scholarly journals Evaluating the Effectiveness of Mitigation Options on Heat Stress for Sydney, Australia

2018 ◽  
Vol 57 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Shaoxiu Ma ◽  
Andy Pitman ◽  
Jiachuan Yang ◽  
Claire Carouge ◽  
Jason P. Evans ◽  
...  
Keyword(s):  
Heat Stress ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Ambient Air ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Ambient Air Temperature ◽  
Populations At Risk ◽  
Urban Heat

AbstractGlobal warming, in combination with the urban heat island effect, is increasing the temperature in cities. These changes increase the risk of heat stress for millions of city dwellers. Given the large populations at risk, a variety of mitigation strategies have been proposed to cool cities—including strategies that aim to reduce the ambient air temperature. This paper uses common heat stress metrics to evaluate the performance of several urban heat island mitigation strategies. The authors found that cooling via reducing net radiation or increasing irrigated vegetation in parks or on green roofs did reduce ambient air temperature. However, a lower air temperature did not necessarily lead to less heat stress because both temperature and humidity are important factors in determining human thermal comfort. Specifically, cooling the surface via evaporation through the use of irrigation increased humidity—consequently, the net impact on human comfort of any cooling was negligible. This result suggests that urban cooling strategies must aim to reduce ambient air temperatures without increasing humidity, for example via the deployment of solar panels over roofs or via cool roofs utilizing high albedos, in order to combat human heat stress in the urban environment.

Urban Heat Island Intensity in Chiang Mai City Using Mobile Surveying Approach

2014 ◽  
Vol 931-932 ◽  
pp. 605-613
Author(s):  
Pisut Sangnum ◽  
Niti Kammuang-Lue ◽  
P. Sakulchangsatjatai ◽  
P. Terdtoon
Keyword(s):  
Population Density ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Ambient Air ◽  
Urban Heat Island Intensity ◽  
Traffic Density ◽  
Heat Island ◽  
Chiang Mai ◽  
Ambient Air Temperature ◽  
Urban Heat

This research aims to evaluate on Urban Heat Island Intensity in Chiang Mai city and to study effects of population density, building density and traffic density on ambient air temperature. The ambient air temperature was measured by thermocouples at a constant altitude of 2 m above the road. The surveyed routes were divided to urban routes and rural routes. The Urban Heat Island Intensity (UHII) was calculated from an average ambient air temperature difference between urban and rural areas. Experimental investigations were carried out in 2 periods, which were a day time (12.30-02.30 pm) and a night time (10.00 pm-00.00 am) on Monday, Wednesday, and Sunday in summer time (March-May, 2013). The results show that the UHII in Chiang Mai city in a day time is +1.1 °C and in a night time is +1.3 °C. Moreover, the population density, building density and traffic density were found to have significant effects on ambient air temperature, especially the population density and building density have direct effect on ambient air temperature. However, the traffic density has direct effect on ambient air temperature only in a day time.

scholarly journals Green Infrastructure as an Urban Heat Island Mitigation Strategy—A Review

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3577
Author(s):  
Fatma Balany ◽  
Anne WM Ng ◽  
Nitin Muttil ◽  
Shobha Muthukumaran ◽  
Man Sing Wong
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Green Infrastructure ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Recent Past ◽  
Simulation Tools ◽  
Human Thermal Comfort ◽  
Different Types ◽  
Urban Heat

Research on urban heat mitigation has been growing in recent years with many of the studies focusing on green infrastructure (GI) as a strategy to mitigate the adverse effects of an urban heat island (UHI). This paper aims at presenting a review of the range of findings from GI research for urban heat mitigation through a review of scientific articles published during the years 2009–2020. This research includes a review of the different types of GI and its contribution for urban heat mitigation and human thermal comfort. In addition to analysing different mitigation strategies, numerical simulation tools that are commonly used are also reviewed. It is seen that ENVI-met is one of the modelling tools that is considered as a reliable to simulate different mitigation strategies and hence has been widely used in the recent past. Considering its popularity in urban microclimate studies, this article also provides a review of ENVI-met simulation results that were reported in the reviewed papers. It was observed that the majority of the research was conducted on a limited spatial scale and focused on temperature and human thermal comfort.

Can climate adaptation solutions fix the urban heat island? An assessment of the thermal conditions during heat waves in Vienna impacted by climate change and urban development scenarios for the mid-21st-century

2020 ◽  
Author(s):  
Paul Hamer ◽  
Heidelinde Trimmel ◽  
Philipp Weihs ◽  
Stéphanie Faroux ◽  
Herbert Formayer ◽  
...  
Keyword(s):  
Climate Change ◽  
Urban Heat Island ◽  
Heat Wave ◽  
Air Temperature ◽  
Urban Areas ◽  
Climate Adaptation ◽  
Heat Waves ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Urban Heat

<p>Climate change threatens to exacerbate existing problems in urban areas arising from the urban heat island. Furthermore, expansion of urban areas and rising urban populations will increase the numbers of people exposed to hazards in these vulnerable areas. We therefore urgently need study of these environments and in-depth assessment of potential climate adaptation measures.</p><p>We present a study of heat wave impacts across the urban landscape of Vienna for different future development pathways and for both present and future climatic conditions. We have created two different urban development scenarios that estimate potential urban sprawl and optimized development concerning future building construction in Vienna and have built a digital representation of each within the Town Energy Balance (TEB) urban surface model. In addition, we select two heat waves of similar frequency of return representative for present and future conditions (following the RCP8.5 scenario) of the mid 21<sup>st</sup> century and use the Weather Research and Forecasting Model (WRF) to simulate both heat wave events. We then couple the two representations urban Vienna in TEB with the WRF heat wave simulations to estimate air temperature, surface temperatures and human thermal comfort during the heat waves. We then identify and apply a set of adaptation measures within TEB to try to identify potential solutions to the problems associated with the urban heat island.</p><p>Global and regional climate change under the RCP8.5 scenario causes the future heat wave to be more severe showing an increase of daily maximum air temperature in Vienna by 7 K; the daily minimum air temperature will increase by 2-4 K. We find that changes caused by urban growth or densification mainly affect air temperature and human thermal comfort local to where new urbanisation takes place and does not occur significantly in the existing central districts.</p><p>Exploring adaptation solutions, we find that a combination of near zero-energy standards and increasing albedo of building materials on the city scale accomplishes a maximum reduction of urban canyon temperature of 0.9 K for the minima and 0.2 K for the maxima. Local scale changes of different adaption measures show that insulation of buildings alone increases the maximum wall surface temperatures by more than 10 K or the maximum mean radiant temperature (MRT) in the canyon by 5 K.  Therefore, additional adaptation to reduce MRT within the urban canyons like tree shade are needed to complement the proposed measures.</p><p>This study concludes that the rising air temperatures expected by climate change puts an unprecedented heat burden on Viennese inhabitants, which cannot easily be reduced by measures concerning buildings within the city itself. Additionally, measures such as planting trees to provide shade, regional water sensitive planning and global reduction of greenhouse gas emissions in order to reduce temperature extremes are required.</p><p>We are now actively seeking to apply this set of tools to a wider set of cases in order to try to find effective solutions to projected warming resulting from climate change in urban areas.</p>

scholarly journals Global long-term mapping of surface temperature shows intensified intra-city urban heat island extremes

2021 ◽  
Author(s):  
Lorenzo Mentaschi ◽  
Gregory Duveiller ◽  
Grazia Zulian ◽  
Christina Corbane ◽  
Martino Pesaresi ◽  
...  
Keyword(s):  
Heat Stress ◽  
Surface Temperature ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Human Impacts ◽  
Warm Season ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Urban Heat

Abstract Surface temperatures are generally higher in cities than in rural surroundings. This phenomenon, known as surface urban heat island (SUHI), increases the risk of heat-related human illnesses and mortality. Past global studies analysed this phenomenon aggregated at city scale or over seasonal and annual time periods, while human impacts strongly depend on shorter term heat stress experienced locally. Here we develop a global long-term high-resolution dataset of daytime SUHI as urban-rural surface temperature differences. Our results show that across urban areas worldwide over the period 2003-2020, 3-day SUHI extremes are on average more than twice as high as the warm-season median SUHI, with local exceedances up to 10 K. Over this period, SUHI extremes have increased more rapidly than warm-season medians, and averaged worldwide are now 1.04 K or 31% higher compared to 2003. This can be linked with increasing urbanisation, more frequent heatwaves, and greening of the earth, processes that are all expected to continue in the coming decades. Within many cities there are hotspots where extreme SUHI intensity is 10 to 15 K higher compared to relatively cooler city parts. Given the limited human adaptability to heat stress, our results advocate for mitigation strategies targeted at reducing SUHI extremes in the most vulnerable and exposed city neighbourhoods.

scholarly journals Retrofitting solutions for a campus building to mitigate urban heat island in a hot humid climate

2021 ◽  
Vol 2042 (1) ◽  
pp. 012062
Author(s):  
Vajreshwari Patil ◽  
Maite Bizcarguenaga ◽  
Katherine Lieberknecht ◽  
Juliana Felkner
Keyword(s):  
Surface Temperature ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Ambient Air ◽  
Cooling Effect ◽  
Heat Island ◽  
Humid Climate ◽  
Temperature Reduction ◽  
Urban Heat ◽  
Hot Humid Climate

Abstract In this study we examine the summer cooling effects of trees and green facades on reducing urban heat island effects. Using ENVI-met model simulations, we investigate the influence of added greenery on the surface and ambient air temperature and its role on air fluctuations in the hot humid climate of Austin, TX, at pedestrian height. Under the specific conditions considered in this model, the results show the combination of trees and green facades has a greater cooling effect. Added greenery to the building mostly impacts the building's surface temperature during the hottest hours of the day, registering a maximum surface temperature reduction of 20.33°C. Simulations also show a maximum overall potential air temperature reduction of 0.54°C, and a maximum potential air temperature cooling effect near the building of 0.91°C. Future research should be conducted to address this study's limitations. Nevertheless, these findings can provide architects, designers, planners, and policymakers with a better understanding of the many benefits trees and green facades have, and provide them with the necessary tools to implement new solutions across sectors and scales to reduce the impacts urban areas have on the environment and provide a better living for all.

scholarly journals Green Infrastructure as an Urban Heat Island Mitigation Strategy - A Review

2020 ◽  
Author(s):  
Fatma balany ◽  
A.W.M Ng ◽  
Nitin Muttil ◽  
Shobha Muthukumaran ◽  
Man Sing Wong
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Green Infrastructure ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Recent Past ◽  
Simulation Tools ◽  
Human Thermal Comfort ◽  
Different Types ◽  
Urban Heat

Research on urban heat mitigation has been growing in recent years with many of the studies focusing on green infrastructure (GI) as a strategy to mitigate the adverse effects of Urban Heat Island (UHI). This paper aims at presenting a review of the range of findings from GI research for urban heat mitigation through a review of scientific articles published during the years 2009-2019. This research includes a review of the different types of GI and its contribution for urban heat mitigation and human thermal comfort. In addition to analyzing different mitigation strategies, numerical simulation tools that are commonly used are also reviewed. It is seen that ENVI-met is one of the modelling tools that is considered as a reliable tool to simulate different mitigation strategies and hence has been widely used in the recent past. Considering its popularity in urban microclimate studies, this article also provides a review of ENVI-met simulation results that were reported in the reviewed papers. It was observed that the majority of the research was conducted on a limited spatial scale and focused on temperature and human thermal comfort.

OVERVIEW OF URBAN HEAT ISLAND (UHI) PHENOMENON TOWARDS HUMAN THERMAL COMFORT

2017 ◽  
Vol 16 (9) ◽  
pp. 2097-2111 ◽  
Author(s):  
Mohanadoss Ponraj ◽  
Yee Yong Lee ◽  
Mohd Fadhil Md Din ◽  
Zainura Zainon Noor ◽  
Kenzo Iwao ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Urban Heat

scholarly journals Combating Urban Heat Island Effect—A Review of Reflective Pavements and Tree Shading Strategies

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 93
Author(s):  
V. R. Sankar Cheela ◽  
Michele John ◽  
Wahidul Biswas ◽  
Prabir Sarker
Keyword(s):  
Urban Heat Island ◽  
Urban Forest ◽  
Critical Role ◽  
Tree Canopy ◽  
Mitigation Measures ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Urban Heat ◽  
Pavement Temperature ◽  
Reflective Coatings

Pavements occupy about 40% of urban land cover, with 75–80% black top roads, playing a critical role in urban connectivity and mobility. Solar energy is absorbed and stored in pavements leading to an increase in surface temperatures. Decreasing green cover is further contributing to rise in regional temperatures. Due to this activity, the city experiences urban heat island (UHI). This study presents a critical review of the literature on mitigation measures to combat UHI using reflective pavements with an emphasis on durability properties and impacts of tree canopy. The strategies with a focus on application of chip seals, white toppings, and coatings were discussed. Role of surface reflectance, including those from asphalt and concrete pavements, albedo improvements, and technological trends, application of waste materials, and industrial by‐products are presented. Also, urban tree shading systems’ contribution to pavement temperature and microclimate systems is presented. The review shows that the development of mitigation measures using tree shading systems can reduce the pavement temperature during daytime and increase human thermal comfort. The outcomes of this review provide a scope for future studies to develop sustainable and state‐of‐the-art engineering solutions in the field of reflective coatings and urban forest systems.

scholarly journals Patterns of Urban Heat Island Effect in Adelaide: A Mobile Traverse Experiment

2017 ◽  
Vol 11 (4) ◽  
pp. 80
Author(s):  
Ehsan Sharifi ◽  
Ali Soltani
Keyword(s):  
Heat Stress ◽  
Urban Heat Island ◽  
Urban Policy ◽  
Urban Heat Island Effect ◽  
Urban Structure ◽  
Heat Island ◽  
Near Surface ◽  
Island Effect ◽  
Urban Rural ◽  
Urban Heat

Urban structure, hard surfaces and shortage of vegetation cause an artificial temperature increase in cities, known as the urban heat island effect. This paper determines the daily patterns of urban heat in Adelaide, Australia. The near-surface temperature profile of Adelaide was mapped in 60 journeys alongside a straight cross route connecting Adelaide Hills to the West Beach between 26 July and 15 August 2013. Results indicate that the most intense urban-rural temperature differences occurred during midnight in Adelaide. However, the afternoon urban heat had more temperature variation in the urban area. In the late afternoon, the near-surface urban heat fluctuates by 2°C within three kilometres and by 1.2°C in just one kilometer. Afternoon heat stress can vary based on space configurations and urban surface covers. Afternoon heat stress causes the highest heat load on urban dwellers. A better understanding of daily urban heat variations in cities assists urban policy making and public life management in the context of climate change.

Sign in / Sign up

Export Citation Format

Share Document