Urban Heat Island RESEARCH: Negative Impacts on Urban's Ecological Niche

URBAN HEAT ISLAND RESEARCH
Research Paper on Urban Heat Island Research
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URBAN HEAT ISLAND RESEARCH
EXECUTIVE SUMMARY
Urban heat island (UHI) affects urban's ecological niche both positively and negatively, though
the negative effects outweigh the positive hence making it undesirable. The negative impacts of
UHI mostly affect human health conditions, climate, and environmental surroundings. Quite a
number of research and studies have been conducted in this field. However, most of these studies
had much resemblance as the scholars used almost the same methodology of education, thus
giving almost giving similar outcomes. This research paper tends to take a different approach in
analyzing different cities through correlation, regression, and parametric statistical analysis to
find the most efficient and effective mitigation strategies for the adverse effects of the urban heat
island. Traversing through different cities around the globe, this paper expresses a dynamic
mechanism on the various impacts of UHI through different seasons. The outcome of analysis
proves that UHI is mostly experienced during winter and summer, but no doubt, the effects of
UHI can still be felt in spring or autumn. The research considered the use and analysis of various
models of UHI, such as the CitySim model, Urban climate model (UC), artificial neural network
model (ANN), MesoScale mode, city energy simulation models, etc.
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URBAN HEAT ISLAND RESEARCH
Figure 1: Summary causes and effects of UHI (Sadhesh, 2018)
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TABLE OF CONTENTS
Executive summary..........................................................................................................................i
List of figures..................................................................................................................................iv
Introduction......................................................................................................................................5
Research objective.......................................................................................................................9
Literature review..............................................................................................................................9
Understanding of the urban heat island.....................................................................................11
Modeling of Urban Heat Island.................................................................................................14
Causes and effects of Urban Heat Island...................................................................................16
Adaptation and mitigation.............................................................................................................19
Urban Cities Modeling..................................................................................................................20
Urban climate modelling...............................................................................................................21
Building energy modeling.............................................................................................................23
Modeling interaction and modeling approaches........................................................................23
Conclusion.....................................................................................................................................25
References......................................................................................................................................27
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URBAN HEAT ISLAND RESEARCH
LIST OF FIGURES
Figure 1: Summary causes and effects of UHI................................................................................3
Figure 2: Map of urban thermal index across north America........................................................10
Figure 3: Map of various land using Guangzhou china.................................................................10
Figure 4: Flow diagram of how to quantify urban Heat Island.....................................................14
Figure 5: Urban heat island............................................................................................................15
Figure 6: The urban Heat Island Process.......................................................................................16
Figure 7: Process of urban canopy level........................................................................................18
Figure 8: Graphical representation of UCL...................................................................................18
Figure 9: Urban heat island effect difference in rural and urban...................................................20
Figure 10: Summary of effects of UHI..........................................................................................23
Figure 11: Illustration of UHI models...........................................................................................24
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INTRODUCTION
Urban heat island refers to the effects that are associated with the formation and development of
urban centers and urbanization in general. The impact of urban heat island is experienced in the
urban centers where the thermal condition of towns is much higher than that in the suburbs. The
disparity in temperature is caused by the many activities that take place in urban centers ranging
from heat emitted by the household chimney, motor vehicles, factories, air conditioning systems,
and heat from hotels and restaurants within the city. These items consume a lot of heat energy
and, in turn, release heat into the atmosphere raising the temperature in the town (Santamouris.,
2014). The presence of tall superstructures and sky creepers in urban areas obstruct the wind and
airflow; therefore, reducing the speed of wind hence exacerbated the heat island effect in towns.
The effect of urban heat island has been more rampant in the past few years due to the rapid
development of urban structures and urbanization of towns. Another reason for the increases
urban heat island effect is the industrialization and centralization concepts where industries are
more concentrated in a confined location. Each factory releasing emitting heat as a result of
manufacturing or production processes increases the temperature of the area, thus causing urban
heat islands in those regions (Mirzaei., 2015). Weather conditions also have an impact on the
urban heat island as extremely hot weather conditions affect the work rate of a human and can
cause health complications and, in the worse scenario, cause death as a result of heatstroke.
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URBAN HEAT ISLAND RESEARCH
Most parts of the world's energy consumption are in the cooling and heating of structures and
buildings. This implies that in areas with a dense population of structural buildings consume a lot
of energy in heating buildings and at the same time, release a lot of heat as a result of cooling
these buildings. Heat exchange between buildings and the proximity of urban structures hinders
the circulation of air; therefore, these released hot gases are retained in the atmosphere rising
temperatures (Guo et al., 2015). With the fast-growing urbanization, the minimization of
buildings' energy consumption in towns has a tremendous advantage in reducing island heat
effect and proves potential in energy savings. The difference in temperature conditions in urban
areas and rural areas is mainly attributed to the urban heat island (UHI) effect caused by tall
structures in urban areas. The difference in wind speed is as a result of wind being obstructed and
sheltered by urban sky creepers. Recent research to establish the physiological correlation that is
derived from similarity patterns between height counters and isotherms showed that UHI
possesses a cliff (region of difference) at the urban-rural fringe in adjacent areas to urban cities
(Debbage and Shepherd., 2015).
The effects of urban heat island is a global challenge, as the heating and cooling phenomenon
occurs to almost all urban centers and is caused by constant constructions in urban areas and
human economic activities in these regions. Research also showed that urban heat island effects
are mostly caused by heat released from buildings, underlying surface, population density,
vegetation cover, and weather conditions.
According to the United States environmental protection agency, continuous development in
structural buildings, construction of roads, and development of other infrastructures cause
changes in the landscape and vegetation cover, leaving the land open making the land than were
once moist and permeable dry and impermeable (Zhou et al., 2014). These eventually cause
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changes in the climatic condition in urban areas, making cities warmer than the rural suburbs
forming an island of increasing temperature in the landscape.
City structures that include buildings, structural morphology, anthropogenic surface heat released
by automobiles, and ventilation equipment such as air conditioning are the most contributing
factors to the increasing temperature in urban centers, causing heat island. These conditions
eventually increase the building’s energy consumption as the system provides comfortability
inside buildings through the use of heat exchangers or refrigerators and also causes air pollution.
Prolonged effects of urban heat island cause greenhouse gas emission that negatively impacts on
human and animal health. Due to urban densification, increased anthropogenic heat, and decline
in vegetation cover, Intragovernmental Panel on Climate change in 2014 conducted research
aimed at finding mitigation plans and strategies that would help in minimizing the emission of
greenhouse gas effects in urban areas (Li, Bou-Zeid and Oppenheimer., 2014).
In relation to the cases mentioned above and the effects of urban heat island UHI. It is crucial for
state authorities and urban management together with urban planning agencies to formulate the
best alternative mitigation strategies through the formulation of regulations, better equipment
tools, and guidelines to offer protection to the urban environment (Santamouris ert al., 2015).
The primary objective of this report is to have a critical analysis of urban heat island,
understanding major contributing factors, dire effects, and possible mitigation strategies that best
overcome the urban heat island in metropolitan cities.
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