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About this book

This book discusses the concepts and technologies associated with the mitigation of urban heat islands (UHIs) that are applicable in hot and humid regions. It presents several city case studies on how UHIs can be reduced in various areas to provide readers, researchers, and policymakers with insights into the concepts and technologies that should be considered when planning and constructing urban centres and buildings. The rapid development of urban areas in hot and humid regions has led to an increase in urban temperatures, a decrease in ventilation in buildings, and a transformation of the once green outdoor environment into areas full of solar-energy-absorbing concrete and asphalt. This situation has increased the discomfort of people living in these areas regardless of whether they occupy concrete structures. This is because indoor and outdoor air quality have both suffered from urbanisation. The development of urban areas has also increased energy consumption so that the occupants of buildings can enjoy indoor thermal comfort and air quality that they need via air conditioning systems. This book offers solutions to the recent increase in the number of heat islands in hot and humid regions.​

Table of Contents


Morphology of Buildings and Cities in Hot and Humid Regions

Hot and humid regions consist of the tropical climate, Middle Eastern climate, and Mediterranean climate. Such regions are normally located near the equator but also include dessert regions located far from the equator, such as the Gobi Desert. These regions experience uncomfortable thermal comfort levels due to the high outdoor air temperature and, in some cases, high humidity. This situation makes it challenging to provide thermal comfort in these regions. The increased economic activities in most of the countries in hot and humid regions have changed the morphology of urban areas, cities, buildings, and houses. The increase in urbanization affects the outdoor and indoor environments of buildings and houses. The increasing urban temperature due to the increase of heat generation from people, cars, appliances, and other human activities affect the chemical and biological situations of urban areas. The increasing outdoor air temperature due to urban heat generation (aka, urban heat island) in hot and humid regions worsens the already unpleasant outdoor air conditions. It has also resulted in an increase in the use of air conditioning systems and energy consumption as the heat sink temperature (outdoor air) increases. With this, the difference between the indoor air and outdoor air temperature has increased.
Napoleon Enteria, Odinah Cuartero-Enteria, Mattheos Santamouris, Ursula Eicker

Assessment of the Effects of Urban Heat Island on Buildings

Climate change and global warming have been indisputable as supported by mounting evidence of more extended, severe, and frequent occurrences of extreme weather events (EHEs), in particular, summertime heatwaves in recent years. EHEs often interact with buildings in urban area centers, which are densely packed by building blocks with vulnerable populations: the homeless, elderly, children, socially disadvantaged people, the physically challenged, or the sick, creating a unique natural phenomenon, urban heat island (UHI). This chapter covers a comprehensive effort to assess the UHI impacts on buildings and the potentially vulnerable populations through a series of surveys and field measurements in schools and hospitals, and a multi-scale climatic modeling framework from global and regional climates, urban microclimate, to building scale simulations. General methodologies are reported in detail for a better understanding of the levels of impacts by UHIs on buildings, e.g., excessively high indoor temperatures, energy demands and peak loads, and on people, e.g., indoor overheating risks. The effort is essential for developing measures and strategies to mitigate the UHI impacts on buildings and occupants for the current and future climates.
Liangzhu (Leon) Wang, Chang Shu

Urban Heat Island Monitoring with Global Navigation Satellite System (GNSS) Data

The Urban Heat Island (UHI) effect occurs when the temperature in an urban area is higher than the temperature in a rural area. UHIs are generally monitored using remote sensing techniques such as satellite imagery or using temperature sensors deployed in a metropolitan area. In this chapter, a newly proposed methodology to monitor the UHI intensity from Global Navigation Satellite Systems (GNSS) data is described. As the GNSS signal travels from the satellite to the receiver it propagates through the troposphere the travelling signal is delayed by the troposphere. The tropospheric delay is proportional to environmental variables. The tropospheric delay in zenith direction (ZTD) is estimated as part of the Precise Point Positioning (PPP) technique. Therefore, this chapter shows how to process GNSS data to obtain ZTD and how to obtain temperature at an urban and a rural site simultaneously from the ZTD. The advantages of using GNSS data is its availability and many GNSS networks have been deployed in different cities so no need to deploy sensor networks. Furthermore, GNSS signal is less affected by bad weather conditions than satellite imagery.
Jorge Mendez-Astudillo, Lawrence Lau, Isaac Yu Fat Lun, Yu-Ting Tang, Terry Moore

An Estimation of Air-Conditioning Energy-Saving Effects Through Urban Thermal Mitigation

This chapter introduces the evaluation cases of the urban heat island (UHI) countermeasures that we conducted in Tokyo. As Tokyo is hot and humid compared to many European and North American cities, measures to mitigate the severe thermal environment have been considered. We evaluated UHI countermeasures on the urban/city block scale and have thus far reported the results in mainly domestic journals. The countermeasures include general-purpose methods that can be used in other areas. We therefore present our evaluation as a case study. First, we propose a method for quantifying energy consumption by taking into consideration the spatial and temporal distributions of both air temperature and human activities. Next, we propose an estimation method for fractional vegetation cover (FVC) and an urban climate simulation method using FVC data. We then quantified the UHI mitigation and energy reduction effects of urban greening. Since the results are only valid for Tokyo, it is important to carry out similar evaluations in cities where urbanization is progressing rapidly, using the methods proposed in this study.
Yujiro Hirano, Tsuyoshi Fujita

Urban Heat Island, Contributing Factors, Public Responses and Mitigation Approaches in the Tropical Context of Malaysia

Urban Heat Island (UHI) is a notable thermal phenomenon of any tropical city in relation to increased urbanization. It records a positive urban thermal balance due to higher air temperatures in the densely built areas compared to the rural or sub-urban peripheries under the same climate conditions. The rapid infrastructure development in high-risk areas of tropical cities will be exposing the urban population to extreme heat. As predicted by International Panel on Climate Change (IPCC) climate change scenario, some of the cities in Southeast Asia may be as much as 4 °C warmer by 2050. Being a Southeast Asian country, this would be a consequential threat to the capital cities of Malaysia which suffered inevitable territorial urban development that manifested into formation of severe UHIs with an average gain in surface temperature of 8.47 °C between 1997 and 2013. The increasing surface temperature is mainly associated with the reduction in vegetation cover, open burning, forest fires, land use changes, land clearing, industrial and traffic emissions. Besides, it also exhibits the potential to emerge as one of the public health menace with reduced outdoor thermal comfort levels, heat exhaustions, heat cramps and respiratory ailments among the tropical city dwellers in various urban settings. To overcome this, a number of mitigation approaches such as increase of vegetation cover, replacement of cooling pavement materials and architectural innovations are studied as viable UHI remedies in the context of Malaysia. In addition, target driven assessments are intended to meet the city population’s health needs to assist in designing initiatives to effectively reduce UHI effects. In line with these, this chapter would provide the state-of-art of UHI, known contributing factors and impacts, community needs and other mitigation efforts targeting at urban temperature reductions via case study approaches in the context of Malaysia.
Nasrin Aghamohammadi, Logaraj Ramakreshnan, Chng Saun Fong, Nik Meriam Sulaiman

Urban Heat Island Studies in Hot and Humid Climates: A Review of the State of Art in Latin-America

Urban heat island is a phenomenon affecting cities across the world. While in cold climates it could be regarded as an even beneficious process, in temperate climates and especially in the inter-tropical latitude range, the increase in urban temperature can generate risks for health, outdoor and indoor discomfort, and an increase in buildings energy needs. This chapter provide a state of art review of UHI studies conducted recently in Latin-American area, with special focus on tropical climate cities. First step is determining which big Latin-American cities are placed in tropical or subtropical climates. Then, Journals articles, Book Chapters and Proceedings are investigated to establish the state of art, putting in evidence which kind of methods are used in determining UHI intensities, which impacts are searched, and which mitigation strategies are proposed.
Massimo Palme

Urban Heat Island Simulation and Monitoring in the Hot and Humid Climate Cities of Guayaquil and Durán, Ecuador

Urban Heat Island (UHI) research has been increasingly impacting science during the last decades. As most of humanity is living in cities, urban climatology is a consolidating field that attract more and more interest with time. Higher temperature in cities are involved in many processes and have impacts on energy needs, thermal comfort, public health and air pollution. Especially in tropical climates, where temperature and humidity ranges are high per se, the impact of urbanization processes can be even deeper. Despite of the high urbanization rates and the climate in which most populated cities of Latin-America are placed, there are only few studies that estimates UHI intensities and proposes mitigation strategies conducted in the region up to now. Here we will briefly look at the most important studies on UHI for tropical cities, then we will describe the pioneer studies that we conducted in the cities of Guayaquil and Durán, Ecuador.
Jaqueline Litardo, Massimo Palme, Mercy Borbor-Cordova, Rommel Caiza, Rubén Hidalgo-Leon, María del Pilar Cornejo-Rodriguez, Guillermo Soriano

Optimization of Urban Cooling Strategies for Parking Lots in Hot and Dry Climates: Case Study of Las Vegas and Adelaide

Urban microclimates are distinguished by the balance between solar gain and heat lost from building envelope and ground surfaces, by convective heat exchange, and by the generation of anthropogenic heat within the city. Global climate change and the urban heat island (UHI) effect—whereby cities are up to 8 °C hotter than their surrounding countryside—carry growing threats to outdoor living, public health, and urban energy demand. Urban heat stress intensifies in cities with hot and dry summer climates such as Las Vegas (USA) and Adelaide (Australia), where the temperature goes frequently above 36 °C (97 °F). Both cities have a dry, hot, and arid climate. Possible adaptation countermeasures include cool surfaces, urban greenery, and active cooling with the consideration of higher demand for water and energy, and potential winter cooling penalties. Large open-air parking lots appear in many modern cities around shopping malls, hospitals and public venues and provide essential access to these public facilities. In this context, a comparative study of different cooling strategies informs more effective decision making for the design and implementation of UHI adaptation and mitigation strategies. This chapter compares urban cooling strategies for typical parking lots in Downtown Las Vegas, Adelaide CBD and the suburban context. Cool surface materials, tree canopy, evaporative cooling and shading scenarios are estimated, and cooling benefits and side effects of each intervention are discussed. The research shows that planting trees between car parking spaces is vital to most urban environments, especially for parking lots where it leads to 1–5 °C summer cooling.
Ehsan Sharifi, Phillip Zawarus, Steffen Lehmann

Urban Heat Island and Mitigation in Tropical India

Urban heat island (UHI) studies using ground-based observations are limited in the tropical cities of India. This chapter reviews the UHI studies in the tropical cities located in the southern and central states of the subcontinent, namely Tamil Nadu, Karnataka, Kerala and Maharashtra. In tropical cities that experience high latent heat fluxes, the thermal environments are also affected by the heterogenous nature of urban settings. Majority of the UHI studies were conducted for a short period using either non-standard stations or mobile surveys, or a combination of these, with the reported UHI intensities ranging from 1.76 to 4.6 °C. Comparison between studies are difficult due to the variation in the methodology and the way results are presented. Ground-based measurements deployed in both micro and macro scales informed by high resolution remote sensing outputs will help to address the gap in the current knowledge. Dense network of stations installed using crowd sourcing approach are proven to be beneficial if uncertainties are carefully addressed. This chapter also discusses the application of UHI mitigation strategies established in similar climatic conditions and land use patterns. Mitigation actions including tree planting, use of appropriate materials as well as enhancing ventilation should be carefully chosen according to the geometry and orientation of the streets.
Priyadarsini Rajagopalan

The Hot Climate of the Middle East

This book chapter includes a brief overview of the climatic and socioeconomic characteristics of Middles East. It is then scrutinizing the urban heat island (UHI) of the region in response to the recent development in its cities as well as the drastic growth in its population. Efforts to study and characterize the UHI from various perspectives, including health, energy, and outdoor thermal comfort, in addition to various implemented observational approaches and simulation techniques are then summarized using a survey over the recent published articles and documents. While the UHI is obviously envisaged as a future challenge in front of many Middle East mega cities, yet there can be identified a gap in development of holistic agendas and systematic action plans by governments and decision-making entities to facilities mitigatory policies against the UHI.
Parham A. Mirzaei, Reihaneh Aghamolaei

Urban Heat Island Effects and Mitigation Strategies in Saudi Arabian Cities

The urban heat island phenomenon is an important factor to be considered in fostering sustainability in urban areas. It has been acknowledged that the phenomenon has relationships with energy consumption, human thermal comfort and general well-being. This chapter examines the effects of urban heat island and the adaptation and mitigation strategies in a desert environment by using Saudi Arabia as a case study. It presents cases of Saudi cities on the issue of UHI and highlights, through a review, the mitigation and adaptation strategies. The strategies include establishing urban green parks, planting trees along road centerlines and implementing public transit projects. It also examines the challenges to these measures. It concludes that more successes can be achieved by exploring other strategies such as cool/green roof and sponge city development.
Yusuf A. Aina, Irshad M. Parvez, Abdul-Lateef Balogun, Elhadi Adam

Monitoring Urban Heat Islands in Selected Cities of the Gulf Region Based on Nighttime MODIS LST Data (2003–2018)

The urban heat island (UHI) effect is the most obvious atmospheric modification related to urbanization and development. During the past twenty years, the Gulf Cooperation Council (GCC) states (Saudi Arabia, Kuwait, Bahrain, Qatar, United Arab Emirates, and Oman) have witnessed tremendous urban developments and urban expansions. At the same time these countries are experiencing some of the highest rates of economic growth in the world accompanied by accelerated living standards due to the huge reserves of oil production and refining processes. The present study aims to delineate the urban heat island effect (UHI) of the major cities in the GCC during the last two decades, including Dammam, Kuwait, Manama, Doha, Dubai, and Bawshar. Thermal infrared data from 736 images covering the period 2003–2018 were utilized to highlight the nighttime land surface temperature (LST) trends. Images were acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the Aqua satellite on the basis of 8-day composite imaging. LST measurements were conducted within the city centers for the nighttime images. It is observed that Dubai and Doha cities have a considerable warming and nighttime trends give more indications on UHI effects. MODIS data proved to be sufficient for giving an insight overview for the warming of the urban environment in the Gulf region.
Abdullah Al-Fazari, Ahmed El-Kenawy, Noura Al-Nasiri, Mohamed Hereher

Revisiting Urban Heat Island Effects in Coastal Regions: Mitigation Strategies for the Megacity of Istanbul

Throughout history, the city of Istanbul has been an important settlement for different civilizations with its geographical location connecting two continents. This metropolis with a population of over 16 million has more than 50% of total economic activity for Turkey. Especially in the last 50 years, the city has been under a catastrophic anthropogenic pressure because of its historical, geographical, and economic attractiveness. These pressures on the city caused some environmental problems due to planning. Some of these problems are intensive urbanization; increase in impervious surface, pollution, traffic, and Urban Heat Island (UHI). The impact of UHI, as a result of wrong urban planning activities causes several adversities in terms of human health, energy efficiency, and ecological sustainability. Factors such as land use/cover (LULC) changes, canyon effect, surface covering material selection, intensive energy usage are effective in the emergence of the UHI effect. In recent years, increasing environmental awareness, international regulations, and developments in landscape planning have led to the emergence of planning strategies to reduce UHI impact. The existence of the UHI effect in Istanbul has been demonstrated and modeled in previous studies. Accordingly, the presence of the UHI effect was identified in both the European and Asian study areas. In the statistical modeling studies, it has been shown that the UHI effect is mainly due to changes in land cover usage components, urban impervious surfaces, green cover, bare soil, and agricultural areas. In this study, various scenarios of land cover elements, which are stated to reduce the UHI effect in Asian and European study areas of Istanbul, have been created. For this purpose, green corridors that are designed in accordance with the urban texture of Istanbul are proposed. As a result of the analyses, UHI intensity mitigation was observed in the European and Asian study regions above 2.5 °C on average. As a result, in addition to land cover usage changes, increasing water surfaces, the use of effective wind corridors, avoiding high buildings, and preferring reflective coating surface materials in landscape design and planning activities are considered to be of utmost importance in terms of UHI reduction.
Mustafa Dihkan, Fevzi Karsli, Abdulaziz Guneroglu, Nilgun Guneroglu
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