scholarly journals Sky View Factors from Synthetic Fisheye Photos for Thermal Comfort Routing—A Case Study in Phoenix, Arizona

2017 ◽  
Vol 2 (1) ◽  
pp. 19-30 ◽  
Author(s):  
Ariane Middel ◽  
Jonas Lukasczyk ◽  
Ross Maciejewski
Keyword(s):  
Thermal Comfort ◽  
Urban Form ◽  
Urban Areas ◽  
Meteorological Data ◽  
Routing Algorithm ◽  
Google Earth ◽  
Urban Environments ◽  
Tree Planting ◽  
Outdoor Thermal Comfort ◽  
View Factor

The Sky View Factor (SVF) is a dimension-reduced representation of urban form and one of the major variables in radiation models that estimate outdoor thermal comfort. Common ways of retrieving SVFs in urban environments include capturing fisheye photographs or creating a digital 3D city or elevation model of the environment. Such techniques have previously been limited due to a lack of imagery or lack of full scale detailed models of urban areas. We developed a web based tool that automatically generates synthetic hemispherical fisheye views from Google Earth at arbitrary spatial resolution and calculates the corresponding SVFs through equiangular projection. SVF results were validated using Google Maps Street View and compared to results from other SVF calculation tools. We generated 5-meter resolution SVF maps for two neighborhoods in Phoenix, Arizona to illustrate fine-scale variations of intra-urban horizon limitations due to urban form and vegetation. To demonstrate the utility of our synthetic fisheye approach for heat stress applications, we automated a radiation model to generate outdoor thermal comfort maps for Arizona State University’s Tempe campus for a hot summer day using synthetic fisheye photos and on-site meteorological data. Model output was tested against mobile transect measurements of the six-directional radiant flux density. Based on the thermal comfort maps, we implemented a pedestrian routing algorithm that is optimized for distance and thermal comfort preferences. Our synthetic fisheye approach can help planners assess urban design and tree planting strategies to maximize thermal comfort outcomes and can support heat hazard mitigation in urban areas.

scholarly journals Assessment of Outdoor Thermal Comfort in Serbia’s Urban Environments during Different Seasons

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1084
Author(s):  
Milica Lukić ◽  
Dejan Filipović ◽  
Milica Pecelj ◽  
Ljiljana Crnogorac ◽  
Bogdan Lukić ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Urban Environments ◽  
Outdoor Thermal Comfort ◽  
Strong Impact ◽  
Data Set ◽  
Different Seasons ◽  
Novi Sad

The urban microclimate is gradually changing due to climate change, extreme weather conditions, urbanization, and the heat island effect. In such an altered environment, outdoor thermal comfort can have a strong impact on public health and quality of life in urban areas. In this study, three main urban areas in Serbia were selected: Belgrade (Central Serbia), Novi Sad (Northern Serbia), and Niš (Southern Serbia). The focus was on the temporal assessment of OTC, using the UTCI over a period of 20 years (1999–2018) during different seasons. The main aim is the general estimation of the OTC of Belgrade, Novi Sad, and Niš, in order to gain better insight into the bioclimatic condition, current trends and anomalies that have occurred. The analysis was conducted based on an hourly (7 h, 14 h, and 21 h CET) and “day by day” meteorological data set. Findings show the presence of a growing trend in seasonal UTCI anomalies, especially during summer and spring. In addition, there is a notable increase in the number of days above the defined UTCI thresholds for each season. Average annual UTCIs values also show a positive, rising trend, ranging from 0.50 °C to 1.33 °C. The most significant deviations from the average UTCI values, both seasonal and annual, were recorded in 2000, 2007, 2012, 2015, 2017, and 2018.

Shading Effect on Outdoor Thermal Comfort in High-Density City a Case Based Study of Beijing

2014 ◽  
Vol 1065-1069 ◽  
pp. 2927-2930 ◽  
Author(s):  
Bai Chuan Ma ◽  
Qi Sang ◽  
Ji Feng Gou
Keyword(s):  
Thermal Comfort ◽  
Field Experiments ◽  
Meteorological Data ◽  
Thermal Conditions ◽  
Central Business District ◽  
Outdoor Thermal Comfort ◽  
View Factor ◽  
Thermal Environments ◽  
Sky View Factor ◽  
Business District

Shading provided by buildings affects outdoor thermal environments and, therefore, influences the long-term thermal comfort of people in outdoor spaces. This study conducted several field experiments to analyze the outdoor thermal conditions on urban streets in central business district (CBD) of Beijing. The RayMan model was utilized for calculating Sky view factor (SVF) and outdoor thermal comfort using meteorological data of one year period. Analytical results indicate that slightly shaded areas (SVF > 0.5) typically have highly frequent hot conditions during summer, particularly at noon; however, highly shaded locations (SVF < 0.3) generally reduce the intra-urban air temperature in winter; moderately shaded areas (0.3 < SVF < 0.5) show the advantage for balancing the hot conditions in summer and cold conditions in winter throughout whole year. Sky view factor can be used as a comprehensive and practical urban planning index at local scale, i.e. urban canyon street and residential estate. It provides a novelty method on scientific planning and sustainable development of city.

scholarly journals Biomimicry-Based Strategies for Urban Heat Island Mitigation: A Numerical Case Study under Tropical Climate

Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 48
Author(s):  
Kevin Araque ◽  
Paola Palacios ◽  
Dafni Mora ◽  
Miguel Chen Austin
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Outdoor Thermal Comfort ◽  
Base Case ◽  
Heat Island ◽  
Urban Heat ◽  
Historical Heritage ◽  
Pet Index ◽  
Radiant Temperature

In recent years, demographic growth has caused cities to expand their urban areas, increasing the risk of overheating, creating insurmountable microclimatic conditions within the urban area, which is why studies have been carried out on the urban heat island effect (UHI) and its mitigation. Therefore, this research aims to evaluate the cooling potential in the application of strategies based on biomimicry for the microclimate in a historical heritage city of Panama. For this, three case studies (base case, case 1, and case 2) of outdoor thermal comfort were evaluated, in which the Envi-met software was used to emulate and evaluate the thermal performance of these strategies during March (highest temperature month) and October (rainier month). The strategies used were extracted from the contrast of zebra skin, human skin, evaporative cooling, and ant skin. The results showed a reduction of 2.8 °C in the air temperature at 11:00, the radiant temperature decreased by 2.2 °C, and the PET index managed to reduce the thermal comfort indicator among its categories. The importance of thinking based on biomimicry in sustainable strategies is concluded; although significant changes were obtained, high risks of discomfort persist due to the layout and proximity of the building.

scholarly journals The most problematic variable in the course of human-biometeorological comfort assessment — the mean radiant temperature

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Noémi Kántor ◽  
János Unger
Keyword(s):  
Thermal Comfort ◽  
Short Wave ◽  
Urban Environments ◽  
Outdoor Thermal Comfort ◽  
Radiation Environment ◽  
Wave Radiation ◽  
Mean Radiant Temperature ◽  
Radiation Fluxes ◽  
The Mean ◽  
Radiant Temperature

AbstractThis paper gives a review on the topic of the mean radiant temperature Tmrt, the most important parameter influencing outdoor thermal comfort during sunny conditions. Tmrt summarizes all short wave and long wave radiation fluxes reaching the human body, which can be very complex (variable in spatial and also in temporal manner) in urban settings. Thermal comfort researchers and urban planners need easy and sound methodological approaches to assess Tmrt. After the basics of the Tmrt calculation some of the methods suitable for obtaining Tmrt also in urban environments will be presented.. Two of the discussed methods are based on instruments which measure the radiation fluxes integral (globe thermometer, pyranometer-pyrgeometer combination), and three of the methods are based on modelling the radiation environment with PC software (RayMan, ENVI-met and SOLWEIG).

scholarly journals Modelling hourly evapotranspiration in urban environments with SCOPE using open remote sensing and meteorological data

2021 ◽  
Author(s):  
Alby Duarte Rocha ◽  
Stenka Vulova ◽  
Christiaan van der Tol ◽  
Michael Förster ◽  
Birgit Kleinschmit
Keyword(s):  
Remote Sensing ◽  
Land Surface ◽  
Urban Areas ◽  
Meteorological Data ◽  
Urban Environments ◽  
Coefficient Of Determination ◽  
World Population ◽  
Model Errors ◽  
Vegetation Fraction ◽  
Process Based Models

Abstract. Evapotranspiration (ET) is a fundamental variable to assess water balance and urban heat island effect. ET is deeply dependent on the land cover as it derives mainly from the processes of soil evaporation and plant transpiration. The majority of well-known process-based models based on the Penman-Monteith equation focus on the atmospheric interfaces (e.g. radiation, temperature and humidity), lacking explicit input parameters to describe the land surface. The model Soil-Canopy-Observation of Photosynthesis and Energy fluxes (SCOPE) accounts for a broad range of surface-atmosphere interactions to predict ET. However, like most modelling approaches, SCOPE assumes a homogeneous vegetated landscape to estimate ET. Urban environments are highly fragmented, exhibiting a blend of pervious and impervious anthropogenic surfaces. Whereas, high-resolution remote sensing (RS) and detailed GIS information to characterise land surfaces is usually available for major cities. Data describing land surface properties were used in this study to develop a method to correct bias in ET predictions caused by the assumption of homogeneous vegetation by process-based models. Two urban sites equipped with eddy flux towers presenting different levels of vegetation fraction and imperviousness located in Berlin, Germany, were used as study cases. The correction factor for urban environments has increased model accuracy significantly, reducing the relative bias in ET predictions from 0.74 to −0.001 and 2.20 to −0.13 for the two sites, respectively, considering the SCOPE model using RS data. Model errors (i.e. RMSE) were also considerably reduced in both sites, from 0.061 to 0.026 and 0.100 to 0.021, while the coefficient of determination (R2) remained similar after the correction, 0.82 and 0.47, respectively. This study presents a novel method to predict hourly urban ET using freely available RS and meteorological data, independently from the flux tower measurements. The presented method can support actions to mitigate climate change in urban areas, where most the world population lives.

scholarly journals A 30-meter resolution national urban land-cover dataset of China, 2000–2015

2019 ◽  
Author(s):  
Wenhui Kuang ◽  
Shu Zhang ◽  
Xiaoyong Li ◽  
Dengsheng Lu
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Urban Areas ◽  
Vegetation Index ◽  
Urban Land ◽  
Google Earth ◽  
Urban Environments ◽  
Urban Land Use ◽  
Environmental Research ◽  
Urban Land Cover

Abstract. Accurate urban land-cover datasets are essential for mapping urban environments. However, a series of national urban land-cover data covering more than 15 years that characterizes urban environments is relatively rare. Here we propose a hierarchical principle on remotely sensed urban land-use/cover classification for mapping intra-urban structure/component dynamics. China's Land Use/cover Dataset (CLUD) is updated, delineating the imperviousness, green surface, waterbody and bare land conditions in cities. A new data subset called CLUD-Urban is created from 2000 to 2015 at five-year intervals with a medium spatial resolution (30 m). The first step is a prerequisite to extract the vector boundaries covered with urban areas from CLUD. A new method is then proposed using logistic regression between urban impervious surface area (ISA) and the annual maximum Normalized Difference Vegetation Index (NDVI) value retrieved from Landsat images based on a big-data platform with Google Earth Engine. National ISA and urban green space (UGS) fraction datasets for China are generated at 30-meter resolution with five-year intervals from 2000 to 2015. The overall classification accuracy of national urban areas is 92 %. The root mean square error values of ISA and UGS fractions are 0.10 and 0.14, respectively. The datasets indicate that the total urban area of China was 6.28 × 104 km2 in 2015, with average fractions of 70.70 % and 26.54 % for ISA and UGS, respectively. The ISA and UGS increased between 2000 and 2015 with unprecedented annual rates of 1,311.13 km2/yr and 405.30 km2/yr, respectively. CLUD-Urban can be used to enhance our understanding of urbanization impacts on ecological and regional climatic conditions and urban dwellers' environments. CLUD-Urban can be applied in future researches on urban environmental research and practices in the future. The datasets can be downloaded from https://doi.org/10.5281/zenodo.2644932.

scholarly journals Vegetation and microclimate in open urban areas. Cuiabá, Mato Grosso - Brazil

2020 ◽  
Vol 7 (3) ◽  
pp. 1089-1099
Author(s):  
Maria Corette Pasa ◽  
Lucas Henrique Vieira Lenci ◽  
Nhaára Da Vila Pereira ◽  
Rosenil Antonia de Oliveira Miranda
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Urban Areas ◽  
Modern Science ◽  
Well Being ◽  
Urban Environments ◽  
Forest Fragment ◽  
Open Spaces ◽  
Mato Grosso ◽  
Significant Difference

The influence of vegetation on the reduction of heat in open urban environments by providing a milder and more pleasant microclimate is highlighted in modern science. The objective of this study was to evaluate the trend of microclimatic variables and thermal comfort, in the Federal University of Mato Grosso - UFMT campus, in open spaces (forest fragment, cerrado and paved) with and without afforestation. Three collection points were selected in open spaces (wooded and without afforestation) at the UFMT campus in Cuiabá. To record the data, we used the Alloet Thermohigrometer mini-markers, model TA-318 with 0.1%. The collections took place in May of 2018, period that begins the local winter. The microclimatic variables such as air temperature, relative humidity (%), wind speed, ultraviolet index and chance of rain were analyzed daily from 09:00 to 17:00 for 15 days. The results highlight the importance of the shade provided by the tree vegetation in the forest fragment, which revealed a significant difference for the thermal comfort in relation to the other sample points and without afforestation. The microclimatic parameters present variations of the temperature and relative humidity of the air at the points allocated, with emphasis on the thermal comfort sensation for the wooded area. The research also suggests new scientific investments in studies on urban micro-climates as a way to stimulate and raise awareness of the importance of vegetation in thermal comfort, which can directly reflect the health and well-being of people in general. 

scholarly journals In-situ Measurement of Pedestrian Outdoor Thermal Comfort in Universities Campus of Malaysia

2019 ◽  
Author(s):  
Nurnida Elmira Othman ◽  
Sheikh Ahmad Zaki ◽  
Nurul Huda Ahmad ◽  
Azli Razak
Keyword(s):  
Thermal Comfort ◽  
Field Measurement ◽  
Thermal Sensation ◽  
Outdoor Thermal Comfort ◽  
View Factor ◽  
Thermal Preference ◽  
Equivalent Temperature ◽  
Physiological Equivalent Temperature ◽  
Sky View Factor

The present study is intended to evaluate an outdoor thermal comfort at two universities campus in Malaysia. Field measurement and questionnaire survey were conducted simultaneously to assess the microclimatic condition and pedestrian thermal sensation. A total of 3033 samples were collected at seven different sky view factor (SVF) values that range from 0.2 to 0.9. The physiological equivalent temperature (PET) was estimated to evaluate outdoor thermal comfort. It was observed that at a highly shaded area (SVF < 0.35) the respondent’s thermal sensation vote (TSV) are neutral (> 25%), acceptable for thermal acceptance vote (TAV) (> 50%) and no change (> 50%) for thermal preference vote (TPV). For moderate shaded (0.35 ≤ SVF ≤ 0.70) TSV was voted as hot (> 25%), acceptable for TAV (40%), and prefer slightly cooler for TPV (>50%). For less shaded area (0.70 < SVF ≤ 1), TSV was voted as hot and very hot (> 25%), acceptable for TAV (>40%) and prefer slightly cooler for TPV (> 40%). Moreover, the PET value increases simultaneously with the increase of SVF. Results thus suggest that at any given activities such as sitting, walking, and standing also caused effects slightly on the way people thermally perceive it during the on-campus daytime.

scholarly journals A microclimate regulation study of Ficus altissima under winter conditions in lower subtropical China

2021 ◽  
Author(s):  
Wan Deng ◽  
Chunhua Xia ◽  
Jingyu Chen ◽  
Yanji Jiang
Keyword(s):  
Thermal Comfort ◽  
Functional Performance ◽  
Meteorological Data ◽  
Ground Cover ◽  
Vital Role ◽  
Tree Planting ◽  
Subtropical China ◽  
Physiological Equivalent Temperature ◽  
Area Index ◽  
Winter Conditions

Abstract As a widespread practice in urban landscape design, tree planting plays a vital role in improving the ecological environment and microclimate. This study obtained the physical, physiological, and meteorological data of Ficus altissima, a typical tree species in lower subtropical China, through field measurement, and analyzed its functional performance in microclimate regulation. Its results indicated that: (1) the leaf area index (LAI), sky visible factor (SVF), ground cover (GC), and other indicators of Ficus altissima had essential relationships with radiation attenuation, temperature, and humidity regulation under winter conditions in lower subtropical China; (2) there were significant differences in leaf surface temperature and transpiration between east, west, north, and south during daytime; and, (3) thermal comfort represented by physiological equivalent temperature(PET)in the shade could be expressed as functions of solar radiation (SR), mean radiation temperature (MRT), air temperature (Ta), air humidity (RH), globe temperature (Tg), and wind speed (V). Based on these results, the following were the suggestions: firstly, Ficus altissima with higher LAI values should be selected for planting; secondly, trees must be planted on the east side of the site should solitary planting be undertaken to obtain maximum thermal comfort; and finally, activities under the canopy of Ficus altissima should be prioritized at 11:00–16:00 during winter.

Sign in / Sign up

Export Citation Format

Share Document