scholarly journals Performance of Different Urban Design Parameters in Improving Outdoor Thermal Comfort and Health in a Pedestrianized Zone

2020 ◽  
Vol 17 (7) ◽  
pp. 2258 ◽  
Author(s):  
Xuan Ma ◽  
Mengying Wang ◽  
Jingyuan Zhao ◽  
Lei Zhang ◽  
Wanrong Liu
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Global Climate ◽  
Urban Heat Islands ◽  
Outdoor Thermal Comfort ◽  
Design Parameters ◽  
Daily Lives ◽  
Heat Islands ◽  
Outdoor Thermal Environment ◽  
Urban Heat

Global climate change and urban heat islands have generated heat stress in summer, which does harm to people’s health. The outdoor public commercial pedestrianized zone has an important role in people’s daily lives, and the utilization of this space is evaluated by their outdoor thermal comfort and health. Using microclimatic monitoring and numerical simulation in a commercial pedestrianized zone in Tai Zhou, China, this study investigates people’s outdoor thermal comfort in extreme summer heat. The final results provide a comprehensive system for assessing how to improve outdoor human thermal health. Under the guidance of this system, local managers can select the most effective strategy to improve the outdoor thermal environment.

Local ventilation and its impacts on urban heat islands and outdoor thermal comfort

2021 ◽  
Author(s):  
Bao-Jie He
Keyword(s):  
Thermal Comfort ◽  
Velocity Ratio ◽  
Sea Breeze ◽  
Urban Heat Islands ◽  
Outdoor Thermal Comfort ◽  
Heat Islands ◽  
Local Ventilation ◽  
Urban Heat ◽  
Ventilation Performance ◽  
Relative Wind

<p>Many cities are facing urban overheating issues where the reduction of urban ventilation is one of the key drivers. To address the urban overheating problems, this study concentrates on the analysis of local-scale urban ventilation and its impacts of urban heat islands and outdoor thermal comfort, in order to support wind-sensitive urban planning and design. To achieve this, this study develops a framework for analysing local ventilation, urban heat islands and outdoor thermal comfort with the consideration of local morphological characteristics, external meteorological conditions, local ventilation performance, urban heat islands and outdoor thermal comfort. In particular, the consideration of local morphological characteristics is supported by the development of precinct morphology classification scheme based on three-component protocol of building height, street structure and compactness. Based on the three-component protocol, 20 types of the local ventilation zones were identified in the context of Greater Sydney, Australia.</p><p>Field measurement was conducted in three typical local ventilation zones, including open low-rise gridiron, open midrise gridiron and compact high-rise gridiron among the 20, to examine the local ventilation performance, urban heat islands and outdoor thermal comfort in summer 2019. The results indicate that the open midrise gridiron precinct underwent the best precinct ventilation performance, followed by the low-rise gridiron precinct and then the compact high-rise gridiron precinct. The local ventilation created by the sea breeze can help alleviate urban heat islands in the open low-rise gridiron and compact high-rise gridiron precincts with every 0.1 increase in relative wind velocity ratio leading to a 0.09-0.12 °C reduction in UHI intensity. However, in the open midrise gridiron precinct, the local ventilation created by the sea breeze made no difference for urban heat islands. However, the precinct ventilation of the open midrise gridiron precinct still partially exhibited UHI alleviation potential with every 0.1 increase in relative wind velocity ratio leading to a 0.06-0.1 °C reduction in UHI intensity depending on the approaching wind temperature and shading conditions.</p><p>Only the precinct ventilation of the open low-rise gridiron precinct leads to outdoor thermal comfort improvement with every 0.1 increase in relative wind velocity ratio leading to 0.29 °C and 0.50 °C physiological equivalent temperature reductions under sea breeze and varying wind conditions, respectively. The results also indicate that within ‘gridiron’ precincts, street orientation is not critical to precinct ventilation performance and its impact on urban heat islands and outdoor thermal comfort. Under wind conditions, trees do not always alleviate urban heat islands and improve outdoor thermal comfort as trees can block sea breeze penetration and inhibit wind cooling potential. These key findings will serve to inform urban heat island mitigation strategies and future planning and design decisions in the built environment.</p>

scholarly journals Characterizing the Hourly Variation of Urban Heat Islands in a Snowy Climate City during Summer

2019 ◽  
Vol 16 (14) ◽  
pp. 2467 ◽  
Author(s):  
Chaobin Yang ◽  
Ranghu Wang ◽  
Shuwen Zhang ◽  
Caoxiang Ji ◽  
Xie Fu
Keyword(s):  
Land Use ◽  
Urban Area ◽  
Air Temperature ◽  
Temporal Variability ◽  
Spatial Information ◽  
Thermal Environment ◽  
Thermal Characteristics ◽  
Urban Heat Islands ◽  
Heat Islands ◽  
Urban Heat

Temporal variation of urban heat island (UHI) intensity is one of the most important themes in UHI studies. However, fine-scale temporal variability of UHI with explicit spatial information is sparse in the literature. Based on the hourly air temperature from 195 meteorological stations during August 2015 in Changchun, China, hourly spatiotemporal patterns of UHI were mapped to explore the temporal variability and the effects of land use on the thermal environment using time series analysis, air temperature profiling, and spatial analysis. The results showed that: (1) high air temperature does not indicate strong UHI intensity. The nighttime UHI intensity (1.51 °C) was much stronger than that in the daytime (0.49 °C). (2) The urban area was the hottest during most of the day except the period from late morning to around 13:00 when there was about a 40% possibility for an “inverse UHI intensity” to appear. Paddy land was the coolest in the daytime, while woodland had the lowest temperature during the nighttime. (3) The rural area had higher warming and cooling rates than the urban area after sunrise and sunset. It appeared that 23 °C was the threshold at which the thermal characteristics of different land use types changed significantly.

scholarly journals Inclusion of vegetation in the Town Energy Balance model for modeling urban green areas

2012 ◽  
Vol 5 (2) ◽  
pp. 1295-1340 ◽  
Author(s):  
A. Lemonsu ◽  
V. Masson ◽  
L. Shashua-Bar ◽  
E. Erell ◽  
D. Pearlmutter
Keyword(s):  
Global Climate ◽  
A Priori ◽  
Urban Canopy ◽  
Bare Soil ◽  
Urban Heat Islands ◽  
Balance Model ◽  
Local Climate ◽  
Heat Islands ◽  
Planning Strategy ◽  
Urban Heat

Abstract. Cities impact both local climate, through urban heat islands, and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representation into urban models will allow to address more accurately these questions. This paper presents an improvement of the TEB urban canopy model. Vegetation is directly included inside the canyon, allowing shadowing of grass by buildings, better representation of urban canopy form, and, a priori, a more accurate simulation of canyon air microclimate. The development is performed so that any vegetation model can be used to represent the vegetation part. Here the ISBA model is used. The model results are compared to microclimatic and evaporation measurements performed in small courtyards in a very arid region of Israel. Two experimental landscaping strategies – bare soil or irrigated grass in the courtyard – are observed and simulated. The new version of the model with integrated vegetation performs better than if vegetation is treated outside the canyon. Surface temperatures are closer to the observations, especially at night when radiative trapping is important. The integrated vegetation version simulates a more humid air inside the canyon. The microclimatic quantities are better simulated with this new version. This opens opportunities to study with better accuracy the urban microclimate, down to the micro (or canyon) scale.

scholarly journals Pet Welfare in Municipal Adaptation Plans: Case of Poland

2021 ◽  
Vol 30 (3) ◽  
pp. 95-107
Author(s):  
Anna Haładyj ◽  
Katarzyna Kułak-Krzysiak
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Thermal Comfort ◽  
Urban Heat Islands ◽  
Adaptation Measures ◽  
Main Hypothesis ◽  
Heat Islands ◽  
Starting Point ◽  
Legal Nature ◽  
Urban Heat

The aim of the article was to explore pet welfare in Municipal Adaptation Plans (MAPs), based on a literature review and case studies of 40 MAPs accepted in Poland as part of the “Let’s Feel the Climate” project, supported by the Polish Ministry of Environment in 2017–2019. The study summarizes the concept of climate change and the importance of adaptation measures with particular emphasis on urban heat islands and heat stress, acknowledged by climate change literature, and outlines pet welfare in the context of thermal comfort and threats caused by heat stress. Because the authors subsequently presented an empirical study of the 40 accepted MAPs, they also discussed the role and legal nature of MAPs. The main hypothesis of this survey of Polish MAPs was that pet welfare in the context of their thermal comfort is an example of the adaptive measures clearly stipulated in Polish MAPs, which was examined after presenting the MAPs’ findings. The starting point was the assumption that the welfare of pets should also be assessed from the perspective of their thermal comfort – a new element of broadly understood animal welfare. This is due to the fact that pets are exposed to the risk of heat stress resulting from urban heat islands and, just like people, have to endure the inconvenience of extreme weather phenomena, which is impossible without the support of amenities such as drinkers or water shelters and the development of green and blue infrastructure.

Study on Outdoor and Semi-Outdoor Thermal Comfort of College Campus in Central Taiwan

2014 ◽  
Vol 1030-1032 ◽  
pp. 624-628
Author(s):  
Wen Pei Sung ◽  
Shih Tai Hu ◽  
Yu Kuang Zhao ◽  
Lei Wei
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Outdoor Environment ◽  
Outdoor Thermal Comfort ◽  
Small Island ◽  
Air Conditioner ◽  
Subtropical Zone ◽  
Outdoor Thermal Environment ◽  
Outdoor Comfort ◽  
Central Taiwan

Taiwan is a small island. Some of college campuses are very tiny with large hard pavement to cause un-comfortable outdoor environment. Most of faculty and students like to stay at classroom and use air-conditioner to establish comfort thermal environment. Thus, the outdoor and semi-outdoor thermal equipments are used to detect the parameters of weather. The test and analysis results show that hard pavements cause the un-comfortable outdoor comfort. Mean Radiant Temperatures of grass in summer is higher than the other pavement because that grass pavement is lack of moisture to causes bad outdoor thermal comfort. Therefore, the fine outdoor and semi-outdoor thermal comfort environment should consider the permeable pavement and grass with suitable moisture to cause better outdoor thermal environment and large arbores should be planted widely in campus to establish a better semi-outdoor thermal temperature in campus of the subtropical zone.

scholarly journals Local Climate Zones for Urban Temperature Studies

2012 ◽  
Vol 93 (12) ◽  
pp. 1879-1900 ◽  
Author(s):  
I. D. Stewart ◽  
T. R. Oke
Keyword(s):  
Surface Characterization ◽  
Global Climate ◽  
Urban Heat Islands ◽  
Local Climate ◽  
Heat Islands ◽  
Local Climate Zones ◽  
Thermal Climate ◽  
Urban Rural ◽  
Urban Heat

The effect of urban development on local thermal climate is widely documented in scientific literature. Observations of urban–rural air temperature differences—or urban heat islands (UHIs)—have been reported for cities and regions worldwide, often with local field sites that are extremely diverse in their physical and climatological characteristics. These sites are usually described only as “urban” or “rural,” leaving much uncertainty about the actual exposure and land cover of the sites. To address the inadequacies of urban–rural description, the “local climate zone” (LCZ) classification system has been developed. The LCZ system comprises 17 zone types at the local scale (102 to 104 m). Each type is unique in its combination of surface structure, cover, and human activity. Classification of sites into appropriate LCZs requires basic metadata and surface characterization. The zone definitions provide a standard framework for reporting and comparing field sites and their temperature observations. The LCZ system is designed primarily for urban heat island researchers, but it has derivative uses for city planners, landscape ecologists, and global climate change investigators.

The Benefits of Tree Shade and Turf on Globe and Surface Temperatures in an Urban Tropical Environment

2020 ◽  
Vol 46 (3) ◽  
pp. 228-244
Author(s):  
Lai Fern Ow ◽  
Subhadip Ghosh ◽  
Mohamed Lokman Mohd Yusof
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Mitigation Strategies ◽  
Urban Heat Islands ◽  
Outdoor Thermal Comfort ◽  
Mitigation Measures ◽  
Heat Islands ◽  
Ambient Temperatures ◽  
Surface Temperatures ◽  
Island State

The process of urbanisation increases temperature and alters the thermal comfort in cities. Urban heat islands (UHIs) result in the rise of ambient temperatures. For example, in the densely populated island state of Singapore, the UHI intensity was some 4.5 °C. Such elevation in heat can negatively impact outdoor thermal comfort and may give rise to serious health problems. The present study investigated the benefits of trees and turf as mitigation strategies for urban areas. Short- and long-term observations were made for surface and globe temperatures over smaller plots of vegetation and hard surfaces involving tree shade and full sun. Similar observations were investigated over a larger extent of vegetation across concrete, asphalt, and turf within an urban park setting. The presence of turf and shade from trees greatly affected surface temperatures, and the effect was most pronounced when both were present. The presence of turf reduced surface temperatures by up to 10 °C, while tree shade led to a 12 °C reduction. Globe temperatures showed that the presence of turf and shading reduced temperatures between 5 and 10 °C. These results suggest that turf and trees can effectively cool surfaces and improve outdoor thermal comfort. The results of this study can be applied to urban planning of greenery and can be used as a reference for other tropical cities with similar climates that are also working to develop mitigation measures to improve the liveability of their cities.

scholarly journals Urban Heat Island: Summer Outdoor Climate Measurement Within the University Campus and City

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Peter Juras
Keyword(s):  
Global Climate ◽  
Urban Heat Islands ◽  
University Campus ◽  
Heat Islands ◽  
Outdoor Climate ◽  
Air Temperatures ◽  
Urban Heat ◽  
Weather Stations ◽  
The Difference ◽  
The University

Abstract Work of researchers from various areas is focused on problematics of urban heat islands. Its importance is rising with the global climate change. The difference of the air temperatures within the area can be also caused by the measurement error. Usual error is not the accuracy of the sensor, but the radiation shield or location of the weather station. In this case, averaged difference can be up to 80 %. Difference of temperatures between the weather stations within the analyzed area can vary from 0.2 up to 6 °C. Difference depends usual on the size of the city and the location influenced by the surrounding geomorphology. In this paper three different radiation shields are compared which influenced the measurement and analyzed are also the results from four different weather stations, two of them are within the University of Zilina campus. One of them is placed on the roof, which is a usual location for the solar radiation measurement; the second one is placed on the grass land at the end of the campus. Other two stations belong to the national weather institute. Comparison is made for two very hot days of August 2020. Averaged difference was 0.3 °C for the whole month and 0.5 °C for selected days.

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