Development of estate level outdoor ventilation prediction models for HDB estates in singapore 1

125 Table 5.3: Parametric study findings and their explanations for point blocks, pedestrian level of GBCR – random configuration .... 130 Table 5.5: Parametric study findings and their

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DEVELOPMENT OF ESTATE LEVEL OUTDOOR VENTILATION PREDICTION MODELS FOR HDB

ESTATES IN SINGAPORE

LEE ROU XUAN @ LEE SEU QUIN

(B.Sc Building (Hons.), NUS; M.Sc (Building Science), NUS)

A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

DEPARTMENT OF BUILDING NATIONAL UNIVERSITY OF SINGAPORE

2013

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ACKNOWLEDGEMENTS

I would like to express my gratitude to all the people who helped me in completing this thesis First and foremost, I want to thank my supervisor and mentor, Prof Wong Nyuk Hien, for all his advice, guidance and encouragement during all the stages of this research

My thanks also go to Dr Demetris Clerides, Mr Peter Ewing and Mr Kynan Maley from CD-Adapco for providing all the necessary technical support in the use of the Star-CCM+ software throughout my candidature here

My appreciation also goes to Mr Komari Bin Tubi, from the School of Design and Environment (SDE) Wind Tunnel Laboratory, for his kind technical assistance in helping to prepare the equipment and sensors before actual experiments Also, thanks to Mr Tan Dong Xing, the student assistant for helping me to construct the scaled wind tunnel models and even took the trouble to come back during his exams period Next, my heartfelt thanks goes

to Mr Clement Choo, the IT expert for helping me to tackle some of my computer hardware problems

I am grateful to Dr Steve Kardinal Jusuf for answering many of my questions regarding research methodologies and for all his insightful comments and suggestions Moreover, I would also want to thank my fellow course-mate Mr Terrance Tan, for letting me use his more powerful computer to supplement

my massive simulation studies; without which, the whole process might stretch out for another one year

Also many thanks go to my entire lab mates - Alex Tan, Erna Tan and also Kelvin Li, for making all these years a funnier and wackier experience to remember From all the laughs and their suggestions with this research, this certainly contributed to the betterment of this study

Furthermore, I am certainly grateful to acknowledge the financial support that comes from the scholarship funding from the National University of Singapore

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(NUS) that has helped to ease some of my financial burden during my study here

Next, I want to thank my parents for bringing me to this world, my siblings for all their love, encouragement and endless moral support Special thanks goes

to my late grandparents who came all the way from China to settle down in Singapore and also drummed us the belief that girls should be given an equal opportunity to study like boys

Lastly, I would like to thank my husband and best friend Soong Chee Keong for sharing his knowledge in CFD research, incredible support, encouragement, taking care of me and making me see light when everything else seems hopeless

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS i

TABLE OF CONTENTS iii

SUMMARY xi

LIST OF TABLES xiv

LIST OF FIGURES xxii

LIST OF ABBREVIATIONS l CHAPTER 1 : INTRODUCTION 1

1.1 Background and Motivation 1

1.1.1 Reduction of Wind Speed 2

1.1.2 Research Motivation 2

1.1.3 Developments in this Research Area 4

1.1.4 Design Standards for Optimal Ventilation 5

1.1.4.1 Singapore – HDB Present Situation 5

1.1.4.2 Other Countries’ Situation 9

1.2 Research Objectives 11

1.3 Structure of Thesis 12

CHAPTER 2 : LITERATURE REVIEW 15

2.1 Effects of Wind 15

2.2 Effects of Urban Environments on Wind Flow 15

2.3 Description of Airflow Phenomenon 20

2.3.1 Indicator of Good Ventilation 20

2.3.2 Parameters that Affect Wind Flow in Urban Environments 21

2.3.2.1 Important Findings from Previous Researches 22

2.3.2.2 Other Factors that Affect Wind Flow 40

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2.4 Experimental Designs Adopted for Airflow and Ventilation Studies 41

2.4.1 Computational Fluid Dynamics (CFD) 42

2.4.1.1 Points to Note in CFD Simulations 43

2.4.1.2 Turbulence Models 47

2.4.1.3 Near-wall Treatment 52

2.4.2 Wind Tunnel Studies 53

2.5 HDB Building Designs and Site Planning 54

2.6 Research Gap 57

CHAPTER 3 : HYPOTHESIS AND METHODOLOGY 59

3.1 Hypothesis 59

3.2 Methodology 60

3.2.1 Scenarios or Cases Adopted 63

3.2.1.1 Orientation of Canyon (ORIENT) 65

3.2.1.2 Building Shape (BS) 66

3.2.1.3 Geometry (GEO) 67

3.2.1.4 Gross Building Coverage Ratio (GBCR) 70

3.2.1.5 Permeability (PERM) 73

3.2.1.6 Buildings’ Height Variation (HV) 78

3.2.1.7 Staggering of Blocks Arrangement (STAG) 81

3.2.2 Computational Fluid Dynamics Simulations 83

3.2.2.1 Model Description 83

3.2.2.2 Model Assumptions and Limitations 84

3.2.2.3 Computational Domain 86

3.2.2.4 Boundary Conditions 88

3.2.2.5 Meshing Type and Size 91

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3.2.3 Wind Tunnel Studies 93

3.3 Conclusion 98

3.4 Importance and Potential Contribution of the Research 99

CHAPTER 4 : WIND TUNNEL STUDY 103

4.1 Introduction 103

4.2 Wind Tunnel Testing 103

4.2.1 Testing Facilities 103

4.2.2 Simulation of the Atmospheric Boundary Layer (ABL) 105

4.2.3 Wind Tunnel Blockage and Model Span 107

4.2.4 Similarity Parameters 109

4.2.5 Locations of the Sensor Taps 112

4.2.6 Selected Cases 113

4.2.7 Assumptions 115

4.2.8 Results 115

CHAPTER 5 : PARAMETRIC STUDY OF THE INFLUENCE OF MORPHOLOGICAL VARIABLES ON ESTATE LEVEL VENTILATION 121

5.2 Parametric Approach 122

5.3 Findings from Parametric Study 122

5.3.1 Gross Building Coverage Ratio (GBCR) 122

5.3.1.1 Point Blocks 125

5.3.1.1.1 Point Blocks, Pedestrian Level 125

5.3.1.1.1.1 Point Blocks, Pedestrian Level - Random Configuration 127

5.3.1.1.1.2 Point Blocks, Pedestrian Level - Group Configuration 128

5.3.1.1.1.3 Point Blocks, Pedestrian Level - Courtyard Configuration 130

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5.3.1.1.2 Point Blocks, Mid-Level 132

5.3.1.1.2.1 Point Blocks, Mid-Level - Random Configuration 133

5.3.1.1.2.2 Point Blocks, Mid-Level - Group Configuration 134

5.3.1.1.2.3 Point Blocks, Mid-Level - Courtyard Configuration 136

5.3.1.2 Slab Blocks 137

5.3.1.2.1 Slab Blocks, Pedestrian Level 137

5.3.1.2.1.1 Slab Blocks, Pedestrian Level - Random Configuration 139

5.3.1.2.1.2 Slab Blocks, Pedestrian Level – Group Configuration 140

5.3.1.2.1.3 Slab Blocks, Pedestrian Level – Courtyard Configuration 142

5.3.1.2.2 Slab Blocks, Mid-Level 145

5.3.1.2.2.1 Slab Blocks, Mid-Level - Random Configuration 146

5.3.1.2.2.2 Slab Blocks, Mid-Level - Group Configuration 148

5.3.1.2.2.3 Slab Blocks, Mid-Level - Courtyard Configuration 149

5.3.2 Buildings’ Height Variation (HV) 150

5.3.2.1.1.1 Point Blocks, Pedestrian Level - Random Configuration 153

5.3.2.1.1.2 Point Blocks, Pedestrian Level - Stratified Configuration 154

5.3.2.1.2.1 Point Blocks, Mid-Level - Random Configuration 157

5.3.2.1.2.2 Point Blocks, Mid-Level - Stratified Configuration 158

5.3.2.2.1.1 Slab Blocks, Pedestrian Level - Random Configuration 161

5.3.2.2.1.2 Slab Blocks, Pedestrian Level - Stratified Configuration 163

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5.3.2.2.2.1 Slab Blocks, Mid-Level - Random Configuration 166

5.3.2.2.2.2 Slab Blocks, Mid-Level - Stratified Configuration 167

5.3.3 Permeability (PERM) 168

5.3.3.1.1.1 Point Blocks, Pedestrian Level – Ground Floor Only Permeability 172

5.3.3.1.1.2 Point Blocks, Pedestrian Level – Ground Floor and Mid-height Permeability 173

5.3.3.1.1.3 Point Blocks, Pedestrian Level – Mid-height Only Permeability 175 5.3.3.1.2 Point Blocks, Mid-Level 177

5.3.3.1.2.1 Point Blocks, Mid-Level – Ground Floor Only Permeability 179

5.3.3.1.2.2 Point Blocks, Mid-Level – Ground Floor and Mid-height Permeability 181

5.3.3.1.2.3 Point Blocks, Mid-Level – Mid-level Only Permeability 183

5.3.3.2.1.1 Slab Blocks, Pedestrian Level – Ground Floor Only Permeability 187

5.3.3.2.1.2 Slab Blocks, Pedestrian Level – Ground Floor and Mid-height Permeability 187

5.3.3.2.1.3 Slab Blocks, Pedestrian Level – Mid-level Only Permeability 190

5.3.3.2.2.1 Slab Blocks, Mid-Level – Ground Floor Only Permeability 192

5.3.3.2.2.2 Slab Blocks, Mid-Level – Ground Floor and Mid-height Permeability 195

5.3.3.2.2.3 Slab Blocks, Mid-Level – Mid-Height Only Permeability 197

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5.3.4 Geometry (GEO) 199

5.3.4.1.1.1 Point Blocks, Pedestrian Level – Geometrical Height Variation (H) 203

5.3.4.1.1.2 Point Blocks, Pedestrian Level – Geometrical Width Variation (W) 205

5.3.4.1.1.3 Point Blocks, Pedestrian Level – Combined Results of Geometric Height (H) and Width (W) Variation 208

5.3.4.1.2.1 Point Blocks, Mid-Level – Geometrical Height Variation (H) 211

5.3.4.1.2.2 Point Blocks, Mid-Level – Geometrical Width Variation (W) 213

5.3.4.1.2.3 Point Blocks, Mid-Level – Combined Results of Geometric Height (H) and Width (W) Variation 217

5.3.4.2.1.1 Slab Blocks, Pedestrian Level – Geometrical Height Variation (H) 220

5.3.4.2.1.2 Slab Blocks, Pedestrian Level – Geometrical Width Variation (W) 222

5.3.4.2.1.3 Slab Blocks, Pedestrian Level – Combined Results of Geometric Height (H) and Width (W) Variation 225

5.3.4.2.2.1 Slab Blocks, Mid-Level – Geometrical Height Variation (H) 228

5.3.4.2.2.2 Slab Blocks, Mid-Level – Geometrical Width Variation (W) 230

5.3.4.2.2.3 Slab Blocks, Mid-Level – Combined Results of Geometric Height (H) and Width (W) Variation 231

5.3.5 Staggering of Blocks Arrangement (STAG) 233

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5.3.5.1.1 Point Blocks – Pedestrian Level 239

5.3.5.1.2 Point Blocks – Mid-Level 245

5.3.5.2.1 Slab Blocks – Pedestrian Level 248

5.3.5.2.2 Slab Blocks – Mid-Level 256

5.3.5.3 Important Points about STAG Index 259

5.4 Conclusion 262

CHAPTER 6 : ESTATE LEVEL WIND VELOCITY RATIO (VR) PREDICTION MODELS 263

6.2 Methodology and Variables Selection on Wind Velocity Ratio (VR) Models Development 263

6.3 Results and Discussion 266

6.3.1 Models Development 266

6.3.2 Models Strength and Accuracy 275

6.4 Conclusion 277

CHAPTER 7 : SENSITIVITY ANALYSES 280

7.2 Methodology 280

7.2.1 Gross Building Coverage Ratio (GBCR) Study 282

7.2.2 Geometry (GEO) Study 282

7.2.3 Buildings’ Height Variation (HV) Study 286

7.3.1 GBCR Study 287

7.3.2 GEO Study 294

7.3.3 HV Study 302

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7.4 Conclusion 315

CHAPTER 8 : MODELS APPLICATION AND VALIDATION 317

8.2 Methodology 317

8.2.1 Base Case Study 318

8.2.2 Increase in Building Height 320

8.2.3 Increase in Void Deck Height 321

8.2.4 Decrease in Spacing between the Blocks 322

8.3 Mapping of Morphological Quantities 324

8.5 Actual Case Study 346

8.6 Conclusion 350

CHAPTER 9 : CONCLUSION 354

9.1 Background Study of Singapore Urban Development 354

9.2 Urban Morphological Indices Development 356

9.3 Wind Velocity Ratio (VR) Models Validation and their Application 359

9.4 General Guidelines for Estate Level Outdoor Ventilation Improvement 361 9.5 Limitations and Suggestions for Future Research 363

BIBLIOGRAPHY 365

GLOSSARY 377

APPENDICES 380

APPENDIX 1 381

APPENDIX 2 385

APPENDIX 3 502

APPENDIX 4 510

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SUMMARY

The trend in urbanization that comes with urban population increase has caused a host of environmental problems in modern society today Moving together with this global trend is an increase in housing demand, which has caused much further deterioration to the urban environment Unstructured and improper planning of urban morphologies is common in areas of rapid urbanization and wind speed is seriously decreased due to the buildings’ roughness and geometry within Air motion within an urban area determines to

a large extent the local microclimate and one good way to counteract or reduce outdoor ventilation problems is to go for urban morphological designs that are optimized for good thermal comfort and encourage ample outdoor ventilation

to dissipate built-up heat within through turbulent transfer, of which is the focus of this research

Based on the literature review, the morphological variables that determine and have an association with outdoor ventilation within a Housing and Development Board (HDB) precinct area are shown in the table below Next,

in order to quantify these variables, morphological indices and the methodology to quantify them were developed in Chapter 3 Following up is a comprehensive parametric numerical study carried out under Chapter 5 in order to study the association of all these quantified variables (in the form of

morphological indices) with the area-averaged Wind Velocity Ratio (V R)

index, an indication of the average outdoor ventilation potential within an estate at a certain level The consistent patterns of behavior from the study

support the first hypothesis that “the differences in area-averaged outdoor

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ventilation within an estate can be explained by the variation of all the seven morphological variables” The general relationships between the morphological variables and VR are as shown in the following table

General relationship between the urban morphological variables and VR

These patterns of behavior have important implications for building and urban planning development of residential estates in future and support the possibility of using all these variables in the form of morphological indices

(independent variables) – to build an overall Wind Velocity Ratio model using the area-averaged Wind Velocity Ratio (V R) as the dependent variable

The development of the models (one for pedestrian level and the other for mid-level) was carried out in Chapter 6 The verification and application of the models were carried out in Chapter 8 using a ‘proposed future’ HDB estate or precinct to study and compare the numerical simulation and predicted (modeled) results The reliability of the prediction models in this exercise

helps to verify the second hypothesis whereby “The multivariate linear

regression Wind Velocity Ratio (VR) models, developed from the parametric study, can help to predict the impact of any morphological variation on an estate’s area-averaged outdoor ventilation”

Urban Morphological Variables Relationship with V R

Pedestrian Level Mid-level

Gross Building Coverage Ratio (GBCR) Negative Negative

Staggering of Blocks Arrangement (STAG) Positive Positive

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The results give an indication of how the different indices, when combined will affect or influence the ventilation potential of the whole estate This is very useful because during the early design stage, problems from any initial urban design proposals can be pinpointed and proper adjustments administered before actual construction commences This helps to optimize good designs at the very early stage and furthermore, comparisons can be made between different proposed urban designs to select the one that is most desirable

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LIST OF TABLES

Table 2.1: Different layers of wind flow over urban areas 16

Table 2.2: Related researches of coupling relationship and threshold values for perpendicular canyon wind flow 25

Table 2.3: Related researches of finite-length canyon effects for perpendicular canyon wind flow 26

Table 2.4: Related researches of coupling relationship and threshold values for parallel canyon wind flow 27

Table 2.5: Related researches of wind behavior for parallel canyon wind flow 27

Table 2.6: Related researches of wind behavior for oblique canyon wind flow 28

Table 2.7: Related researches of coupling relationship and threshold values for oblique canyon wind flow 29

Table 2.8(a): Related researches of canyon geometries on perpendicular canyon wind flow 32

Table 2.8(b): Related researches of canyon geometries on perpendicular canyon wind flow 33

Table 2.8(c): Related researches of canyon geometries n perpendicular canyon wind flow 34

Table 2.9: Related researches on Gross Building Coverage Ratio 36

Table 2.10: Related researches on permeability provision 37

Table 2.11: Related researches on buildings' height variation 39

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Table 2.12: Related researches on staggering of blocks arrangement 40

Table 2.13: Other factors that affect wind flow besides the buildings' urban morphologies 41

Table 2.14: Indices by other researchers that overlap and are also related to morphological variables 41

Table 2.15: Suggestion of domain sizes from previous researchers 44

Table 2.16: Limitations of wind tunnel studies 54

Table 3.1: Tabulation of Prevailing Wind Direction and Speed obtained from NEA (National Environment Agency) over a period of 18 years (BCA, 2012) 89

Table 3.2: Input variables for the inlet boundary conditions 89

Table 3.3: Wall boundary conditions 91

Table 4.1: Dimensional similarity parameters to be considered for wind tunnel test 111

Table 5.1: Tabulated values of GBCR for the parametric study for random and group configurations of point and slab blocks 124

Table 5.2: Tabulated values of GBCR for the parametric study for courtyard configurations of point and slab blocks 125

Table 5.3: Parametric study findings and their explanations for point blocks, pedestrian level of GBCR – random configuration 129

Table 5.4: Parametric study findings and their explanations for point blocks, pedestrian level of GBCR - group configuration 130

Table 5.5: Parametric study findings and their explanations for point blocks, pedestrian level of GBCR - courtyard configuration 131

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Table 5.6: Parametric study findings and their explanations for point blocks, mid-level of GBCR - random configuration 134

Table 5.7: Parametric study findings and their explanations for point blocks, mid-level of GBCR - group configuration 135

Table 5.8: Parametric study findings and their explanations for point blocks, mid-level of GBCR - courtyard configuration 136

Table 5.9: Parametric study findings and their explanations for slab blocks, pedestrian level of GBCR - random configuration 141

Table 5.10: Parametric study findings and their explanations for slab blocks, pedestrian level of GBCR - group configuration 142

Table 5.11: Parametric study findings and their explanations for slab blocks, pedestrian level of GBCR - courtyard configuration 144

Table 5.12: Parametric study findings and their explanations for slab blocks, mid-level of GBCR - random configuration 147

Table 5.13: Parametric study findings and their explanations for slab blocks, mid-level of GBCR - group configuration 148

Table 5.14: Parametric study findings and their explanations for slab blocks, mid-level of GBCR - courtyard configuration 149

Table 5.15: Tabulated values of HV for the parametric study for point and slab blocks 151

Table 5.16: Parametric study findings and their explanations for point blocks, pedestrian level of HV - random configuration 153

Table 5.17: Parametric study findings and their explanations for point blocks, pedestrian level of HV - stratified configuration 155

Table 5.18: Parametric study findings and their explanations for point blocks, mid-level of HV - random configuration 158

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Table 5.19: Parametric study findings and their explanations for point blocks, mid-level of HV - stratified configuration 159

Table 5.20: Parametric study findings and their explanations for slab blocks, pedestrian level of HV - random configuration 162

Table 5.21: Parametric study findings and their explanations for slab blocks, pedestrian level of HV - stratified configuration 163

Table 5.22: Parametric study findings and their explanations for slab blocks, mid-level of HV - random configuration 166

Table 5.23: Parametric study findings and their explanations for slab blocks, mid-level of HV - stratified configuration 168

Table 5.24: Tabulated values of point blocks porosity (PERM) for the parametric study 170

Table 5.25: Tabulated values of slab blocks porosity (PERM) for the parametric study 170

Table 5.26: Parametric study findings and their explanations for point blocks, pedestrian level of PERM - ground floor only permeability configuration 173

Table 5.27: Parametric study findings and their explanations for point blocks, pedestrian level of PERM - ground floor and mid-height permeability configuration 174

Table 5.28: Parametric study findings and their explanations for point blocks, pedestrian level of PERM - mid-height only permeability configuration 176

Table 5.29: Parametric study findings and their explanations for point blocks, mid-level of PERM - ground floor only permeability configuration 180

Table 5.30: Parametric study findings and their explanations for point blocks, mid-level of PERM - ground floor and mid-height permeability configuration 182

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Table 5.31: Parametric study findings and their explanations for point blocks, mid-level of PERM - mid-height only permeability configuration 184

Table 5.32: Parametric study findings and their explanations for slab blocks, pedestrian level of PERM - ground floor only permeability configuration 187

Table 5.33: Parametric study findings and their explanations for slab blocks, pedestrian level of PERM - ground floor and mid-height permeability configuration 189

Table 5.34: Parametric study findings and their explanations for slab blocks, pedestrian level of PERM - mid-height only permeability configuration 190

Table 5.35: Parametric study findings and their explanations for slab blocks, mid-level of PERM - ground floor only permeability configuration 194

Table 5.36: Parametric study findings and their explanations for slab blocks, mid-level of PERM - ground floor and mid-height permeability configuration 196

Table 5.37: Parametric study findings and their explanations for slab blocks, mid-level of PERM - mid-height only permeability configuration 198

Table 5.38: Tabulated values of point blocks Geometry (GEO) for the parametric study 201

Table 5.39: Tabulated values of slab blocks Geometry (GEO) for the parametric study 202

Table 5.40: Parametric study findings and their explanations for point blocks, pedestrian level of GEO - geometric height variation (H) configuration 204

Table 5.41: Parametric study findings and their explanations for point blocks, pedestrian level of GEO - geometric width variation (W) configuration 207

Table 5.42: Pedestrian level GEO values for geometrical height variation (H) and geometrical width variation (W) configurations for point blocks 209

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Table 5.43: Parametric study findings and their explanations for point blocks, mid-level of GEO - geometric height variation (H) configuration 212

Table 5.44: Parametric study findings and their explanations for point blocks, mid-level of GEO - geometric width variation (W) configuration 215

Table 5.45: Mid-level GEO values for geometrical height variation (H) and geometrical width variation (W) configurations for point blocks 218

Table 5.46: Parametric study findings and their explanations for slab blocks, pedestrian level of GEO - geometric height variation (H) configuration 221

Table 5.47: Parametric study findings and their explanations for slab blocks, pedestrian level of GEO - geometric width variation (W) configuration 223

Table 5.48: Pedestrian level GEO values for geometrical height variation (H) and geometrical width variation (W) configurations for slab blocks 226

Table 5.49: Parametric study findings and their explanations for slab blocks, mid-level of GEO - geometric height variation (H) configuration 228

Table 5.50: Parametric study findings and their explanations for slab blocks, mid-level of GEO - geometric width variation (W) configuration 231

Table 5.51: Mid-level GEO values for geometrical height variation (H) and geometrical width variation (W) configurations for slab blocks 232

Table 5.52: Tabulated values of point blocks staggering arrangement (STAG) for the parametric study 234

Table 5.53: Tabulated values of slab blocks staggering arrangement (STAG) for the parametric study 234

Table 5.54: Parametric study findings and their explanations for point blocks, pedestrian level of STAG - staggering configuration 241

Table 5.55: Parametric study findings and their explanations for point blocks, mid-level of STAG - staggering configuration 246

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Table 5.56: Parametric study findings and their explanations for slab blocks, pedestrian level of STAG - staggering configuration 251

Table 5.57: Parametric study findings and their explanations for slab blocks, mid-level of STAG - staggering configuration 257

Table 6.1: Model summary for both pedestrian and mid-level models of all

835 numerical study cases 267

Table 6.2: Regression results of the Wind Velocity Ratio (VR) models for pedestrian and mid-levels of all 835 numerical study cases 267

Table 6.3: Model summary for both pedestrian and mid-level models of all

665 numerical study cases 270

Table 6.4: Regression results of the Wind Velocity Ratio (VR) models for pedestrian and mid-levels of 665 numerical study cases minus the data of GBCR random and courtyard configurations 271

Table 7.1: Tabulated values of GBCR for the sensitivity analyses for group configurations of point and slab blocks 283

Table 7.2: Tabulated values of GEO for the sensitivity analyses of point and slab blocks at pedestrian level 284

Table 7.3: Tabulated values of GEO for the sensitivity analyses of point and slab blocks at mid-level 285

Table 7.4: Tabulated values of HV for the sensitivity analyses for point and slab blocks 286

Table 8.1: Basic information about the proposed base HDB precinct design 319

Table 8.2: Basic information about the proposed alternative HDB precinct design with higher buildings heights 321

Table 8.3: Basic information about the proposed alternative HDB precinct design with higher ground level void decks 322

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Table 8.4: Basic information about the proposed alternative HDB precinct design with narrower spacing (canyons) between the blocks 324

Table A3-1: Tabulated values of urban morphological variables for GBCR random configuration only parametric cases 502

Table A3-2: Tabulated values of urban morphological variables for GBCR courtyard configuration only parametric cases 503

Table A3-3: Tabulated values of urban morphological variables from parametric study used for multi-linear regression analysis 504

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LIST OF FIGURES

Figure 1.1: The definition of average height and overlapping area between opposing buildings (HDB, 2005) 8

Figure 1.2: Solar Radiation Index (R) calculation (HDB, 2005) 8

Figure 2.1: Schematic representation of the urban atmosphere illustrating a layer classification of urban modification (Oke, 1987) 17

2-Figure 2.2: Wind speed variation with height and terrain conditions (http://www.wind.ttu.edu/) (Yang, 2004) 17

Figure 2.3: Wind flow layers in the urban boundary layer (UBL) (Ricciardelli and Polimeno, 2006) 18

Figure 2.4: Davenport roughness classification (Wieringa, 1992) 19

Figure 2.5: Velocity ratio (VR) explained (CUHK, 2008) 21

Figure 2.6: General parameters for describing an urban canyon 22

Figure 2.7: Orientation of street grids (Ng, 2009) 23

Figure 2.8: Perpendicular flow regimes in urban canyons for different aspect ratios (Oke, 1988; Hussain and Lee, 1980) 24

Figure 2.9: Threshold for flow regimes in urban canyons as functions of urban canyon H/W and L/W ratios (Hunter et al., 1990/91) 30

Figure 2.10: Different flow patterns for skimming flow regimes (Li et al., 2006) 31

Figure 2.11: Pollutant concentration for different h2/h1 (Chan et al., 2001) 33

Figure 2.12: Pollutant concentration for different h/w (Chan et al., 2001) 34

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Figure 2.13: Pollutant concentration for different l/h (Chan et al., 2001) 35

Figure 2.14: Wind speed at leeward side of the windbreak with different permeability (Brown and Dekay, 2001) 38

Figure 2.15: Closed outdoor spaces or streets perpendicular to the wind flow not included in permeability calculation (Adolphe, 2001) 38

Figure 2.16: Schematic illustration of the 2-layer zonal model (Wolfstein, 1969) 53

Figure 2.17: Areas of height restriction in Singapore (Khoo and Su, 2007) 58

Figure 3.1: Point blocks layout in a 500x500m HDB estate Readings from all the mesh cells within the red box (for the studied level) are extracted and each area-averaged over the total area of all cells, for outdoor wind velocity magnitude 62

Figure 3.2: Slab blocks layout in a 500x500m HDB estate Readings from all the mesh cells within the red box (for the studied level) are extracted and each area-averaged over the total area of all cells, for outdoor wind velocity magnitude 62

Figure 3.3: BASE CASE: Point blocks layout in a 500x500m HDB estate Each block is 30x30x112m in dimension with a spacing of 20m from each other The numbers indicate the blocks' height 64

Figure 3.4: BASE CASE: Slab blocks layout in a 500x500m HDB estate Each block is 100x20x50m in dimension with a spacing of 20m from each other The numbers indicate the blocks' height 64

Figure 3.5: Wind coming from the different orientations into the cylindrical atmospheric domain 65

Figure 3.6: Point blocks arrangement in a 500x500m estate area 67

Figure 3.7: Slab blocks arrangement in a 500x500m estate area 67

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Figure 3.8: Illustration of the different geometric parameters where, H1 = height of upwind building, H2 = height of downwind building and W = horizontal distance between both buildings 68

Figure 3.9: Illustration of the composite height-to-width ratio for a residential section of a study area in Phoenix (Burian et al., 2002) 69

Figure 3.10: GBCR ratio for point blocks random configuration 71

Figure 3.11: GBCR ratio for point blocks group configuration 71

Figure 3.12: GBCR ratio for point blocks courtyard configuration 72

Figure 3.13: GBCR ratio for slab blocks random configuration 72

Figure 3.14: GBCR ratio for slab blocks group configuration 73

Figure 3.15: GBCR ratio for slab blocks courtyard configuration 73

Figure 3.16: Typical void parameters 75

Figure 3.17: Typical void parameters 76

Figure 3.18: Point blocks arrangement in a 500x500m estate area for ground floor permeability only 76

Figure 3.19: Slab blocks arrangement in a 500x500m estate area for ground floor permeability only 77

Figure 3.20: Point blocks arrangement in a 500x500m estate area for ground floor and mid-height permeability 77

Figure 3.21: Slab blocks arrangement in a 500x500m estate area for ground floor and mid-height permeability 77

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Figure 3.22: Point blocks arrangement in a 500x500m estate area for height permeability only 78

Figure 3.23: Slab blocks arrangement in a 500x500m estate area for height permeability only 78

mid-Figure 3.24: HV value for point blocks in some random configurations (a) 21, (b) 34, (c) 52, (d) 63 79

Figure 3.25: HV value for slab blocks in some random configurations (a) 11, (b) 17, (c) 21, (d) 27 80

Figure 3.26: HV value for point blocks in some stratified configurations (a) 21, (b) 34, (c) 52, (d) 63 80

Figure 3.27: HV value for slab blocks in some stratified configurations (a) 11, (b) 17, (c) 21, (d) 27 81

Figure 3.28: Different degree of staggering arrangement for point blocks (a) 10m to the right, (b) 20m to the right, of all subsequent rows consecutively 83

Figure 3.29: Different degree of staggering arrangement for slab blocks (a) 10m to the right, (b) 20m to the right, of all subsequent rows consecutively 83

Figure 3.30: Computational domain; the middle estate area of 500x500m will

be subjected to various morphological variations 88

Figure 3.31: Unstructured polyhedral meshing for domain - (a) Overall view, (b) Plan view (2m above ground) and (c) Side view (Section A-A) 94

Figure 3.32: Mesh independence study for Point Blocks (BASE case, 0 North)

at 2m constrained plane 95

at 56m (mid-level) constrained plane 95

at 84m (three-quarter level) constrained plane 96

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Figure 3.35: Mesh independence study for Slab Blocks (BASE case, 0 North)

at 2m constrained plane 96

at 25m (mid-level) constrained plane 97

at 37.5m (three-quarter level) constrained plane 97

Figure 3.38: Methodology flow chart 102

Figure 4.1: Plan and section view of the BLWT in NUS 104

Figure 4.2: Test model placed at the wind tunnel's test section 104

Figure 4.3: Power-law wind profile used in wind tunnel and CFD analysis 106

Figure 4.4: Sensor probe positions for point blocks (top) and slab blocks (bottom) 114

Figure 4.5: Comparison of wind tunnel and CFD readings for point blocks, 0˚ north wind orientation, at both the pedestrian and mid-level 116

Figure 4.6: Comparison of wind tunnel and CFD readings for point blocks, 22.5˚ north wind orientation, at both the pedestrian and mid-level 117

Figure 4.7: Comparison of wind tunnel and CFD readings for point blocks, 45˚ north wind orientation, at both the pedestrian and mid-level 117

Figure 4.8: Comparison of wind tunnel and CFD readings for slab blocks, 0˚ north wind orientation, at both the pedestrian and mid-level 118

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Figure 4.11: Box-plot for the difference between CFD and wind tunnel readings (CFD minus wind tunnel readings in m/s) for (a) point blocks and (b) slab blocks 120

Figure 5.1: Pedestrian level area-averaged VR against GBCR for (a) random, (b) group and (c) courtyard configuration of point blocks 127

Figure 5.2: Mid-level area-averaged VR against GBCR for (a) random, (b) group and (c) courtyard configuration of point blocks 133

Figure 5.3: Pedestrian level area-averaged VR against GBCR for (a) random, (b) group and (c) courtyard configuration of slab blocks 139

Figure 5.4: Mid-level area-averaged VR against GBCR for (a) random, (b) group and (c) courtyard configuration of slab blocks 146

Figure 5.5: Pedestrian level area-averaged VR against HV for (a) random and (b) stratified configuration of point blocks 152

Figure 5.6: Mid-level area-averaged VR against HV for (a) random and (b) stratified configuration of point blocks 157

Figure 5.7: Pedestrian level area-averaged VR against HV for (a) random and (b) stratified configuration of slab blocks 161

Figure 5.8: Mid-level area-averaged VR against HV for (a) random and (b) stratified configuration of slab blocks 165

Figure 5.9: Pedestrian level area-averaged VR against PERM for (a) Ground, (b) G&M and (c) Mid configurations of point blocks 172

Figure 5.10: Mid-level area-averaged VR against PERM for (a) Ground, (b) G&M and (c) Mid configurations of point blocks 178

Figure 5.11: Pedestrian level area-averaged VR against PERM for (a) Ground, (b) G&M and (c) Mid configurations of slab blocks 186

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Figure 5.12: Mid-level area-averaged VR against PERM for (a) Ground, (b) G&M and (c) Mid configurations of slab blocks 192

Figure 5.13: Pedestrian level area-averaged VR against GEO for (a) Geometrical height variation (H) and (b) Geometrical width variation (W) configurations of point blocks 203

Figure 5.14: Pedestrian level area-averaged VR against GEO for combined geometrical height variation (H) and geometrical width variation (W) configurations of point blocks 209

Figure 5.15: Mid-level area-averaged VR against GEO for (a) Geometrical height variation (H) and (b) Geometrical width variation (W) configurations of point blocks 210

Figure 5.16: Mid-level area-averaged VR against GEO for combined geometrical height variation (H) and geometrical width variation (W) configurations of point blocks 218

Figure 5.17: Pedestrian level area-averaged VR against GEO for (a) Geometrical height variation (H) and (b) Geometrical width variation (W) configurations of slab blocks 219

Figure 5.18: Pedestrian level area-averaged VR against GEO for combined geometrical height variation (H) and geometrical width variation (W) configurations of slab blocks 226

Figure 5.19: Mid-level area-averaged VR against GEO for (a) Geometrical height variation (H) and (b) Geometrical width variation (W) configurations of slab blocks 227

Figure 5.20: Mid-level area-averaged VR against GEO for combined geometrical height variation (H) and geometrical width variation (W) configurations of slab blocks 232

Figure 5.21: Staggering arrangement example for point blocks for stagger configuration of 'Point Blocks - 0 North (can be for other orientations) - Stagger - 5m' 235

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Figure 5.22: Staggering arrangement example for slab blocks for stagger configuration of 'Slab Blocks - 0 North (can be for other orientations) - Stagger - 5m' 236

Figure 5.23: Different degree of staggering arrangements to the right of all subsequent rows consequently for point blocks 237

Figure 5.24: Different degree of staggering arrangements to the right of all subsequent rows consecutively for slab blocks 238

Figure 5.25: Pedestrian level area-averaged VR against stagger (in metres) for staggering of blocks arrangement configuration of point blocks 239

Figure 5.26: Mid-level area-averaged VR against stagger (in metres) for staggering of blocks arrangement configuration of point blocks 245

Figure 5.27: Pedestrian level area-averaged VR against stagger (in metres) for staggering of blocks arrangement configuration of slab blocks 249

Figure 5.28: Mid-level area-averaged VR against stagger (in metres) for staggering of blocks arrangement configuration of slab blocks 257

Figure 6.1: The comparison between modeled results and actual numerical study results for VR at pedestrian level - (a) line graph, (b) comparison graph and (c) box and whisker plot of the VR difference (modeled minus simulated readings) 278

Figure 6.2: The comparison between modeled results and actual numerical study results for VR at mid-level - (a) line graph, (b) comparison graph and (c) box and whisker plot of the VR difference (modeled minus simulated readings) 279

Figure 7.1: Predicted VR for point blocks at (a) pedestrian level and (b) level for various values of GBCR 288

mid-Figure 7.2: Predicted VR for slab blocks at (a) pedestrian level and (b) level for various values of GBCR 289

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mid-Figure 7.3: Predicted VR for point blocks (a) and (b); and slab blocks (c) and (d) at pedestrian and mid-levels for various values of GBCR at 0˚ north wind orientation 291

Figure 7.4: Predicted VR for point blocks (a) and (b); and slab blocks (c) and (d) at pedestrian and mid-levels for various values of GBCR at 45˚ north wind orientation 292

Figure 7.5: Predicted VR for point blocks (a) and (b); and slab blocks (c) and (d) at pedestrian and mid-levels for various values of GBCR at 90˚ north wind orientation 294

Figure 7.6: Predicted VR for point blocks at (a) pedestrian level and (b) level for various values of GEO 296

mid-Figure 7.7: Predicted VR for slab blocks at (a) pedestrian level and (b) level for various values of GEO 297

mid-Figure 7.8: Predicted VR for point blocks (a) and (b); and slab blocks (c) and (d) at pedestrian and mid-level for various values of GEO at 0˚ north wind orientation 299

Figure 7.9: Predicted VR for point blocks (a) and (b); and slab blocks (c) and (d) at pedestrian and mid-level for various values of GEO at 45˚ north wind orientation 300

Figure 7.10: Predicted VR for point blocks (a) and (b); and slab blocks (c) and (d) at pedestrian and mid-level for various values of GEO at 90˚ north wind orientation 301

Figure 7.11: Predicted VR for point blocks for random ((a) and (b)) and stratified ((c) and (d)) configurations at pedestrian and mid-levels for various values of HV 304

Figure 7.12: Predicted VR for slab blocks for random ((a) and (b)) and stratified ((c) and (d)) configurations at pedestrian and mid-levels for various values of HV 306

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Figure 7.13: Predicted VR for point blocks (a), (b), (c) and (d); and slab blocks (e), (f), (g) and (h) at pedestrian and mid-level for various values of HV for random and stratified configurations at 0˚ north wind orientation 309

Figure 8.1: Proposed HDB precinct base design layout plan; point blocks are highlighted in pink 318

Figure 8.2: Perspective view of proposed HDB precinct base design 319

Figure 8.3: Perspective view of proposed HDB precinct alternative design with higher building heights 320

Figure 8.4: Perspective view of proposed HDB precinct alternative design with higher ground level void decks 322

Figure 8.5: Proposed HDB precinct design layout plan with narrower spacing (canyons) between the blocks; point blocks are highlighted in pink 323

Figure 8.6: Perspective view of proposed HDB precinct alternative design with narrower spacing (canyons) between the blocks 323

Figure 8.7: Plan view of proposed HDB precinct base design indicating the unobstructed canyons or breezeways and their angles relative to the wind direction 327

Figure 8.8: Plan view of proposed HDB precinct base design indicating the perimeter outline of the enclosed precinct area 327

Figure 8.9: Plan view of proposed HDB precinct base design indicating the perimeter outline of the enclosed precinct area and individual outdoor grid space 329

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Figure 8.10: Plan view of proposed HDB precinct base design indicating the building perimeter that faces the wind direction normally without being blocked (red) for wind orientation from (a) 0˚ north, (b) 22.5˚ north, (c) 45˚ north, (d) 67.5˚ north and (e) 90˚ north 334

Figure 8.11: Comparison of VR readings for base case scenario at (a) pedestrian level and (b) mid-level 335

Figure 8.12: Velocity magnitude scalar diagrams for base case scenario at (a) pedestrian level and (b) mid-level for 0˚ north wind orientation 336

Figure 8.13: Comparison of VR readings for increase in building height case scenario at (a) pedestrian level and (b) mid-level 339

Figure 8.14: Velocity magnitude scalar diagrams for the increase in building height scenario at (a) pedestrian level and (b) mid-level for 0˚ north wind orientation 340

Figure 8.15: Comparison of VR readings for increase in void deck height case scenario at (a) pedestrian level and (b) mid-level 342

Figure 8.16: Velocity magnitude scalar diagrams for the increase in void decks height scenario at (a) pedestrian level and (b) mid-level for 0˚ north wind orientation 343

Figure 8.17: Comparison of VR readings for decrease in spacing between blocks case scenario at (a) pedestrian level and (b) mid-level 345

Figure 8.18: Velocity magnitude scalar diagrams for the decrease in spacing between blocks scenario at (a) pedestrian level and (b) mid-level for 0˚ north wind orientation 346

Figure 8.19: Existing Punggol township map (arrow indicates C40 proposed location) 347

Figure 8.20: Proposed C40 location 348

Figure 8.21: Proposed C40 perspective view 348

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Figure 8.22: Plan view of proposed C40 349

Figure 8.23: Plan view of proposed C40 broken down into simple block shapes 350

Figure 8.24: Extra-over designs like (a) recess within a block, (b) connectors between blocks, (c) covolutions on block and (d) central core connection a few blocks 350

Figure A1-1: Range of homogeneous surface roughness (Z0) from good experiments (Wieringa, 1992) 381

Figure A1-2: Longitudinal velocity profiles over uniform terrain in neutral flow (n here is actually α which is the power-law coefficient) (Cochran, 2002) 382

Figure A1-3: Turbulent intensity profiles over uniform terrain in neutral flow (n here is actually α which is the power-law coefficient) (Cochran, 2002) 383

Figure A1-4: Power-law wind velocity plot of worked out from BCA’s specifications (α=0.21) 384

Figure A2-1(a): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.054 for wind from 0˚ north (pedestrian level) 385

Figure A2-1(b): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.126 for wind from 0˚ north (pedestrian level) 385

Figure A2-1(c): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.234 for wind from 0˚ north (pedestrian level) 386

Figure A2-1(d): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.306 for wind from 0˚ north (pedestrian level) 386

Figure A2-1(e): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.090 for wind from 45˚ north (pedestrian level) 387

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Figure A2-1(f): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.198 for wind from 45˚ north (pedestrian level) 387

Figure A2-1(g): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.342 for wind from 45˚ north (pedestrian level) 388

Figure A2-2(a): POINT BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.054 for wind from 0˚ north (pedestrian level) 388

Figure A2-2(b): POINT BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.162 for wind from 0˚ north (pedestrian level) 389

Figure A2-2(c): POINT BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.306 for wind from 0˚ north (pedestrian level) 389

Figure A2-3(a): POINT BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.230 for wind from 0˚ north (pedestrian level) 390

Figure A2-3(b): POINT BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.274 for wind from 0˚ north (pedestrian level) 390

Figure A2-3(c): POINT BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.346 for wind from 0˚ north (pedestrian level) 391

Figure A2-4(a): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.054 for wind form 0˚ north (mid-level) 391

Figure A2-4(b): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.126 for wind from 0˚ north (mid-level) 392

Figure A2-4(c): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.234 for wind from 0˚ north (mid-level) 392

Figure A2-4(d): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.306 for wind from 0˚ north (mid-level) 393

Figure A2-4(e): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.090 for wind from 45˚ north (mid-level) 393

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Figure A2-4(f): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.198 for wind from 45˚ north (mid-level) 394

Figure A2-4(g): POINT BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.342 for wind from 45˚ north (mid-level) 394

Figure A2-5(a): POINT BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.054 for wind from 0˚ north (mid-level) 395

Figure A2-5(b): POINT BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.162 for wind from 0˚ north (mid-level) 395

Figure A2-5(c): POINT BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.306 for wind from 0˚ north (mid-level) 396

Figure A2-6(a): POINT BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.230 for wind from 0˚ north (mid-level) 396

Figure A2-6(b): POINT BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.274 for wind from 0˚ north (mid-level) 397

Figure A2-6(c): POINT BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.346 for wind from 0˚ north (mid-level) 397

Figure A2-7(a): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.104 for wind from 0˚ north (pedestrian level) 398

Figure A2-7(b): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.312 for wind from 0˚ north (pedestrian level) 398

Figure A2-7(c): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.104 for wind from 90˚ north (pedestrian level) 399

Figure A2-7(d): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.312 for wind from 90˚ north (pedestrian level) 399

Figure A2-7(e): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.104 for wind from 45˚ north (pedestrian level) 400

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Figure A2-7(f): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.312 for wind from 45˚ north (pedestrian level) 400

Figure A2-8(a): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.104 for wind from 90˚ north (pedestrian level) 401

Figure A2-8(b): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.312 for wind from 90˚ north (pedestrian level) 401

Figure A2-8(c): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.104 for wind from 0˚ north (pedestrian level) 402

Figure A2-8(d): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.312 for wind from 0˚ north (pedestrian level) 402

Figure A2-9(a): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.352 for wind from 90˚ north (pedestrian level) 403

Figure A2-9(b): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.384 for wind from 90˚ north (pedestrian level) 403

Figure A2-9(c): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.352 for wind from 0˚ north (pedestrian level) 404

Figure A2-9(d): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.384 for wind from 0˚ north (pedestrian level) 404

Figure A2-10(a): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.104 for wind from 0˚ north (mid-level) 405

Figure A2-10(b): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.312 for wind from 0˚ north (mid-level) 405

Figure A2-10(c): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.104 for wind from 90˚ north (mid-level) 406

Figure A2-10(d): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.312 for wind from 90˚ north (mid-level) 406

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Figure A2-10(e): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.104 for wind from 45˚ north (mid-level) 407

Figure A2-10(f): SLAB BLOCKS, Random Configuration - Velocity vectors for GBCR = 0.312 for wind from 45˚ north (mid-level) 407

Figure A2-11(a): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.104 for wind from 90˚ north (mid-level) 408

Figure A2-11(b): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.312 for wind from 90˚ north (mid-level) 408

Figure A2-11(c): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.104 for wind from 0˚ north (mid-level) 409

Figure A2-11(d): SLAB BLOCKS, Group Configuration - Velocity vectors for GBCR = 0.312 for wind from 0˚ north (mid-level) 409

Figure A2-12(a): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.352 for wind from 90˚ north (mid-level) 410

Figure A2-12(b): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.384 for wind from 90˚ north (mid-level) 410

Figure A2-12(c): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.352 for wind form 0˚ north (mid-level) 411

Figure A2-12(d): SLAB BLOCKS, Courtyard Configuration - Velocity vectors for GBCR = 0.384 for wind from 0˚ north (mid-level) 411

Figure A2-13(a): Point blocks: Random configuration - 0˚ north wind orientation, HV = 21 (Section view) 412

Figure A2-13(b): Point blocks: Random configuration - 0˚ north wind orientation, HV = 63 (Section view) 413

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Figure A2-14: (a) Point blocks: Random configuration - 0˚ north wind orientation, HV = 21(Plan view, 2m above ground); (b) Slab blocks: Random configuration - 0˚ north wind orientation, HV = 21 (Plan view, 2m above ground) 413

Figure A2-15: Point blocks: Stratified configuration - 0˚ north wind orientation, HV = 52 (Section view) 414

Figure A2-16(a): Point blocks: Stratified configuration - 45˚ north wind orientation, HV = 21 (Plan view, 2m above ground) 415

Figure A2-16(b): Point blocks, Random configuration - 45˚ north wind orientation, HV = 21 (Plan view, 2m above ground) 415

Figure A2-17: Point blocks: Random configuration - 0˚ north wind orientation,

HV = 52 (Section view) 416

Figure A2-18: Slab blocks: Random configuration - 0˚ north wind orientation,

HV = 27 (Plan view, 2m above ground) 417

Figure A2-19: Slab blocks: Random configuration - 0˚ north wind orientation,

HV = 27 (Section view) 418

Figure A2-20(a): POINT BLOCKS, ground floor only permeability configuration - Velocity vectors for PERM = 0.007 (1 floor) for wind from 0˚ north (pedestrian level), Plan and part section view 419

Figure A2-20(b): POINT BLOCKS, ground floor only permeability configuration - Velocity vectors for PERM = 0.045 (3 floors) for wind from 0˚ north (pedestrian level), Plan and part section view 420

Figure A2-21(a): POINT BLOCKS, ground floor and mid-height permeability configuration - Velocity vectors for PERM = 0.014 (1 Floor, 1 Mid) for wind from 0˚ north (pedestrian level), Plan view 421

Figure A2-21(b): POINT BLOCKS, ground floor and mid-height permeability configuration - Velocity vectors for PERM = 0.090 (3 Floor, 3 Mid) for wind from 0˚ north (pedestrian level), Plan view 421

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