationship between SVF and LST was analysed in the whole study area. Mean LST was found to increase linearly with SVF at a rate of about 0.2 °C per 0.1 SVF value. Moreover, effects of the underlying surface and urban morphology on LST were also discussed. Water bodies were found to effectively reduce LST, whereas in built-up areas, LST was also affected by building height (negative correlation) and building density (positive correlation). When using building height as a variable, the mean LST difference reached 3.5 °C in four seasons, while it was only 1.2 °C between areas with different building densities. These findings are useful to urban planning and provide insights to evaluate wind corridors’ effectiveness holistically.

The relationships between ecological urbanization, green areas, and air pollution in Erzurum/Turkey

The aim of this research is to determine the design criteria of habitable spaces with microclimate data for ecological urbanization. Different types of housing in the city of Erzurum, which is in the northeast region of Turkey, were used in this study. The hourly microclimate and air pollution data from 2018 for the city center were used to analyze the relationships between different residential textures, air pollution, green area, and thermal comfort. The data of Ata Botanical Garden, where trees are dense, and the vicinity of the city center, where air pollution is most intense, are discussed. The physiological equivalent temperature (PET) and sky view factor (SVF) data were analyzed with a RayMan Pro 2.1 computer model. Spatial settlement area analyses were conducted by evaluating the SVF values in ArcGIS 10.3. The relationships between air pollution, residential textures, and SVF data were determined. A comparative analysis of existing green areas was undertaken with the pollution forecast maps. The statistical results indicated that there is a difference in the relationship between the thermal comfort and air pollution of the residential textures and the SVF value of the study area according to the seasons. A strong relationship was found in the present study between pollutants and SVF, while it is weaker for green areas. Air pollution was observed to have the lowest density in the areas where detached house types are located among the different residential textures. In addition, in the same area, street geometry is closer to its ideal form, and therefore thermal comfort is also at a higher level. As a result of this study, residential textures were found to have effects on air pollution and thermal comfort.

An efficient method of evaluating large scale urban residential skylight environment and an empirical study of Beijing main area

A good skylight environment in urban residential areas is an important component of a healthy city, and has always been highly valued. With the rapid development of new-type urbanization, the density of buildings continues to increase, and megacities have entered the stage of stock transformation. An effective method for evaluating the skylight environment of large-scale urban residential areas is urgently needed. However, there is still a lack of empirical research methods and cases of large-scale residential skylight environment. In this regard, this article takes the megacity Beijing as the research object, and proposes an efficient analysis method of residential skylight environment that integrates multiple real-world data at city scale. In terms of data, it collects and integrates 3D data of urban-scale building space and residential boundary data; in terms of algorithm, Sky View Factor (SVF) is used as the evaluation index of residential skylight environment, and an efficient analysis method of urban-scale skylight environment based on cloud parallel simulation is realized. Through analysis, it is found that: (1) the average SVF value of Beijing residential area is 61%, which means that its skylight quality is in general level; (2) the skylight environment of Beijing residential area is distributed in a circle, and there are 4 types of skylight environment quality residential areas; (3) The skylight environment of Beijing residential area is relatively weakly related to the distance from the residential area to the city center and the average height of the residential buildings, and is closely related to the plot volume ratio, the residential building density and the shading from surrounding buildings. The highlight of this study lies in the empirical research on the skylight environment of mega-city residential areas that incorporates multiple real data for the first time, which can promote the study of skylight environment on a city scale and provide a reference for the updating of Beijing’s residential daylight environment.

Assessment of Outdoor Air Temperature with Different Shaded Area within an Urban University Campus in Hot-Humid Climate

This study investigated the variation of outdoor air temperature in the shaded area covered by buildings in an urban university campus in Malaysia. In-situ field measurements were conducted to measure the distribution of outdoor air temperature at eight different locations for seven days. Meanwhile, the building-induced shadows were generated using the AutoCAD Revit software to investigate the air temperature change. The study used four urban morphological parameters namely building to greenery ratio, sky view factor (SVF), and height-to-street width (H/W) ratio. The relationship between building-induced shadow and outdoor air temperature (Tout) obtained from the in-situ measurement was investigated. The results showed that the building-induced shadows could lower air temperature. It can be noted that a high ratio of building to greenery resulted in a higher air temperature. In contrast, the area with a low SVF value due to the combination of prolonged shading by buildings and trees had a lower air temperature. Thus, the area with a high building ratio, low greenery ratio, higher SVF value, and low H/W ratio potentially has a higher outdoor air temperature. Conclusively, combination of building shading created by appropriate ratio of building morphology and sufficient greenery able to improve the microclimate of a campus area.

Right tree, right place (urban canyon): Tree species selection approach for optimum urban heat mitigation - development and evaluation

The re-integration of trees into the urban landscape is a veritable strategy for urban climate mitigation and adaptation. However, dysfunctional trees in terms of urban heat mitigation are dominant in many sub-tropical cities' landscapes due to the lack of scientific basis of tree selection. Therefore, this study proposes and evaluates a methodological framework as an approach for “right tree, right place” for urban heat mitigation through parametric ENVI-met simulations that involve the combination of 54 generic tree forms and 10 characteristic urban morphology – Sky-View Factor (SVF). Results show variable temperature regulation by tree forms (species) with varying magnitude in different urban morphology. Daytime and nighttime temperature regulation effects were between 0.3 °C – 1.0 °C and 0.0 °C – 2.0 °C, respectively depending on tree forms and SVF value. Furthermore, the Heat Reduction Potential (HRP) of trees forms were determined in terms of their human thermal comfort improvement. In general, we found a range of +5% and − 20% depending on SVF, negative and positive values imply heat reduction and increment, respectively. With the competing shading effect of buildings, the HRP of trees reduces from high to low SVF area with variable magnitude among tree forms (species). Hence, the proposed morphology-based tree selection approach was evaluated by comparison with two uninformed selection approaches in a realistic urban neighborhood in Hong Kong. Results clearly indicate the proposed approach's capability in improving human thermal comfort by up two times more than either of the other approaches. Finally, evidence-based recommendations were given for the reference of policy-makers when they make urban green development plan.

Evaluating the effect of trees on UHI mitigation and reduction of energy usage in different built up areas in Cairo

Cairo experiences higher temperatures than its neighbouring rural and suburban areas. This is due to the lack of vegetation and the wide scale use of sealed surfaces. This phenomenon is known as Urban Heat Island (UHI). This leads to the greater use of air conditioning in indoor spaces during the summer time and the electricity bills are higher. This study seeks to find the best urban vegetation ratio in order to reduce the buildings' energy demand through mitigating UHI and enhancing thermal performance in high and low density built up areas in hot and arid climate. Two areas in Cairo were chosen (Imbaba - 65% urban density, and officers residential in Elsalam district - 23% urban density) with different sky view factor values. The two areas were compared in terms of the cooling effect of 30% trees, 50% trees and 70% grass scenarios using ENVI-met. Then the meteorological outputs for each scenario were used in DesignBuilder in order to calculate the energy consumption. This study shows that, while trees can reduce daily air temperature by 0.2–0.4 K in very high density built up areas, they also increase air temperature by 3 K in low density built up areas due to humidity and evaporation. Therefore, trees are effective at lowering air temperature and reducing energy usage in very high density built up areas, but ineffective in low density built up areas. Furthermore, trees reduce PET in both densities by 1–3 K.

A two-level nested model for extracting positive and negative terrains combining morphology and visualization indicators

Abstract Topography affects the resource distribution and limits physical living and production conditions in mountainous regions. Depicting the specific positive and negative terrains in karst region would support for understanding ecosystem process and land resources managing in ecologically fragile areas. However, positive and negative terrains, specific topographic types in karst region, have been difficult to extract by the automatic machine quantitative method. The novelty of this study is developing a two-level nested (TLN) model to quantify and extract positive and negative terrains features of karst through utilizing visualization indicators, openness and the sky-view factor (SVF), combing an insight of morphological analysis. The algorithms of the two visualization indicators detected the surface morphological changes in 3D sphere and realized self-adaptive of complicated topographic changes. There were three main modules included in the two-level nested model: optimum radius analysis of selected indicators, optimum threshold judgement of positive and negative terrains edges and a morphological postprocessing module. The two-level chained process designed in the second module reached the quantitative potential critical thresholds detection and optimizing expression of positive and negative terrains boundaries, which integrated analyzing the variation trend of openness difference, SVF value and SVF change. Through the TLN framework, the accuracy and stability of positive and negative terrains boundaries extraction by openness and SVF were further strengthened. The TLN model was tested in seven counties where the karst terrain morphologies were quite different. The boundaries extracted by our TLN model were compared with the visual interpretation results, and the accuracy assessment validated that the overlapping areas of test and reference results were more than 90% and the boundaries’ distance deviations were less than one grid. Positive terrain was predominant in all study areas and the proportions varied from 75.33 to 85.23%. Different positive and negative terrains percentages and formations indicated different phases in landform and ecosystem evolution process. The largest proportion of cultivated land appeared in the 0–150 m buffer ring where mutations were detected, which implied an increased ecological risk of karst region. Therefore, it is urgent to resolve the increasingly serious ecological and environmental issues while ensure agricultural production and economic development. The positive and negative terrains distribution patterns could provide theoretical reference for a rational land use planning in the future.

Field Study on the Microclimate of Public Spaces in Traditional Residential Areas in a Severe Cold Region of China.

As residential environment science advances, the environmental quality of outdoor microclimates has aroused increasing attention of scholars majoring in urban climate and built environments. Taking the microclimate of a traditional residential area in a severe cold city as the study object, this study explored the influence of spatial geometry factors on the microclimate of streets and courtyards by field measurements, then compared the differences in microclimate of distinct public spaces. The results are as follows. (1) The temperature of a NE-SW (Northeast-Southwest) oriented street was higher than that of a NW-SE (Northwest-Southeast) oriented street in both summer and winter, with an average temperature difference of 0.7–1.4 °C. The wind speeds in the latter street were slower, and the difference in average wind speed was 0.2 m/s. (2) In the street with a higher green coverage ratio, the temperature was much lower, a difference that was more obvious in summer. The difference in mean temperature was up to 1.2 °C. The difference in wind speed between the two streets was not obvious in winter, whereas the wind speed in summer was significantly lower for the street with a higher green coverage ratio, and the difference in average wind speed was 0.7 m/s. (3) The courtyards with higher SVF (sky view factor) had higher wind speeds in winter and summer, and the courtyards with larger SVF values had higher temperatures in summer, with an average temperature difference of 0.4 °C. (4) When the spaces had the same SVF values and green coverage ratios, the temperature of the street and courtyard were very similar, in both winter and summer. The wind speed of the street was significantly higher than the courtyard in summer, and the wind speed difference was 0.4 m/s.

Evaluation of Four Sky View Factor Algorithms Using Digital Surface and Elevation Model Data

AbstractThe sky view factor (SVF) is a crucial variable widely used to quantify the characteristics of surface structures and estimate surface radiation budget. Many SVF models based on raster data have been developed but not yet evaluated in a more quantitative and uniform manner. In this paper, four typical SVF models (Dozier‐Frew (D‐F), Manners, Lindberg‐Grimmond (L‐G), and Helbig_h) are evaluated using the SVF derived from simulated fisheye images based on the digital surface model (DSM) and digital elevation model data. The SVF calculated by D‐F method using DSM data has the best accuracy, with a mean bias error of −0.007, root‐mean‐square error of 0.069, and coefficient of determination (R2) of 0.914. For the SVF value derived from digital elevation model data, L‐G method shows good performance, with an mean bias error of 0.013, root‐mean‐square error of 0.032, and R2 of 0.897. The pixels near the edges of buildings, within the valley or along ridgelines, have higher SVF deviations. In addition, the slope angle calculated using DSM data has some artificial defects that make the significant impact on the SVF biases due to their calculation method and the discontinuous surface in urban areas. Thus, L‐G and Helbig_h methods are more applicable for the DSM data due to the difficulty in defining slope and aspect angles. Moreover, the high accordance of SVFs between Helbig_h and L‐G methods implies that the Helbig_h method is an alternative in virtue of its simpler form and lower computation cost than L‐G method.

Quantification of thermal comfort based on different street orientation in winter months of urban city Dadaşkent

For healthy cities, climatic and ecological data important for thermal comfort should be considered. Especially in cities with cold winters, such data are important in terms of directed streets and building facades. The objective of this study was to assess thermal comfort for different street orientations in Dadaskent, Erzurum. The measurements were taken on 10th, 20th and 30th days of each month during a 3-month period from November 2016 through January 2017. The thermal comfort measurements were taken in four different directions; North to South - Camlica Villages Street (1), East to West - Camlica Village Street (2), North-West to South-East - Milli Egemenlik Street (3) and North-East to South-West - Emir-Seyh Street (4). Integrated average values of 4 locations on each Street and 3 measurements on each location were evaluated using area-averaged sky view factor (SVFa) and RayMan model for thermal comfort. The measurements indicated that while the average temperature and relative humidity changed between -1.5 and 0°C and 26-30% in the NE-SW oriented street, they were -1.9 and -0.2°C and 28-32% in the NW-SE oriented street, -3.0 and -1.0°C and 30-34% in the E-W oriented street and -3.3 and -1.6°C and 31-33% in the N-S oriented street, respectively. These values clearly indicated that the most suitable oriented street for the winter thermal comfort was the NE-SW oriented street, but the worst was the N-S oriented street. The results clearly indicated that the thermal comfort was better in the sub-street with lower SVFa values. It was concluded that street orientation, public space layouts, height and shape of the buildings and vegetation strongly affect thermal conditions of the cities and therefore are important parameters for landscape architects and planners for creating healthy urban environments.

Identification of urban park activity intensity at different thermal environments and visible sky by using sound levels.

An efficient urban environmental design considers appropriate thermal comfort condition, shaded space, and activity intensity. Physiologically equivalent temperature (PET) and visible sky, i.e., the sky view factor (SVF), are usually used as indicators to determine the outdoor thermal comfort and amount of shaded space, respectively. The activity intensity in urban parks, which is dependent on culture and micrometeorological conditions, was represented inappropriately by attendance density in Taiwan. To optimize the park design and improve the park utilization rate in Taiwan, several environmental factors such as sound pressure levels and numbers of park visitors were measured, and PET values and SVF values were calculated from primary micrometeorological data such as wind speed and globe temperature. This study proposed equivalent continuous sound pressure level (Leq) as a novel indicator to represent park activity intensity and investigated the correlation between Leq and SVF at different PET values. Leq was more appropriate than was attendance density in representing the park activity intensity in Taiwan. In addition, Leq was highly negatively correlated with SVF when visitors felt that the outdoor thermal comfort condition was hot or very hot. In other words, a lower degree of shading in the park resulted in lower activity intensity. Park visitors tended to engage in activities in the shaded regions because of more favorable thermal comfort conditions (i.e., neutral PET). The established quantitative relationships among Leq, PET, and SVF can serve as a reference for park planning.

Assessment of the effects of different tree species on urban microclimate.

Trees in urban areas are important for their ecological functions in addition to their esthetic characteristics. Trees provide positive effects on urban microclimate by canopy, reflection, and transpiration activities; therefore, they help to decline formation of heat island. The objective of this study was to determine thermal effects of 15 different tree types: 4 coniferous and 11 deciduous species commonly found in the city of Erzurum located at the northeastern part of Turkey. The relationships between sky view factor and surface temperature regarding the differences in leaf density and tree species. In August 2016, the surface temperature of trees was measured using a thermal camera at 10:00am and 4:00pm hours. Sky view factor (SVF) was obtained by fisheye photos and physiologically characteristics of trees were determined. In all trees while the surface temperature was 20.1°C at 10:00am, it was 23.4°C at 4:00pm. Among the deciduous tree species, Betula verrucosa Ehrh. and Robinia pseudoacacia "Umbracuifera" had the lowest surface temperature; however, Abies concolor (Gord. & Glen.) had the lowest surface temperature among the coniferous tree species. The results indicated that the surface temperatures of different tree species varied considerably, and the SVF value had a significant effect on tree surface temperatures. However, it was obtained that the leaf types had no statistically significant effect on tree surface temperature.

Evaluating the Urban Heat Effects of High Rise Non-Green Buildings: A Case Study in Kota Bharu, Kelantan, Malaysia

This study provides an overview of the urban heat effect of the high rise non-green building in theurban area located in Kota Bharu, Kelantan by collecting and analyzing related data using skyview factor (SVF).The SVF is one of the essential aspects related to pollution, temperaturevariations, heat island and several other environmental specifications. A common method throughfish-eye photographs were taken at ground level with a digital camera together with a detachable180’ fish-eye lens. The result highlighted the SVF value at six high rise non-green buildings wasin a range between 0.24 and 0.67. The highest temperature recorded was 42°C on rooftop ofKelantan Trade Center building whilst the lowest was 30°C on rooftop of Ibu Pejabat PolisKontinjen Kelantan. The surrounding and building materials were found to have a persistentinfluence on the formation of urban heat.

Assessing the relationship between sky view factor and land surface temperature to the spatial resolution

ABSTRACTThis article compares the land surface temperature (LST) and sky view factor (SVF) as indicator of the impact of urban morphology on the urban heat island effect. For this purpose, the work investigates the dependence of this relationship to spatial resolutions varying from coarse to very fine and related scaling effect. For this purpose, several daytime Landsat 8, Advanced Spaceborne Thermal Emission and Reflection Radiometer and airborne TASI-600 images acquired in different months of the year were used to retrieve LST. Moreover, a three-dimensional building vector database was used to produce SVF maps at different spatial resolutions, according to the thermal ones. The results show a positive relationship between LST and SVF; these trends are almost superimposable for same-sensor images, but vary for images at different resolutions. This is likely due to the interference on the SVF and LST values of micro-scale factors, e.g. thermal properties of building materials, anthropogenic heat, humidity and pollutants, and others, which in a macro-scale analysis are smoothed becoming irrelevant. Therefore, a digital database able to represent urban features at suitable spatial scale is a requirement for a reliable analysis. In particular, when airborne thermal data are used, the lack of a reliable cartographic digital data could represent a limiting factor. Specifically, the data set used in the computation of SVF and other geographical parameters involved in the LST assessment should be consistent with the resolution of airborne thermal data.

Assessment of continuous sky view factor based on ultra-high resolution natural colour images acquired by remotely piloted airborne systems for applications in an urban area of Athens

ABSTRACTThe thermal comfort conditions in a complex urban area is influenced by the surrounding structures and obstacles which modify the incoming radiation fluxes. A measure of this modification is the sky view factor (SVF), which could be estimated in each point of a selected area if a high resolution digital elevation model (DEM), or other urban morphological data including the manmade infrastructure, are available. The goal of this study is to model the continuous SVF for a complex building environment in the campus of National and Kapodistrian University of Athens, based on a high resolution DEM (0.09 m). For this purpose, we applied the structure-from-motion (SfM) technique, which takes advantage of the interpretation of ultra-high resolution colour images acquired by remotely piloted airborne systems, also known as drones or unmanned aerial vehicles. A quantitative analysis, by applying statistical metrics, yields perfect agreement between modelled and observed SVF values, over the examined area. The proposed methodology could be applied for human-biometeorology research in micro scale complex urban environments.

Effect of the position of the visible sky in determining the sky view factor on micrometeorological and human thermal comfort conditions in urban street canyons

Poor daytime and night-time micrometeorological conditions are issues that influence the quality of environmental conditions and can undermine a comfortable human lifestyle. The sky view factor (SVF) is one of the essential physical parameters used to assess the micrometeorological conditions and thermal comfort levels within city streets. The position of the visible sky relative to the path of the sun, in the cardinal and ordinal directions, has not been widely discerned as a parameter that could have an impact on the micrometeorological conditions of urban streets. To investigate this parameter, different urban streets that have a similar SVF value but diverse positions of visible sky were proposed in different street directions intersecting with the path of the sun, namely N–S, NE–SW and NW–SE. The effects of daytime and night-time micrometeorological variables and human thermal comfort variables on the street were investigated by applying ENVI-met V3.1 Beta software. The results show that the position of the visible sky has a greater influence on the street’s meteorological and human thermal comfort conditions than the SVF value. It has the ability to maximise or minimise the mean radiation temperature (Tmrt, °C) and the physiological equivalent temperature (PET, °C) at street level. However, the visible sky positioned to the zenith in a NE–SW or N–S street direction and to the SW of a NW–SE street direction achieves the best daytime micrometeorological and thermal comfort conditions. Alternatively, the visible sky positioned to the NE for a NW–SE street direction, to the NW and the zenith for a NE–SW street direction and to the zenith for a N–S street direction reduces the night-time air temperature (Ta, °C). Therefore, SVF and the position of the visible sky relative to the sun’s trajectory, in the cardinal and ordinal directions, must be considered during urban street planning to better understand the resultant micrometeorological and human thermal comfort conditions.