scholarly journals Mitigation measures for urban heat island and their impact on pedestrian thermal comfort

2021 ◽  
Vol 2069 (1) ◽  
pp. 012058
Author(s):  
A Kubilay ◽  
D Strebel ◽  
D Derome ◽  
J Carmeliet
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Coupled Model ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
Heat Island ◽  
Heat And Moisture Transport ◽  
Urban Heat ◽  
Urban Square ◽  
Heat And Moisture

Abstract A multiscale coupled model is presented that allows for the detailed analysis of the local impact of urban heat island mitigation measures. The model uses coupled computational fluid dynamics (CFD) simulations with unsteady heat and moisture transport (HAM) in porous urban materials in order to take into account the dynamic heat and moisture storage in the built environment. A realistic case study is performed for a public urban square in the City of Zurich during heat wave conditions. The impacts of two different mitigation strategies, i.e. adding artificial wetting of pavements and adding vegetation, on pedestrian thermal comfort are evaluated and compared with the existing situation. The results show an improvement in thermal comfort in both conditions. The improvement resulting from the addition of trees is larger and lasts longer due to shadowing effects, even though a reduced ventilation and an increased relative humidity by trees have an adverse effect on the thermal comfort.

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.

scholarly journals Spatial Superposition Method via Model Coupling for Urban Heat Island Albedo Mitigation Strategies

2012 ◽  
Vol 51 (11) ◽  
pp. 1971-1979 ◽  
Author(s):  
Humberto Silva ◽  
Jay S. Golden
Keyword(s):  
Urban Heat Island ◽  
Mesoscale Model ◽  
Coupled Model ◽  
Mitigation Strategies ◽  
Turbulence Theory ◽  
Superposition Method ◽  
Heat Island ◽  
Lumped Model ◽  
Hourly Temperature ◽  
Urban Heat

AbstractA spatial superposition design is presented that couples the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) with the National Center of Excellence (NCE) lumped urban thermal model for application to the city of Phoenix, Arizona. This technique utilizes an approach similar to Reynolds decomposition from turbulence theory. The presented decomposition takes the NCE model prediction from a mitigated strategy as the mean temperature and the difference between the NCE and MM5 predictions without mitigation strategy as the perturbed temperature. The goal of this coupled model is to provide spatial variability when simulating mitigation strategies for the urban heat island effect, as compared with the spatially invariant lumped model. A validation analysis was performed incorporating a maximum 35% change from the baseline albedo value for the urban environment. It is shown that the coupled model differs by up to 0.39°C with comparable average surface temperature predictions from MM5. The coupled model was also used to perform analysis of three different albedo-driven spatial mitigation schemes. This resulted in the identification that having a lesser number of mitigated points on a square urban grid in Phoenix with the same average albedo leads to a greater reduction in average hourly temperature.

scholarly journals Willingness to Pay for Urban Heat Island Mitigation: A Case Study of Singapore

Climate ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 82
Author(s):  
Natalia Borzino ◽  
Samuel Chng ◽  
Muhammad Omer Mughal ◽  
Renate Schubert
Keyword(s):  
Willingness To Pay ◽  
Urban Heat Island ◽  
Survey Design ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
Heat Island ◽  
Related Information ◽  
Policy Interventions ◽  
Positive Attitudes ◽  
Urban Heat

In many countries, urban heat island (UHI) effects come along with urbanization in metropolitan areas. They have relevant adverse effects on the health and wellbeing of citizens. Singapore is strongly affected by UHI. In this study, we assess Singaporeans’ willingness to pay (WTP) for UHI mitigation by implementing a contingent valuation analysis. Specifically, we employ a double-bounded dichotomous survey design on a representative sample of 1822 online respondents. We find that Singaporeans are willing to sacrifice on average 0.43% of their annual income to mitigate UHI. The total WTP for mitigation strategies among Singapore citizens and permanent residents is estimated at SGD$783.08 million per year, the equivalent of USD$563.80 per year. Our findings suggest that there is a positive and significant relationship between the size of UHI effects and the citizens’ WTP. People living in the region with the highest intensity of UHI are willing to pay 3.09 times more than those living in the region with the lowest UHI intensity. Furthermore, demographic and socio-economic characteristics are significant determinants of Singaporeans’ WTP. The WTP increases with income and education but decreases with age. Students, men, and people with children are willing to pay more. Additional analyses show that the level of UHI awareness, positive attitudes towards UHI mitigation strategies as well as preferences for outdoor activities are positively correlated with the WTP. Our findings suggest that citizens are aware of the impacts of UHI and support UHI mitigation measures to be financed by their taxes. Policy interventions to promote UHI-related education and disseminating UHI-related information might increase the support of UHI mitigation policies.

scholarly journals Development of a Zero-Dimensional Mesoscale Thermal Model for Urban Climate

2009 ◽  
Vol 48 (3) ◽  
pp. 657-668 ◽  
Author(s):  
Humberto R. Silva ◽  
Rahul Bhardwaj ◽  
Patrick E. Phelan ◽  
Jay S. Golden ◽  
Susanne Grossman-Clarke
Keyword(s):  
Energy Balance ◽  
Urban Heat Island ◽  
Mitigation Strategies ◽  
Anthropogenic Heat ◽  
Mitigation Measures ◽  
Balance Model ◽  
Time Range ◽  
Heat Island ◽  
Time Step ◽  
Urban Heat

Abstract A simple energy balance model is created for use in developing mitigation strategies for the urban heat island effect. The model is initially applied to the city of Phoenix, Arizona. There are six primary contributions to the overall energy balance: incident solar radiation, anthropogenic heat input, conduction heat loss, outgoing evapotranspiration, outgoing convection, and outgoing emitted radiation. Meteorological data are input to the model, which then computes an urban characteristic temperature at a calculated time step for a specified time range. The model temperature is shown to have the same periodic behavior as the experimentally measured air temperatures. Predicted temperature changes, caused by increasing the average urban albedo, agree within 0.1°C with comparable maximum surface temperature predictions from the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5). The present model, while maintaining valid energy-balance physics, allows users to quickly and easily predict the relative effects of urban heat island mitigation measures. Representative mitigation strategies, namely changes in average albedo and long-wavelength emissivity are presented here. Increasing the albedo leads to the greater reduction in daytime maximum temperatures; increasing the emissivity leads to a greater reduction in nighttime minimum temperatures.

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 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.

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