Sky View Factor Research Articles

Research on the spatial form effects of thermal comfort on urban waterfront trails in summer – a case study of West Lake in Hangzhou, China

ABSTRACT The waterfront trail is a crucial outdoor activity area for urban residents, but the increasing high temperature in summer has negatively affected the quality of outdoor activities. To address this issue, this article examines the relationship between the spatial form of the waterfront trails and thermal comfort, using the West Lake Hangzhou trails as an example. Seven waterfront trail spaces were selected for the study, and six spatial structure parameters and three climatic parameters were measured on three representative summer days. The Rayman model was then used to calculate the Physiological Equivalent Temperature (PET) value of each sample plot based on five climate parameters, human body parameters, and Sky View Factor (SVF). The results indicate that the primary spatial form factors affecting the microclimate and thermal comfort of the waterfront trails in summer are the average tree height, the average tree spacing, and the ratio of shadow-generating side tree height to the trail width. The average tree height significantly impacts thermal comfort, followed by the tree spacing and the shadow-generating side tree height ratio to the trail width. These parameters primarily affect the thermal comfort of the waterfront trails through air temperature and wind speed. The study’s findings can guide the design of waterfront trail spaces and help create waterfront trails that combine climate comfort and landscape.

Study on the Correlation Analysis between Urban Morphological Factors and Microclimate Based on Empirical Methods on a University Campus in a Hot-Summer–Cold-Winter Region

With the continuous progress of urbanization, contemporary scholars are increasingly focusing their attention on the study of urban microclimates. This research aims to investigate the relationship between urban morphology and microclimates in regions characterized by hot summers and cold winters. Environmental meteorological data, including temperature, solar radiation, and wind speed during the spring and summer seasons, were collected through on-site monitoring in a specific area of Shanghai. Various methods, such as on-site surveys and drone photography, were employed to obtain and analyze a range of urban morphological parameters, including floor area ratio (FAR) and greenery ratio (GnPR). The sky view factor (SVF) was determined using a fisheye lens technique. Subsequently, the collected datasets were analyzed to assess the varying impact of distinct urban morphological factors on microclimates. The findings indicate a significant correlation between different building morphology factors and temperature and solar radiation during spring, while their associations with wind speed become more prominent in summer. Notably, greenery and pavement demonstrate stronger correlations with temperature and radiation in summer, aligning with the seasonal growth patterns of plants. These research findings provide both a theoretical foundation and practical guidelines for the urban design of environmental microclimates.

Comparison of an unmaned aerial vehicle based physical environment with thermal properties from in-situ measurements: Campus of Changwon National University, South Korea

The rapid development of urban areas has adversely affected the thermal environment. Analysis of the various characteristics of the physical environment in urban spaces that affect the thermal environment and appropriate measures for urban and environmental planning are required to address these problems sustainably. Therefore, the application of unmaned aerial vehicles (UAVs) for the precise analysis of the physical environment in urban spaces was studied. The present study compared the thermal properties measured in the field and the physical environment derived using a UAV in the Changwon National University campus in Changwon-si, South Korea. The physical environment was analyzed using UAV-based parameters such as normalized difference vegetation index (NDVI) and sky view factor (SVF). The thermal property was collected using radiant energy and land surface temperature that were measured using mobile equipment. UAV NDVI and UAV SVF were strongly correlated with the upward and downward long-wave radiation, respectively. The physical environment measured by the UAV was strongly correlated with the thermal properties. Therefore, UAVs could be useful for monitoring the thermal characteristics of urban spaces.

Effects of Sky View Factor on Thermal Environment in Different Local Climate Zoning Building Scenarios—A Case Study of Beijing, China

As an essential structural indicator of buildings, sky view factor (SVF) is one of the most critical factors affecting the urban thermal environment. However, the relationship between SVF and the thermal environment at the neighborhood scale has not been adequately studied. Therefore, this paper investigates the relationship between SVF and air temperature in different building scenarios based on the Local Climate Zone (LCZ) classification framework. Firstly, the study is based on multi-source urban data and the Open Street Map (OSM) to map the local climate zones in Beijing. Then, a simulation model with different LCZs was constructed based on realistic scenarios using the microclimate simulation software ENVI-met, and the thermal environment was simulated in 24 h on a single day in summer. Finally, the SVF and air temperature relationship under different LCZ scenarios was calculated and analyzed. The results show that (1) the SVF values of LCZ 1, LCZ 2, and LCZ 5 show a more apparent positive correlation with air temperature than other categories, and the SVF values of LCZ 6–9 show a negative and then positive correlation with air temperature; (2) in the morning, the dense building areas show a weak correlation with air temperature, and the differences in air temperature corresponding to the SVF values in different zones are greater; (3) in the morning, the air temperature in the dense building areas showed a weak correlation, the difference between the SVF values and the air temperature in different intervals was different, and when the SVF was larger or smaller, the air temperature change was smaller and concentrated, and the correlation between the air temperature and the SVF in the open building areas was not obvious; (4) with 12:00 as the dividing line, the SVF and the air temperature in all categories showed a weak positive correlation after this time. This study can provide guidance on optimizing building layouts and mitigating the impacts of urban heat on human health.

Cooling effects of wetland parks in hot and humid areas based on remote sensing images and local climate zone scheme

Wetland parks, as essential components of urban blue and green landscapes, have long been proven to provide cooling benefits to high-temperature urban spaces. This study aims to clarify the comprehensive cooling effects of wetland parks on the surrounding built-up areas. Ten typical wetland parks in Guangzhou, China, were selected as the research objects, and the local climate zone (LCZ) around these parks was divided considering a radius of 600 m. Land surface temperature (LST) distribution transitions from winter to summer were obtained for a six-month period using a mono-window algorithm retrieved from remote sensing image data from Landsat 8. Cooling factors of wetland park morphological indices and LCZ indicators were calculated using buffer zone analysis and treated as independent variables. Cooling effect indicators, namely cooling distance (PCD), cooling range (PCR) and cooling gradient (PCG), were considered as dependent variables. A quantitative correlation factor analysis was performed to examine the relationship between these variables. The results showed that these factors have varying degrees of influence on the cooling indices. Among them, LCZ characteristic factors, including sky view factor (SVF), permeable surface fraction (PSF), and aspect ratio (AR), have a greater influence on the cooling effects than the wetland park's own characteristics. Based on these results, we attempted to determine quantitative equations illustrating the relationships between the cooling effect indices and the influencing factors to provide theoretical guidance for climate-sensitive urban design near wetland parks.

The effects of greening a parking lot as a heat mitigation strategy on outdoor thermal stress using fixed and mobile measurements: case-study project “tertiary forest”

An asphalt-concrete parking lot was converted to a small urban forest with 72 trees and permeable pavement as an urban heat island countermeasure. Microclimate monitoring was performed pre- and post-renovation using fixed and mobile measurements. We propose a protocol to estimate robust statistical effects over 24 h constructed with several days of observation, and to compare the spatial distribution of heat stress pre- and post-conversion regardless of differences in weather conditions. Detailed effects on solar and infrared radiation, microclimate and pedestrian heat stress are assessed and tested for statistical significance. Great improvements of pedestrian heat stress are reported, especially in daytime, following the creation of shade which significantly reduces the radiative load of the area. UTCI-equivalent temperature is reduced up to 6.2 °C (3.1 °C on a 24h-average). Mobile measurements were used to characterize the spatial disparity of heat stress. Strong thermal discomfort is exhibited under direct insolation. At night, positive effects on pedestrian heat stress are slightly counterbalanced by an increase in infrared trapping due to the reduction of the sky view factor beneath the trees while wind speed is slowed. Recommendations are formulated for urban planners.

Road surface temperature evaluated with streetview-derived parameters in a hot and humid megacity

This study explores the potential of a novel method that uses streetview-derived parameters to explain road surface temperature (RST) variations. The relationships between RST and streetview-derived parameters, including view factors (VFs), sunlit/shaded status, and sunlit hours, are investigated in an urban central district in a hot and humid climate. Thermal mapping of RST was conducted in 14 traverses at different times on a hot summer day and on both sides of the street canyon. The performances of streetview-derived parameters were also compared with commonly used urban morphological parameters. Results show that the correlations between RST and streetview-derived sky view factor (SVF) and green view factor (GVF) can reach 0.92 and − 0.93, respectively, at around 11:25. Building view factor (BVF) shows a weak correlation with RST and exhibits different directions of influence at different times of the day and in different types of routes. Correlations between streetview-derived VFs and RST are scale-dependent, varying by time of day and showing different patterns on the two sides of one canyon. The correlations between RST and traditional morphological parameters (BCR, FAR and meanH) are weaker than streetview-derived ones (sunlit hours, screen status, SVF and GVF). Multiple linear regressions show that streetview-derived view factors can explain 59% ∼ 82% of the spatial variation in daily maximum RST. The study highlights the potential of using streetview-derived parameters to predict RST.

Fast and accurate estimation of solar irradiation on building rooftops in Hong Kong: A machine learning-based parameterization approach

Harvesting solar energy on rooftops can be a promising solution for providing affordable energy. This requires accurately estimating spatio-temporal solar photovoltaic (PV) potential on urban surfaces. However, it is still a challenge to obtain a fast and accurate estimation of rooftop solar PV potential over large urban built-up areas. Thus, this study proposes a parametric-based method to estimate annual rooftop solar irradiation at a fine spatial resolution. Specifically, seven parameters (Digital Surface Model, Sky View Factor, shadow from buildings, shadow from terrain, building volume to façade ratio, slope, and aspect) are determined that having great importance in modeling rooftop solar irradiation. Three machine learning methods (Random Forest (RF), Gradient Boost Regression Tree (GBRT), and AdaBoost) trained by the selected parameters are cross-compared based on R2, Mean Absolute Error (MAE), and computation time. As a case study in Hong Kong, China, the RF outperformed GBRT and AdaBoost, with R2=0.77 and MAE=22.83kWh/m2/year. The time for training and prediction of rooftop solar irradiation is within 13 h, achieving a 99.32% reduction in time compared to the physical-based hemispherical viewshed algorithm. These results suggest that the proposed method can provide an accurate and fast estimation of rooftop solar irradiation for large datasets.

How Urban Morphology Relates to the Urban Heat Island Effect: A Multi-Indicator Study

Urban morphology quantitatively expresses a city’s spatial structure, internal relationships, and physical form. It has advantages for predicting urban growth and analyzing the current state of cities in the literature. A comprehensive study on the complex relationships between urban morphology and urban heat island intensity (UHII) is of great importance for mitigating the urban heat island (UHI) effect for megacities. This study models urban morphological indicators in fine resolution based on three aspects: building morphology, ecological infrastructure, and human activities. The model accurately captures UHII by employing the definition of UHI effects. The relationship between urban morphology and UHII was further examined using extreme gradient boosting (XGBoost) and Shapley additive explanations (SHAP). By taking central Beijing, China as study area, major findings include the following: (1) Significant daytime UHI effects were observed within the research area, particularly during the summer months, when it appears to be most severe. More than 90% of the region experiences varying degrees of the UHI effects. (2) UHI is significantly correlated with both 2D and 3D urban morphological indicators. Low sky view factor (SVF) and high SVF tend to mitigate UHI, whereas moderate SVF tends to aggravate UHI. (3) In densely populated areas, tall trees may be more effective than other forms of vegetation at mitigating UHI. Based on the aforementioned findings, this article suggests that urban morphology optimization should focus on seasonality, spatial specificity, and indicator specificity for megacities in urban design and spatial planning aimed at mitigating UHI.

Multi-city assessments of human exposure to extreme heat during heat waves in the United States

There is a lack of understanding of the complex spatiotemporal patterns of heat exposure during heat waves, and the impact of urbanization intensity and urban morphology on heat exposure in urban thermal environments. To address these issues, this study used mean radiant temperature (Tmrt) as an index to indicate human exposure to extreme heat, and generated hourly heat exposure maps at a 1-m spatial resolution in Summer 2020 for heat wave and non-heat wave days across three diversely urbanized and climatically different U.S. cities (Riverside, CA; Des Moines, IA; and Boston, MA) using the SOlar LongWave Environmental Irradiance Geometry (SOLWEIG) model and multi-source remote sensing and GIS data. Based on these high-frequency and microscale maps, we found that heat exposure in urban canyons of downtown areas was high due to relatively low building's height to street's width (H/W) ratio, which resulted in a limited shading effect in the studied cities. Heat exposure during heat waves was enhanced by 6 °C to 10 °C compared to non-heat wave conditions, with the main differences occurring in the early afternoon between 12 pm and 2 pm. We found that hot cities (Riverside, 63 °C) had higher heat exposure than warm cities (Des Moines and Boston, 53 °C and 51 °C) during heat waves. Heat exposure in urban core areas was approximately 5C higher than that in rural areas during heat waves. Additionally, we found that sky view factor was the most important urban morphology factor influencing heat exposure, with a relative importance of over 67% in these cities, but the role of impervious surface and trees varied among these cities. Impervious surface area (ISA) contributed more to heat exposure than trees in dry and hot regions (Riverside), but not in humid and warm cities (Des Moines and Boston). This study is the first to generate hourly heat exposure maps at a 1-m resolution for heat wave and non-heat wave days, and to investigate spatiotemporal patterns and the impacts of urbanization intensity and urban morphology on heat exposure in multiple cities. The findings of this study can be useful in developing urban policies to improve urban thermal environments in diverse urban settings, and our transferable framework can potentially be applied to other cities for heat exposure studies.

Thermal Performance Study of Building Materials in an Urban Form

A tropical Chennai city, is already enduring heat stresses in its urban areas and is extremely vulnerable to temperature rise. Furthermore, Chennai continues to expand, thus the need to conduct research and make informed decisions on sensible strategies and regulations on how to construct and with what to construct attains much significance in recent times. One of the major contributors to the urban heat is the materials used on the surfaces of the urban form. The current paper assesses and demonstrates the performance of two wall materials – Clay Brick and AAC, usually utilized in urban developments within the context of an optimal urban morphological region. This is accomplished by making a compact mid-rise urban form of residential typology and utilizing ENVI-met 4.0 and re-creating the outdoor microclimatic conditions with AAC and Clay Brick walls. The urban form created with the Clay brick walls are found to be cooler by 0.010°C. Compared to daytime, at night time, the outside air temperature with clay brick walls and AAC dividers are cooler respectively. This investigation additionally discovered that a huge distinction to outside air temperature for studied urban form structure can be made by expanding the Sky View Factor (SVF), contrasted with an adjustment of material. The understandings from this study can be expanded and be applied productively to impact changes in Urban development guidelines.

The advancement of research in cool roof: Super cool roof, temperature-adaptive roof and crucial issues of application in cities

Cool roofs play a significant role in mitigating urban heat islands, improving indoor thermal comfort, and saving energy. In recent years, with advances in the manufacturing of nanophotonics and metamaterials, researchers have developed super cool roofs where the surface temperature remains below the air temperature in direct daylight and temperature-adaptive roofs where the solar reflectance or thermal emissivity can change with temperature. This paper reviews the research progress and status of conventional cool roofs, super cool roofs, and temperature-adaptive roofs. This paper affirms the role of cool roofs in mitigating urban heat islands and energy conservation. And this paper also summarizes some of the crucial issues that cool roofs may face when used in cities. The effects of cool roofs on urban wind fields, planetary boundary layer heights, and pollutants above cities as well as the effects of sky view factor, atmospheric humidity, dust, and aging on the performance of cool roofs are discussed. The results show that the use of cool roofs is limited by geography and climate. The net cooling power can reach 150 W/m2 in dry, rainless, and clear sky areas. Cool roof technology is less effective in hot and humid climates because the first atmospheric window is affected to varying degrees by the increased radiation medium in the atmosphere, while the second atmospheric window is nearly closed in hot and humid climates, weakening the terrestrial long-wave radiation entering space. The use of cool roofs in warm and humid climates (over 80% relative humidity, with temperature over 24 °C) for most summer nights may limit the radiative cooling performance of the cool roof. The large-scale use of cool roofs in cities near huge lakes or seas may affect the urban wind field, causing a cooling island effect and a local build-up of pollutants. Finally, an outlook on the research prospects of cool roofs was given to provide ideas for further research.

Impacts of urban morphology on sensible heat flux and net radiation exchange

Urban morphology affects the sensible heat flux and net radiation exchange which can alter urban heat mitigation plans. This study first parameterized the geometric effects on the net radiation, and then calculated the net radiation and sensible heat flux in the urban landscape of Hong Kong. Considering that the sensible heat flux is the main heat sink in compact urban areas, this study proposes a Normalized Urban Sensible Heat Mitigation Index (NUSHMI) based on the ratio of the net radiation and sensible heat flux. Overall, there is major difference in the dependence of net radiation and sensible heat flux on geometric parameters. Net radiation Rn, reaches an optimal value, either maximum or minimum depending on the parameters of SVF and a standard deviation of building height σh, at intermediate parameter values, which suggests a guideline relevant to urban design targeting the mitigation of urban climate. Contrariwise, sensible heat flux decreases or increases, again depending on SVF and σh, is being considered, with increasing values of the same parameters. For example, Rn, reaches a minimum value for a Sky View Factor (SVF) between 0.5 and 0.6, while it reaches a maximum value for a standard deviation of building height σh between 20 and 30 m. These two results suggest that radiative forcing, i.e. Rn, can be minimized by urban space with SVF around 0.55 and σh around 25 m. The relationships between sensible heat flux and SVF or σh do not show multiple minima or maxima (as with Rn), with the exception of building density, which could also be applied as a guideline in urban design. The results based on the proposed NUSHMI indicated the NUSHMI reaches the highest values when building density is about 0.7 and building height is about 80 m and when the building height standard deviation within an area is about 10 m to 20 m. These findings revealed how the urban morphology affects the surface heat flux exchange between urban canopy and atmosphere boundary layer, and can help to design an efficient urban landscape towards urban heat mitigation for highly compacted cities, e.g. controlling the building density, height, and the height deviation. This combination of urban geometric parameters identifies an urban configuration maximizing the dissipation of absorbed radiant energy as sensible heat. It should be noted, however, that heat load upon buildings would be reduced at the price of maximizing heat dissipation within the built-up space.

Investigating the intra-urban thermal and air quality environment: New transect sensing methodology and measurements

Mobile monitoring can offer data of high spatial resolution within various urban contexts. Yet, devising efficient monitoring protocols for mobile campaigns is still a challenge. Relevant studies typically follow protocols based on the accumulated knowledge of authors and not standardized protocols. Thus the results may be prone to biases. Here, we present a transect monitoring methodology focused on urban areas’ thermal environment and air quality. The methodology follows a specific protocol for choosing the monitoring days and evaluating post-process corrections of the retrieved data and is applied within a city in central Italy at a seasonal scale with respect to the Sky View Factor. The presented method is simple, yet comprehensive and can be easily applied to almost any city and urban context. Results showed significant variations of the parameters measured, i.e. air temperature, humidity, short-wave radiation, wind speed, CO2 and PM10. For example, differences of air temperature within the same city may be up to 5.1 °C in autumn and differences of short-wave radiation may be up to 501 W/m2 in spring. The results of this study enhance the understanding of how to efficiently assess the quality of urban environments. As such, they could serve as a catalyst for developing mobile monitoring protocols, with the goal of enhancing the evaluation of urban environmental quality.

Investigation and Evaluation of Insolation and Ventilation Conditions of Streetscapes of Traditional Settlements in Subtropical China

Global warming, the urban heat island effect (UHI), and the risks of fossil fuel depletion necessitate a re-evaluation of traditional settlements that have been adapted to local climatic conditions, topography, and available resources, including materials and construction methods, through passive strategies to achieve thermal comfort. Although vernacular settlements have received considerable attention, few have examined and evaluated their streetscapes. This study investigates the impact of topographical features and architectural forms on insolation and ventilation conditions in traditional settlements in China’s southern subtropical climate. The aim is to explore traditional planning configurations of streetscapes at different altitudes to identify architectural forms and planning strategies that effectively improve outdoor users’ thermal comfort conditions. For this purpose, case studies are conducted on three traditional settlements in Lingnan; the Lingnan region has a typical subtropical climate in southern China. The chosen cases represent the main features of different topographical conditions, architectural forms, and climate zones in the Lingnan. We systematically simulated the insolation and ventilation in these settlements’ streetscapes on a monthly and quarterly basis and analyzed their sunlight hours, incident solar radiation, shading percentages, sky view factors (SVF), and wind speed. The findings show the following: (1) Specific terrains can affect streetscapes’ shading percentages and wind speed. The mountain settlement (With an average elevation of 600 m) is located on a southeast-facing slope (10° < slope < 20°). It receives an additional 10% of incident solar radiation compared to gentle terrain. (2) Compared to settlements located in coastal hills and mountainous, plain settlements have better shading and ventilation conditions in streetscapes. In terms of insolation, plain settlements have denser building configurations and narrower, elongated street corridors with a height-to-width ratio (H/W) = 1.9~5.5 (the height–width ratio value as street’s H/W (H = height, W = width); note that it is unitless), which can generate greater lower SVF (44.5%), and shading percentages (63.6%). Regarding ventilation, it is easier to create a “cool lane” (i) when the main street, oriented towards the dominant wind direction in summer, forms an angle <30° with it, (ii) when the primary street follows a NE–SW longitudinal orientation, while SE–NW horizontal streets intersect and weave through it, and (iii) with a H/W = 3~4 resulting in wind speeds of 2.9~4.0 m/s. (3) All the streetscapes have overshadowing occurring in winter; similarly, varying sizes of calm wind zones are created in summer. To alleviate these issues, widening the streetscapes along the buildings can permit solar penetration and natural ventilation. (4) In summer, installing shading devices along the horizontal plane of covered street corridors with a H/W = 1~4 and N–S longitudinal orientation can provide an additional shading of 3.6–22%.

Examining individual-level tri-exposure to greenspace and air/noise pollution using individual-level GPS-based real-time sensing data

ObjectiveAlthough exposure to air/noise pollution and greenspace has been found to significantly affect people's physical and mental health outcomes, there is still a lack of knowledge on what built-environment and socioeconomic factors are significantly associated with people's tri-exposure to air/noise pollution and greenspace. This study analyzes the associations between built-environment and socioeconomic factors and the tri-exposure to greenspace and air/noise pollution in Hong Kong. MethodBased on individual-level activity data, real-time GPS trajectories, and exposure data collected by portable sensors as well as remote sensing satellite imagery, we employ multinomial logistic regression to determine the socioeconomic and built-environment factors that are significantly associated with the type of participants’ tri-exposure at the grid cell level. ResultsThe results show that higher transit nodal accessibility, building density, building height and land-use mix are significantly associated with a higher likelihood of being disadvantaged in terms of tri-exposure to air/noise pollution and greenspace. While more advantageous tri-exposures are significantly related to higher median monthly household income and sky view factor. ConclusionOld high-rise high-density neighborhoods are more likely to be triply disadvantaged with low greenspace exposure but high air pollution and noise pollution exposure. The findings provide policymakers with critical reference in terms of addressing the inequalities in the tri-exposure outcomes.

Optimization of residential urban-block morphology based on its synthetic effects on indoor and outdoor natural lighting environments

The qualities of indoor and outdoor natural lighting environments are important aspects of sustainable urban design, which are inseparable, especially in high-density cities. This study aimed to reveal the synthetic effects of mesoscale urban morphology on indoor and outdoor natural lighting environments and propose corresponding design strategies for the sustainability of cities. Through data mining, 1680 residential blocks in Hangzhou, China, were selected for simulation analysis; urban morphology indicators that have a significant influence on daylighting performance were extracted. A multi-objective optimization algorithm was adopted to explore the optimal morphological features of urban morphology within a typical site. The extracted features were verified by morphological modifications in real cases. 1) The floor area ratio had the most significant effect on indoor daylighting (p= -0.673), while density was the most influential indicator for outdoor environments (p= -0.406); 2) in a typical site, morphological optimization can effectively improve lighting quality, with the average daylighting factor and sky view factor increasing by 3.7 and 6.7%, respectively; 3) two design strategies can simultaneously improve the indoor and outdoor natural lighting: dispersing the overall building mass to the perimeter of the site and dispersing the slab buildings of large masses as much as possible.

Green Is Not the Same as Green: Differentiating Between the Association of Trees and Open Green Spaces With Children’s Brain Structure in the Netherlands

There is accumulating evidence for positive effects of green spaces on mental and brain health. Here we investigated whether differentiating the types of green spaces may be relevant. On longitudinal data of children ( N = 95) from the Netherlands, we quantified the link between green space exposure at home from birth onwards and MRI brain structure at 12.5 years. We differentiated between green space resulting from trees versus open green spaces and also associated visibility of sky (sky view factor) with brain structure (200 m buffer around home address). We observed a positive association between grey matter volume in different prefrontal clusters and green open space coverage as well as sky view, but a negative association within prefrontal clusters for tree cover density. Most importantly, in the medial prefrontal cortex, the only region in which all three analyses overlapped, the visibility of sky was the most important predictor. Our findings advance knowledge on health-promoting, evidence-based urban planning.

A Spatial Analysis Methodology for the examination of Solar, Wind and Sky View Conditions in Traditional Squares of the Eastern Mediterranean Region

The study of microclimatic conditions, their ability to form determinant parameters of urban morphologies and their impact on the choices for the social interaction of dwellers, has been of increased interest to researchers over the last decades. In this context, spatial analysis methods for assessing the microclimate in public spaces, which can be exploited as means for improving the quality of life in the built environment, are increasingly used. In the framework of this study a spatial analysis methodology of solar, wind and sky view considerations was followed involving public open spaces, i.e., squares, in traditional settlements of Cyprus. Based on this investigation, the study presented herein focused on the spatial examination of the solar, wind and sky view conditions in three typical traditional case-study squares in different climatic regions of Cyprus, pertaining to the Mediterranean climate. The purpose of the study is to discern the potentials and limitations of various traditional built form structured outlines with respect to climate-conscious design, but more importantly to present qualitative comfort assessment tools which allow a spatial – visual perception of the parameters affecting thermal comfort. The assessment methodology which has been applied is based on seasonal image processing techniques of solar, wind and sky view factor parameters. The resulting thermal comfort maps open the road for a major advance in assessing outdoor open spaces through bioclimatic principles and can be used as tool by architects and planners to identify outdoor public spaces that require design interventions or as an initial design step in implementing new climate-based outdoor public spaces.

How to quantify the cooling effects of green infrastructure strategies from a spatio-temporal perspective: Experience from a parametric study

Urban green infrastructures (GI) are efficient nature-based solutions for urban heat mitigation. Typically, three GI typologies, i.e., green roof, green wall, and street tree, are often recommended and implemented for outdoor thermal comfort modification and passive energy saving. However, the current evaluation of the cooling effects for GI strategies is not comprehensive for two reasons: 1) lacking a holistic assessment to involve different combinations of GI typologies; 2) lacking a spatio-temporal lens to quantify the cooling effects.This study proposes a systematic approach to quantify the cooling effects of GI strategies from a spatio-temporal perspective. Through a parametric study in ENVI-met model, the cooling effect of seven GI strategies were quantified, and different street orientations and sky view factor (SVF) were also involved. Three cooling indicators were proposed for different sustainable planning targets: cooling intensity (CI), cooling area (CA), and cooling duration (CD). The results showed that the seven GI strategies performed differently under various urban morphologies. The greatest cooling effect of GI strategies was observed at SVF = 0.7, after which additional strategies may be needed for urban heat mitigation. Three proposed indicators were found to show similar patterns across the GI strategies, but revealed the details of cooling effects differently.Overall, this study represents the first assessment of the cooling effects of seven GI strategies across different morphological settings. The evidence-based understanding contributed by this study can help planners and designers to optimize the thermal environment in subtropical climate. The systematic approach from a spatio-temporal lens can be transferred to other cities and climate backgrounds.