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 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 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.

Study on Design Strategies for Improving Outdoor Thermal Comfort in the Cold Regions of China

2011 ◽  
Vol 250-253 ◽  
pp. 3798-3801 ◽  
Author(s):  
Jing Li ◽  
Yu Liu
Keyword(s):  
Thermal Comfort ◽  
North China ◽  
Outdoor Environment ◽  
Outdoor Thermal Comfort ◽  
Design Strategies ◽  
Cold Regions ◽  
Winter Climate ◽  
Thermal Environments ◽  
The North ◽  
Xi’An City

Along with the improvement of dwelling quality, the length of time and frequency of outdoor activities in winter greatly increase in the north China area, although the outdoor thermal environments are still unsatisfactory. It is necessary for both planners and architects to improve outdoor thermal environments in the cold regions of north China. This paper firstly introduces the general winter climate features in some north China cities. Then, it takes Xi'an city as an example to show the shortage of uncomfortable outdoor environment. Thirdly, the design strategies to improve outdoors thermal comfort include wind and snow protection, sunlight usage, environmental zones and recreational facilities, etc. are discussed.

scholarly journals Measuring thermal comfort in a built environment: A case study in a Central Business District, Jakarta

2021 ◽  
Vol 918 (1) ◽  
pp. 012024
Author(s):  
N A Putri ◽  
R Hermawan ◽  
L Karlinasari
Keyword(s):  
Built Environment ◽  
Thermal Comfort ◽  
Open Space ◽  
Positive Impact ◽  
Central Business District ◽  
High Humidity ◽  
Open Spaces ◽  
Temperature Conditions ◽  
Air Temperatures ◽  
Business District

Abstract It is obvious that an increase in the built environment in many major cities is not balanced with the availability of green open space causing environmental problems such as an increase in accumulative city temperature (e.g., urban heat island). Therefore, many initiatives have been implemented to integrate more green open spaces in an effort to deal with increasing air temperatures in cities, but baseline information on the positive impact on the built environment is still lacking. The objective of this study was to identify thermal comfort in green open spaces and built environments in a central business district. Basic microclimate variables and thermal humidity index (THI) were analyzed in three sites representing the district by also considering the distribution of green open spaces, buildings, and traffics. Results showed that in the morning, the average temperature at the three sampling points have a low temperature (T=27.77-28.50°C) with high humidity (RH=77.21-80.97%) and the THI value is quite comfortable (THI=26.72-27.22°C), while during the daytime, the temperature conditions at the three sites have high temperatures (T=31.37-33.04°C) with low humidity (RH=63.30-65.80%) and high THI values (THI=29.22-30.62°C). In the afternoon, the temperature conditions at the three sample points have a high enough temperature (T=29.70-30.61°C) and high humidity (RH=67.36-71.02%), while the THI value is only in point two, which is close to the quite comfortable category (THI=27.98°C), while other locations have a value THI=28.60°C and 28.62°C. The results of this study mark the presence of green open space with the trees in the district has a positive effect on decreasing air temperature and hence increasing environmental comfort. The addition and enrichment of trees can be done to increase thermal comfort in the built environment.

scholarly journals REGIONAL CLIMATE CHANGES IN NORTH-EASTERN POLAND AND THEIR IMPACT ON MAIZE CROPS

2021 ◽  
Vol 20 (1) ◽  
pp. 3-18
Author(s):  
Leszek Kuchar ◽  
◽  
Zbigniew Szwejkowski ◽  
Bogumił Rychcik ◽  
Ewa Dragańska ◽  
...  
Keyword(s):  
Climate Changes ◽  
Field Experiments ◽  
Linear Models ◽  
Meteorological Data ◽  
Regional Climate ◽  
Atmospheric Precipitation ◽  
Thermal Conditions ◽  
Maize Yield ◽  
Air Temperatures ◽  
Maize Varieties

Aim of the study. Indication of changes in maize yield for grain and silage in connection with the observed climate changes. Material and methods.Data from field experiments of the experimental station of the University of Warmia and Mazury since 1972 as well as meteorological data (air temperatures and precipitation). Calculations using the trend analysis of original variables and determined indexes (GDD, SPI, Sielianinov index), weather-yield linear models and elements of spectral analysis. Results and conclusions. Changes in thermal conditions were demonstrated based on average air temperatures and the GDD index. There were no significant changes in atmospheric precipitation, showing a small periodicity of ten years, and no changes in monthly frequency with a deficit of precipitation (SPI analysis). It was demonstrated that changes in thermal conditions as well as the introduction of new maize varieties over fifty years significantly improved plant maturation, which resulted in a significant increase in grain weight. However, this did not affect the yield of maize for silage, neither in crop rotation nor in the monoculture system.

scholarly journals Sea Breeze Front and Outdoor Thermal Comfort during Summer in Northeastern Brazil

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1013
Author(s):  
Max Anjos ◽  
António Lopes ◽  
Andrews José de Lucena ◽  
Francisco Mendonça
Keyword(s):  
Heat Stress ◽  
Thermal Comfort ◽  
Meteorological Data ◽  
Sea Breeze ◽  
Weather Conditions ◽  
Northeastern Brazil ◽  
Outdoor Thermal Comfort ◽  
Physiological Equivalent Temperature ◽  
Local Climate ◽  
Local Climate Zones

Characterizing the behaviour of the sea breeze phenomenon is the foremost factor in the reduction in the heat stress and the achievement of the pleasant environment in coastal cities globally. However, this seminal study shows that the Sea Breeze Front (SBF) development can be related to an increase in outdoor thermal discomfort in a northeastern Brazilian city during summer. We explored the relationship between SBF and thermal comfort conditions using in situ meteorological observations, the SBF identification method, local climate zones (LCZs) classification, and the Physiological Equivalent Temperature (PET) thermal comfort index. SBF days and Non-SBF days were characterized in terms of weather conditions, combining meteorological data and technical bulletins. SBF days included hot and sunny days associated with the centre of the Upper Tropospheric Cyclonic Vortices (UTCV). In contrast, Non-SBF days were observed in UTCV’s periphery because of cloudy sky and rainfall. The results showed that the mean temperature and PET in the SBF days were 2.0 °C and 3.8 °C higher, respectively, compared to Non-SBF days in all LCZ sites. The highest PET, of 40.0 °C, was found on SBF days. Our findings suggest that SBF development could be an aggravating factor for increasing heat stress of the people living in the northeastern coast of the Brazilian city, after SBF passage.

scholarly journals A Numerical Study on the Correlation between Sky View Factor and Summer Microclimate of Local Climate Zones

Atmosphere ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 438 ◽  
Author(s):  
Tong Lyu ◽  
Riccardo Buccolieri ◽  
Zhi Gao
Keyword(s):  
Wind Speed ◽  
Thermal Comfort ◽  
Numerical Study ◽  
Local Effect ◽  
Urban Morphology ◽  
View Factor ◽  
Urban Microclimate ◽  
Local Climate ◽  
Sky View Factor ◽  
Local Climate Zones

In the context of urbanization, research on urban microclimate and thermal comfort has become one of the themes of eco-city design. Sky view factor (SVF), one of the parameters of urban spatial form, combines multiple morphological information, such as plane opening, aspect ratio, and building density and has an important impact on the urban microclimate. However, there is still no clear research conclusion on the correlation between SVF and microclimate. In this paper, nine Local Climate Zone (LCZ) models are used and typical summer meteorological conditions of Nanjing are applied as an attempt to partially fill this gap. The calculated microclimate and thermal comfort indices include air temperature (AT), surface temperature (ST), relative humidity (RH), wind speed (WS), mean radiant temperature (MRT), and predicted mean vote (PMV). Results show that the local effect of urban morphology on thermal comfort can be retrieved from the use of comprehensive parameters such as SVF (which takes into account the building height, layout, and density) whose distribution in the investigated models showed to be correlated with MRT, so did PMV under low wind speed conditions.

scholarly journals Effects of Urban Configuration on Human Thermal Conditions in a Typical Tropical African Coastal City

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Emmanuel Lubango Ndetto ◽  
Andreas Matzarakis
Keyword(s):  
Thermal Comfort ◽  
Climate Model ◽  
Meteorological Data ◽  
Urban Climate ◽  
Thermal Conditions ◽  
Urban Street ◽  
Coastal City ◽  
Human Thermal Conditions ◽  
Comfort Parameters

A long-term simulation of urban climate was done using the easily available long-term meteorological data from a nearby synoptic station in a tropical coastal city of Dar es Salaam, Tanzania. The study aimed at determining the effects of buildings’ height and street orientations on human thermal conditions at pedestrian level. The urban configuration was represented by a typical urban street and a small urban park near the seaside. The simulations were conducted in the microscale applied climate model of RayMan, and results were interpreted in terms of the thermal comfort parameters of mean radiant (Tmrt) and physiologically equivalent (PET) temperatures. PET values, high as 34°C, are observed to prevail during the afternoons especially in the east-west oriented streets, and buildings’ height of 5 m has less effect on the thermal comfort. The optimal reduction ofTmrtand PET values for pedestrians was observed on the nearly north-south reoriented streets and with increased buildings’ height especially close to 100 m. Likewise, buildings close to the park enhance comfort conditions in the park through additional shadow. The study provides design implications and management of open spaces like urban parks in cities for the sake of improving thermal comfort conditions for pedestrians.

Determination of acceptable thermal range in outdoor built environments by various methods

2016 ◽  
Vol 5 (4) ◽  
pp. 352-371 ◽  
Author(s):  
Salman Shooshtarian ◽  
Ian Ridley
Keyword(s):  
Comparative Analysis ◽  
Thermal Comfort ◽  
Thermal Conditions ◽  
Outdoor Thermal Comfort ◽  
Built Environments ◽  
Direct Measure ◽  
Thermal Perception ◽  
Content Type ◽  
Thermal Range ◽  
Indirect Measures

Purpose Assessment of outdoor thermal perception in urban spaces is of particular importance due to its financial, social and ecological consequences. Thermal perception includes four elements: thermal sensation votes (TSV), thermal preference (Tpref), overall thermal comfort (Tc) and thermal acceptability (Taccept). Thermal acceptability can offer a benchmark that specifies the acceptable thermal range (ATR), which is useful for urban planners, designers, and bio-meteorologists. ATR, however, can be defined either using direct or indirect measures. The purpose of this paper is to investigate the validity of the indirect measures of ATR, which are most commonly used in outdoor thermal comfort assessments. Design/methodology/approach This study was conducted in the context of Melbourne, which has an oceanic temperate climate (Cfb). Three sites forming RMIT University City Campus (RUCC) were selected as the case studies, which were located in the heart of Melbourne Central Business District. A field survey was conducted in RUCC during three seasons, from November 2014 (Spring) to May 2015 (Autumn), which consisted of concurrent field measurements and questionnaire surveys from 9:00 a.m. to 5:00 p.m. Findings In total, 1,059 valid questionnaires were collected from the three sites of RUCC. The results of comparative analysis between the different measures of ATR determination showed that the various elements of thermal perceptions expressed the users’ thermal judgements in different ways. Therefore, it was found that the instruction recommended by the thermal comfort standards on the definition of ATR failed to provide an appropriate estimation of ATR for outdoor built environments. The ATR, defined using TSV, therefore, was revised by the direct measure of thermal acceptability. The resulting range showed broader limits in acceptable thermal conditions in RUCC outdoor spaces users. Lastly, the results suggest that in the absence of directly measured acceptability of thermal conditions in field surveys, overall comfort is the most appropriate indirect measure to use. Originality/value Some indoor thermal comfort studies have used the alternatives for defining ATR. However, as the applicability of these four methods is yet to be fully explored in outdoor conditions with large weather variations, it is valuable to conduct a comparative analysis among these methods. This study also intended to understand the dynamics of comfort range under non-steady and non-uniform outdoor conditions. The resultant outcome has provided information on the relationship between different measures of thermal perceptions. Ultimately, this research aimed to explore the extent to which the indirect measures of acceptability are considered as a reliable source of information compared to the direct measure.

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