vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
THESIS TITLE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xii
LIST OF FIGURES
xiv
LIST OF ABBREVIATIONS
xviii
LIST OF SYMBOLS
xix
GENERAL INTRODUCTION
1
1.1
Introduction
1
1.2
The Problem Statement
4
1.3
Research Hypothesis
5
1.4
Research Questions
6
1.5
Research Gap
6
1.6
Research Objectives
8
1.7
Scope and Limitations
9
1.8
Importance of the Research
12
viii
1.9
2
Thesis Organization
13
URBAN PLANNING CODES, COLONNADE AND
LOW-RISE STREET CANYON MICROCLIMATE
16
2.1
Urban Canopy Layer Microclimate
17
2.1.1 Energy Balance of an Urban Canyon Layer
19
2.1.2 Effects of Urban Features to the Energy
Balance
22
2.1.3 Strategies to Improve Microclimate of
Tropical Urban Canopy Layer
2.2
2.3
Low-Rise Street Canyon Microclimate
28
2.2.1 Air Temperature
28
2.2.2 Relative Humidity
30
2.2.3 Thermal Comfort
30
2.2.4 Wind Flow
31
2.2.5 Urban Heat Island
31
Low-Rise Street Canyon Design Strategies
32
2.3.1 Street Orientation
33
2.3.2 Overhead Shading
33
2.3.2.1 Overhangs
34
2.3.3 Urban Form
2.4
2.5
26
36
2.3.3.1 Solar Angle Induced Models
37
2.3.3.2 Courtyard
39
2.3.4 Ventilative Cooling
40
2.3.5 Vegetation and Green Area
41
2.3.6 Solar Reflectivity (Albedo)
41
Colonnade
42
2.4.1 Rationale of Strategy
43
2.4.2 Envelope Ratio
44
2.4.3 Thermal Performance
46
2.4.4 Overhead Shading
47
Urban Canyon Layer of Commercial Street in
Johor Bahru
48
ix
2.5.1 Urban Planning Codes
51
2.5.2 Colonnade
54
Summary
55
METHODOLOGY
57
3.1
The Need for the Experiment
58
3.2
Qualitative Analysis of Current Urban Planning
2.6
3
3.3
3.4
Codes
58
Development of Colonnade and Street Configurations
59
3.3.1 Street Aspect Ratio
60
3.3.2 Street Orientation
60
3.3.3 Colonnade Depth to Height Ratio
60
3.3.4 Colonnade to Street Width Ratio
61
3.3.5 Envelope Ratio
62
Shading Analysis
63
3.4.1 Methods of Shading Analysis
64
3.4.1.1 Manual Calculation Method
64
3.4.1.2 Computer Simulation
65
3.4.2 Selection of Shading Simulation Software
66
3.4.3 Ecotect Simulation Procedure
67
3.4.3.1 Step I: Data Requirement
68
3.4.3.2 Step II: Preparation of the Models
69
3.4.3.3 Step III: Detailed Interface – Selecting
Simulation Parameters and Perform
Simulation
3.4.3.4 Step IV: Review Simulation Results
3.5
70
72
3.4.4 Simulation Limitations
73
Urban Canyon Layer Air Temperature Prediction
73
3.5.1 Methods of Air Temperature Prediction
74
3.5.1.1 Field Experiment
74
3.5.1.2 Physical Model Method
75
3.5.1.3 CFD
76
3.5.1.4 Statistical Model
76
x
3.5.1.5 Digital Elevation Models
77
3.5.1.6 Computer Simulation
77
3.5.1.7 Calculation Method
78
3.5.2 Selection of Air Temperature Prediction Model
78
3.5.3 The Cluster Thermal Time Constant (CTTC)
Model
3.6
4
78
Envelope Ratio
88
3.6.1 Calculation Procedure
91
3.6.1.1 Step I: Data Requirement
91
3.6.1.2 Step II: Preparation of the Models
93
3.6.1.3 Step III: Calculation
93
3.6.1.4 Step IV: Review Simulation Results
94
3.6.2 Simulation Assumptions & Limitations
94
3.7
Simulation Analysis Criteria
95
3.8
Conclusion
98
RESULTS, ANALYSIS AND FINDINGS
99
4.1
Shading Analysis on Colonnade
100
4.1.1 North-South Oriented Street
100
4.1.2 East-West Oriented Street
105
4.1.3 Influence of Colonnade Depth to Height on
Shade Percentage
109
4.1.4 Influence of Street Aspect Ratio on
Shade Percentage
110
4.1.5 Influence of Street Orientation on Shade
Percentage
111
4.1.6 Impact of Current Urban Planning Codes on
Shade Percentage
112
4.1.7 Summary of Colonnade Depth to Colonnade
Height Ratio (Dc/Hc)
4.2
Solar Radiation Absorption, ∆𝑇!"#$% (K)
114
115
4.2.1 Influence of Envelope Ration to the Solar
Radiation Absorption
118
xi
4.2.2 Impact of Current Urban Planning Codes on
Solar Irradiation Absorption
4.3
4.4
4.5
4.6
5
120
Net Long-Wave Radiation, ∆𝑇!"#$
121
4.3.1 Influence of Sky View Factor in Heat Release
123
Air Temperature
125
4.4.1 Envelope Ratio Effect
127
Summary of Colonnade Depth to Street Width Ratio
(C/W)
129
Summary
130
SUMMARY AND RECOMMENDATION
132
5.1
Review of Thesis Objectives and Research Questions
132
5.2
Thesis Conclusion
134
5.2.1 Colonnade and Shading
135
5.2.2 Colonnade Depth and Envelope Ratio
135
5.2.3 Envelope Ratio and Air Temperature
136
5.2.4 Sky View Factor and Air Temperature
137
5.2.5 Influence of Existing Urban Planning Codes
138
5.3
Envelope Ratio and CTTC
138
5.4
Suggestions for Further Research
139
REFERENCE
140
APPENDIX
150
A
150
B
C
Example of CTTC Calculation Spreadsheet
A1.
Solar radiation absorption, ∆𝑇!"#$% calculation
151
A2.
Net long-wave radiation loss, ∆𝑇!"#$ calculation
152
Conference Paper: Effect of Urban Geometry on Solar Insolation
Threat In JSNAC (Pilot Study)
153
Conference Poster: Colonnade in Cooling Urban Canopy Layer
154
xii
LIST OF TABLES
TABLE NO.
1.1
TITLE
PAGE
Summary of previous research related to tropical urban
street design, colonnade and urban canopy layer
microclimate
7
2.1
Climatic scales in an urban area
17
2.2
Thermal properties of materials
21
2.3
Radiative properties of materials
24
2.4
Effects of urban features to the energy balance
26
2.5
Simulated colonnade effects in canyon streets and closed
courtyards at 15:00, July data, Tel Aviv
45
Roles and functions of authorities in different level
regarding town and country planning in Malaysia
51
Town and country planning regulations in Johor Bahru
City Centre
53
Commercial Projects in Johor Bahru and the Built-up
Geometry Analysis. Average H/W= 0.51
54
2.9
Microclimate of low-rise street canyon
55
3.1
Colonnade depth to height ratio (D/H) and colonnade depth
To street width ratio (C/W)
59
3.2
Envelope ratio for the research
62
3.3
Design variables for shading analysis
66
2.6
2.7
2.8
xiii
3.4
The variables and parameters which are included in the
CTTC model
79
3.5
Cluster Thermal Time Constant (CTTC) values
84
3.6
Comparison of sky view factor by using calculation method
and Ecotect simulation
87
3.7
Climatological element and their relation to urban features
88
3.8
Temperature and solar insolation on 18 August 2009
91
3.9
Urban variables and input parameters to the CTTC model
92
3.10
Independent variables, dependent variables and constants
of the CTTC model
94
3.11
Data analysis indicators and their interpretation
96
4.1
Depth of shaded area, x on colonnade ground of east facing
facade (H/W= 0.25, colonnade height = 4m)
110
Difference between north-south oriented street and east
-west oriented street
112
4.3
Simulated colonnade effect at 14:00, 18 August
127
4.4
Colonnade depths (in meter) in various street aspect ratios
130
4.5
Colonnade depths (in meter) in various colonnade heights
131
4.2
xiv
LIST OF FIGURES
FIGURE NO.
1.1
TITLE
PAGE
Sectional diagram of a typical commercial street in
Malaysia
5
Main variables for heat stress reduction analysis – Street
aspect ratio (H/W) and Colonnade depth to street width
ratio (C/W)
11
Main variables for shading analysis – Colonnade depth
to colonnade height ratio (Dc/Hc)
11
1.4
Requirement of colonnade design chart
12
1.5
The flow of research process and thesis structure
15
2.1
Climatic scales in urban areas: meso, local and
micro-scale
18
The urban street canyon and the energy balance in
equation 2.1
20
2.3
Sky view factor. Source: Sebastian Wypych
25
2.4
Overhang in a street canyon
34
2.5
Adjustable vertical and horizontal shading device
35
2.6
Building types: (a) pavilions (b) courts
36
2.7
Urban block design using shadow umbrella theory
37
2.8
Self-shading building by Capeluto
38
2.9
Courtyards in various ratios
39
2.10
The relationship between the surface-air temperature
difference (∆T) and the albedo of selected paints
and roofing materials facing the sun
42
Colonnades at both sides of the street
42
1.2
1.3
2.2
2.11
xv
2.12
Map of Johor Bahru city
49
2.13
Air Temperature and Solar Radiation of Johor Bahru
on a Typical Clear Day (18 August 2009)
50
Illustration of shophouse and urban planning codes in
Malaysia
52
3.1
Investigated colonnade depth to its height ratios
61
3.2
Investigated colonnade depth to the street width ratios
62
3.3
The calculation of shadow points on a flat ground given
the azimuth and altitude of the sun
65
3.4
Colonnade shading simulation procedures in Ecotect
68
3.5
Formulated 3D simulation models in Sketchup
69
3.6
Simulated plane line (in orange) representing the 2D
section of the ground for infinite canyon length simulation
70
3.7
Site location and time zone input in Ecotect
71
3.8
Overshadowing percentage simulation under sun-path
diagram window
71
3.9
Shading simulation results
72
3.10
Selection of desired simulation date
73
3.11
Variables in net solar 𝑇!"#$% exchanges
81
3.12
Variables in Partial Shaded Area (PSA) equation
82
3.13
Typical vertical cross-section of a symmetrical urban
street canyon showing open space area external wall
area and plot area
83
Site obstructions projected back onto an imaginary
hemisphere centred at the point of interest
86
Projected site obstructions shown in a sun-path diagram
centred at the point of interest
86
3.16
Envelope ratio
89
3.17
Overall simulation procedures with design variables and
performance variables
97
2.14
3.14
3.15
xvi
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
Shading percentage on colonnade ground for east-facing
façade in (a) H/W 0.25, (b) H/W 0.5, (c) H/W 1, (d) H/W
2 streets on 21 June.
101
Shading type: (a) overhead shading on a colonnade with
D/H 0.5 (colonnade depth = 2m, height = 4m), (b) mutual
shading effect on a colonnade with Dc/Hc 0.5, (c) overhead
shading on a colonnade with Dc/Hc 0.5 (colonnade depth
= 2m, height = 4m)
102
Shading percentage for west-facing façade in (a) H/W 0.25,
(b) H/W 0.5, (c) H/W 1, (d) H/W 2 streets on 21 June
104
Shading percentage for north-facing façade in (a) H/W 0.25,
(b) H/W 0.5, (c) H/W 1, (d) H/W 2 streets on 21 June
105
Monthly shading percentage on colonnade ground of north
facing façade in east-west oriented street in H/W 0.25 street
107
Shading percentage for south-facing façade in (a) H/W
0.25, (b) H/W 0.5, (c) H/W 1, (d) H/W 2 streets on 21
December
108
Shading percentage on colonnade ground of (a) D/H 0.5
and (b) D/H 2.5 in various street aspect ratios from 17:30
to 14:00 on 21 June
111
Overhead shading from 11:00 to 16:00 in various D/H ratios
for north-south oriented street
113
Overhead shading from 11:00 to 16:00 in various D/H ratios
for east-west oriented street
113
Simulated solar radiation absorption in various colonnade
depth to street width ratios, in (a) H/W0.25, (b) H/W 0.5,
(c) H/W 1, (d) H/W 2 streets on 18 August
115
The effect of colonnade depth to street width ratio (C/W)
and aspect ratio on absorbed solar radiation (K) on 14:00,
18 August
117
Envelope ratio of various colonnade depth to street width
ratio (C/W) in low-rise street aspect ratio
118
Envelope ratio and colonnade effect on solar radiation
absorption at 14:00, 18 August
119
Current urban planning code (C/W0.15) and the solar
radiation absorption reduction (K)
120
xvii
4.15
Simulated net long-wave radiation on (a) H/W 0.25, (b)
H/W 0.5, (c) H/W 1, (d) H/W 2 street by various SVF
121
Sky view factor of various colonnade depth to street
width ratio (C/W) in low-rise street aspect ratio
123
Effect of SVF in net long-wave radiation loss in (a) 15:00,
(b) 20:00
124
Simulated air temperature by various colonnade depth to
street width ratio in (a) H/W 0.25, (b) H/W 0.5, (c) H/W 1,
(d) H/W 2 streets on 18 August
125
4.19
Simulated air temperature reduction (K)
128
5.1
Colonnade depth and various variables
134
5.2
Simulated air temperature rise by colonnade depth in
various street aspect ratio
137
4.16
4.17
4.18
xviii
LIST OF ABBREVIATIONS
2D
-
Two-dimensional
3D
-
Three-dimensional
CBD
-
Central business district
CFD
-
Computational fluid dynamic
CTTC
-
Cluster Thermal Time Constant
DEM
-
Digital elevation model
E
-
East
GIS
-
Geographic information system
H/W
-
Aspect ratio
HSA
-
Horizontal shading angle
N
-
North
NE
-
North-east
NLWR
Net long-wave radiation loss
NW
-
North-west
PET
-
Physiological Equivalent Temperature
RH
-
Relative humidity
RMT
-
Radiant mean temperature
S
-
South
SE
-
South-east
SVF
-
Sky view factor
SW
-
South-west
UCL
-
Urban canopy layer
UHI
-
Urban heat island
VSA
-
Vertical shading angle
W
-
West
xix
LIST OF SYMBOLS
∝
-
Reflectivity of short-wave radiation
𝛼
-
Albedo
𝛽!
-
Sun altitude angle (°) at time 𝑡
Br
-
Brunt number
C
-
Heat capacity (J m-3 K-1 x 106)
C/W
-
Colonnade depth to street width ratio
D
-
Diffuse-beam radiation (W/m2)
D
-
Depth of building (m)
Dc/Hc
-
Colonnade depth to colonnade height ratio
dx
-
Offset from the shading point
dy
-
The depth of the shade
𝑒!
-
Solar azimuth angle (°) measured from the south, at
time 𝑡
𝜀
-
Emissivity for long-wave radiation at the surface
FA
-
Plan area of building roofs in cluster (m2)
GA
-
Ground area (m2)
h
-
Overall heat transfer coefficient at surface (W/m2 K)
H
-
Building height
h roof
-
Overall heat transfer coefficient at roof surface (W/m2
K)
𝐼!"#$%# !"# (𝑡)
-
Solar radiation intensity on rooftop (W/m2)
𝐼!
-
Solar radiation intensity on the ground (W/m2)
𝐼!"#
-
The total absorbed solar irradiation on surface (W/m2)
𝐼!"#$
-
Net long wave radiation loss from an unobstructed
xx
black surface
𝐼𝑣!
-
Solar radiation intensity on the sunny part of the ith
wall (W/m2)
K
-
Temperature degree Kelvin
k
-
Thermal conductivity (W m-1 K-1)
𝐾∗
-
Incoming short-wave radiation (W/m2)
𝐾↑
-
Reflected radiation (W/m2)
𝐾↓
-
Incoming global radiation (W/m2)
𝐿∗
-
Incoming long-wave radiation (W/m2)
𝐿↑
-
Outgoing long-wave radiation (W/m2)
𝐿↓
-
Incoming long-wave radiation (W/m2)
m
-
Surface solar radiation absorptivity
mg
-
Ground surface solar radiation absorptivity
mH
-
Wall surface solar radiation absorptivity
𝜎
-
Stefan-Boltzmann constant
PSA!
-
Walls’ partial shaded areas on the ground
PSA
-
Partial shaded area
𝜌
-
Density (in kg m-3 x 103)
∆𝑄!
-
Net advection through the sides of the volume
∆𝑄!
-
Net heat storage
𝑄!
-
Latent heat
𝑄!
-
Anthropogenic heat
𝑄!
-
Sensible heat
S
-
Direct-beam radiation (W/m2)
S
-
Total investigated area (m2)
SVF roof
-
Sky view factor of the roof surfaces
t
-
Time (h)
t min
-
Minimum value a time t
𝑇!
-
Base temperature (°C)
𝑇!
-
Air temperature variation (K)
𝑇!"#
-
Ambient air temperature (K)
𝑇!"#$
-
Contribution of net long-wave radiation exchange to air
temperature (K)
xxi
𝑇!"#$%
-
Contribution of solar radiation absorption to air
temperature (K)
Ts
-
Temperature of the surface
𝑢
-
mean wind speed (m/s)
𝜇
-
Thermal admittance (J m-2 S-1/2 K-1)
V
-
Envelope ratio
V
-
Envelope ratio
WA
-
Wall area (m2)
X!
-
Shaded strip width (m) at time 𝑡
λ
-
Time (h) of indexing