Review and Critical Analysis of International UHI Studies

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signals and computer evaluation of a 3D database [120]. Dense buildings patterns lock heat into the area without winds to dissipate it. Yamashita took controlled sky view factor (SVF) readings from a number of locations and recorded the air temperature also, he found that in all cities as SVF decreased air temperatures rose, he also mapped SVF against heat island intensity for day and night time temperatures, this showed that the daytime temperatures showed stronger correlation to minimum SVF. Because of these studies sky view is considered a causal element of an urban heat island [118]. Blankenstein and Kuttler studied urban geometry and its effects on air temperature and downward long‐wave radiation and found that the interrelation between SFV and long‐wave radiation was very strong but was weak with air temperature, they concluded that air temperature was influenced by many other factors and thus was very challenging to predict using SVF alone [122]. Jusuf’s analysis on a green Singapore estate when studying SVF and its affect on air temperature found there was a strong correlation in day time temperatures but a weak correlation in night time temperatures [123]. Yamashita discusses Sky View Ratio (SVR) as the ratio of wall height to street width to calculate urban canyons, he believes SVR is a better measure of air temperature in the urban canyon as it takes into account the heat flows from all directions [116]. 2.2 Measured Impacts Measured Impacts Number of References Continent Considered Temperature Increase 13 Asia, South America, Europe Air Quality 9 North America, Africa, Asia Energy Use 11 Asia, North America, Europe Climate Types Review and Critical Analysis of International UHI Studies Considered List of references Equatorial, Arid, Warm temperate Equatorial, Arid, Warm temperate Equatorial, Arid, Warm temperate, Snow, Polar Peak Power 4 North America Warm temperate, Snow CO2 Emissions 10 North America, Asia, Europe Health Impacts 6 Europe, North America, Arid, Warm temperate, Snow Arid, Warm temperate 078, 047, 145, 137, 138, 022, 143, 144, 146, 147, 096, 148, 157 078, 157, 141, 136, 140, 039, 139, 135, 014 078, 155, 153, 154, 150, 149, 080, 112, 152, 151, 157 168, 169, 170, 171 167, 163, 165, 166, 162, 159, 158, 164, 132, 133 078, 117, 129, 133, 132, 131, 174 Economic Impacts 5 North America Warm temperate 173, 172, 175, 080 Page 9
Some UHI impacts are positive such as increased growing seasons for plants, but most are negative. Increased air temperatures can cause or exacerbate poor air and water quality, impaired health and psychological conditions, increased energy consumption and negative impacts on the economy such as agricultural losses, impacts to tourism and financial losses due to increased extreme weather events [078]. The following papers review the literature found in this area, the papers are categorized into impacts on: temperature; air quality; energy use; peak power; CO2 emissions; health; and the economy. 2.2.1 Temperature Increase The urban heat island effect is quantified by rises in air and surface temperatures in urban areas compared to the surrounding rural areas. Increased temperatures make city living more uncomfortable and when nighttime temperatures rise it can affect or even inhibit sleep. High temperatures in extreme circumstances such as heat waves can cause death. Rising temperatures boost energy consumption due to the demand for cooling appliances such as air conditioning units and fans [078]. Temperature increases are also linked to increased rainfall and the production of photochemical oxidants [047]. Urban heat islands follow a similar temperature pattern from city to city, with a few exceptions. Starting from rural areas temperatures start to rise at the edge of the city and continue to rise until they reach their peak over the city centre, where buildings are most dense. Pockets of cooler air are often found over parks or woodland [157]. Air and surface temperatures in urban areas are affected by many different variables, topography, the features of an area, the climate type of the region and temporary conditions like weather patterns and breezes. Breezes can negate the urban heat island effect by the mixing of cooler winds with the warmer city winds thus creating an overall cooling effect [157]. There are 11 papers addressing air temperature changes in urban climates. Of those 11 studies three are from China, three from Japan, one from Singapore, one from Hong Kong, two from the USA and one from the UK. Studies in Tokyo have recorded the total number of hours where air temperature was more than 30°C in a typical summer has doubled in the last 20 years [148]. The papers measured urban growth on surface temperature [145, 137, 147] and land use on surface temperature [138, 144, 096]. For the impact of urban growth on surface temperature various research methods were used: remote sensing, Landsat, GIS modeling and data from weather stations. In a study in China results showed uneven growth, an increase of 13.01 Kelvin. The study found that the spatial pattern of radiant temperatures correlated with urban expansion [145]. This particular study however failed to take into consideration the land surface type/ roughness and emissivity which can have a significant impact on temperature readings. Review and Critical Analysis of International UHI Studies Page 10
Page 1 and 2: Assessment of International Urban H
Page 3 and 4: Comments iii Bibliographic Report a
Page 5 and 6: List of Acronyms and Abbreviations
Page 7 and 8: TABLE OF CONTENTS vii Bibliographic
Page 9 and 10: ix Bibliographic Report and Study o
Page 11 and 12: xi Bibliographic Report and Study o
Page 13 and 14: The mitigation technologies were fo
Page 15 and 16: a forward path; provides an economi
Page 17 and 18: 2.1.1 Population Size/Density Popul
Page 19: workday effect and weekends. Studie
Page 23 and 24: correlation with vehicles and traff
Page 25 and 26: 2.2.4 Peak Power Peak power describ
Page 27 and 28: temperature and climate, thus chang
Page 29 and 30: 3 QUANTITATIVE MODELING & SIMULATIO
Page 31 and 32: The following papers use a number o
Page 33 and 34: Another study in Japan simulated ai
Page 35 and 36: This paper applied a model to calcu
Page 37 and 38: 3.2 Simulations of UHI 3.2.1 Introd
Page 39 and 40: A study in France sought to find ou
Page 41 and 42: Traffic flow was calculated using c
Page 43 and 44: Implementation Issues 4 North & Asi
Page 45 and 46: These studies were founded primaril
Page 47 and 48: (humidification and heat sink insta
Page 49 and 50: emissions and the tree topology rel
Page 51 and 52: At a City scale one study focuses o
Page 53 and 54: This section reports the findings f
Page 55 and 56: Recent steps taken in cities in the
Page 57 and 58: � Most US States encourage tree p
Page 59 and 60: o 29 German cities offer subsidies
Page 61 and 62: 4.5.1 Review for Cool Roofs: 4.5.1.
Page 63 and 64: the global emitted CO2 offset poten
Page 65 and 66: standards to promote the cool roofs
Page 67 and 68: The expected savings generated in c
Page 69 and 70: � The degree to which the change
Page 71 and 72:
enefits are complex to measure dire
Page 73 and 74:
controls of the active cooling/heat
Page 75 and 76:
temperature increases due to paveme
Page 77 and 78:
curb‐side planting. Data gatherin
Page 79 and 80:
location, orientation, growth/morta
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seasons, climate types, etc. Furthe
Page 83 and 84:
the summer than the winter, thus ra
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A study in Japan tested the effect
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One US study written in 1998 seeks
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This section reports the findings f
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planning approach. Medium resolutio
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Urban design and planning is a comp
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5 CRITICAL REVIEW OF UHI COUNTERMEA
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� Implementation Issues: The esti
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savings are used over solutions tha
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� 10.5 MtCO2 emissions per year f
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� Preparation: Substantial prepar
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5.3.3 Green Roofs and Urban Green A
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5.4 Economic Review The magnitude o
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5.5 Opportunities for Scale Up (Bar
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technology, it evaluates the availa
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Availability: the level and type of
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integration would make them accepta
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Awareness: Planners and designers w
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would seek to incentivize UHI count
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homeowner for example to choose whe
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Planning issues for new builds, the
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5.6.4 Energy Efficiency Measures Pl
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� Political will - The government
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not to create dedicated policy vehi
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� When developing costing analyse
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7 GLOBAL SCIENTIFIC PANEL 7.1 Intro
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an understanding of planning policy
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Role Name Institution Country of Or
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Role Name Institution Country of Or
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sustainable architecture. He is an
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energy buildings, natural and mixed
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Name: Hashem Akbari Current Positio
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momentum in cities are measured and
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Ms MacDonald was formerly Director
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Name: Dr Dale Quattrochi Current Po
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Name: Joe Huang Current Position: L
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State University. He is former Pres
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Bank for Reconstruction and Develop
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planners/designers are equipped wit
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Paper Ref Title of Paper Author Ins
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