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Special Issue "Urban Heat Island"

A special issue of Sustainability (ISSN 2071-1050).

Deadline for manuscript submissions: closed (30 June 2017)

Special Issue Editors

Guest Editor
Prof. Dr. Constantinos Cartalis

Department of Environmental Physics, University Athens, Athens 15125, Greece
Website | E-Mail
Phone: +30-2107-276-774
Interests: urban environment; environmental design of cities; low carbon cities; resilient cities; sustainable urban development
Guest Editor
Prof. Dr. Matheos Santamouris

Group of Building Environmental Research, Department of Physics, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Athens, Greece
Website | E-Mail
Phone: +30-2107-276847
Fax: +30-2107-295282
Interests: heat island; urban mitigation; advanced materials; low energy buildings and settlements

Special Issue Information

Dear Colleagues,

More than half of the people on the planet now live in cities. By 2050, the world is expected to add an additional 2.5 billion urban dwellers, with nearly 90 percent of the increase concentrated in Asia and Africa. A great number of cities worldwide have experienced urbanization and have developed “urban heat islands” (UHI) of varying strengths depending the characteristics and operational patterns of the city concerned, as well as the construction materials. As a result, the thermal environment in cities degrades, thermal comfort decreases and energy consumption for cooling increases, whereas the resilience of the city to heat waves is negatively affected. In addition, UHIs have been indirectly related to climate change due to their contribution to the greenhouse effect and therefore to global warming.

This Special Issue will comprise a selection of papers addressing the Urban Heat Island. Research papers will focus on (1) the links between urbanization, urban climatic zones and the development of UHIs, (2) assessments on the presence and strength of UHIs in various world cities, (3) the links between land use/land cover and UHIs, (4) ecosystem services and UHI, (5) the impact of UHIs on air quality, thermal comfort and health in the cities concerned, (6) energy studies related to the presence of UHIs, (7) the use of remote sensing for the study of UHIs, (8) mitigation and adaptation techniques to counterbalance the impact of UHI including cool materials, urban green, and other innovations, (9) analysis of the influence of UHIs to climate change, and (10) the impact of UHI on energy poverty and urban vulnerability.

Prof. Dr. Constantinos Cartalis
Prof. Dr. Matheos Santamouris
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • Urbanization
  • Air and surface temperature
  • Thermal environment
  • Land use/land cover
  • Energy
  • Cool materials
  • Remote sensing
  • Mitigation/adaptation plans
  • Air quality-thermal comfort-urban health
  • Climate change

Published Papers (17 papers)

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Research

Open AccessArticle Surface Urban Heat Island Analysis of Shanghai (China) Based on the Change of Land Use and Land Cover
Sustainability 2017, 9(9), 1538; doi:10.3390/su9091538
Received: 29 June 2017 / Revised: 20 August 2017 / Accepted: 22 August 2017 / Published: 29 August 2017
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Abstract
In this paper, we present surface urban heat island (SUHI) analysis of Shanghai (China) based on the change in land use and land cover using satellite Landsat images from 2002 to 2013. With the rapid development of urbanization, urban ecological and environmental issues
[...] Read more.
In this paper, we present surface urban heat island (SUHI) analysis of Shanghai (China) based on the change in land use and land cover using satellite Landsat images from 2002 to 2013. With the rapid development of urbanization, urban ecological and environmental issues have aroused widespread concern. The urban heat island (UHI) effect is a crucial problem, as its generation and evolution are closely related to social and economic activities. Land-use and land-cover change (LUCC) is the key in analyzing the UHI effect. Shanghai, one of China’s major economic, financial and commercial centers, has experienced high development density for several decades. A tremendous amount of farmland and vegetation coverage has been replaced by an urban impervious surface, leading to an intensive SUHI effect, especially in the city’s center. Luckily, the SUHI trend has slowed due to reasonable urban planning and relevant green policies since the 2010 Expo. Data analyses demonstrate that an impervious surface (IS) has a positive correlation with land surface temperature (LST) but a negative correlation with vegetation and water. Among the three factors, impervious surface is the most relevant. Therefore, the policy implications of land use and control of impervious surfaces should pay attention to the relief of the current SUHI effect in Shanghai. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Effect of Land-Use Change on the Urban Heat Island in the Fukuoka–Kitakyushu Metropolitan Area, Japan
Sustainability 2017, 9(9), 1521; doi:10.3390/su9091521
Received: 30 June 2017 / Revised: 19 August 2017 / Accepted: 23 August 2017 / Published: 26 August 2017
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Abstract
In coastal cities, the effect of the sea breeze in mitigating the urban heat island (UHI) phenomenon has attracted attention. This study targeted the Fukuoka–Kitakyushu metropolitan area, the fourth largest metropolitan area in Japan which is also coastal. Doppler Light Detection And Ranging
[...] Read more.
In coastal cities, the effect of the sea breeze in mitigating the urban heat island (UHI) phenomenon has attracted attention. This study targeted the Fukuoka–Kitakyushu metropolitan area, the fourth largest metropolitan area in Japan which is also coastal. Doppler Light Detection And Ranging (LiDAR) observations were conducted in the summer of 2015 to clarify the transition of the wind field over the targeted area. To investigate the effects on the UHI of land-use change related to urbanization, the National Land Numerical Information (NLNI) land-use datasets for Japan in 1976 (NLNI-76) and 2009 (NLNI-09) were used in the Weather Research and Forecasting (WRF) model. The results of the simulation showed that most of the northern part of the Kyushu region became warmer, with an average increase of +0.236 °C for the whole simulation period. Comparing the two simulations and the Doppler LiDAR observations, the simulation results with the NLNI-09 dataset (for the year closest to the study period in 2015) showed closer conformity with the observations. The results of the simulation using NLNI-76 showed faster sea breeze penetration and higher wind velocity than the observations. These results suggest that the land-use change related to urbanization weakened the sea breeze penetration in this area. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Heatstroke Risk Predictions for Current and Near-Future Summers in Sendai, Japan, Based on Mesoscale WRF Simulations
Sustainability 2017, 9(8), 1467; doi:10.3390/su9081467
Received: 30 June 2017 / Revised: 13 August 2017 / Accepted: 14 August 2017 / Published: 18 August 2017
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Abstract
The incidence of heatstroke has been increasing in Japan, and future climate change is likely to increase heatstroke risk. We therefore developed a method to quantify the spatial distribution of outdoor heatstroke risk and predicted future changes in this risk considering the predicted
[...] Read more.
The incidence of heatstroke has been increasing in Japan, and future climate change is likely to increase heatstroke risk. We therefore developed a method to quantify the spatial distribution of outdoor heatstroke risk and predicted future changes in this risk considering the predicted climate change in Sendai, Japan. Heatstroke risk was quantified by assessing hazard, vulnerability and exposure. Daily maximum wet-bulb globe temperature (WBGT) was selected as the hazard index. The distribution of WBGT was predicted by mesoscale meteorological simulations using the Weather Research and Forecasting (WRF) model. The relationship between daily maximum WBGT and the daily incidence rate was approximated by analyzing emergency transport data. This relationship was selected as the vulnerability index. Using the hazard and vulnerability indices, a spatial distribution of the monthly incidence rate was obtained. Finally, the total number of heatstroke patients per month was estimated by multiplying the monthly incidence rate by the population density. The outdoor heatstroke risk for August was then estimated for current (2000s) and near-future (2030s) climatic conditions in Sendai. WBGT at coastal areas in the 2030s increased owing to increases in humidity, while WBGT at inland areas increased owing to increases in air temperature. This increase in WBGT drove increases in heatstroke risk. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Deduction of Optimum Surface Design Factors for Enhancement of Outdoor Thermal Environment in a Micro-Scale Unit
Sustainability 2017, 9(8), 1381; doi:10.3390/su9081381
Received: 29 June 2017 / Revised: 23 July 2017 / Accepted: 2 August 2017 / Published: 4 August 2017
Cited by 1 | PDF Full-text (15014 KB) | HTML Full-text | XML Full-text
Abstract
To solve some of the problems associated with changing urban climates, such as the heat island effect, the exterior building skin and ground surfaces should be analyzed because they are directly exposed to the outdoor climate and have the greatest impact on energy
[...] Read more.
To solve some of the problems associated with changing urban climates, such as the heat island effect, the exterior building skin and ground surfaces should be analyzed because they are directly exposed to the outdoor climate and have the greatest impact on energy consumption. Research is needed to identify design factors to improve the effect of a building’s skin in the outdoor summer season’s thermal environment. In this study, the current conditions of outdoor thermal environments were identified by conducting field measurements at an apartment housing complex. A simulation analysis was conducted based on cases that included different design factors for a building’s skin and ground surfaces. When the significance probability of the design factors for the surface plans for apartment buildings and surface cover was analyzed based on the Taguchi experimental design method, the window plan and surface cover plan influenced the outdoor thermal environment. Notably, the surface cover plan had the most significant impact on the outdoor thermal environment. The result of the analysis of the correlation between the design factors for an apartment complex’s surface plans and outdoor thermal environment indices showed that the window plan correlated with the entire surface temperature of building and heat island potential (HIP). Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Urban Heat Island and Park Cool Island Intensities in the Coastal City of Aracaju, North-Eastern Brazil
Sustainability 2017, 9(8), 1379; doi:10.3390/su9081379
Received: 9 July 2017 / Revised: 31 July 2017 / Accepted: 2 August 2017 / Published: 4 August 2017
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Abstract
In this study, an evaluation of the Urban Heat Island (UHI) and Park Cool Island (PCI) intensities in Aracaju, North-Eastern Brazil, was performed. The basis of our evaluation is a 2-year dataset from the urban climatological network installed with the principles and concepts
[...] Read more.
In this study, an evaluation of the Urban Heat Island (UHI) and Park Cool Island (PCI) intensities in Aracaju, North-Eastern Brazil, was performed. The basis of our evaluation is a 2-year dataset from the urban climatological network installed with the principles and concepts defined for urban areas related to climatic scales, sitting and exposure, urban morphology, and metadata. The current findings update UHI intensities in Aracaju refuting the trend registered in previous studies. On average, the UHI was more intense in the cool season (1.3 °C) than in hot season (0.5 °C), which was caused by wind speed decrease. In relation to the PCI, mitigation of high air temperatures of 1.5–2 °C on average was registered in the city. However, the urban park is not always cooler than the surrounding built environment. Consistent long-term monitoring in the cities is very important to provide more accurate climatic information about the UHI and PCI to be applied in urban planning properly, e.g., to provide pleasant thermal comfort in urban spaces. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Urban Heat Island and Overheating Characteristics in Sydney, Australia. An Analysis of Multiyear Measurements
Sustainability 2017, 9(5), 712; doi:10.3390/su9050712
Received: 4 February 2017 / Revised: 31 March 2017 / Accepted: 25 April 2017 / Published: 29 April 2017
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Abstract
It has become increasingly important to study the urban heat island phenomenon due to the adverse effects on summertime cooling energy demand, air and water quality and most importantly, heat-related illness and mortality. The present article analyses the magnitude and the characteristics of
[...] Read more.
It has become increasingly important to study the urban heat island phenomenon due to the adverse effects on summertime cooling energy demand, air and water quality and most importantly, heat-related illness and mortality. The present article analyses the magnitude and the characteristics of the urban heat island in Sydney, Australia. Climatic data from six meteorological stations distributed around the greater Sydney region and covering a period of 10 years are used. It is found that both strong urban heat island (UHI) and oasis phenomena are developed. The average maximum magnitude of the phenomena may exceed 6 K. The intensity and the characteristics of the phenomena are strongly influenced by the synoptic weather conditions and in particular the development of the sea breeze and the westerly winds from the desert area. The magnitude of the urban heat island varies between 0 and 11°C, as a function of the prevailing weather conditions. The urban heat island mainly develops during the warm summer season while the oasis phenomenon is stronger during the winter and intermediate seasons. Using data from an extended network of stations the distribution of Cooling Degree Days in the greater Sydney area is calculated. It is found that because of the intense development of the UHI, Cooling Degree Days in Western Sydney are about three times higher than in the Eastern coastal zone. The present study will help us to better design and implement urban mitigation strategies to counterbalance the impact of the urban heat island in the city. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Mortality Associated with High Ambient Temperatures, Heatwaves, and the Urban Heat Island in Athens, Greece
Sustainability 2017, 9(4), 606; doi:10.3390/su9040606
Received: 23 November 2016 / Revised: 29 March 2017 / Accepted: 11 April 2017 / Published: 13 April 2017
Cited by 2 | PDF Full-text (1087 KB) | HTML Full-text | XML Full-text
Abstract
Abstract: Climate change looms as the biggest threat of the 21st century, and its effect on urban mortality is exacerbated by urban heat islands. This study analyzes the impact of high temperatures, heatwaves, and the urban heat island on the cardiovascular and
[...] Read more.
Abstract: Climate change looms as the biggest threat of the 21st century, and its effect on urban mortality is exacerbated by urban heat islands. This study analyzes the impact of high temperatures, heatwaves, and the urban heat island on the cardiovascular and respiratory mortality of people over 65 years of age for the years 2002 to 2012. The area of application is Athens, Greece, an urban agglomeration experiencing an urban heat island of high intensity. The correlation of the daily cardiovascular and respiratory mortality count of people over 65 years of age with various temperature measures confirmed a U-shaped exposure response curve, with fewer deaths in the range of moderate temperatures. At high and very high temperatures, this mortality increased by 20 to 35% correspondingly, at a 99.9% significance level. Mortality was further investigated with ordinary least squares, Poisson, and negative binomial times series models, which, although suffering from poor fit, showed a one-day lag for the maximum temperature effect on mortality. Finally, cluster analysis for observations confined to May to September, confirmed by multiple discriminant analysis, showed the existence of six clusters, with the highest excess mortality count of 23% for the cluster that included the hottest days and 20.6% for the heatwave cluster. To this end, it is recommended that policies target high ambient temperatures and heatwaves as a priority. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Mapping the Influence of Land Use/Land Cover Changes on the Urban Heat Island Effect—A Case Study of Changchun, China
Sustainability 2017, 9(2), 312; doi:10.3390/su9020312
Received: 30 December 2016 / Accepted: 13 February 2017 / Published: 20 February 2017
Cited by 3 | PDF Full-text (14973 KB) | HTML Full-text | XML Full-text
Abstract
The spatio-temporal patterns of land use/land cover changes (LUCC) can significantly affect the distribution and intensity of the urban heat island (UHI) effect. However, few studies have mapped a clear picture of the influence of LUCC on UHI. In this study, both qualitative
[...] Read more.
The spatio-temporal patterns of land use/land cover changes (LUCC) can significantly affect the distribution and intensity of the urban heat island (UHI) effect. However, few studies have mapped a clear picture of the influence of LUCC on UHI. In this study, both qualitative and quantitative models are employed to explore the effect of LUCC on UHI. UHI and LUCC maps were retrieved from Landsat data acquired from 1984, 1992, 2000, 2007, and 2014 to show their spatiotemporal patterns. The results showed that: (1) both the patterns of LUCC and UHI have had dramatic changes in the past 30 years. The urban area of Changchun increased more than four times, from 143.15 km2 in 1984 to 577.45 km2 in 2014, and the proportion of UHI regions has increased from 15.27% in 1984 to 29.62% in 2014; (2) the spatiotemporal changes in thermal environment were consistent with the process of urbanization. The average LST of the study area has been continuously increasing as many other land use types have been transformed to urban regions. The mean temperatures were higher in urban regions than rural areas over all of the periods, but the UHI intensity varied based on different measurements; and (3) the thermal environment inside the city varied widely even within a small area. The LST possesses a very strong positive relationship with impervious surface area (ISA), and the relationship has become stronger in recent years. The UHI we employ, specifically in this study, is SUHI (surface urban heat island). Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Adaptation to Climate Change through Spatial Planning in Compact Urban Areas: A Case Study in the City of Thessaloniki
Sustainability 2017, 9(2), 271; doi:10.3390/su9020271
Received: 24 November 2016 / Revised: 11 January 2017 / Accepted: 7 February 2017 / Published: 15 February 2017
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Abstract
One of the problems urban areas are facing is the coupled effect of climate change and the Urban Heat Island (UHI) effect. This article attempts to demonstrate the potential of spatial planning to reduce the UHI effect and, hence, to contribute to climate
[...] Read more.
One of the problems urban areas are facing is the coupled effect of climate change and the Urban Heat Island (UHI) effect. This article attempts to demonstrate the potential of spatial planning to reduce the UHI effect and, hence, to contribute to climate change adaptation in compact urban areas. After a brief review of the relevant literature, the article focuses on one case study within the compact urban area of the city of Thessaloniki. The geographical, socio-economic and urban form data of the study area and its subsequent vulnerability to UHI were initially assessed. Based on these features, a local spatial planning strategy is proposed, and the study proceeds to a detailed amendment of the land use plan, within part of the vulnerable zone. This takes into account the existing urban form, the lack of resources and the availability of the spatial planning tools within the Greek spatial planning system. Τhe main purpose of this article is to highlight the fact that, even in urban areas where the potential for intervention seems to be marginal, because of their existing form, the complexities of the local planning system and resource limitations, improvements to the UHI effect and adaptation to climate change can be achieved by better land use planning and urban design. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle The Extent and Implications of the Microclimatic Conditions in the Urban Environment: A Vienna Case Study
Sustainability 2017, 9(2), 177; doi:10.3390/su9020177
Received: 12 December 2016 / Revised: 16 January 2017 / Accepted: 23 January 2017 / Published: 25 January 2017
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Abstract
Recent challenges in the realm of urban studies concern better understanding of microclimatic conditions. Changes in urban climate affect cities at local and global scales, with consequences for human health, thermal comfort, building energy use, and anthropogenic emissions. The extent of these impacts
[...] Read more.
Recent challenges in the realm of urban studies concern better understanding of microclimatic conditions. Changes in urban climate affect cities at local and global scales, with consequences for human health, thermal comfort, building energy use, and anthropogenic emissions. The extent of these impacts may vary due to different morphologies and materials of the built environment. The present contribution summarizes the results of a multi-year effort concerned with the extent and implications of urban heat in Vienna, Austria. For this purpose, high-resolution weather data across six locations are obtained and analyzed. This allowed for an objective assessment of urban-level climatic circumstances across distinct low-density and high-density typologies. Subsequently, a systematic framework was developed for identification of essential properties of the built environment (geometric and material-related) that are hypothesized to influence microclimate variation. Results point to a number of related (positive and negative) correlations with microclimatic tendencies. Additionally, the impact of this location-specific weather data on building performance simulation results is evaluated. The results suggest that buildings' thermal performance is significantly influenced by location-specific microclimatic conditions with variation of mean annual heating load across locations of up to 16.1 kWhm−2·a−1. The use of location-independent weather data sources (e.g., standardized weather files) for building performance estimations can, thus, result in considerable errors. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle The Impact of Morphological Features on Summer Temperature Variations on the Example of Two Residential Neighborhoods in Ljubljana, Slovenia
Sustainability 2017, 9(1), 122; doi:10.3390/su9010122
Received: 28 November 2016 / Revised: 6 January 2017 / Accepted: 12 January 2017 / Published: 14 January 2017
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Abstract
The study conducted in this paper is focused on a predominantly residential area of the City of Ljubljana—Koseze, which is characterized by generally favorable (bio)climatic conditions. Nonetheless, thermal satellite images showed that residential neighborhoods within the Koseze district display unexpected variations in summer
[...] Read more.
The study conducted in this paper is focused on a predominantly residential area of the City of Ljubljana—Koseze, which is characterized by generally favorable (bio)climatic conditions. Nonetheless, thermal satellite images showed that residential neighborhoods within the Koseze district display unexpected variations in summer temperatures. This observation called into question the benefits of existing bioclimatic features and indicated the need to investigate and compare two neighborhoods with similar urban parameters, with the aim to identify morphological differential characteristics impacting urban heat island (UHI) intensity. By applying the study methodology based on a literature review, surveys of key precedents, detailed mapping in two Koseze locations, in situ measurements, observations and recordings, thermal imagery, and the analyses of statistical data, as well as by defining the four main categories of morphological urban parameters—structure, cover, fabric and metabolism, it was concluded that both neighborhoods have common morphological elements mitigating the UHI effect. Additionally, it was found that the neighborhood with higher UHI intensity has several less favorable features, such as busier roads, larger surface of parking corridors, and the existence of underground parking space. The traffic as an element of urban morphology hence represents the main cause of differences among UHI levels in the two Koseze neighborhoods. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Improving Heat-Related Health Outcomes in an Urban Environment with Science-Based Policy
Sustainability 2016, 8(10), 1015; doi:10.3390/su8101015
Received: 17 July 2016 / Revised: 25 September 2016 / Accepted: 28 September 2016 / Published: 12 October 2016
Cited by 3 | PDF Full-text (1373 KB) | HTML Full-text | XML Full-text
Abstract
We use the Northeast US Urban Climate Archipelago as a case study to explore three key limitations of planning and policy initiatives to mitigate extreme urban heat. These limitations are: (1) a lack of understanding of spatial considerations—for example, how nearby urban areas
[...] Read more.
We use the Northeast US Urban Climate Archipelago as a case study to explore three key limitations of planning and policy initiatives to mitigate extreme urban heat. These limitations are: (1) a lack of understanding of spatial considerations—for example, how nearby urban areas interact, affecting, and being affected by, implementation of such policies; (2) an emphasis on air temperature reduction that neglects assessments of other important meteorological parameters, such as humidity, mixing heights, and urban wind fields; and (3) too narrow of a temporal focus—either time of day, season, or current vs. future climates. Additionally, the absence of a direct policy/planning linkage between heat mitigation goals and actual human health outcomes, in general, leads to solutions that only indirectly address the underlying problems. These issues are explored through several related atmospheric modeling case studies that reveal the complexities of designing effective urban heat mitigation strategies. We conclude with recommendations regarding how policy-makers can optimize the performance of their urban heat mitigation policies and programs. This optimization starts with a thorough understanding of the actual end-point goals of these policies, and concludes with the careful integration of scientific knowledge into the development of location-specific strategies that recognize and address the limitations discussed herein. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle The Effect of a Denser City over the Urban Microclimate: The Case of Toronto
Sustainability 2016, 8(8), 822; doi:10.3390/su8080822
Received: 14 July 2016 / Revised: 17 August 2016 / Accepted: 17 August 2016 / Published: 19 August 2016
Cited by 4 | PDF Full-text (14307 KB) | HTML Full-text | XML Full-text
Abstract
In the last decades, several studies have revealed how critical the urban heat island (UHI) effect can be in cities located in cold climates, such as the Canadian one. Meanwhile, many researchers have looked at the impact of the city design over the
[...] Read more.
In the last decades, several studies have revealed how critical the urban heat island (UHI) effect can be in cities located in cold climates, such as the Canadian one. Meanwhile, many researchers have looked at the impact of the city design over the urban microclimate, and have raised concerns about the development of too dense cities. Under the effect of the “Places to Growth” plan, the city of Toronto is experiencing one of the highest rates of building development in North America. Over 48,000 and 33,000 new home permits were issued in 2012 and 2013 respectively, and at the beginning of 2015, almost 500 high-rise proposals across the Greater Toronto Area were released. In this context, it is important to investigate how new constructions will affect the urban microclimate, and to propose strategies to mitigate possible UHI effects. Using the software ENVI-met, microclimate simulations for the Church-Yonge corridor both in the current situation and with the new constructions are reported in this paper. The outdoor air temperature and the wind speed are the parameters used to assess the outdoor microclimate changes. The results show that the new constructions could increase the wind speed around the buildings. However, high-rise buildings will somewhat reduce the air temperature during day-time, as they will create large shadow areas, with lower average mean radiant temperature. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle High-Reflectance Technology on Building Façades: Installation Guidelines for Pedestrian Comfort
Sustainability 2016, 8(8), 785; doi:10.3390/su8080785
Received: 15 June 2016 / Revised: 3 August 2016 / Accepted: 9 August 2016 / Published: 10 August 2016
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Abstract
The focus of this study is on the impact of solar radiation reflected from the building façade to a pedestrian. The possibility of using high-reflectance technology on building façades was evaluated by using a two-dimensional simple building façade model. The effectiveness of applying
[...] Read more.
The focus of this study is on the impact of solar radiation reflected from the building façade to a pedestrian. The possibility of using high-reflectance technology on building façades was evaluated by using a two-dimensional simple building façade model. The effectiveness of applying retroreflective materials to building façades was also evaluated in regards to avoiding adverse effects on pedestrians. The ratio of diffusely-reflected solar radiation to a pedestrian from a given floor is proportional to the ratio of the angle of the reflective arc reaching a pedestrian from that floor to the angle of the reflective arc from the entire building. Specular reflection of solar radiation from the building façade is calculated by ray-tracing method corresponding to solar angle θ. In Japanese cities that are located at mid-latitudes, applying high-reflectance technology to a building façade at the fourth floor and above produces reflection of solar radiation that does not have adverse effects on pedestrians. High-reflectance technology is applicable on building façades above the fourth floor at any latitude, if we ignore a negative effect, since incident direct solar radiation to the building façade around noon is small at low latitude. Retroreflective material was considered for use on building façades below the third floor in order to avoid impacts on pedestrians from the reflection of solar radiation. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Towards a Climate-Responsive Vertical Pedestrian System: An Empirical Study on an Elevated Walkway in Shanghai China
Sustainability 2016, 8(8), 744; doi:10.3390/su8080744
Received: 12 June 2016 / Revised: 26 July 2016 / Accepted: 28 July 2016 / Published: 4 August 2016
Cited by 1 | PDF Full-text (6903 KB) | HTML Full-text | XML Full-text
Abstract
Elevated walkways can bring pedestrian-friendly urban space back to high-density urban centers that are planned largely for vehicle traffic—for instance, the Lujiazui CBD in Shanghai. Most studies on elevated walkways have focused on transportation planning, structural safety as well as urban form and
[...] Read more.
Elevated walkways can bring pedestrian-friendly urban space back to high-density urban centers that are planned largely for vehicle traffic—for instance, the Lujiazui CBD in Shanghai. Most studies on elevated walkways have focused on transportation planning, structural safety as well as urban form and design. Few have paid attention to thermal conditions and pedestrian comfort issues on elevated levels. Considering all of the environmental factors that influence human thermal comfort, one could claim that there will be more breezes on elevated levels compared to sidewalks at the ground levels, but they can be exposed to increased solar radiation and thus higher radiant temperatures, if not properly shaded. The overall effect of the change in elevation on human thermal comfort is thus unknown. This study attempts to investigate the microclimate and human thermal comfort of a recently completed Lujiazui Elevated Walkway (LEW) system in the Lujiazui CBD, Shanghai, under a hot-humid sub-tropical climate. Micrometeorological measurements and a guided questionnaire survey were carried out on peak summer days. The data analysis indicates that the LEW is thermally more uncomfortable than its ground level counterpart. Air temperature was higher, whereas wind velocity is lower on the skywalk level than on the ground level, which is counter-intuitive. The resultant physiological equivalent temperature (PET) indicates warm conditions on the ground level (with good shading) while there are hot conditions on the skywalk. Based on the empirical findings, design strategies are proposed to improve the thermal comfort conditions on the LEW, and to better support pedestrian activities in this typical high-rise high-density urban area. Full article
(This article belongs to the Special Issue Urban Heat Island)
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Open AccessArticle Urban Heat Island Simulations in Guangzhou, China, Using the Coupled WRF/UCM Model with a Land Use Map Extracted from Remote Sensing Data
Sustainability 2016, 8(7), 628; doi:10.3390/su8070628
Received: 5 May 2016 / Revised: 28 June 2016 / Accepted: 30 June 2016 / Published: 5 July 2016
Cited by 2 | PDF Full-text (5329 KB) | HTML Full-text | XML Full-text
Abstract
The Weather Research and Forecasting (WRF) model coupled with an Urban Canopy Model (UCM) was used for studying urban environmental issues. Because land use data employed in the WRF model do not agree with the current situation around Guangzhou, China, the performance of
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The Weather Research and Forecasting (WRF) model coupled with an Urban Canopy Model (UCM) was used for studying urban environmental issues. Because land use data employed in the WRF model do not agree with the current situation around Guangzhou, China, the performance of WRF/UCM with new land-use data extracted from Remote Sensing (RS) data was evaluated in early August 2012. Results from simulations reveal that experiments with the extracted data are capable of reasonable reproductions of the majority of the observed temporal characteristics of the 2-m temperature, and can capture the characteristics of Urban Heat Island (UHI). The “UCM_12” simulation, which employed the extracted land-use data with the WRF/UCM model, provided the best reproduction of the 2-m temperature data evolution and the smallest minimum absolute average error when compared with the other two experiments without coupled UCM. The contributions of various factors to the UHI effect were analyzed by comparing the energy equilibrium processes of “UCM_12” in urban and suburban areas. Analysis revealed that energy equilibrium processes with new land use data can explain the diurnal character of the UHI intensity variation. Furthermore, land use data extracted from RS can be used to simulate the UHI. Full article
(This article belongs to the Special Issue Urban Heat Island)
Open AccessArticle Highly Reflective Roofing Sheets Installed on a School Building to Mitigate the Urban Heat Island Effect in Osaka
Sustainability 2016, 8(6), 514; doi:10.3390/su8060514
Received: 4 May 2016 / Revised: 18 May 2016 / Accepted: 25 May 2016 / Published: 27 May 2016
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Abstract
Currently, strategies to mitigate urban heat island (UHI) effects and reduce building energy consumption are implemented worldwide. In Japan, as an effective means of mitigating UHI effects and saving energy of buildings, highly reflective (HR) roofs have increasingly been used. In this study,
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Currently, strategies to mitigate urban heat island (UHI) effects and reduce building energy consumption are implemented worldwide. In Japan, as an effective means of mitigating UHI effects and saving energy of buildings, highly reflective (HR) roofs have increasingly been used. In this study, in order to evaluate the effect of HR roofs on building energy conservation, we investigated the solar reflectivity of a subject school roof in Osaka, Japan, in which HR roofing sheets were installed on the roof from 2010. Additionally, monthly and annual thermal loads, including the cooling load and heating load of the top floor of the school, were calculated using the thermal load calculation software New HASP/ACLD-β. Comparing the calculated thermal loads of the school after HR roofing sheet installation to before, the annual thermal load decreased about 25 MJ/m2/year, and the cooling load decreased about 112 MJ/m2/year. However, the heating load increased about 87 MJ/m2/year in winter. To minimize the annual thermal load, thermal insulation of the roof was also considered to be used together with HR roofing sheets. Thermal load calculations showed that the combination of HR roofing sheets and thermal insulation can be effective in further reducing the annual thermal load. Full article
(This article belongs to the Special Issue Urban Heat Island)
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