Review
The urban heat island effect, its causes, and mitigation, with reference to the thermal properties of asphalt concrete

https://doi.org/10.1016/j.jenvman.2017.03.095Get rights and content

Highlights

  • Background and Timeline to the Urban Heat Island (UHI) is provided.

  • Key causes and consequences of the UHI are outlined and analysed.

  • Asphalt concrete's thermal properties are shown to significantly affect the UHI.

  • Existing mitigation measures discussed, and future methods outlined.

  • Combining different mitigation methods is an effective strategy against the UHI.

Abstract

The Urban Heat Island (UHI) is a phenomenon that affects many millions of people worldwide. The higher temperatures experienced in urban areas compared to the surrounding countryside has enormous consequences for the health and wellbeing of people living in cities. The increased use of manmade materials and increased anthropogenic heat production are the main causes of the UHI. This has led to the understanding that increased urbanisation is the primary cause of the urban heat island. The UHI effect also leads to increased energy needs that further contribute to the heating of our urban landscape, and the associated environmental and public health consequences. Pavements and roofs dominate the urban surface exposed to solar irradiation. This review article outlines the contribution that pavements make to the UHI effect and analyses localized and citywide mitigation strategies against the UHI. Asphalt Concrete (AC) is one of the most common pavement surfacing materials and is a significant contributor to the UHI. Densely graded AC has low albedo and high volumetric heat capacity, which results in surface temperatures reaching upwards of 60 °C on hot summer days. Cooling the surface of a pavement by utilizing cool pavements has been a consistent theme in recent literature. Cool pavements can be reflective or evaporative. However, the urban geometry and local atmospheric conditions should dictate whether or not these mitigation strategies should be used. Otherwise both of these pavements can actually increase the UHI effect. Increasing the prevalence of green spaces through the installation of street trees, city parks and rooftop gardens has consistently demonstrated a reduction in the UHI effect. Green spaces also increase the cooling effect derived from water and wind sources. This literature review demonstrates that UHI mitigation techniques are best used in combination with each other. As a result of the study, it was concluded that the current mitigation measures need development to make them relevant to various climates and throughout the year. There are also many possible sources of future study, and alternative measures for mitigation have been described, thereby providing scope for future research and development following this review.

Introduction

The aim of this literature review is to present and define the various developments and studies that have occurred with regard to the thermal properties of asphalt concrete (AC), and their associated effect on the environment. This study summarises the surface temperature, albedo and other limiting factors of AC, and links these closely to the urban heat island (UHI) effect. The UHI effect is defined and analysed, and the mitigating methods for this phenomenon ailing urban environments, as described in the literature, is discussed. This review also identifies areas in which there has been minimal study, and provides scope for future research and development accordingly.

Section snippets

Background to the urban heat island

The UHI is a global issue that threatens the operation and habitability of our cities and urban environments. According to Oke (1982), the concept of the UHI has been well researched and documented; however, the understanding of the topic is quite limited. This has changed in recent years as a result of a greater focus on global warming and climate effects, the greater prevalence of hotter cities, and due to changes in technology for measurement and analysis. The heat island effect is

Timeline of contributions to study

The first studies on the UHI were conducted in the early 1800s, making studies on the topic more than a century old (Yang et al., 2015). The timeline in Table 1 below illustrates some of the most critical contributions to the study of thermal conductivity of asphalt pavements and the associated UHI, and is derived from the various references listed at the end of this paper.

Key causes of the urban heat island

Fig. 1 below illustrates the relationship between atmospheric heat, increased use of manufactured materials, and various other causes that can be attributed to the UHI, which will be discussed further.

Pavement structure

Pavements form the arterial transport connections within our cities, and research shows that they are a powerful contributor to the UHI. Many paths in our cities are referred to as pavements. From pedestrian footpaths and garden paths to highway roads, the term ‘pavement’ is applied to a diverse array of structures. Although there are many studies researching the effect of pavements on UHI, they often do not specify what sort of pavement structure they are researching. Roads are perhaps the

Key mitigation measures

Mitigation measures to combat the UHI effect have been well studied and well documented. Fig. 3 below illustrates some of the common mitigation measures. Many measures have been developed over time, and some of the key measures are outlined in this review. These include designing cool pavements by increasing the albedo of surfaces and making them more reflective, permeable, porous and water retentive; the increased utilisation of green spaces within our urban landscape (Gorsevski et al., 1998,

Discussion

The most common theme within the literature is the need to conduct a greater number of studies within the field. The issue with studies to date is that demonstration projects are not at a large enough scale to quantify the effects of a given mitigation method on an urban environment or city (Santamouris, 2013b). Researchers suggest that a city of the world needs to implement solutions on a large scale to allow researchers to better quantify the effects of the UHI. The range of studies on UHI is

Conclusion

In conclusion, it has been found that the thermal properties of asphalt concrete are a strong contributory factor to the UHI effect in cities. There is a constant need to reduce the effects of the UHI, due to the adverse effect it has on liveability, wellbeing and health in urban environments. The constantly expanding nature of cities and the increased use of hard, heat absorbing substances make a significant contribution to the UHI. Various mitigation measures have been proposed within the

References (98)

  • A. García et al.

    Experimental evaluation of dense asphalt concrete properties for induction heating purposes

    Constr. Build. Mater

    (2013)
  • A. García et al.

    How to transform an asphalt concrete pavement into a solar turbine

    Appl. Energy

    (2014)
  • A. Hassn et al.

    Thermal properties of asphalt pavement under dry and wet conditions

    Mater. Des.

    (2016)
  • E.A. Hathway et al.

    The interaction of rivers and urban form in mitigating the Urban Heat Island effect: a UK case study

    Build. Environ.

    (2012)
  • G. Hatvani-Kovacs et al.

    Heat stress risk and resilience in the urban environment

    Sustain. Cities Environ.

    (2016)
  • H. Higashiyama et al.

    Field measurements of road surface temperature of several asphalt pavements with temperature rise reducing function

    Case Stud. Constr. Mater

    (2016)
  • C.-M. Hsieh et al.

    Mitigating urban heat islands: a method to identify potential wind corridor for cooling and ventilation

    Comput. Environ. Urban

    (2016)
  • T. Ichinose et al.

    Chapter 15-Counteracting Urban Heat Islands in Japan

  • W. Jiang et al.

    Experimental study on materials composition design and mixture performance of water-retentive asphalt concrete

    Constr. Build. Mater

    (2016)
  • A. Kavianipour et al.

    Thermal property estimation utilizing the Laplace transform with application to asphaltic pavement

    Int

    (1977)
  • A. Lemonsu et al.

    Vulnerability to heat waves: impact of urban expansion scenarios on urban heat island and heat stress in Paris (France)

    Urban Clim.

    (2015)
  • H. Li et al.

    Experimental investigation on evaporation rate for enhancing evaporative cooling effect of permeable pavement materials.Constr

    Build. Mater

    (2014)
  • H. Li

    4-A comparison of thermal performance of different pavement materials

  • R.A. Memon et al.

    Effects of building aspect ratio and wind speed on air temperatures in urban-like street canyons

    Build. Environ.

    (2010)
  • P.A. Mirzaei et al.

    Approaches to study urban heat island - abilities and limitations

    Build. Environ.

    (2010)
  • J. Mullaney et al.

    The effect of permeable pavements with an underlying base layer on the growth and nutrient status of urban trees

    Urban For. Urban Gree

    (2015)
  • S. Murakawa et al.

    Study of the effects of a river on the thermal environment in an urban area

    Energ. Build.

    (1991)
  • C.A. Murray et al.

    Characterization of permeable pavement materials based on recycled rubber and chitosan

    Constr. Build. Mater

    (2014)
  • T. Nakayama et al.

    Cooling effect of water-holding pavements made of new materials on water and heat budgets in urban areas

    Landsc. Urban Plan.

    (2010)
  • T. Nakayama et al.

    Analysis of the ability of water resources to reduce the urban heat island in the Tokyo megalopolis

    Environ. Pollut.

    (2011)
  • P. Pascual-Muñoz et al.

    Thermal and hydraulic analysis of multilayered asphalt pavements as active solar collectors

    Appl. Energ

    (2013)
  • Y. Qin

    A review on the development of cool pavements to mitigate urban heat island effect

    Renew. Sust. Energy Rev.

    (2015)
  • Y. Qin

    Urban canyon albedo and its implication on the use of reflective cool pavements

    Energy Build.

    (2015)
  • Y. Qin et al.

    Understanding pavement-surface energy balance and its implications on cool pavement development

    Energy Build.

    (2014)
  • A. Rafiee et al.

    Local impact of tree volume on nocturnal urban heat island: a case study in Amsterdam

    Urban For. Urban Gree

    (2016)
  • P. Rajagopalan et al.

    Urban heat island and wind flow characteristics of a tropical city

    Sol. Energ

    (2014)
  • M. Razzaghmanesh et al.

    The role of green roofs in mitigating Urban Heat Island effects in the metropolitan area of Adelaide, South Australia

    Urban For. Urban Gree

    (2016)
  • F. Rossi et al.

    Analysis of retro-reflective surfaces for urban heat island mitigation: a new analytical model

    Appl. Energ

    (2014)
  • M. Santamouris

    Using cool pavements as a mitigation strategy to fight urban heat island - a review of the actual developments

    Renew. Sust. Energy Rev.

    (2013)
  • M. Santamouris

    On the energy impact of urban heat island and global warming on buildings

    Energy Build.

    (2014)
  • M. Santamouris

    Analyzing the heat island magnitude and characteristics in one hundred Asian and Australian cities and regions

    Sci. Total Environ.

    (2015)
  • M. Santamouris

    Regulating the damaged thermostat of the cities—status, impacts and mitigation challenges

    Energy Build.

    (2015)
  • M. Scholz et al.

    Review of permeable pavement systems

    Build. Environ.

    (2007)
  • S. Sen et al.

    Aging albedo model for asphalt pavement surfaces

    J. Clean. Prod.

    (2016)
  • G.J. Steeneveld et al.

    Refreshing the role of open water surfaces on mitigating the maximum urban heat island effect

    Landsc. Urban Plan.

    (2014)
  • B. Stone et al.

    Land use planning and surface heat island formation: a parcel-based radiation flux approach

    Atmos. Environ.

    (2006)
  • A. Synnefa et al.

    Experimental testing of cool colored thin layer asphalt and estimation of its potential to improve the urban microclimate

    Build. Environ.

    (2011)
  • C.L. Tan et al.

    Impact of plant evapotranspiration rate and shrub albedo on temperature reduction in the tropical outdoor environment

    Build. Environ.

    (2015)
  • Z. Tan et al.

    Urban tree design approaches for mitigating daytime urban heat island effects in a high-density urban environment

    Energy Build.

    (2016)
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